S-parameter and EVM evaluation on internal EMI with various types of metals shielding a 6-GHz low-noise amplifier package

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Most of the metal-based plates showed a similar electromagnetic wave reflection performance at 6 GHz. A 6- GHz LNA packaged in an aluminum die-casting showed a sharp peak at 5.2 GHz in the output signal when the package was covered with a metal lid. The inter- nal output signal radiated at the signal pin between the PCB and the aluminum die-casting is radiated and reflected at the bottom of the lid and propagated along the λ/ 2 path, and incident into the input stage of the 6-GHz LNA fabri- cated on the PCB. When the electromagnetic wave shielding (EWAS) sheet was attached to the metal lid, the signal reflection at the lid bottom was suppressed by about 10 dB, and the sharp peak on the S 21 curve disappeared. When the LNA package was covered with an aluminum die-casting lid, the EVM in the 64 QAM-OFDM transmission measurement increased by approximately 10 dB, due to the quadrature error increase. When the LNA package was covered with an alu- minum die-casting/EMWS lid, the increase in the EVM and the quadrature error were substantially suppressed. It is effective both to shield the electronic devices from external electromagnetic waves and to suppress the internal reflection to suppress the internal EMI for achieving high-quality QAM-OFDM transmission. Electrical Engineering Electronic Materials and Devices EVM S-parameter EMI 6GHz LNA lid reflection quadrature error Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 1 Introduction It is essential to reduce the electromagnetic interference for highly sensitive devices such as a low-noise amplifier (LNA) packaged in a metal box. Many materials of metals and composite non-metals are applied for the EM shielding [1, 2, 4]. The electromagnetic wave shielding effectiveness (SE), is classified as SER (dB)= 10log (1/(1-R)), reflective SE, SET(dB) = 10 log (1/T), transmission SE, and SEA (dB)= 10log ((1-R)/T), absorption SE, where R = S 11 2 , T = S 21 2 , and A = 1 - R - T. To design a highly efficient shielding material, the high SET is realized by increasing R. Hence, most metals of high R are suitable for the high SET[5, 6]. However, when using the high SET material as a package for the highly sensitive electronics and undesired electromagnetic waves occurring in the package, the high SET material increases the internal electromagnetic interference (EMI). Hence, a high SEA and SET material is preferable to reduce both internal and external EMI. The absorption loss, A (dB), of metal is theoretically determined by 8.7( t /δ ), where t (m) is thickness, δ (m) is skin depth, and the reflective loss, R loss (dB), is 20log (377/ (4 πη ), where η (Ω), impedance, is determined by 2 πfµ/σ , and f (Hz) is frequency, µ (H/m) is permeability, and σ (S/m) is conductivity. However, these theoretical values of the parameters are varied due to the surface treatment, oxidation, fabrication process, thermal treatment, and purity; hence, we evaluated the transmission coefficient of the various metals being used. There has been almost no report on internal EMI about the LNA packaged with high SER and SEA material. This article reports for the first time how the internal EMI affects highly sensitive electronic devices, such as a 6-GHz LNA, in the S-parameter measurements over a high-frequency range from 3 to 7 GHz, when covered with eight different types of metal lids. Furthermore, the 6-GHz LNA was evaluated on the error vector magnitude (EVM) in the 64-QAM- OFDM digital signal transmission when the package was covered with different types of metal lids. This article reports on the investigation of the cause of the change in the EVM and the result of the improved performance. 2 S-parameter measurements for different types of metal plates placed between transmitter and receiving patch antennas The reflection and transmission of electromagnetic waves for different types of metals were evaluated using reflection and transmission efficiency, S 11 and S 21 measurements. The S-parameter measurement setup is shown in Fig. 1. The signal transmitter and receiver were both 6-GHz patch antennas. The patch antenna was used since the directional emission angle is slight and the frequency bandwidth is narrow. A 6-GHz LNA was attached to the rear of the receiving patch antenna to increase the signal-to- noise ratio, S/N. The patch area is 10×12 mm in size, made with copper on a Flame Retardant Type 4 (FR-4). The LNA was fabricated on a FR-4 plate and exhibits a 17 dB gain at 6 GHz. The vector network analyzer (VNA) is a portable type of LiteVNA. The metal sheet is 100×200 mm in size and placed in the front, about 5 mm apart from the receiver patch antenna. A measured result of the S-parameters is shown in Fig. 2. Figure 2 (a) and (b) show the reflective coefficients of S 11 and the transmission coefficients of S 21 measured at 2.4 GHz and 6.1 GHz, respectively, without using LNA. The S 11 value mainly exhibits a reflectivity between the signal generator and the transmitter patch antenna. The difference in the peak value of S 21 is due to the difference in propagation loss (dB) in the air between 2.4 GHz and 6.1 GHz, which is 20log( λ 2 . 4 GHz / λ 6 . 1 GHz ) = 7.8 dB. The measurement dynamic range in the change in S 21 measurement was about 40 dB due to the noise floor level. The metal sheets are used to shield the electronic devices from electromagnetic waves. The S-parameter measurement evaluated thirteen different types of metals, and the composition and thickness are listed in Table 1. The electromagnetic wave shielding (EMWS) is a synthetic rubber containing iron (Fe) and nickel (Ni) powder [7]. The iron has a significant relative permeability, µ r 5,000, and is formed as carbonyl 97.5 % pure iron powder (CIP) with a1-8 µ m spherical diameter, and its magnetic moment absorbs the electromagnetic wave and changes to a heat energy loss by collision at a resonant frequency. Hence, the EMWS is adequate material to achieve both low reflectivity and high absorption, rather than using a metal plate or mesh as a composite structure [8]. The aluminum die-casting is a casting material used for packaging low-noise high-frequency devices, and a composite metal of 83 to 87 % aluminum,12 % silicon, and 1.5 to 3 % copper. The PCB is 35 µ m-thick gold (Au) plated on one side of the glass epoxy sheet, and used as the substrate to fabricate a printed circuit, and surface-mount devices are soldered on. The whiteboard contains a 0.23 mm-thick iron (Fe) plate. Eva-Al is a plastic sheet with an ultra-thin layer of aluminum, 0.2 to 0.3 nm thick, evaporated, and is close to the metal fiber and hybrid nano-fiber membranes[5, 7, 9–11]. Since the thickness is smaller than the skin depth, the multiple reflections and collisions of the electrons increase the SEA. The Fe/Sn is iron (Fe), thin tin (Sn) of 3 to 20 µ m is plated on. The Fe/Sn metal is used as a metal package to electromagnetically shield high-frequency electronic devices inside from the outside electromagnetic wave noise. 3 Change in S21 measurements with thirteen types of metal sheets The change in the transmitted coefficient, S 21 , values was measured using thirteen types of metal plates for electromagnetic shielding at 2.4 and 6 GHz frequencies, as shown in Fig. 3. The reference value was measured in air without placing a metal plate. The S 21 values measured with the EWAS sheet were decreased by about 10 dB at both 6 GHz and 2.4 GHz. Since the EWAS sheet was a synthetic rubber, and Table 1 Metal sheets, evaluated with S-parameters, and its composition Metal sheet Composition thickness (mm) EMWS Fe and Ni powders in synthetic rubber 0.6 Cu 100% Cu 0.3 Al 100% Al 0.5 Aluminum die-casting 83 to 87% Al, 12% Si, 1.5 to 3% Cu 2 PCB 35 µ m Cu plated glass epoxy 1.6 Sus 304 18 to 20% Cr and 8 to 10.5% Ni in Fe 0.1 Permalloy 78% Ni, 22% Fe 0.1 Whiteboard 2 to 25 µ m Zn metalized on 0.23 mm Fe plate 0.23 Aluminum foil Aluminum 9 µ m 0.009 Eva Al 0.1 to 0.3 nm Al Evaporated on 1 mm plastic sheet 0.0003 Cu mesh 20 mesh, 1.27 mm hole 0.5 Sus mesh 100 mesh, 0.254 mm hole 0.1 Fe/Zn 3 to 20 µ m Zn metalized on Fe sheet 0.5 Fe/Sn 3 to 20 µ m Sn metalized on Fe sheet 0.3 the electromagnetic wave reflection was low, the change in S 21 was substantial to the electromagnetic wave absorption. On the other hand, most of the metal plates showed almost the same change value in S 21 . Therefore, the reflectivity of the metal plates was nearly the same. The reflectivity of the metal plates at 6 GHz was approximately 5 dB lower than at 2.4 GHz, due to the lower impedance of the metal. Because, the reflective loss, R m (dB) equals 20 log(377 / (4 Z m )) as the impedance of the metal, Z m (Ω), equals (2 πfµ m /σ m ) 0 . 5 , where µ m and σ m are permeability and conductivity, respectively. Since the EMWS has a large resistivity, ρ = 5 10 6 Ω cm, and significantly low absorption or radiation of electromagnetic waves by electrons, there was almost no difference in the reflective loss at different frequencies. When the EMWS sheet was attached to the metal plate, the absorption was increased by approximately 5 dB at 6 GHz and 10 dB at 2.4 GHz, due to a high magnetic moment absorbing efficiency by carbonyl iron powder. Since the absorption efficiency and the resonant frequency are dependent on the size of the carbonyl iron particle, the absorption efficiency can be optimized. It is possible to increase the absorption loss by an additional 10 dB by increasing the thickness of the EMWS to 6 mm or increasing the content of the carbonyl iron particle [12, 13]. 4 Design and fabrication of a 6-GHz low noise amplifier with metal package A 6 GHz low-noise amplifier (LNA) was designed and fabricated using a SiGe hetero bipolar transistor (HBT). Figure 4 shows the sectional internal view of the LNA and the photos of the LNA package with and without the lid. When the LNA was not pack- aged in any enclosure, the LNA showed undesired performance due to electromagnetic wave incident[14]. The LNA package was made with aluminum die-casting to prevent electromagnetic signal leakage from the joint gap. The LNA circuit was fabricated on top of the printed circuit board (PCB) of FR-4. The electromagnetic input signal into the package from the outside was reflected at the top of the lid. The reflected signal at the LNA output inside was radiated and reflected at the lid bottom inside and propa- gates to the surface mount devices (SMDs) soldered on the top of the PCB. Since usual soldering is difficult when using the aluminum die-casting PCB, and SMA,[15, 16], electrical impedance matching degradation at the connection between the aluminum die-casting and copper circuit pattern causes electromagnetic wave radiation. 5 S-parameter measurements for low noise amplifier covered with different types of metal plates The S-parameters, S 11 and S 21 , measurements for the 6-GHz LNA were carried out using a setup of vector network analyzer, N5230A[17], as shown in Fig. 5. The reflective coefficient, S 11 , is defined by a ratio of b 1 /a 1 , and the transmission coefficient, S 21 , is determined by b 2 /a 1 . Where a 1 is the standardized input voltage, b 1 , is the standard- ized reflected voltage, and b 2 is the standardized output voltage. The S-parameters were measured with four different types of lid: (a) copper (Cu) plate, (b) aluminum die-casting plate, (c) aluminum foil sheet, and (d) evaporated aluminum plastic sheet. A sharp peak around 5.2 GHz was observed in the S 21 and S 11 curves when the metal lid covered the LNA, as shown in Fig. 6. Since the extraordinary peak height was measured in both the S 11 and S 21 curves, a resonant oscillation caused by a positive feedback occurred at around 5.2 GHz. This resonant frequency value was equal for every metal lid. It is notable that, relatively, the evaporated aluminum plastic sheet exhibited a low peak height. However, it is desirable to use metal as the lid of the LNA package to reduce the impedance mismatch between the box body and the lid,and the electromagnetic reflection at the boundary of the lid. Therefore, the use of the evaporated plastic sheet and the compound shielding sheet [12] is of low priority. Figure 7 shows an example of how to return the output signal to the input stage of the LNA circuit fabricated on the PCB. The output signal reflects and changes the phase by π at the boundary of the LNA circuit output and the signal pin in the aluminum die-casting. It is radiated to the metal lid bottom along a path of λ/ 4, 14.4 mm, and changes the phase by π , and reflected along a path of λ/ 4, 14.4mm, to the signal input stage in the LNA circuit. Since the wavelength λ is 57.7 mm for a 5.2 GHz electromagnetic wave, the returned signal causes a sharp peak in the S 21 curve due to a resonance and oscillation, when θ LNA + λ/ 2 equals 2 nπ , where θ LNA is the change in the output signal phase at the signal pin from the input of LNA. Since it is not sufficient to avoid EMI over a wide frequency range by changing the mechanical design of the package, because there are many signal reflection points in electronic circuits and packages, a design of low and high reflective materials for the inside and outside the package is required. Figure 8 shows S-parameter measurement results for the iron-based metal lid: (a) tin (Sn) plated iron (Fe) plate, (b) stainless (304 type) plate, (c) Permalloy (78 type) plate, and (d) aluminum die-casting attached with electromagnetic wave shielding (EMWS) sheet. Except for the aluminum die-casting/EMWS lid, a sharp peak was observed in every S 21 curve. Therefore, there is no substantial difference between the iron-based lids and the electrically conductive metal-based lids in causing a sharp peak in the S 21 curve. It was confirmed that every metal plate prevented the reflection of the electromagnetic wave at the bottom surface when the EMWS sheet was attached. Even though most of the metal lids shield the electromagnetic wave incident from the outside into the LNA package, it is effective to attach the EMWS sheet to the bottom surface of the metal lid to suppress the reflection of the radiated signal at the output of the LNA inside. Since the SEA of the EMWS in 0.6 mm thick is approximately 10 dB when attached to the bottom surface, the returned output signal to the input stage of the LNA does not cause the signal oscillation. It is confirmed that a SEA of 10 dB is enough even when increasing the LNA gain to 30 dB. The aluminum die- casting/EMWS is effective in reducing the radiated and reflected signal power across a wide range of frequencies caused by the digital switching device and high-power amplifier in the package. 6 EVM evaluation on QAM-OFDM digital signal modulation with a 6-GHz low noise amplifier A 6-GHz LNA covered with a metal lid was evaluated using a quadrature amplifier modulation (QAM) - orthogonal frequency division modulation (OFDM) to investigate how the internal reflection at the lid affects the digital signal modulation. The QAM- OFDM has been used in wireless fidelity (WiFi), such as WiFi 7 (IEEE 802.11be, 46 Gb/s throughput in the maximum), and digital mobile communications, such as 5G (20 Gb/s throughput in the maximum). The setup of the QAM-OFDM is shown in Fig. 9. The vector signal generator (VSG, E4438C) generates BPSK, QPSK, 16-QAM, and 64-QAM modulated sub-frames and sends these combined signals to the 6-GHz LNA [18]. The 6-GHz LNA amplified these signals and outputs them to the vector signal analyzer (VSA, 896008)[19]. The VSA analyzes the received signal and outputs the relative constellation error (RCE), averaged error vector magnitude (EVM) of the four format modulations, spectrum, EVM per sub-carrier, and error information. The error information includes RCE, EVM, quadrature error, gain imbalance, IQ offset, frequency error, and synchronous clock error. In addition, a circuit simulator of AWR [20]was used for further analysis. The EVM is a substantial indicator to evaluate the quality of the digital signal transmission. Figure 10 shows how the EVM is determined with a symbol, including N bits of data as 2 N = QAM, in the in-phase ( I ) and quadrature ( Q ) coordinates. When the VSG generates a signal with an ideal symbol and transmits it to the LNA, and the amplified signal exhibits a measured symbol with an error, there are two differences: gain imbalance and quadrature error. Hence, the EVM is determined by the ratio of the magnitudes of the error vector and the ideal symbol. Figure 11 shows the measurement result of the EVM and constellation of symbols modulated with BPSK, QPSK, 16-QAM, and 64-QAM at a carrier frequency of 5 GHz, and the output power from the VSG is -40 dBm. When the 6-GHz LNA is not covered with the metal lid, the EVM is -40 dB, and every symbol is clear. When the LNA is covered with an aluminum die-casting lid, the EVM is -30 dB, 10 dB worse than the LNA with no cover, and every symbol is spread. When the LNA is covered with an aluminum die-casting attached with EMWS, the EVM is -39 dB, and every symbol is clear. The detailed error information is shown in Table 2. When the LNA was covered with aluminum die-casting, the EVM increased by 10 dB due to a significant quadra- ture error of 56 mdeg compared to -56 mdeg of the LNA without a cover. When the LNA was covered with the aluminum die-casting attached to the EMWS sheet, the EVM increased by only 1 dB, and the quadrature error was close to that without a cover. The received power was decreased by only 1 dB, and the gain imbalance was not changed; hence, the increase in the EVM was substantially due to the quadrature error. Therefore, the output signal reflected by the metal lid to the LNA circuit on the PCB substantially increased the quadrature error when the QAM-OFDM signal was transmitted. The internal EMI significantly degraded the quadrature error and the EVM, rather than the degradation in the received power. Figure 12 shows the EVM measured with a 6-GHz LNA, when covered with alu- minum die-casting and with aluminum die casting/EMWS, and not covered. The input power to the LNA was varied from -60 to -20 dBm. When increasing the input power from -60 to -40 dBm, the EVM decreased due to the increase in the ideal symbol power, for the LNA without a cover. When increasing the input power from -40 to -20 dBm, the EVM increased due to the amplitude saturation of the LNA and VSG. When the LNA was covered with aluminum die-casting, the EVM increased over the entire range of input power. The change in the phase of the LNA circuit, θ LNA , did not change the IQ offset nor increase the quadrature error. The increase in the input power by 10 dB from -50 to -40 dBm did not decrease the EVM. Therefore, the quadrature error only caused by the reflection at the lid bottom and resonant interference at the LNA input stage increased the EVM. By only using the aluminum die casting/EMWS as the lid, the EVM decreased to the original value measured with the LNA without a lid, for a wide input power range. It is confirmed that an adequate design to suppress the internal EMI using a high reflection and absorption configured lid enables achieving high-quality QAM-OFDM transmission. Table 2 64-QAM-OFDM signal modulation error summary for a 6-GHz low noise amplifier covered with three different types of lids Measurement No cover Covered with aluminum die-cast Covered with aluminum die-cast/ EMWS Unit EVM -40 -30 -39 dB Quadrature Error -56 56.0 -75 mdeg Gain Imbalance 0.013 0.013 0.019 dB Received Power -15.6 -16.6 -15.2 dBm 7 Conclusion It is essential to shield electric devices from unwanted electromagnetic waves incident on the devices. Thirteen metal plates commonly used as electromagnetic wave shielding were evaluated by measurements of S 21 . Most of the conductive metal-based plates, such as aluminum, copper, and aluminum die-casting, and iron-based plates, such as tin-plated iron and stainless steel, show a similar SER performance at frequencies of 2.4 and 6 GHz. Since the change in S 21 for the EWAS, which contains carbonyl iron and nickel powders in synthetic rubber, is relatively low due to the low SER, the EWAS is not adequate for electromagnetic wave shielding by reflection. A 6-GHz LNA is designed and fabricated on a PCB and packaged in an aluminum die-casting. When the package was not covered with any metal lid, the LNA showed a smooth flatness in the S 21 curve; a sharp peak at 5.2 GHz was observed when the package was covered with a metal lid. The LNA output inside signal returned to the transistor on the PCB is causing the sharp peak in the S 21 curve. Since the aluminum die-casting used as the package can not be soldered, an impedance mismatch occurs at the signal pin at the output port. The reflected signal is radiated and reflected at the lid bottom surface and propagated along the λ/ 2 path, and incident into the input stage of the LNA on the PCB. When the EWAS sheet is attached to the meta lid, the reflection at the lid bottom surface is suppressed by approximately 20 dB at 2.4 GHz and 10 dB at 6 GHz, hence the sharp peak on S 21 disappeared. An EVM measurement was carried out to investigate how the internal signal reflec- tion affects the QAM-OFDM transmission quality. When a 6-GHz LNA package was covered with an aluminum die-casting lid, the EVM increased by approximately 10 dB. According to the VSA analysis, the quadrature error increased due to the signal reflec- tion at the bottom of the lid. When the LNA package was covered with an aluminum die-casting/ EMWS lid, the increase in the EVM and the quadrature error were sub- stantially suppressed. It is effective both to shield the electronic devices from external electromagnetic waves and to suppress the internal reflection using an aluminum die- casting/ EMWS. It is confirmed that a robust design to suppress the internal EMI using an adequately configured metal lid of the electronic devices enables achieving high-quality QAM-OFDM transmission. Declarations Acknowledgements Not applicable Author contributions Chinen K. contributed to idea generation and implementa- tion of experiments and article writing. Kinjo I. contributed to measurements and analysis of the measurements result. All authors have read and approved the final version and the submission to Discover Electronics. Funding The authors did not receive financial assistance from any organization for carrying out this research study. Code availability Not applicable. Ethics approval and consent to participate Not applicable. Consent for publication Not applicable. Competing interests The authors declare that they have no competing interests associated with this work. Clinical trial number Not applicable. Data Availability Yes. 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1","display":"","copyAsset":false,"role":"figure","size":331125,"visible":true,"origin":"","legend":"\u003cp\u003eS-parameter measurement setup for the metal plate. The transmitter is a 6-GHz patch antenna, and the receiver is a 6-GHz patch antenna attached with a 6-GHz low noise amplifier\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/340483bd3e2902514d67213f.png"},{"id":95529898,"identity":"062859c0-15c8-4380-81ae-716f19cc2d1e","added_by":"auto","created_at":"2025-11-10 10:17:38","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":46785,"visible":true,"origin":"","legend":"\u003cp\u003eThe measured S-parameters, S\u003csub\u003e11\u003c/sub\u003e and S\u003csub\u003e21\u003c/sub\u003e, for (a) 2.4 GHz and (b) 6 GHz band frequencies transmissions, without using LNA. The patch antennas were used for signal transmission and reception\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/c9b98d02b44f1757b448fdc0.png"},{"id":95508712,"identity":"6ce4bc60-9359-4b1f-9932-77db525e5ce6","added_by":"auto","created_at":"2025-11-10 06:54:06","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":47779,"visible":true,"origin":"","legend":"\u003cp\u003eThe transmitted S-parameter, S\u003csub\u003e21\u003c/sub\u003e, was measured for fourteen different types of metal plates. The dashed curves show the S\u003csub\u003e21\u003c/sub\u003e values when an electromagnetic wave shielding sheet (EMWS) is attached to the metal sheet. The reference value of the S\u003csub\u003e21\u003c/sub\u003e is measured without any metal\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/e71fc30cf33fa89612edd64a.png"},{"id":95508717,"identity":"f712afb6-00cd-4ea5-80e0-77adecdb6e1f","added_by":"auto","created_at":"2025-11-10 06:54:06","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":189995,"visible":true,"origin":"","legend":"\u003cp\u003eThe sectional internal view of a 6-GHz low-noise amplifier (LNA) and the photos of the LNA package with lid and without lid. The input signal into the package from the outside is reflected at the lid outside. The reflected signal at the LNA inside output is reflected at the lid inside and propagates to the surface mount device (SMD) soldered on the top of the printed circuit board (PCB)\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/fe5c848a8c2344640a87d858.png"},{"id":95529500,"identity":"1a6bf4ab-4c05-4e4f-8b6b-ad40c341b3e0","added_by":"auto","created_at":"2025-11-10 10:17:11","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":250806,"visible":true,"origin":"","legend":"\u003cp\u003eS-parameter measurement setup, using a vector network analyzer, N5230A, for evaluation of a 6-GHz low noise amplifier\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/b3bfc98b105728b24fe35fe4.png"},{"id":95508720,"identity":"eb99cb73-872d-44ed-9011-e3bc6bcc6e7f","added_by":"auto","created_at":"2025-11-10 06:54:06","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":213353,"visible":true,"origin":"","legend":"\u003cp\u003eThe S-parameters, S\u003csub\u003e11\u003c/sub\u003e and S\u003csub\u003e21\u003c/sub\u003e, were measured with four different types of lid: (a) copper (Cu), (b) aluminum die-casting, (c) aluminum foil, and (d) evaporated aluminum plastic\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/96acb5d669c78980f193cf01.png"},{"id":95508718,"identity":"1e0bb415-688a-4535-bb58-166b49c77f87","added_by":"auto","created_at":"2025-11-10 06:54:06","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":68436,"visible":true,"origin":"","legend":"\u003cp\u003eThe reflected signal at the output port of the LNA inside is reflected at the metal lid inside and propagated to a place between the first stage transistor, Tr1, and the second transistor, Tr2, on the top of the PCB. The propagation path is \u003cem\u003eλ/\u003c/em\u003e2 when the carrier frequency is 5.2 GHz\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/57bb613e5b012ea8421389dc.png"},{"id":95529081,"identity":"79bf3d5d-42ce-4866-bd1f-e59093187c6f","added_by":"auto","created_at":"2025-11-10 10:16:46","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":217537,"visible":true,"origin":"","legend":"\u003cp\u003eThe S-parameters, S\u003csub\u003e11\u003c/sub\u003e and S\u003csub\u003e21\u003c/sub\u003e, were measured with four different types of lid: (a) tin (Sn) plated iron (Fe), (b) stainless sheet (304 type), (c) Permalloy (78 type), and (d) aluminum die-casting attached with electromagnetic wave shielding sheet\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/2051f59e4ab0a3259a268601.png"},{"id":95508742,"identity":"0d7895e8-804c-4c35-9a3b-d643e452d9b8","added_by":"auto","created_at":"2025-11-10 06:54:07","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":230312,"visible":true,"origin":"","legend":"\u003cp\u003eBPSK, QPSK, 16-QAM, and 64-QAM OFDM signal modulation error measurement setup for a 6-GHz low noise amplifier. The measured EVM, constellation, spectrum, EVM for each sub- carrier, and error summary are displayed\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/a00fd0b03735cc7024a770a3.png"},{"id":95528791,"identity":"296e6974-f2ef-4af7-9f70-3ba39f0221d7","added_by":"auto","created_at":"2025-11-10 10:16:30","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":39869,"visible":true,"origin":"","legend":"\u003cp\u003eThe error vector magnitude (EVM) is defined as the difference in gain and quadrature (phase) between the measured symbol and the ideal symbol\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/d1498387718bd7dafcc65610.png"},{"id":95529716,"identity":"fd5a842b-f06f-46d9-8b33-c7acd13c359d","added_by":"auto","created_at":"2025-11-10 10:17:25","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":99275,"visible":true,"origin":"","legend":"\u003cp\u003eError Vector Magnitude (EVM) and constellation measured for a 6-GHz low noise amplifier covered (a) without a lid and with two different types of lids: (b) aluminum die-casting and (c) aluminum die-casting attached with EMWS\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/8687fcf7f28d0f3db58d551b.png"},{"id":95528544,"identity":"63cceab5-6a54-4c9b-88a4-33452f6b8d6d","added_by":"auto","created_at":"2025-11-10 10:16:15","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":22711,"visible":true,"origin":"","legend":"\u003cp\u003eThe relative constellation error (RCE, EVM) was measured for the 6-GHz LNA package covered with a lid of aluminum die-sating, and a lid of aluminum die-sating attached with EMWS\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/d60c786b505ab54e4e856056.png"},{"id":95654242,"identity":"f358d2bf-e64f-4321-bf35-258c33ce4bd4","added_by":"auto","created_at":"2025-11-11 16:10:39","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2298648,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8051715/v1/90ab6e9c-05b2-4276-9644-f2e45948f4c1.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eS-parameter and EVM evaluation on internal EMI with various types of metals shielding a 6-GHz low-noise amplifier package\u003c/p\u003e","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eIt is essential to reduce the electromagnetic interference for highly sensitive devices such as a low-noise amplifier (LNA) packaged in a metal box. Many materials of metals and composite non-metals are applied for the EM shielding [1, 2, 4]. The electromagnetic wave shielding effectiveness (SE), is classified as SER (dB)= 10log (1/(1-R)), reflective SE, SET(dB) = 10 log (1/T), transmission SE, and SEA (dB)= 10log ((1-R)/T), absorption SE, where R = S\u003csub\u003e11\u003c/sub\u003e \u003csup\u003e2\u003c/sup\u003e, T = S\u003csub\u003e21\u003c/sub\u003e \u003csup\u003e2\u003c/sup\u003e, and A = 1 - R - T. To design a highly efficient shielding material, the high SET is realized by increasing R. Hence, most metals of high R are suitable for the high SET[5, 6]. However, when using the high SET material as a package for the highly sensitive electronics and undesired electromagnetic waves occurring in the package, the high SET material increases the internal electromagnetic interference (EMI). Hence, a high SEA and SET material is preferable to reduce both internal and external EMI.\u003c/p\u003e\n\u003cp\u003eThe absorption loss, A (dB), of metal is theoretically determined by 8.7(\u003cem\u003et\u003c/em\u003e\u003cem\u003e/\u0026delta;\u003c/em\u003e), where \u003cem\u003et \u003c/em\u003e(m) is thickness, \u003cem\u003e\u0026delta;\u003c/em\u003e(m) is skin depth, and the reflective loss, R\u003csub\u003eloss\u003c/sub\u003e(dB), is 20log (377/ (4\u003cem\u003e\u0026pi;\u0026eta;\u003c/em\u003e), where \u003cem\u003e\u0026eta; \u003c/em\u003e(Ω), impedance, is determined by 2\u003cem\u003e\u0026pi;f\u0026micro;/\u0026sigma;\u003c/em\u003e, and \u003cem\u003ef \u003c/em\u003e(Hz) is frequency, \u003cem\u003e\u0026micro; \u003c/em\u003e(H/m) is permeability, and \u003cem\u003e\u0026sigma; \u003c/em\u003e(S/m) is conductivity. However, these theoretical values of the parameters are varied due to the surface treatment, oxidation, fabrication process, thermal treatment, and purity; hence, we evaluated the transmission coefficient of the various metals being used. There has been almost no report on internal EMI about the LNA packaged with high SER and SEA material. This article reports for the first time how the internal EMI affects highly sensitive electronic devices, such as a 6-GHz LNA, in the S-parameter measurements over a high-frequency range from 3 to 7 GHz, when covered with eight different types of metal lids. Furthermore, the 6-GHz LNA was evaluated on the error vector magnitude (EVM) in the 64-QAM- OFDM digital signal transmission when the package was covered with different types of metal lids. This article reports on the investigation of the cause of the change in the EVM and the result of the improved performance.\u003c/p\u003e"},{"header":"2\tS-parameter measurements for different types of metal plates placed between transmitter and receiving patch antennas","content":"\u003cp\u003eThe reflection and transmission of electromagnetic waves for different types of metals were evaluated using reflection and transmission efficiency, S\u003csub\u003e11\u003c/sub\u003e and S\u003csub\u003e21\u003c/sub\u003e measurements. The S-parameter measurement setup is shown in Fig. 1. The signal transmitter and receiver were both 6-GHz patch antennas. The patch antenna was used since the directional emission angle is slight and the frequency bandwidth is narrow. A 6-GHz LNA was attached to the rear of the receiving patch antenna to increase the signal-to- noise ratio, S/N. The patch area is 10\u0026times;12 mm in size, made with copper on a Flame Retardant Type 4 (FR-4). The LNA was fabricated on a FR-4 plate and exhibits a 17 dB gain at 6 GHz. The vector network analyzer (VNA) is a portable type of LiteVNA. The metal sheet is 100\u0026times;200 mm in size and placed in the front, about 5 mm apart from the receiver patch antenna.\u003c/p\u003e\n\u003cp\u003eA measured result of the S-parameters is shown in Fig. 2. Figure 2 (a) and (b) show the reflective coefficients of S\u003csub\u003e11\u003c/sub\u003e and the transmission coefficients of S\u003csub\u003e21\u003c/sub\u003e measured at 2.4 GHz and 6.1 GHz, respectively, without using LNA. The S\u003csub\u003e11\u003c/sub\u003e value mainly exhibits a reflectivity between the signal generator and the transmitter patch antenna. The difference in the peak value of S\u003csub\u003e21\u003c/sub\u003e is due to the difference in propagation loss (dB) in the air between 2.4 GHz and 6.1 GHz, which is 20log(\u003cem\u003e\u0026lambda;\u003c/em\u003e\u003csub\u003e2\u003cem\u003e.\u003c/em\u003e4\u003cem\u003eGHz\u003c/em\u003e\u003c/sub\u003e/\u003cem\u003e\u0026lambda;\u003c/em\u003e\u003csub\u003e6\u003cem\u003e.\u003c/em\u003e1\u003cem\u003eGHz\u003c/em\u003e\u003c/sub\u003e) = 7.8 dB. The measurement dynamic range in the change in S\u003csub\u003e21\u003c/sub\u003e measurement was about 40 dB due to the noise floor level. The metal sheets are used to shield the electronic devices from electromagnetic waves. The S-parameter measurement evaluated thirteen different types of metals, and the composition and thickness are listed in Table 1. The electromagnetic wave shielding (EMWS) is a synthetic rubber containing iron (Fe) and nickel (Ni) powder [7]. The iron has a significant relative permeability, \u003cem\u003e\u0026micro;\u003csub\u003er\u003c/sub\u003e \u003c/em\u003e5,000, and is formed as carbonyl 97.5 % pure iron powder (CIP) with a1-8 \u003cem\u003e\u0026micro;\u003c/em\u003em spherical diameter, and its magnetic moment absorbs the electromagnetic wave and changes to a heat energy loss by collision at a resonant frequency. Hence, the EMWS is adequate material to achieve both low reflectivity and high absorption, rather than using a metal plate or mesh as a composite structure [8]. The aluminum die-casting is a casting material used for packaging low-noise high-frequency devices, and a composite metal of 83 to 87 % aluminum,12 % silicon, and 1.5 to 3 % copper. The PCB is 35 \u003cem\u003e\u0026micro;\u003c/em\u003em-thick gold (Au) plated on one side of the glass epoxy sheet, and used as the substrate to fabricate a printed circuit, and surface-mount devices are soldered on. The whiteboard contains a 0.23 mm-thick iron (Fe) plate. Eva-Al is a plastic sheet with an ultra-thin layer of aluminum, 0.2 to 0.3 nm thick, evaporated, and is close to the metal fiber and hybrid nano-fiber membranes[5, 7, 9\u0026ndash;11]. Since the thickness is smaller than the skin depth, the multiple reflections and collisions of the electrons increase the SEA. The Fe/Sn is iron (Fe), thin tin (Sn) of 3 to 20 \u003cem\u003e\u0026micro;\u003c/em\u003em is plated on. The Fe/Sn metal is used as a metal package to electromagnetically shield high-frequency electronic devices inside from the outside electromagnetic wave noise.\u003c/p\u003e\n"},{"header":"3\tChange in S21 measurements with thirteen types of metal sheets","content":"\u003cp\u003eThe change in the transmitted coefficient, S\u003csub\u003e21\u003c/sub\u003e, values was measured using thirteen\u0026nbsp;types of metal plates for electromagnetic shielding at 2.4 and 6 GHz frequencies, as shown\u0026nbsp;in\u0026nbsp;Fig.\u0026nbsp;3.\u0026nbsp;The\u0026nbsp;reference\u0026nbsp;value\u0026nbsp;was\u0026nbsp;measured\u0026nbsp;in\u0026nbsp;air\u0026nbsp;without\u0026nbsp;placing\u0026nbsp;a\u0026nbsp;metal plate.\u0026nbsp;The\u0026nbsp;S\u003csub\u003e21\u003c/sub\u003e values measured with the EWAS sheet were decreased by about 10 dB at both 6 GHz and 2.4 GHz. Since the EWAS sheet was a synthetic rubber, and\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eMetal sheets, evaluated with S-parameters, and its composition\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eMetal sheet\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003eComposition\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003ethickness\u0026nbsp;(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eEMWS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003eFe\u0026nbsp;and\u0026nbsp;Ni\u0026nbsp;powders\u0026nbsp;in synthetic rubber\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eCu\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e100% Cu\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eAl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e100%\u0026nbsp;Al\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eAluminum\u0026nbsp;die-casting\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e83\u0026nbsp;to\u0026nbsp;87%\u0026nbsp;Al,\u0026nbsp;12%\u0026nbsp;Si,\u0026nbsp;1.5\u0026nbsp;to\u0026nbsp;3% Cu\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003ePCB\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e35 \u003cem\u003e\u0026micro;\u003c/em\u003em\u0026nbsp;Cu\u0026nbsp;plated\u0026nbsp;glass\u0026nbsp;epoxy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e1.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eSus 304\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e18\u0026nbsp;to\u0026nbsp;20%\u0026nbsp;Cr\u0026nbsp;and\u0026nbsp;8\u0026nbsp;to\u0026nbsp;10.5%\u0026nbsp;Ni\u0026nbsp;in Fe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003ePermalloy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e78%\u0026nbsp;Ni,\u0026nbsp;22%\u0026nbsp;Fe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eWhiteboard\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e2 to 25 \u003cem\u003e\u0026micro;\u003c/em\u003em\u0026nbsp;Zn metalized on 0.23 mm Fe plate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eAluminum foil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003eAluminum 9 \u003cem\u003e\u0026micro;\u003c/em\u003em\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.009\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eEva Al\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e0.1 to 0.3 nm Al Evaporated on 1 mm plastic sheet\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.0003\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eCu mesh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e20 mesh, 1.27 mm hole\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eSus mesh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e100\u0026nbsp;mesh,\u0026nbsp;0.254\u0026nbsp;mm\u0026nbsp;hole\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eFe/Zn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e3 to 20 \u003cem\u003e\u0026micro;\u003c/em\u003em\u0026nbsp;Zn\u0026nbsp;metalized\u0026nbsp;on\u0026nbsp;Fe sheet\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.7881%;\"\u003e\n \u003cp\u003eFe/Sn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57.4153%;\"\u003e\n \u003cp\u003e3 to 20 \u003cem\u003e\u0026micro;\u003c/em\u003em\u0026nbsp;Sn\u0026nbsp;metalized\u0026nbsp;on\u0026nbsp;Fe sheet\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.7966%;\"\u003e\n \u003cp\u003e0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003ethe electromagnetic wave reflection was low, the change in S\u003csub\u003e21\u003c/sub\u003e was substantial to the electromagnetic wave absorption. On the other hand, most of the metal plates showed almost the same change value in S\u003csub\u003e21\u003c/sub\u003e. Therefore, the reflectivity of the metal plates was\u0026nbsp;nearly\u0026nbsp;the\u0026nbsp;same.\u0026nbsp;The\u0026nbsp;reflectivity\u0026nbsp;of\u0026nbsp;the\u0026nbsp;metal\u0026nbsp;plates\u0026nbsp;at\u0026nbsp;6\u0026nbsp;GHz\u0026nbsp;was\u0026nbsp;approximately 5 dB lower than at 2.4 GHz, due to the lower impedance of the metal. Because, the reflective\u0026nbsp;loss,\u0026nbsp;R\u003csub\u003em\u003c/sub\u003e(dB) equals 20 log(377\u003cem\u003e/\u003c/em\u003e(4\u003cem\u003eZ\u003csub\u003em\u003c/sub\u003e\u003c/em\u003e)) as the impedance of the metal, \u003cem\u003eZ\u003csub\u003em\u003c/sub\u003e\u0026nbsp;\u003c/em\u003e(Ω), equals (2\u003cem\u003e\u0026pi;f\u0026micro;\u003csub\u003em\u003c/sub\u003e/\u0026sigma;\u003csub\u003em\u003c/sub\u003e\u003c/em\u003e)\u003csup\u003e0\u003cem\u003e.\u003c/em\u003e5\u003c/sup\u003e, where \u003cem\u003e\u0026micro;\u003csub\u003em\u003c/sub\u003e\u0026nbsp;\u003c/em\u003eand \u003cem\u003e\u0026sigma;\u003csub\u003em\u003c/sub\u003e\u0026nbsp;\u003c/em\u003eare permeability and conductivity, respectively. Since the EMWS has a large resistivity, \u003cem\u003e\u0026rho;\u0026nbsp;\u003c/em\u003e= 5 10\u003csup\u003e6\u003c/sup\u003e Ω cm, and significantly low absorption or radiation of electromagnetic waves by electrons, there was almost no difference in the reflective loss at different frequencies. When the EMWS sheet was attached to the metal plate, the absorption was increased by approximately 5 dB at 6 GHz and 10 dB at 2.4 GHz, due to a high magnetic moment absorbing efficiency by carbonyl iron powder. Since the absorption efficiency and the resonant frequency are dependent on the size of the carbonyl iron particle, the absorption efficiency can be optimized. It is possible to increase the absorption loss by an additional 10 dB by increasing the thickness of the EMWS to 6 mm or increasing the content of the carbonyl iron particle [12, 13].\u003c/p\u003e"},{"header":"4\tDesign and fabrication of a 6-GHz low noise amplifier with metal package","content":"\u003cp\u003eA 6 GHz low-noise amplifier (LNA) was designed and fabricated using a SiGe hetero bipolar transistor (HBT). Figure 4 shows the sectional internal view of the LNA and the photos of the LNA package with and without the lid. When the LNA was not pack- aged in any enclosure, the LNA showed undesired performance due to electromagnetic wave incident[14]. The LNA package was made with aluminum die-casting to prevent electromagnetic signal leakage from the joint gap. The LNA circuit was fabricated on top of the printed circuit board (PCB) of FR-4. The electromagnetic input signal into the package from the outside was reflected at the top of the lid. The reflected signal at the LNA output inside was radiated and reflected at the lid bottom inside and propa- gates to the surface mount devices (SMDs) soldered on the top of the PCB. Since usual soldering is difficult when using the aluminum die-casting PCB, and SMA,[15, 16], electrical impedance matching degradation at the connection between the aluminum die-casting and copper circuit pattern causes electromagnetic wave radiation.\u003c/p\u003e"},{"header":"5\tS-parameter measurements for low noise amplifier covered with different types of metal plates","content":"\u003cp\u003eThe S-parameters, S\u003csub\u003e11\u003c/sub\u003e and S\u003csub\u003e21\u003c/sub\u003e, measurements for the 6-GHz LNA were carried out using a setup of vector network analyzer, N5230A[17], as shown in Fig. 5. The reflective coefficient, S\u003csub\u003e11\u003c/sub\u003e, is defined by a ratio of \u003cem\u003eb\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e\u003cem\u003e/a\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e, and the transmission coefficient, S\u003csub\u003e21\u003c/sub\u003e, is determined by \u003cem\u003eb\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e\u003cem\u003e/a\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e. Where \u003cem\u003ea\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e is the standardized input voltage, \u003cem\u003eb\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e, is the standard- ized reflected voltage, and \u003cem\u003eb\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e is the standardized output voltage. The S-parameters were measured with four different types of lid: (a) copper (Cu) plate, (b) aluminum die-casting plate, (c) aluminum foil sheet, and (d) evaporated aluminum plastic sheet. A sharp peak around 5.2 GHz was observed in the S\u003csub\u003e21\u003c/sub\u003e and S\u003csub\u003e11\u003c/sub\u003e curves when the metal lid covered the LNA, as shown in Fig. 6. Since the extraordinary peak height was measured in both the S\u003csub\u003e11\u003c/sub\u003e and S\u003csub\u003e21\u003c/sub\u003e curves, a resonant oscillation caused by a positive feedback occurred at around 5.2 GHz. This resonant frequency value was equal for every metal lid. It is notable that, relatively, the evaporated aluminum plastic sheet exhibited a low peak height. However, it is desirable to use metal as the lid of the LNA package to reduce the impedance mismatch between the box body and the lid,and the electromagnetic reflection at the boundary of the lid. Therefore, the use of the evaporated plastic sheet and the compound shielding sheet [12] is of low priority.\u003c/p\u003e\n\u003cp\u003eFigure 7 shows an example of how to return the output signal to the input stage of the LNA circuit fabricated on the PCB. The output signal reflects and changes the phase by \u003cem\u003e\u0026pi;\u0026nbsp;\u003c/em\u003eat the boundary of the LNA circuit output and the signal pin in the aluminum die-casting. It is radiated to the metal lid bottom along a path of \u003cem\u003e\u0026lambda;/\u003c/em\u003e4, 14.4 mm, and changes the phase by \u003cem\u003e\u0026pi;\u003c/em\u003e, and reflected along a path of \u003cem\u003e\u0026lambda;/\u003c/em\u003e4, 14.4mm, to the signal input stage in the LNA circuit. Since the wavelength \u003cem\u003e\u0026lambda;\u0026nbsp;\u003c/em\u003eis 57.7 mm for a 5.2 GHz electromagnetic wave, the returned signal causes a sharp peak in the \u003cem\u003eS\u003c/em\u003e\u003csub\u003e21\u003c/sub\u003e curve due to a resonance and oscillation, when \u003cem\u003e\u0026theta;\u003csub\u003eLNA\u003c/sub\u003e\u003c/em\u003e+\u003cem\u003e\u0026lambda;/\u003c/em\u003e2 equals 2\u003cem\u003en\u0026pi;\u003c/em\u003e, where \u003cem\u003e\u0026theta;\u003csub\u003eLNA\u003c/sub\u003e\u0026nbsp;\u003c/em\u003eis the change in the output signal phase at the signal pin from the input of LNA. Since it is not sufficient to avoid EMI over a wide frequency range by changing the mechanical design of the package, because there are many signal reflection points in electronic circuits and packages, a design of low and high reflective materials for the inside and outside the package is required.\u003c/p\u003e\n\u003cp\u003eFigure 8 shows S-parameter measurement results for the iron-based metal lid: (a)\u0026nbsp;tin (Sn) plated iron (Fe) plate, (b) stainless (304 type) plate, (c) Permalloy (78 type) plate, and (d) aluminum die-casting attached with electromagnetic wave shielding (EMWS) sheet. Except for the aluminum die-casting/EMWS lid, a sharp peak was observed in every S\u003csub\u003e21\u003c/sub\u003e curve. Therefore, there is no substantial difference between the iron-based lids and the electrically conductive metal-based lids in causing a sharp peak in the S\u003csub\u003e21\u003c/sub\u003e curve. It was confirmed that every metal plate prevented the reflection of the electromagnetic wave at the bottom surface when the EMWS sheet was attached. Even though most of the metal lids shield the electromagnetic wave incident from the outside into the LNA package, it is effective to attach the EMWS sheet to the bottom\u003c/p\u003e\n\u003cp\u003esurface of the metal lid to suppress the reflection of the radiated signal at the output of the LNA inside. Since the SEA of the EMWS in 0.6 mm thick is approximately 10 dB when attached to the bottom surface, the returned output signal to the input stage of the LNA does not cause the signal oscillation. It is confirmed that a SEA of 10 dB is enough even when increasing the LNA gain to 30 dB. The aluminum die- casting/EMWS is effective in reducing the radiated and reflected signal power across a wide range of frequencies caused by the digital switching device and high-power amplifier in the package.\u003c/p\u003e"},{"header":"6\tEVM evaluation on QAM-OFDM digital signal modulation with a 6-GHz low noise amplifier","content":"\u003cp\u003eA 6-GHz LNA covered with a metal lid was evaluated using a quadrature amplifier modulation (QAM) - orthogonal frequency division modulation (OFDM) to investigate how the internal reflection at the lid affects the digital signal modulation. The QAM- OFDM has been used in wireless fidelity (WiFi), such as WiFi 7 (IEEE 802.11be, 46 Gb/s throughput in the maximum), and digital mobile communications, such as 5G (20 Gb/s throughput in the maximum). The setup of the QAM-OFDM is shown in Fig. 9. The vector signal generator (VSG, E4438C) generates BPSK, QPSK, 16-QAM, and 64-QAM modulated sub-frames and sends these combined signals to the 6-GHz LNA [18]. The 6-GHz LNA amplified these signals and outputs them to the vector signal analyzer (VSA, 896008)[19]. The VSA analyzes the received signal and outputs the relative constellation error (RCE), averaged error vector magnitude (EVM) of the four format modulations, spectrum, EVM per sub-carrier, and error information. The error information includes RCE, EVM, quadrature error, gain imbalance, IQ offset, frequency error, and synchronous clock error. In addition, a circuit simulator of AWR [20]was used for further analysis.\u003c/p\u003e\n\u003cp\u003eThe EVM is a substantial indicator to evaluate the quality of the digital signal transmission. Figure 10 shows how the EVM is determined with a symbol, including N bits of data as 2\u003cem\u003e\u003csup\u003eN\u003c/sup\u003e\u003c/em\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e= QAM, in the in-phase (\u003cem\u003eI\u003c/em\u003e) and quadrature (\u003cem\u003eQ\u003c/em\u003e) coordinates. When the VSG generates a signal with an ideal symbol and transmits it to the LNA, and the amplified signal exhibits a measured symbol with an error, there are two differences: gain imbalance and quadrature error. Hence, the EVM is determined by the ratio of\u0026nbsp;the magnitudes of the error vector and the ideal symbol.\u003c/p\u003e\n\u003cp\u003eFigure 11 shows the measurement result of the EVM and constellation of symbols modulated with BPSK, QPSK, 16-QAM, and 64-QAM at a carrier frequency of 5 GHz, and the output power from the VSG is -40 dBm. When the 6-GHz LNA is not covered with the metal lid, the EVM is -40 dB, and every symbol is clear. When the LNA is covered with an aluminum die-casting lid, the EVM is -30 dB, 10 dB worse than the LNA with no cover, and every symbol is spread. When the LNA is covered with an aluminum die-casting attached with EMWS, the EVM is -39 dB, and every symbol is clear.\u003c/p\u003e\n\u003cp\u003eThe detailed error information is shown in Table 2. When the LNA was covered with\u0026nbsp;aluminum\u0026nbsp;die-casting,\u0026nbsp;the\u0026nbsp;EVM\u0026nbsp;increased\u0026nbsp;by\u0026nbsp;10\u0026nbsp;dB\u0026nbsp;due\u0026nbsp;to\u0026nbsp;a\u0026nbsp;significant\u0026nbsp;quadra- ture error of 56 mdeg compared to -56 mdeg of the LNA without a cover. When the LNA was covered with the aluminum die-casting attached to the EMWS sheet, the EVM increased by only 1 dB, and the quadrature error was close to that without a cover.\u0026nbsp;The\u0026nbsp;received\u0026nbsp;power\u0026nbsp;was\u0026nbsp;decreased\u0026nbsp;by\u0026nbsp;only\u0026nbsp;1\u0026nbsp;dB,\u0026nbsp;and\u0026nbsp;the\u0026nbsp;gain\u0026nbsp;imbalance\u0026nbsp;was not\u0026nbsp;changed;\u0026nbsp;hence,\u0026nbsp;the\u0026nbsp;increase\u0026nbsp;in\u0026nbsp;the\u0026nbsp;EVM\u0026nbsp;was\u0026nbsp;substantially\u0026nbsp;due\u0026nbsp;to\u0026nbsp;the\u0026nbsp;quadrature error. Therefore, the output signal reflected by the metal lid to the LNA circuit on the PCB substantially increased the quadrature error when the QAM-OFDM signal was transmitted. The internal EMI significantly degraded the quadrature error and the EVM, rather than the degradation in the received power.\u003c/p\u003e\n\u003cp\u003eFigure 12 shows the EVM measured with a 6-GHz LNA, when covered with alu- minum die-casting and with aluminum die casting/EMWS, and not covered. The input power to the LNA was varied from -60 to -20 dBm. When increasing the input power from -60 to -40 dBm, the EVM decreased due to the increase in the ideal symbol power, for the LNA without a cover. When increasing the input power from -40 to -20 dBm, the EVM increased due to the amplitude saturation of the LNA and VSG. When the LNA was covered with aluminum die-casting, the EVM increased over the entire range of input power. The change in the phase of the LNA circuit, \u003cem\u003e\u0026theta;\u003csub\u003eLNA\u003c/sub\u003e\u003c/em\u003e, did not change the IQ offset nor increase the quadrature error. The increase in the input power by 10 dB from -50 to -40 dBm did not decrease the EVM. Therefore, the quadrature error only caused by the reflection at the lid bottom and resonant interference at the LNA input stage increased the EVM. By only using the aluminum die casting/EMWS as the lid, the EVM decreased to the original value measured with the LNA without a lid, for a wide input power range. It is confirmed that an adequate design to suppress the internal EMI using a high reflection and absorption configured lid enables achieving high-quality QAM-OFDM transmission.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e64-QAM-OFDM signal modulation error summary for a 6-GHz low noise amplifier covered with three different types of lids\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eMeasurement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13.1696%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eNo cover\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.8839%;\"\u003e\n \u003cp\u003eCovered with aluminum\u0026nbsp;die-cast\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.9286%;\"\u003e\n \u003cp\u003eCovered with aluminum\u0026nbsp;die-cast/\u0026nbsp;EMWS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.58929%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eUnit\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003eEVM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13.1696%;\"\u003e\n \u003cp\u003e-40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.8839%;\"\u003e\n \u003cp\u003e-30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.9286%;\"\u003e\n \u003cp\u003e-39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.58929%;\"\u003e\n \u003cp\u003edB\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003eQuadrature\u0026nbsp;Error\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13.1696%;\"\u003e\n \u003cp\u003e-56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.8839%;\"\u003e\n \u003cp\u003e56.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.9286%;\"\u003e\n \u003cp\u003e-75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.58929%;\"\u003e\n \u003cp\u003emdeg\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003eGain Imbalance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13.1696%;\"\u003e\n \u003cp\u003e0.013\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.8839%;\"\u003e\n \u003cp\u003e0.013\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.9286%;\"\u003e\n \u003cp\u003e0.019\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.58929%;\"\u003e\n \u003cp\u003edB\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003eReceived\u0026nbsp;Power\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13.1696%;\"\u003e\n \u003cp\u003e-15.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.8839%;\"\u003e\n \u003cp\u003e-16.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.9286%;\"\u003e\n \u003cp\u003e-15.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.58929%;\"\u003e\n \u003cp\u003edBm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"7 Conclusion","content":"\u003cp\u003eIt is essential to shield electric devices from unwanted electromagnetic waves incident on the devices. Thirteen metal plates commonly used as electromagnetic wave shielding were evaluated by measurements of \u003cem\u003eS\u003c/em\u003e\u003csub\u003e21\u003c/sub\u003e. Most of the conductive metal-based plates, such as aluminum, copper, and aluminum die-casting, and iron-based plates, such as\u0026nbsp;tin-plated\u0026nbsp;iron\u0026nbsp;and\u0026nbsp;stainless\u0026nbsp;steel,\u0026nbsp;show\u0026nbsp;a\u0026nbsp;similar\u0026nbsp;SER\u0026nbsp;performance\u0026nbsp;at\u0026nbsp;frequencies of\u003c/p\u003e\n\u003cp\u003e2.4 and 6 GHz. Since the change in \u003cem\u003eS\u003c/em\u003e\u003csub\u003e21\u003c/sub\u003e for the EWAS, which contains carbonyl iron and nickel powders in synthetic rubber, is relatively low due to the low SER, the EWAS is not adequate for electromagnetic wave shielding by reflection.\u003c/p\u003e\n\u003cp\u003eA 6-GHz LNA is designed and fabricated on a PCB and packaged in an aluminum die-casting. When the package was not covered with any metal lid, the LNA showed a smooth flatness in the \u003cem\u003eS\u003c/em\u003e\u003csub\u003e21\u003c/sub\u003e curve; a sharp peak at 5.2 GHz was observed when the package was covered with a metal lid. The LNA output inside signal returned to the transistor on the PCB is causing the sharp peak in the \u003cem\u003eS\u003c/em\u003e\u003csub\u003e21\u003c/sub\u003e curve. Since the aluminum die-casting used as the package can not be soldered, an impedance mismatch occurs at the signal pin at the output port. The reflected signal is radiated and reflected at the lid bottom surface and propagated along the \u003cem\u003e\u0026lambda;/\u003c/em\u003e2 path, and incident into the input stage of the LNA on the PCB. When the EWAS sheet is attached to the meta lid, the reflection at the lid bottom surface is suppressed by approximately 20 dB at 2.4 GHz and 10 dB at 6 GHz, hence the sharp peak on \u003cem\u003eS\u003c/em\u003e\u003csub\u003e21\u003c/sub\u003e disappeared.\u003c/p\u003e\n\u003cp\u003eAn EVM measurement was carried out to investigate how the internal signal reflec- tion affects the QAM-OFDM transmission quality. When a 6-GHz LNA package was covered with an aluminum die-casting lid, the EVM increased by approximately 10 dB. According to the VSA analysis, the quadrature error increased due to the signal reflec- tion at the bottom of the lid. When the LNA package was covered with an aluminum die-casting/ EMWS lid, the increase in the EVM and the quadrature error were sub- stantially suppressed. It is effective both to shield the electronic devices from external electromagnetic waves and to suppress the internal reflection using an aluminum die- casting/ EMWS. It is confirmed that a robust design to suppress the internal EMI using an adequately configured metal lid of the electronic devices enables achieving high-quality QAM-OFDM transmission.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eAuthor\u0026nbsp;contributions\u0026nbsp;Chinen\u0026nbsp;K.\u0026nbsp;contributed\u0026nbsp;to\u0026nbsp;idea\u0026nbsp;generation\u0026nbsp;and\u0026nbsp;implementa- tion of experiments and article writing. Kinjo I. contributed to measurements and analysis of the measurements result. All authors have read and approved the final version and the submission to Discover Electronics.\u003c/li\u003e\n \u003cli\u003eFunding The authors did not receive financial assistance from any organization for carrying out this research study.\u003c/li\u003e\n \u003cli\u003eCode\u0026nbsp;availability\u0026nbsp;Not\u0026nbsp;applicable.\u003c/li\u003e\n \u003cli\u003eEthics\u0026nbsp;approval\u0026nbsp;and\u0026nbsp;consent\u0026nbsp;to\u0026nbsp;participate\u0026nbsp;Not\u0026nbsp;applicable.\u003c/li\u003e\n \u003cli\u003eConsent\u0026nbsp;for\u0026nbsp;publication\u0026nbsp;Not\u0026nbsp;applicable.\u003c/li\u003e\n \u003cli\u003eCompeting\u0026nbsp;interests\u0026nbsp;The\u0026nbsp;authors\u0026nbsp;declare\u0026nbsp;that\u0026nbsp;they\u0026nbsp;have\u0026nbsp;no\u0026nbsp;competing\u0026nbsp;interests\u0026nbsp;associated with this work.\u003c/li\u003e\n \u003cli\u003eClinical\u0026nbsp;trial\u0026nbsp;number\u0026nbsp;Not\u0026nbsp;applicable.\u003c/li\u003e\n \u003cli\u003eData Availability Yes. All data generated or analyzed during this study are included in this published article (and its supplementary information files).\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eLoya, and S, Habibullakhan. Analysis of Shielding Effectiveness in the Electric Field and Magnetic Field and Plane Wave for Infinite Sheet Metals. International Journal of Electromagnetics and Applications. 2016; 6(2): 31-41. http://article. sapub.org/10.5923.j.ijea.20160602.02.html\u003c/li\u003e\n \u003cli\u003eShukla V. Review of electromagnetic interference shielding materials fabricated by iron ingredients. Nanoscale Adv. 2019; 1, 1640\u0026ndash;1671. https://doi.org/10.1039/ c9na00108e\u003c/li\u003e\n \u003cli\u003eBuzko V, Babushkin M, Ivanin S, Goryachko A, and Petriev I. Study of Electromagnetic Shielding Properties of Composites Based on Glass Fiber Met- allized with Metal Films. 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Formation of Die Soldering and the Influence of Alloying Elements on the Intermetallic Interface. Materials. 2021; 14, 1580. https://www.mdpi.com/1996-1944/14/7/1580\u003c/li\u003e\n \u003cli\u003eN5230A(VNA). https://www.keysight.com/us/en/product/N5230A/ 2port-pnal-series.html\u003c/li\u003e\n \u003cli\u003eE4438C(VSG). https://www.keysight.com/us/en/assets/7018-01039/ data-sheets-archived/5988-4039.pdf.\u003c/li\u003e\n \u003cli\u003eS(VSA). https://www.keysight.com/us/en/products/software/ pathwave-test-software/89600-vsa-software.html.\u003c/li\u003e\n \u003cli\u003eAWR Design Environment Platform. https://www.cadence.com/en US/home/ tools/system-analysis/rf-microwave-design/awr-design-environment-platform. html\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"GLEX","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"EVM, S-parameter, EMI, 6GHz LNA, lid reflection, quadrature error","lastPublishedDoi":"10.21203/rs.3.rs-8051715/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8051715/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTransmission coefficients, \u003cb\u003eS\u003c/b\u003e\u003csub\u003e\u003cb\u003e21\u003c/b\u003e\u003c/sub\u003e, for thirteen metal plates considered as shielding unwanted electromagnetic waves were measured. Most of the metal-based plates showed a similar electromagnetic wave reflection performance at 6 GHz. A 6- GHz LNA packaged in an aluminum die-casting showed a sharp peak at 5.2 GHz in the output signal when the package was covered with a metal lid. The inter- nal output signal radiated at the signal pin between the PCB and the aluminum die-casting is radiated and reflected at the bottom of the lid and propagated along the \u003cb\u003eλ/\u003c/b\u003e\u003cb\u003e2\u003c/b\u003e path, and incident into the input stage of the 6-GHz LNA fabri- cated on the PCB. When the electromagnetic wave shielding (EWAS) sheet was attached to the metal lid, the signal reflection at the lid bottom was suppressed by about 10 dB, and the sharp peak on the \u003cb\u003eS\u003c/b\u003e\u003csub\u003e\u003cb\u003e21\u003c/b\u003e\u003c/sub\u003e curve disappeared. When the LNA package was covered with an aluminum die-casting lid, the EVM in the 64 QAM-OFDM transmission measurement increased by approximately 10 dB, due to the quadrature error increase. When the LNA package was covered with an alu- minum die-casting/EMWS lid, the increase in the EVM and the quadrature error were substantially suppressed. It is effective both to shield the electronic devices from external electromagnetic waves and to suppress the internal reflection to suppress the internal EMI for achieving high-quality QAM-OFDM transmission.\u003c/p\u003e","manuscriptTitle":"S-parameter and EVM evaluation on internal EMI with various types of metals shielding a 6-GHz low-noise amplifier package","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-10 06:54:01","doi":"10.21203/rs.3.rs-8051715/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"33b29dad-86d9-4236-b64b-478ab3b38c24","owner":[],"postedDate":"November 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":57581523,"name":"Electrical Engineering"},{"id":57581524,"name":"Electronic Materials and Devices"}],"tags":[],"updatedAt":"2025-11-10T06:54:02+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-10 06:54:01","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8051715","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8051715","identity":"rs-8051715","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}