Antenna Array and Front End Design for GNSS to Cancel Low Elevation Jamming Signals

Abstract In this study, we propose antenna array and a front-end design to mitigate jamming signals coming from low elevation angles without changing the receiver system. Many navigation systems based on terrestrial signals assume that jamming signals are at low elevation angles. There is a need for a feedback system that detects the presence of interference signals and switches to an interference-resistant mode by activating switches. Signals in the range of 750 MHz to 2 GHz are observed without interference with our designed system. The system receives signals at levels close to -70 dBm for frequencies outside the GNSS band, while signals received within the GNSS band from GPS, Galileo, and GLONASS satellites are close to -130 dBm. Without jamming signals, the C/N value of the received navigation signals is 25–30 dB. When jamming signals are present, C/N values drop to 10 dB. The designed system was tested in both laboratory and open field environments. When the system sense jam signals, it switches to array mode in127 micro seconds, and cancel the jam signals about 30 dB.