A Design of Wideband Loaded Sleeve Monopole Embedded with Filtering High-Low Impedance Structure

In this paper, A wideband and filtering monopole is presented for applying in remote terrestrial omnidirectional communication systems. The antenna consists of a sleeve monopole loaded by lumped parallel RLC circuit and an embedded high-low impedance structure in the sleeve section. The high-low impedance structure makes the antenna acquire filtering character in a compact structure. The sleeve structure and the lumped parallel RLC loads make the antenna a wideband radiation character in omni-direction. For verification, a prototype of the designed antenna, operating in 200-1500 MHz, is designed, fabricated and measured. The experiment results show that the antenna covers the design band with a VSWR<2.5, a measured gain>0 dB and a satisfactory filtering character from 1700 to 4000 MHz.