Gain enhancement for circularly polarized double layered printed hemispherical helical antenna arrays

Abstract

To improve the performance of mobile satellite communications, such as for INMARSAT-M mobile vehicles, antenna with high gain and circular polarization over a wide angular range is important. With only 3-elements circularly polarized double-layered printed hemispherical helical antenna arrays that incorporated with parasitic helical wire in the structure, the array can produce significant improvement where it has been demonstrated that the gain and the 3 dB axial ratio (AR) bandwidth and beam width can be increased by properly adjusting the relative angular displacement δ1, δ2, δ3, and the inter-element spacing dx and dy. Experimental and theoretical results demonstrate that the array can produce a gain of 11 dBi, the 3 dB AR bandwidth of more than 11% with AR beam width of ~136°, and the mutual couplings between each element less than −23 dB at required 3 dB AR bandwidth frequency range. The antenna design is performed in computer simulation technology and verified by measurement.