Double half-ring flat CP-antenna for multifrequency applications

Antenna for mobile terminal of satellite navigation and/or terrestrial communication systems is proposed. The novel design presented here takes two half-ring patches of different radii, fed by a single microstrip line via a crossed slots in the ground plane, to produce an antenna with a CP axial ratio <; 3 dB, and 2.0%-impedance bandwidth. Dimensions of the antenna parts are determined approximately as for conventional annular-ring microstrip patch operating in the TM₁₁ mode. As an example, an antenna designed for an Iridium satellite communication terminal operating over the band from 1.60 to 1.63 GHz with CP is presented. This antenna can be designed as a multi-band (1.7 ÷ 17 GHz), with orthogonal linear polarizations, and re-used in many communications systems operation.