Broadband circularly polarised slot antenna array for L- and S-band applications

A new design of a broadband circularly polarised square slot antenna array (CPSSAA) fed by a symmetric coplanar waveguide (CPW) for L- and S-band applications is presented. The proposed antenna is composed of 2×2 CPSS antennas and a sequentially rotated feed network. In this model, compared with the previous CPSSAA with an asymmetric fed structure, the impedance bandwidth of the antenna is increased, and is 71% wider than the impedance bandwidth of a previous similar design. The designed antenna operates over the frequency band 1-4.34 GHz (4.34:1, 125%) for VSWR <; 1.6 exhibiting a 120% (1.11-3.98 GHz, 3.58:1) circular polarisation bandwidth. The proposed CPSSAA can provide a peak gain of about 8.9 dBic at 3 GHz, with gain variations less than 1.5 dB at operating frequencies. Measured and simulated results validate the proposed design.