Abstract

A wideband circularly polarized (CP) slot antenna array is presented by employing cavity-backed CP multi-feed slot antenna as the element. The antenna element consists of four microstrip-fed circular stubs that excite the circular slot to generate circular polarization, a circular back cavity and a separate corporate feed network layer. The measured 3-dB axial-ratio (AR) bandwidth of the element is 38.6% (4.6–6.8 GHz) in which the reflection coefficient (|S11|) is below −10 dB. The investigation is extended to a 2 × 2 antenna array by using sequentially rotated technique. Wilkinson power dividers are applied to design the feed network of the array. The fabricated antenna array can provide a 1-dB AR bandwidth of 55.7% (4.4–7.8 GHz). In the 1-dB AR bandwidth, the |S11| is below −10 dB and the gain is more than 10.0 dBic. The 3-dB gain bandwidth is about 40.0% (4.8–7.2 GHz) with the maximum gain 15.1 dBic.