Wideband Circularly Polarized Antenna Array Using Three-Layer Segmented Patches for Q-Band Application

A compact wideband circularly polarized (CP) millimeter-wave (mm-wave) antenna array using a three-layer segmented patches (SEP) element is presented in this letter. To achieve miniaturization and wideband feature, three-layer SEP with four
L
-shaped branches is first designed to generate three CP modes (AR minimum points) within a compact size. With the three CP modes, a broad AR bandwidth of 31.7% is achieved by the proposed CP element. Then, four metallic vias and an
L
-shaped feeding line are used to improve impedance matching. As a result, a wide impedance bandwidth of 33.1% is also obtained by the proposed CP element. Based on the proposed wideband CP element, a compact 4 × 4 CP antenna array fed by a simple full-incorporate microstrip network is designed. Measured results of the array show a 3 dB AR bandwidth of 29.7% from 30.1 to 40.6 GHz, an impedance bandwidth of 36.1% from 29.15 to 42.0 GHz, and a peak gain of 18.2 dBic, which is well suited for Q-band satellite communications.