Gain-Bandwidth Enhancement of Subarray CP Antenna for L Band CP-SAR

This paper presents a new subarray design of circularly polarized antenna for L band CP-SAR application with an operating frequency of 1.275 GHz. This proposed subarray CP antenna provides a high gain and bandwidth with RHCP. It increases the gain and bandwidth of the proposed subarray CP antenna by applying the SSR technique. It consists of four-unit element antennas. The patch radiator of the unit element antenna is made of a truncated corner and crossed-slot square patch. The unit element antennas are connected serially by using the serial-sequential-rotation technique. In addition, the proposed subarray CP antenna uses a full ground plane. Slotting and corner truncation of the patch radiator generate a circular polarization of the CP antenna. Applying array antennas is to make higher gain and broaden bandwidth. For a single CP antenna, the simulated impedance bandwidth (S11 ⩽ -10 dB) and axial ratio bandwidth (⩽ 3 dB) is achieved at approximately 132 MHz and 118 MHz, respectively. Furthermore, the subarray CP antenna yields a broad bandwidth, 421 MHz of impedance bandwidth, and 409 MHz of axial ratio bandwidth. There is a significant improvement in gain, a single CP antenna provides a 7.84 dBic of gain, and a subarray CP antenna generates a 12.016 dBic of gain.