Development of Compact Wideband and High Gain Circularly Polarized Antenna for C-Band Applications

In this paper, the development of a new compact CP antenna for C band applications specifically, as a SAR sensor, is proposed. It works at a center frequency of 5.3 GHz with wide bandwidth and high gain, as required in a CP-SAR system. It uses two-staked substrates (lower and upper substrates) and has a compact size of 28 × 32 mm (0.49 × 0.56 \(\lambda_{0}\)). Applying two-staked substrates is addressed to widen the bandwidth. Three stages of development are applied to get wide bandwidth and high gain, such as modification of the radiator patch, shifting of the radiator patch, and adding the parasitic patch at the upper substrate. Adding a parasitic patch will provide higher gain and wider bandwidth. First, this proposed CP antenna has a wide bandwidth for both IBW and ARBW. The measured and simulated IBWs ( \(\le \) − 10 dB) are approximately 673 and 744 MHz, respectively. Moreover, the simulated and measured ARBWs (\( \le \)3 dB) are achieved around 548 and 536 MHz. Second, the VSWR values are less than 2 dB spanning from 4842 to 5563 MHz, with the VSWR at a center frequency of 5.3 GHz being around 1.2. Third, the simulated and measured gain is 6.9–7 dBic at a center frequency of 5.3 GHz. The proposed CP antenna has good characteristics and is suitable to be deployed as a CP-SAR sensor.