Developing and examining a compact dual band circularly polarized ultra-wideband antenna covering C-band and X-band applications

Abstract

A novel circularly polarized (CP) ultra-wide band (UWB) microstrip antenna is presented in this investigation. A FR4 substrate with a thickness of 1.6 mm and a dielectric constant of 4.4 serves as the foundation of proposed antenna. Comprehensive measurements of the antenna are 0.65$\lambda _0$ X 0.55$\lambda _0$ X 0.0031$\lambda _0$, whereas $\lambda _0$ is the wavelength of open space at first resonating frequency 6.89 GHz. The uppermost layer is made of a compact, asymmetric radiating patch designed along with two parasitic elements at the bottom side of the path to achieve circular polarization at three frequencies, while the bottom layer incorporates an incomplete ground plane including two stubs to improve the radiation characteristics like axial ratio (AR) along with impedance bandwidth while retaining a minimal spatial envelope. With maximum return loss ($S_{11}$) of -24.473 at 11.21 GHz with bandwidth of 11.4 GHz spanning from 3.7 GHz to 15.1 GHz, the proposed antenna also exhibits maximum gain of 2.65 dBi at 8.85 GHz. The circular polarization for the proposed antenna, with axial ratio (AR) less than 3 dB, is observed at two bands from 6.67 GHz-8.37 GHZ and 8.51 GHz-9.45 GHz. The suggested antenna gives optimum performance with circular polarization which is validated from the measurements.