Abstract
In this paper, we present a composite feed circularly polarised aperture-coupled microstrip antenna at X-band with improved characteristics. The feed element is intended to produce right-hand circular polarization (RHCP). Along the periphery of the circular patch, two notches are cut at diametrically opposite points. The dimension of these diametrically opposite notches determines the AR. A prototype antenna has been designed, built-up and experimentally measured which allows the analysis and discussion about different characteristics of the antenna. The simulated 2:1 VSWR bandwidth is about 2.33 GHz (c GHz). The measured 3-dB AR bandwidth is about 1.7 GHz (8.7–10.4 GHz) and the centre frequency of the impedance bandwidth is 9 GHz which agrees with the simulation result. It is revealed by experimental results that the designed antenna achieves about 19% axial ratio bandwidth as much as 8.7 dBi gain.