A Low-Profile Broadband Circularly Polarised Wide-Slot Antenna with an Artificial Magnetic Conductor Reflector

In this letter, a novel broadband circularly polarisation (CP) wide-slot antenna with an artificial magnetic conductor (AMC) as the reflector is presented. The wide-slot antenna is composed of a knife-shaped radiator and an improved ground plane. A broadband CP characteristic can be achieved by slotting the ground plane to make it an asymmetric ground shape. However, the average gain of the wide-slot antenna is only about 3 dBic because of bidirectional radiation. An AMC reflector is adopted to enhance the gain of the wide-slot antenna without introducing a high profile similar to the PEC reflector. In addition, the four metal plates are vertically placed around the antenna to broaden the axial ratio (AR) bandwidth of the antenna with the AMC reflector. The measurement results show that the 3dB AR bandwidth of the proposed CP antenna is 32.4% (2.35GHz─3.26GHz), the average gain is 6.5dBic in the AR bandwidth and the value of VSWR in the AR bandwidth is less than 2. The size of the antenna is 0.84λ0× 0.84λ0× 0.13λ0 at the centre frequency of 2.805 GHz. The proposed antenna has a low profile, broad AR bandwidth and high gain, thereby being a good candidate for various wireless communication systems.