Circularly Polarized Rectangular Ring-Slot Antenna with Chamfered Corners for Off-Body Communication at 5.8 GHz ISM Band

This paper deals with a substrate integrated waveguide (SIW) circularly polarized rectangular ring-slot antenna with chamfered corners designed for 5.8 GHz ISM frequency band for off-body communication. The antenna consists of a substrate integrated waveguide, which operates in the fundamental mode TE10, and the rectangular ring-slot radiator with chamfered corners etched in the top wall of the SIW. It radiates a right-handed circularly polarized (RHCP) wave in the boresight direction. Experimental results prove that the proposed antenna located in free space achieves the impedance bandwidth of 2.41 % (for the reflection coefficient less than -10 dB) and the RHCP gain of 6.57 dBi, and the impedance bandwidth of 2.6 % and the RHCP gain of 6.98 dBi for its location on the phantom. The axial ratio (AR) bandwidth (for the AR less than 3 dB) is 0.9 % for both configurations