Dual circularly polarised travelling wave slot antenna array

A series-fed dual circularly polarised planar slot antenna array is presented. The radiating slots of the antenna are located on the ground plane and are excited by means of a ring-shaped microstrip line comprising of rectangular sections. A metallic reflector lies underneath the feed network separated by an air-layer to augment the gain of the antenna. The parameters of a fabricated prototype are measured for validation. Based on the measured data, the antenna is found to have an impedance bandwidth of 1189 MHz which is 18.46% of the centre frequency f(0) = 6.45 GHz. Also, the axial ratio (AR) bandwidth is 880 MHz centred at f(AR) = 6.54 GHz. The inter-port isolation ranges from 25 to 45 dB and the gain ranges from 8.2 to 9.5 dBic within the AR band. The antenna exhibits beam scanning capability and is therefore suitable for various applications like satellite communication, radiometry and polarimetry.