Investigating Small Aperture Radial Line Slot Array Antennas for Medium Gain Communication Links

This paper investigates the performance of a relatively small aperture circularly polarized (CP) radial line slot array (RLSA) antenna with medium gain for the Ku-band. The antenna is composed of two parallel metal plates which form a parallel-plate waveguide and supports rotationally symmetric transverse electromagnetic (TEM) travelling wave. The top plate consists of radiating slot elements. The slots are arrayed on the aperture in a way to produce a circularly polarised broadside beam. The antenna was designed at the central operating frequency of 11 GHz having a circular aperture with radius of 90 mm. The predicted results indicated that the return magnitude of reflection coefficient is less than -10 dB in a operating frequency band from 10.5 GHz to 11.5 GHz. The antenna has achieved a peak directivity of 22.4 dBic with a peak gain of 22.1 dBic at 11 GHz. The CP-RLSA antenna has a predicted aperture efficiency of 40%, and a total efficiency of 93% at 11 GHz.