A substrate-integrated waveguide-based wideband circularly polarized slot antenna using the parasitic square patch array

Abstract

In this paper, a planar low-profile wideband circularly polarized substrate-integrated waveguide (SIW) based antenna is investigated. The antenna comprises two substrates stacked over each other. The top layer of the antenna is loaded with a 4 × 4 array of parasitic square patches stacked over a spiral slot loaded in the SIW cavity. The spiral slot is utilized for the generation of narrow band circular polarization and to enhance the CP bandwidth, the parasitic patch array is excited through the electromagnetic coupling mechanism without any air gap between them. The antenna is fabricated and tested to validate the simulated results. A wide relative impedance bandwidth of 33% (8.25–11.55 GHz) and the axial ratio bandwidth of 8.55–9.70 GHz (12.60%) is exhibited. The broadside radiation characteristics are achieved with peak gain of 8.05dBic at 9 GHz. The overall size of the antenna structure is 0.8λ0 × 0.8λ0. The proposed antenna is suitable for various satellite applications.