A Hybrid Rx/Tx Phased Array Antenna With a Spiral Lattice for Sidelobe Level Reduction

A hybrid antenna array in a compact shared aperture for Rx and Tx is presented in this paper. Each antenna is a dual-band, polarisation reconfigurable, circularly polarised radiator. It consists of two concentric elements, a slotted circular patch nested in an annular ring. The inner element operates in the Tx band (30 GHz) and the outer element operates in the Rx band (20 GHz). Both the elements are excited with two orthogonal feeds in phase quadrature which generates a reconfigurable, circularly polarised axial beam. The Tx and Rx beams have a directivity of 6.6 dBi and 6.4 dBi respectively. Further, an array scanning performance of such elements in triangular and spiral geometry is compared and investigated for sidelobe level reduction.