Broadband Circularly Polarized 2 × 2 Antenna Array with Sequentially Rotated Feed Network for C-Band Application

Abstract

In this paper, a unique broad-band circularly polarized antenna array with sequentially rotated feed-network for C-band applications is proposed. In order to, implement presented array element, a novel and miniaturized square slot antenna, with one pair of attached L-shaped and a T-shaped strips at ground surface, for decreasing cross polarization purity, is presented. Two L-shaped strips with different length are inserted at slot antenna’s patch to enhance impedance matching. The symmetric coplanar waveguide is used for feeding the slot element. The antenna element obtains a 3 dB axial ratio bandwidth from 5.85 to 6.25 GHz. For further improving of radiation attributes, elements in 2 × 2 array are linked together by sequentially rotated feed to achieve wider axial ratio and impedance matching bandwidths. The main advantage of feed network is designed in a way that to have less coupling effect between elements. The axial ratio (AR) and impedance bandwidths of array is from 4.9 to 6.45 GHz (for AR <3 dB) and 4 to 8.1 GHz (for VSWR <2), respectively. Simulation and measurement results validated the proposed array design.