Wideband omnidirectional circularly polarized antenna with offsetting slots and vertical strips

Abstract

A wideband omnidirectional circularly polarized (CP) antenna is proposed in this paper. The antenna is comprised of two slotted square patches which are connected by four vertical metal strips at the edges and a simple feeding probe in the centre. Loop currents can be yielded on the patches when rotation-symmetrically offsetting slots are cut. By combining the two orthogonal fields radiating from the loop and the feeding probe, omnidirectional circular polarization is obtained in the azimuth plane. One group of slots are cut to verify the CP performance and two groups of slots are cut to further broaden the operating bandwidth. Measured results show that the proposed antenna with a small size of 40 × 40 × 10 mm3 obtains an effective bandwidth of 22% (2.1–2.62 GHz) for |S11| < −10 dB and axial ratio < 3dB. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:675–680, 2015.