Dual-Circularly Polarized Patch Antenna using Simple Isolation Techniques and its Array Application

This paper presents low cost, low complexity,dual-circularly polarized patch antenna designs. The aperture coupled antennas employ simple square slot line loop elements to provide surface current cancellation in the critical regions of the antenna structure. High isolation (below 50 dB) is then obtained between the two antenna inputs, one for each polarization state. Circular polarization (CP) is produced thanks to the use of a planar hybrid coupler, feeding the antenna with two quadrature signals. Reciprocity of these components allows for the use of one port as the input (Tx) and the other one as an output (Rx), making the antenna work in full duplex mode. Also, both right-hand and left-hand circular polarizations are possible by interchanging the Tx and Rx ports, bringing a valuable degree of versatility. The proposed antenna design is also grouped in a 2x2 array for operation at C band (2.45 GHz), and its corresponding results are reported.Possible applications for the single-element and the low profile array include modern short range wireless communications, polarization diversity, direction finding, radar, and other beam steering array applications.