High-Efficiency High-Isolation Dual-Orthogonally Polarized Patch Antennas Using Nonperiodic RAMC Structure

This communication presents dual-orthogonally polarized patch antennas using nonperiodic rectangle artificial magnetic conductor (RAMC) structure, which take the features of high efficiency and high isolation. The artificial ground composed of several nonperiodic RAMC cells is first theoretically analyzed by projecting it onto a cylindrical surface. It is found that the nonperiodic plane can be similarly equivalent to a cylindrical metal reflector for strongly focusing electromagnetic waves to realize an extremely directive antenna with high aperture efficiency. Based on the above analysis, a novel spherically projected nonperiodic RAMC plane is proposed, and two differentially fed dual-polarized patch antennas using the newly proposed plane are well designed accordingly. Both simulated and measured results demonstrate dual-polarized radiations with very high aperture efficiencies of about 90% and low cross-polarization levels of less than -20 dB at each state, as well as high polarization-isolations of over 30 dB. Compared with 3-D physical reflectors, the proposed artificial grounds not only have similar strong reflections for high-efficiency antennas, but also exhibit a low-profile planar structure, which would be more easily integrated with antennas for applications in wireless communication systems.