Aperture Fed Microstrip Dual Polarization Wide Scan Phased Array Antenna With Mutual Coupling Reduction

Abstract

The mutual coupling between the elements of an aperture-fed, dual-polarized, low cross-polarization, scanning phased array microstrip antenna is investigated and a simple rectangular planar resonator between the elements is proposed to reduce the mutual coupling. The mutual coupling effect on antenna performance is studied based on active reflection coefficient. The rectangular resonating structure is positioned on the antenna top layer between patch elements, with dimensions optimized for resonance within the desired frequency range without significantly compromising cross-polarization performance. The antenna is a $2\times 8$ planar-phased array operating in the frequency range of 2.77 - 3.10 GHz using the aperture-coupled dual-polarization elements. Based on simulations and measurements, it is observed that the resonator effectively suppresses mutual coupling between antenna elements by 6 and 7 dB for V- and H-polarizations, respectively while maintaining cross-polarization levels below −35 dB for both polarizations within the required scan angle range. The reduced mutual coupling allows for elements to be placed at a distance of $0.45\lambda $ which in turn supports a scan angle range of −60° to 60° as verified by measurements and simulations. The design is simple enough such that the array size can be increased to achieve very fine beamwidth and high gain needed for polarimetric weather radar applications.

Keywords

• Weather radars
• cross-polarization
• mutual coupling
• dual-polarized antennas
• phased array