A Pattern Reconfigurable Miniaturized Quarterwave Patch Antenna Design with Isolated Ports

A novel miniaturized multi-port beam scanning antenna element is presented. The isolation problem of a multi-port antenna is addressed by capacitive or inductive feeding network design. The antenna achieves beam scanning at the same frequency by varying the phase difference between the ports. To reduce port-to-port isolation between elements, the antenna is miniaturized by using a substrate with a high dielectric coefficient and the slots on the antenna surface. These techniques achieve a 61.7% reduction in antenna size. To compensate for the bandwidth reduction due to miniaturization, an aperture-coupled feeding method is preferred. The shorted antenna houses two excitation ports on the same patch, creating an isolation problem. This problem is addressed by developing a novel feeding network that utilizes capacitive or inductive elements to increase port isolation. As a consequence of the feeding network, the |S-21| parameter is reduced from -5 dB to -22 dB.