A Novel Wideband Differentially-Fed Higher-Order Mode Millimeter-Wave Patch Antenna

This paper presents a novel differentially-fed wide-band patch antenna working at millimeter-wave band. The antenna is fabricated using conventional low-cost printed-circuit-board and plated-through-hole technologies and the patch size of the element has been enlarged by exploiting higher-order mode operation for good fabrication tolerance. The antenna element is a 0.86 guided wavelength (lambda(g) at 60 GHz) long patch shorted at one end. A slot of 0.09 lambda(g) in width is introduced on the shorted patch and the distance between the slot center to the other end of the patch is 0.5 lambda(g). The shorted patch resonates at TM30 mode and the 0.46 lambda(g) patch, created by presence of the slot, operates at TM10 mode. The combination of these two modes broadens the impedance bandwidth of the element to 18%. Asymmetric radiation patterns in the E-plane and large cross-polarization levels in the H-plane generated by a single patch are eradicated by feeding two mirrored elements differentially. The designed differentially-fed prototype has more than 18% measured impedance bandwidth, stable gain at 9-10 dBi and symmetric and stable radiation patterns across the operating band from 56 to 67 GHz.