A Broadband Multimode Substrate Integrated Cavity Antenna With High-Gain and Low Cross-Polarization

In this paper, a broadband substrate integrated cavity (SIC) antenna is proposed and analyzed. The radiator structure is constructed by integrating a slot-fed resonant square SIC operating in high-order-mode with a shorted-patch (SP) on its top surface. By utilizing the slot mode, TM10 mode and antiphase TM20 mode of the SP, and the TM211 mode of the SIC, the proposed design combines the cavity-backed SP radiation mechanism and high-order mode SIC radiation mechanism to realize wideband high-gain radiation. Moreover, the SIC further reduced cross-polarization (cross-pol) by restricting the E-field distribution and suppressing surface waves. Simulation results demonstrate an overlapping bandwidth of 59.54% (19.53–36.09 GHz) considering both −10 dB reflection coefficient and 3-dB gain bandwidth, with a maximum gain of 11.61 dBi at 33.50 GHz. Especially, the antenna maintains H-plane cross-pol below −45 dB over the entire operational band.