A Low-Profile Wideband Shared-Aperture Dual-Polarized Antenna Utilizing Dual-Function Slot

Abstract

The design of a low-profile wideband shared-aperture dual-polarized antenna is proposed. The proposed antenna consists of a cavity-backed slot antenna to produce vertical polarization and a slot-backed monopole antenna for horizontal polarization. The slot operates as a radiator for vertical polarization and at the same time, it works as a reflector for horizontal polarization. Two antenna prototypes are designed and simulated. The initial design has a profile of $0.28{\lambda }_{\max }$ , where ${\lambda }_{\max }$ is the free space wavelength at the lowest frequency. The vertical and horizontal polarized antennas exhibit 36.1% and 39.7% bandwidths, respectively. By adding a notch in the slot, the current path increases, which reduces the operating frequency band; hence, the low-profile design is accomplished. The new version features a profile of $0.17{\lambda }_{\max }$ with 28.2% and 36% bandwidths for vertical and horizontal polarizations, respectively. The low-profile prototype is fabricated and measured. The measured S-parameters are consistent with the simulated one. The measured realized gain varies from 1 to 4.2 dBi for vertical polarization, while it varies from 1 to 2.5 dBi for horizontal polarization. The total efficiency of the proposed antenna is above 85% within the operating band for both polarizations. The far-field radiation pattern is measured, and a good agreement is achieved with the simulated one.