Dual-Band Shared-Aperture Antenna Hybridizing Patch and Transmitarray With Large Frequency Ratio and Wideband Characteristics

This article presents a novel microwave (MW)/millimeter-wave (MMW) dual-band shared-aperture antenna. The antenna operates as a patch antenna in the MW band (2.4 GHz) and as a transmitarray (TA) in the MMW band (60 GHz). It was found that the transmitting surface (TS) of the TA can be equivalent to a MW patch at a large frequency ratio, and therefore, the two kinds of antennas can be tightly integrated and share the same radiating aperture through structure reuse. To accommodate the TA into the patch antenna, the TA is folded by adopting a polarization rotating surface (PRS), and its profile height is reduced to 1/3 of the focal length, which matches the profile of the patch antenna. Thanks to the spatial feeding architecture of the TA, the proposed antenna eliminates the need for a complicated feeding network and features low feeding loss and high gain in the MMW band. Additionally, the proposed antenna adopts a pair of differentially fed L-probes for the MW feeding network and a nondispersive stripline for the MMW TA, which contribute to the wideband performance of the antenna in both bands. To validate the design idea, a prototype is fabricated and measured. The experimental results show that it can achieve 3-dB gain bandwidths of 26.3% and 20.1% in the MW and MMW bands, respectively. It can be a promising solution for Wi-Fi/Wi-Gig applications.