A Tri-Frequency Shared-Aperture Antenna for Cooperative Work of V2X and Millimeter-Wave Bands

The microwave (MW)/millimeter-wave (MMW) shared aperture technique is a promising approach to support different frequency bands within limited space. In this letter, a 1 × 4 beam-scanning linear antenna array operating at the MMW (28/39 GHz) band and a vehicle-to-everything (V2X) (5.9 GHz) patch antenna are integrated to share the same aperture. Not only are the entire MMW bands covered, but also the mutually enhanced characteristic between the MW and MMW bands is achieved with the slot-loaded patch. The MW patch nested outside of the MMW radiators can enhance the gain and extend the beam-scanning angles of the MMW antenna array. Furthermore, the hollowed space reserved for MMW antenna can improve the radiation pattern of the MW patch TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> mode. The proposed tri-band antenna was fabricated and measured. Measured results show that the MMW antenna can cover the bandwidths of 24.4 GHz to 29.3 GHz/36.7 GHz to 41.4 GHz, with the peak gains of 11 dBi/11.3 dBi at 28 GHz/39 GHz frequency bands, while the proposed MW antenna achieves a bandwidth of ∼170 MHz with a peak gain of 8.03 dBi.