A Fixed-Frequency Beam-Scanning Leaky Wave Antenna Based on 2-bit Phase Control Units for Millimeter-Wave Applications

This article presents a fixed-frequency beam-scanning leaky wave antenna (LWA) based on phase control in a millimeter-wave (mm-wave) band. The antenna is composed of a groove gap waveguide (GGW) with TE01 single-mode transmission and 56 perturbation elements with 2-bit phase modulation capability. The radiation of each patch unit is controlled by four diodes which are welded on the bottom pads. By controlling the states of diodes, the unit can realize four phase states of 0 degrees, 90 degrees, 180 degrees, and 270 degrees. By changing the phase states of all the perturbation elements located on the LWA aperture, the beam-scanning property at a fixed frequency can be realized. Then a method to suppress the sidelobe levels (SLLs) caused by high-order harmonics is proposed. The overall transmission structure of the antenna is based on an air-filled GGW, which is utilized to reduce the dielectric loss in the mm-wave band. The antenna is simulated and manufactured. The measured results show that the antenna has a high realized gain of 16.4 dBi, and a wide beam-scanning range of more than 110 degrees over the operating frequency band, demonstrating the feasibility and potential application values of the antenna.