A Broadband Millimeter-Wave Fixed-Beam Leaky Wave Antenna Loaded With Printed Quasi-Yagi Radiating Elements for Gain Enhancement

In this communication, a novel broadband fixed-beam leaky wave antenna (LWA) suitable for millimeter-wave (mm-Wave) application is proposed. The antenna comprises a ridge gap waveguide (RGW), a set of equal-length microstrip branches, and a printed quasi-Yagi antenna array with inclined arms. Periodic slots are etched on top surface of RGW, which couple energy to microstrip branches from RGW. The microstrip branches then transmit the energy to quasi-Yagi antennas for radiation. Using quasi-Yagi antenna array to enhance the gain makes LWA attractive in mm-Wave applications. Because of the nondispersive characteristics of RGW, the LWA can radiate at a fixed angle within a broadband. By selecting the ratio of period of slots to distance between adjacent radiating elements, the main beam in any forward direction can be realized. For verification, an LWA with a beam direction of 40° is fabricated. The experimental results indicate that the designed antenna achieves excellent fixed-beam radiation performance within the frequency range of 22–37 GHz (50.8%), with only a slight beam deviation of 6° (varies from 37.8° to 43.8°), and a peak gain of 16.5 dBi can be realized. This design shows great potential in wideband mm-Wave applications.