Multi-Beam Higher-Order Space Harmonics-Enabled Leaky-Wave Antenna Using Microstrip Phase Delay Lines

We present a novel higher-order space-harmonics-enabled leaky wave antenna (LWA) based on a half-mode substrate integrated waveguide (HMSIW) and microstrip phase delay (PD) lines, a design that allows for multibeam radiation. The unit cells (UCs) of the proposed LWA are connected by microstrip PD lines, which allows for the excitation of different nth higher-order space harmonics, resulting in an n-beam radiation pattern. Notably, by appropriate design of the microstrip PD lines, a pair of phase constants with equal amplitude but reverse lateral directions can be created, which ensures that the radiation beam remains fixed in the lateral direction. Furthermore, the inclusion of microstrip PD lines provides phase compensation (PCs) for each UC. Computer simulations demonstrate that the microstrip PD lines significantly improve the realized gain of the LWA while reducing the operating bandwidth. Consequently, the scanning rates, i.e., scanning range divided by operating bandwidth, experience a remarkable increase. The radiation from the proposed LWA is emitted from the open edges of the HMSIW, with tilt slots etched on the HMSIW to facilitate continuous beam scanning. A protype of a tri-beam LWA was fabricated and characterized, and the measurement results confirm excellent performance with a high peak gain ranging from 11 to 13.98 dBi across a continuous beam-scanning angle range from -48 degrees to +47 degrees. The achieved scanning rate is 6.02.