(40 to 65) GHz Higher Order Mode Microstrip-Based Dual Band Dual Beam Tunable Leaky-Wave Antenna for Millimeter Wave Applications

Abstract

This article proposes a microstrip leaky-wave antenna with dual symmetrical side beams for complete $V$ -band radiation coverage. The frequency sweeping dual-beam scanning is obtained from 50–65 GHz due to wideband excitation of the microstrip second higher order mode. Appropriate metallic via hole placement realized a back-to-back half-mode pair, which can also generate two symmetrical side beams in the E-plane with enhanced gain within 40–55 GHz. Mode switching was achieved electronically by incorporating p-i-n diodes with a proper biasing network. The final antenna design was prototyped to validate the design concept. The leaky band in microstrip higher order modes was analyzed by dispersion characteristics and Bloch impedance. An operating frequency range and a scanning range in the H-plane were obtained from 50–65 GHz with 12°–80° for unbiased state and 41–53 GHz with 20.4–76° for biased state, respectively. The antenna exhibited a measured 10 dB return loss bandwidth of 26% and 27.65% and a peak gain of 19 and 18.6 dBi, for the two states, respectively, with average sidelobe level of <−15 dB and minimum cross-polarization of 25 dB. The simulated results agreed well with the experimental data, thus validating this single-layered structure for millimeter-wave wireless applications.