Circularly Polarized Periodic Leaky-Wave Antenna Based on Dielectric Image Line for Millimeter-Wave Radar Applications

In this letter, a novel design of a circularly polarized dielectric image line (DIL) based periodic leaky-wave antenna (P-LWA) is presented, which is comprised of only dielectric radiation discontinuities, side gratings, and inclined slots. The unit cell of the proposed design is first optimized with a full-wave eigenmode simulator for the center frequency of 79 GHz. Later, a total of 10 unit cells are cascaded to form the DIL P-LWA, which is connected to an in-plane dielectric transition to feed the antenna from a standard WR12 waveguide. Full-wave simulation and experimental results are provided to verify the functionality of the proposed design in the frequency range 75-85 GHz, where the measured main beam is scanned from -10
^°
to 8
^°
with an axial ratio below 4.2 dB. The simulated gain in the same range varies from 11.2 to 12.7 dBi. The proposed design can be a suitable candidate for millimeter-wave radar applications.