Circular Polarized Antennas With Harmonic Radar: Passive Nonlinear Tag Localization

This research proposes a high performance, low-profile planar design, and demonstration of circularly polarized harmonic antenna arrays for 4 and 8 GHz harmonic radar system, which is equipped, and the antenna's circular polarization (CP) performance is tested using a passive nonlinear harmonic tag (snowflake) in a noisy environment. This work mainly concentrates on investigation of the wave polarization (circular), gain estimation and impedance matching of the antenna arrays that will be potentially assembled to the second-order harmonic radar system operating at 4 and 8 GHz, which plays a critical role in 2-D tag localization and post processing methods. The passive snowflake tag design is implemented in the simulation to determine the current distribution and gain plot patterns in comparison to a classic dipole antenna tag structure. In experiments: a combination of fundamental circular polarized (left-hand) antennas were demonstrated to find axial ratio $ \leq $ 3 dB band. A novel tag 2-D localization measurement, combination of CP harmonic antenna arrays is utilized to perform and obtain the circular polarized received signal power in dBm versus angle rotation by every 10° on a rotating platform setup. Finally, the wireless tag tracking result is achieved by using the designed circularly polarized antennas and the passive nonlinear tag orientation setup.