Microstrip antenna array design for harmonic radar applications
University of New Brunswick
Harmonic radars are employed in the entomology field to facilitate the detection and tracking of small insects as it requires a radio transceiver to be low mass, in the milligram range, enabling the transceiver to be curried by insects. The focus of this work is to design, simulate, fabricate and test two lightweight microstrip antennas to replace the currently used parabolic and horn antennas. Ultimately the radar is to be mounted on a UAV so the microstrip technology provides compact lightweight microwave components fitting into a relatively small lightweight planar structure. Microstrip technology combined with antenna array theory and modern PCB fabrication techniques were studied and implemented as a weight reduction method to produce the antenna system. The design of the antennas was realized after computing full wave 3D electromagnetic simulations during the design process where both the transmitting and the receiving antennas are targeted to each have a fan shaped radiation pattern with 25° by 5° beamwidth, a 2:1 SWR or better, a side lobe level below −10 dB and minimum self-interference. The antenna system was characterized in an anechoic chamber by measuring the main parameters using a signal generator, a spectrum analyzer and a vector network analyzer. The design requirements were achieved with antennas weighing 9% of the original components and an SIR of 25.2 dB was produced when a harmonic transponder was 130 cm away from the transceiver.