Design of Dual-Band Miniaturized Loop Antenna for Harmonic Radar Transponder

A dual-band miniaturized loop antenna that can be applied to a bee-tracking harmonic radar transponder has been proposed. This antenna has the following characteristics. First, the overall size of the antenna is compact and measures 5 × 4 × 0.5 mm3. Second, the operating bands of the antenna cover the fundamental frequency range between 9.3-9.5 GHz and the first harmonic frequency at 18.8 GHz. Third, the radiation patterns in both operational bands are similar and omnidirectional. Besides, a novel integrated matching circuit has been proposed to realize the impedance matching of this dual-band miniaturized loop antenna. The structure of this matching circuit is symmetrical without affecting the patterns and does not require additional SMD components. Finally, a prototype antenna with this novel matching circuit is designed and implemented. ? 2021 Taiwan Microwave Association.