Miniaturized wearable harmonic 5G transponders for multi-object search and rescue applications

In this paper, an innovative dual-split microwave ring resonator is designed for a Fifth Generation (5G) transponder, enabling multi-object search and rescue operations. The proposed novel 5G transponders with resonating patch and defective ground structures exhibit harmonic resonance frequencies at 2.8 GHz, 5.8 GHz, 3.01 GHz, 4.72 GHz, 5.96 GHz, and 7.97 GHz, respectively. The developed single-band and dual-band spiral transponder can effectively differentiate the clutter from the object of interest through high resonant harmonic frequencies. With the novel spiral patch design, the proposed single and dual-band transponders exhibit a reflection coefficient in the range of − 25.23 to − 34.60 dB, gain in the range of − 7.5 to 0.68 dBi, a voltage standing wave ratio of less than 2 dB, and minimum and maximum axial ratios of 7.5 dB and 14.3 dB, respectively. To address the size limitations, the proposed multi-band transponders are designed to be compact, with dimensions of 78.5 × 40 mm2. Its compact size enables easy placement within a safety jacket. Finally, the prototype is fabricated and tested to ensure its functionality and performance.