volume | PIER Journals

Abstract

In order to improve the efficiency and safety of emergency rescue operations, a wearable circularly polarized (CP) antenna suitable for GPS applications has been designed. It adopts a coplanar waveguide (CPW) feed structure, where the ground plane and radiation patch form an annular gap. The impedance bandwidth and axial ratio performance are enhanced by adjusting the amplitude and phase difference of the current distribution through two pairs of notches and open-circuit branches. When the single antenna is more than 20 millimeters away from the human body model, its CP radiation performance is acceptable, and the peak Specific Absorption Rate (SAR) also meets the required standards. To minimize the separation distance between the antenna and the human body, a 2×2 Artificial Magnetic Conductor (AMC) with in-phase reflection characteristics is integrated at the antenna's bottom as a reflector, which increases the antenna gain and reduces the SAR. Simulation and test results indicate that in the GPS L1 frequency band, the antenna achieves a gain greater than 7 dBi, an axial ratio less than 2 dB, a front-to-back ratio of 24 dB, and a peak SAR of 0.53 W/Kg, which is well below the standard limit of 1.6 W/Kg set by the Federal Communications Commission (FCC). Compared with other relevant antennas, this antenna features compact size, wide impedance bandwidth, and robust anti-interference capability, effectively improving the flexibility and compatibility of the wearable antenna, thereby meeting the demand for efficient and reliable positioning of rescuers.

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Dr. Shuqi Wang

Dr. Yuqin Shi