Design and analysis of a dual-band 2 × 2 circularly polarized microstrip patch array antenna for IoMT applications

A compact planar dual-band 2×2 circularly polarized (CP) microstrip patch array antenna operating at 1.6GHz and 2.4GHz for Internet of Medical Things (IoMT) applications is presented. The proposed configuration is derived from a conventional linearly polarized square patch, where circular polarization is achieved through asymmetric corner truncation. The dual-band operation and CP characteristics at both frequency bands are realized by incorporating a defected ground structure (DGS) and integrating L-shaped stubs into the ground plane. An equivalent transmission-line model of the proposed corporate-fed array is developed to explain its operating mechanism. The antenna is fabricated on a 1.6-mm-thick FR4 substrate to validate the design. The measured results indicate that the incorporation of L-shaped stubs improves the impedance bandwidth (IBW) from 16% to 22.8% (2.02–2.54GHz) and from 11% to 13% (1.52–1.73GHz). In addition, axial-ratio bandwidths (ARBWs) of 2.08%, 1.83%, and 8.62% are achieved at 1.6, 2.16, and 2.4GHz, respectively. The antenna provides peak gains of 0.82dBi at 1.6GHz and 5.0dBi at 2.4GHz. Experimental integration into an Arduino/ESP32-based IoMT test demonstrates successful real-time wireless transmission of physiological sensor data with minimal packet loss, confirming the suitability of the proposed antenna for IoMT applications.