AMC-Based Low-Profile Dual-Band Slotted Patch Antenna for IoT Devices in the Healthcare System

Abstract

An artificial magnetic conductor (AMC)-based patch antenna with a low profile is developed for wireless devices in IoT-based healthcare systems. The proposed antenna comprises two pairs of circular-shaped patches with circular-shaped slots and a dual-band 4 × 4 array of AMC reflectors with two zero-degree reflection responses to enhance the antenna's radiation performance. For the 2.45 GHz ISM and 5.4 GHz WLAN bands, the patch antenna has dimensions of 0.44λ0 × 0.52λ0 × 0.013λ0, with partial ground structures to improve radiation characteristics. Following that, a unique dual-band symmetrical AMC unit cell with dimensions of 22 × 22 × 1.6 mm3 is developed. There is a gap of 15 mm between the antenna and the AMC surface. The antenna is supported by a 4 × 4 AMC array that has a total dimension of 0.72λ0 × 0.72λ0 × 0.15λ0. The reflection coefficient values of less than − 10 dB in the 1.7–2.5 and 5.1–5.6 GHz bands, with a bandwidth percentage of 38 and 9.3%, respectively. The antenna's gains were 7.2 and 4 dBi inside the bands. Furthermore, the Specific Absorption Rate (SAR) value did not match the WHO's safety and health guidelines. The issue was solved by including an AMC surface in the proposed antenna. At 2.45 and 5.4 GHz, SAR values of 0.58 and 1.04 W/Kg were measured. Vector network analyser and anechoic chamber were used to test the performance of antenna and AMC surface prototypes. There is a substantial agreement among measured and simulated parameters of an antenna. Consequently, the developed antenna combination with the AMC structure is suited for wireless devices in ISM and WLAN bands, often used in IoT-based healthcare systems.