Modified Inverted F-Shaped Microstrip Patch Antenna with Circular and Rectangular Slots and Partial Ground for the Internet of Things (IoT) Applications

The paper describes a miniaturized, high-performance modified inverted F-shaped microstrip patch antenna designed for Internet of Things (IoT) applications, which need to operate at the 2.45 GHz ISM band. The antenna was designed on a substrate (εr = 4.4, tan δ = 0.025, FR-4) whose overall dimension was 40 × 25 × 1.6 mm³, and had both rectangular and circular slot perturbations along with a partial ground plane for simultaneously enhancing the bandwidth, impedance matching, and radiation efficiency. The designed structure provides a simulated return loss of −19.17 dB, 23.26% fractional bandwidth (2.19–2.76 GHz), 3.40 dBi peak gain, and 83.84% radiation efficiency. Its bi-directional radiation makes it extremely suitable for short-range IoT networks. Experimental verification through a Vector Network Analyzer (VNA) proves close correspondence with the simulation results. To validate real-world usage, the antenna was incorporated into an IoT-enabled home automation setup using an ESP8266 NodeMCU. The substitution of the onboard antenna with the presented fabrication resulted in reliable and stable wireless correspondence, validating its functional usability for IoT-enabled intelligent environments requiring broadband, low-form, and energy-efficient wireless solutions.