Broadband Microstrip Antenna Array Design for Wireless Communication in the 2.3–2.5 GHz Band
Abstract
This paper presents the design, simulation, and experimental validation of a planar broadband microstrip patch antenna array with passive beam tilt capability, optimized for operation in the 2.3–2.5 GHz ISM band. A 2×2 rectangular patch array was developed on a low-cost FR-4 substrate, employing a quarter-wave transformer (QWT)-based corporate feeding network with asymmetrical feedline lengths to introduce phase shifts. This configuration achieves a fixed downward beam tilt of approximately 30° without the use of active components or complex geometries. The fabricated antenna demonstrates a measured impedance bandwidth of 202 MHz (2.34–2.542 GHz), an S_11 parameter of approximately -20 dB, and a half-power beamwidth (HPBW) of 60° in the E-plane. Full-wave simulations in HFSS and outdoor experimental measurements confirm the intended radiation behavior and impedance characteristics. The proposed antenna design offers a compelling combination of bandwidth, gain, mechanical simplicity, and directional control, making it well-suited for industrial IoT nodes, ceiling-mounted access points, and wireless sensor networks.