Design and Evaluation of Octet Rectangular Microstrip Patch Arrays: Impact of Feed Line Discontinuities on Antenna Performance

Abstract

The optimal and miniaturized design of the patch antennas is an open field of research. The gain of the antenna and pattern can be improved by efficiently designing an array of patch antennas. This paper presents the design, simulation, and experimental validation of octet rectangular microstrip patch-array antennas operating at 2.45 GHz. The impact of feed-line discontinuities on antenna performance was investigated by comparing arrays with uninterrupted, single-step, and double-step feed lines. Computational simulations using the Finite Element Method (FEM) were conducted, followed by fabrication on FR4 substrate printed circuit boards (PCBs). The antennas were evaluated based on their reflection coefficients (S11), bandwidths, and radiation patterns. The simulated results show that the double-step feed line configuration exhibits superior performance, with an S11 of -13.5045 dB at 2.45 GHz, compared to -8.1193 dB and -8.9194 dB for the uninterrupted and single-step feed lines, respectively. The bandwidth increased from 0.2 GHz for the single-step feed increased from 0.36 GHz for the double-step feed. The experimental measurements of the fabricated antennas closely match the simulated results, with slight deviations attributed to manufacturing inaccuracies and measurement errors. The near-field and far-field radiation patterns demonstrate that the double-step feed configuration achieves higher directivity as well as increased side-lobe levels owing to fabrication errors. The study suggests that the double- step feed line configuration enhances impedance matching, bandwidth, and directivity; however, further optimization is needed to minimize losses and enhance antenna performance.