Design and Study Analysis of a Patch Antenna for Two Different Substrates

This study investigates the effects of substrate dielectric constant (εr) and thickness (h) on the impedance and radiation performance of a microstrip patch antenna operating in the 2.3–2.4 GHz bands. According to simulation results, substrate parameters significantly affect return loss, gain bandwidth, and voltage standing wave ratio. Low-permittivity substrate ɛr = 2.2 (RT-duroid) antennas with a return loss of at least −24.19dB and a voltage standing wave ratio of 1.07 at substrate height h = 2.8 mm demonstrate good radiation efficiency and impedance matching. Fringing fields are improved by moderate substrate thickness (2.8–3.2 mm), which improves matching and gain without appreciably exciting surface waves. In contrast, antennas with substrates like FR4 with higher-permittivity ɛr= 4.4, offer return loss of at least −22.91dB and higher bandwidth (≈90 MHz), but their matching is acceptable but inferior with reduced gain (≈3.2–3.6 dB). In every scenario, resonance stays constant in the 2.3–2.4 GHz range with only slight frequency shifts brought on by changes in effective permittivity. Overall, the study confirms that ɛr = 2.2 with h ≈ 2.8–3.2 mm is an ideal configuration for effective ISM band antenna design since it offers the best trade-off between return loss, gain, directivity and matching.