Design and Analysis of Microstrip Patch Antennas for Sub-6GHz 5G: A Comparative Study of Substrates and Feeding Techniques

In this paper, Microstrip patch antennas were designed at a center frequency of 3.7GHz, and the performance parameters were analyzed using three different feeding techniques on two different substrates. The antennas were designed using Direct, Inset and Quarter wave feeds on FR4 substrate having a dielectric constant (εr) of 4.4 as well as using low loss RT-Duroid substrate with Dielectric constant 2.2 by keeping the constant size of 60mm*60mm*1.6mm. The antennas' performance variations regarding Return Loss (S11), voltage standing wave ratio (VSWR), Gain, Radiation Efficiency, Bandwidth, and Impedance were analyzed using the ANSYS HFSS simulator. The analysis shows S11 of -21.2316 dB, -32.1585 dB, -22.9989 dB and -22.27 dB, -29.2056 dB, and -21.45 dB, respectively, for the Direct, Inset, Quarter wave feeds on FR4 and RT Duroid substrates respectively at 3.7GHz. The study shows that better impedance matching was obtained using an Inset Feed than the other two, with VSWR values of 1.0506 and 1.0718, for the equal length and width of the substrate and ground plane. The gain of the antennas was found to be 4.72 dBi,4.3 dBi,4.33 dBi and, 8.08 dBi, 8.05 dBi, and 8.10 dBi, respectively. The moderate radiation efficiencies of 65.06%,50.84% and 51.54% were obtained for the design using a lossy FR4 substrate. The study reveals that the design on low-loss RT Duroid substrate improves the Radiation efficiency and the Gain but minimizing the bandwidth compared to the design on FR4 substrates.