Comparative Study of Ground-Slot Geometries for 5G Microstrip Antenna Performance Enhancement

This research paper investigates the impact of inserting a ground slot on the frequency performance of a monopole-type microstrip patch antenna. To examine this, a reference antenna, which is a simple rectangular monopole with the dimensions 2.4 × 2.04 mm2, was mounted on a 12 × 12 mm2 Rogers RT 5880 substrate with a thickness of 0.254 mm and a dielectric constant of εᵣ = 2.2. It was also fed by a 50 Ω microstrip line. This work compares the effects of four different geometries of rectangular ground slots: rectangular, triangular, half-ring, and half-circle, on the performance of the microstrip patch antenna. The no-slot baseline antenna showed a resonance of 12.55 GHz and a reflection coefficient of −15.9 dB. Adding a ground slot allowed the advent of single or dual-resonant frequencies, which significantly enhanced the appropriateness of the antenna in 5G usage. Notably, the rectangular slot with b1 = 3 mm achieved a resonance of 22.5 GHz, with a reflection coefficient of −33.7 dB, while b1 = 1 mm enabled dual-band operation at 11.77 GHz and 38.3 GHz. Triangular slots provided strong single-frequency operation between 26 GHz and 31 GHz, and the half-circle slot with r3 = 1 mm resonated at 12 GHz with a reflection coefficient of −39.5 dB. Although the half-ring slot had a comparatively lower reflection coefficient, it still showed dual-band potential at 11.1 GHz and 34.14 GHz. The simulation results were validated using HFSS, demonstrating good alignment. The gain of the selected antennas was also investigated, where the highest gain of 4.2 dBi was achieved by the half-ring slot design, and the lowest gain of 3.09 dBi was obtained with the half-circle slot. These findings confirm that ground-slot integration is an effective technique for frequency tuning and performance enhancement in 5G antenna design.