Asymmetric‐fed triband antenna for military radars and 5G applications using microstrip technology

Abstract

Achieving antenna size reduction while maintaining high efficiency and multiband characteristics with wide bandwidths across all the operating frequency bands is highly demanded and challenging in microstrip antennas. A novel compact triband quasi-rho-shaped and cost-effective antenna is designed on a 7 × 7 × 1 mm3 FR4 substrate having a permittivity of 4.4 and a loss tangent of 0.02. With an electrical size of 0.39λ0 × 0.39λ0 × 0.056λ0, where λ0 is the free space wavelength at 16.84 GHz, a circular slot and asymmetric microstrip feed are used to achieve the desires performance. The proposed antenna is designed, simulated, and optimized using high-frequency structure simulator (HFSS) software, and its prototype is fabricated to validate its electromagnetic performance. Furthermore, an equivalent circuit is proposed using the Foster canonical model. The proposed antenna exhibits a maximum stable gain of 5.32 dB and an average radiation efficiency of 77.87% in all the operating frequency bands. The measurement results show that the antenna covers (16.84–18.15 GHz), (24.78–27.40 GHz), and (34.47–37.22 GHz) bands centred at 17.39 GHz, 25.98 GHz, and 35.83 GHz, respectively, with a minimum wide bandwidth (S11 ≤ −10 dB) of 1.31 GHz. The acquired results illustrate that the quasi-rho-shaped antenna is suitable for military radars and 5G applications.