A low-cost FR-4 microstrip patch antenna with high realized gain and radiation efficiency is presented in this paper using a novel asymmetric dual air-gap stack to effectively reduce dielectric loss and suppress surface-wave excitation. Beginning from a traditional FR-4 patch foundation, the configuration is developed through symmetrical and then asymmetrical air-gap integration in which both gaps enable additional design freedom to tune the resultant effective permittivity and coupling to parasitic patch. Full-wave simulations (CST) indicate that the gain of the prototype configuration reaches a maximum realized gain as high as 9.05 dB and the radiation efficiency is 83.1% compared with 2.29 dB and 36.5% for the template FR-4 design, respectively. The optimized air-gap spacing enables dual-band operation at 4.953 GHz and 8.146 GHz, with an impedance bandwidth of 526 MHz at the upper band. Surface-current distributions allude to the diminished surface-wave activity and enhanced radiation property of the investigated configuration. Because of its straightforward stack-up and use of standard FR-4, the antenna provides a pragmatic pathway to high-efficiency operation for sub-6 GHz and X-band wireless applications.

A low-cost FR-4 microstrip patch antenna with high realized gain and radiation efficiency is presented in this paper using a novel asymmetric dual air-gap stack to effectively reduce dielectric loss and suppress surface-wave excitation. Beginning from a traditional FR-4 patch foundation, the configuration is developed through symmetrical and then asymmetrical air-gap integration in which both gaps enable additional design freedom to tune the resultant effective permittivity and coupling to parasitic patch. Full-wave simulations (CST) indicate that the gain of the prototype configuration reaches a maximum realized gain as high as 9.05 dB and the radiation efficiency is 83.1% compared with 2.29 dB and 36.5% for the template FR-4 design, respectively. The optimized air-gap spacing enables dual-band operation at 4.953 GHz and 8.146 GHz, with an impedance bandwidth of 526 MHz at the upper band. Surface-current distributions allude to the diminished surface-wave activity and enhanced radiation property of the investigated configuration. Because of its straightforward stack-up and use of standard FR-4, the antenna provides a pragmatic pathway to high-efficiency operation for sub-6 GHz and X-band wireless applications.