A Patch Filtenna With High Out-of-Band Suppression Levels

A patch filtenna with high out-of-band suppression levels is presented in this letter. The proposed antenna is configured with a parasitic patch and a driven patch fed by a rectangular strip connected to a vertical coaxial probe. Etching four rectangular slots on the rhombus-shaped driven patch can introduce a high-frequency radiation null. One open rectangular ring connected to the rectangular feeding strip will produce a low-frequency radiation null and introduce a resonance mode, making the operating bandwidth wider. Meanwhile, the parasitic patch is placed above the driven patch further to improve the impedance bandwidth and the high-frequency filtering performance. The designed filtenna is 0.62λ₀ × 0.62 λ₀ × 0.13 λ₀, where λ₀ is the free space wavelength at the center frequency. The measured prototype demonstrates that the proposed antenna has a flat gain of 7.9 ± 0.4 dBi over the −10-dB fractional bandwidth of 12.4% from 2.05 to 2.32 GHz, as well as a high suppression level of 26.1 and 20.6 dB at low- and high-frequency out-band. These advantages make the antenna suitable for 5G n34 band communication systems.