A compact quad‐band circular cavity backed substrate integrated waveguide antenna for millimeter wave applications.

In this letter, a compact circular cavity‐backed, circularly polarized substrate integrated waveguide (SIW) multiband antenna is proposed. In the outer circular cavity, an array of two periodic metal slots, tilted at an angle, resonate at 25.32, 26.44, and 28.83 GHz, and the inner circular cavity's periodic slots radiate at 28.01 GHz. Two concentric SIW cavities are structured in such a distinct manner that no loss due to leakage takes place thus, achieving a maximum isolation of −43.8 dB at 28.83 GHz. The miniaturized antenna has dimensions of 2.2λo × 2.2λo × 0.1λo where λo is the operating wavelength. It achieves a maximum gain of 9.1 dBi at 26.44 GHz, and VSWR < 2 is achieved at all frequency bands. The antenna is circularly polarized at 26.44 and 28.01 GHz as well. The design results are plotted in the Ansys high‐frequency structure simulator version EM19.2 tool. The proposed antenna is fabricated and tested using an Anritsu Vector Network Analyzer version v4.0 with an anechoic chamber setup. [ABSTRACT FROM AUTHOR]