Millimeter-Wave Wideband Circularly Polarized SIW Cavity-Backed Stacked Dipole Array Antenna

In this letter, a wideband circularly polarized (CP) substrate integrated waveguide (SIW) cavity-backed stacked dipole array antenna is proposed for millimeter-wave (mm-wave) applications. First, double-layer SIW cavities are utilized to construct the CP stacked dipole element, which consists of two crossed stacked linearly polarized electric dipoles and four metallic probes in driven, short-circuited, and suspended states. These probes can achieve orthogonal phase and energy coupling through a magnetic field without additional baluns. Next, the wideband CP working principle and the parameter analysis of the element are addressed. A full corporate feeding scheme with a four-way SIW power divider and four SIW cavities is adopted for array verification. Finally, a 4 × 4 array is designed, fabricated, and measured, which demonstrates a wide impedance bandwidth of 28.1%, a wide axial ratio bandwidth of 23%, and a peak gain of 19.35 dBic. These results demonstrate that the CP stacked dipole is a promising candidate for mm-wave wireless systems.