Wideband millimeter wave circularly polarized substrate integrated waveguide end-fire antenna array

Abstract

A wideband circularly polarized (CP) substrate integrated waveguide (SIW) end-fire antenna array operating at millimeter wave band is proposed in this paper. Wideband CP performance (with |S 11 | lower than −10 dB and axial ratio (AR) lower than 3 dB) of an array element is achieved by placing an antipodally printed electric dipole in front of an SIW aperture with a tapered balun transition. The configuration of the proposed CP end-fire element shows great superiority as flexibility in feeding structure, compactness in size, as well as implementability in array construction. As a proof, a four-element array is thereby designed by employing a T-shaped four-way power divider. Results indicate that the proposed array operates with a 14.3% impedance bandwidth ranging from 19.4 GHz to 22.4 GHz and a 17.5% 3-dB AR bandwidth ranging from 19.3 GHz to 23 GHz.