A Circularly Polarized Planar Aperture Antenna Array at 60 GHz Band

A new circularly polarized (CP) planar aperture antenna array for cost sensitive, broadband and high gain millimeter-wave applications is proposed. The antenna is composed of an aperture-patch formation on one substrate layer while a network of substrate integrated waveguide (SIW) is implemented on another layer below that easily feeds the array arrangement through aperture coupling. Circular polarization is achieved by virtue of the diagonal feeding slot and the cross-shaped patch whereas the relatively large opening cavity structure making the physical aperture of the radiating element guarantees high gain at the broadside direction. A 2x2-elements array has been designed at 60 GHz band using printed-circuitboard (PCB) technology, which shows wide axial ratio (AR< 3dB) and impedance (S-11<-10dB) bandwidths of 31% and 25%, respectively, and high left-handed CP (LHCP) gain up to 19 dBic.