60-GHz Circularly Polarized Antenna Array Made in Low-Cost Fabrication Process

Circularly polarized (CP) antenna operating in the unlicensed 60 GHz frequency range is useful for millimeter-wave radio and radar applications. In this letter, a 2 × 2 right-handed circularly polarized (RHCP) planar array is demonstrated by using four CP antenna elements. A single element has a gain of 7.5 dBiC, while the resulting 2 × 2 array yields a CP gain of 12.5 dBiC. Substrate integrated waveguide (SIW) cavity is used to back each element in order to reduce the mutual coupling between elements and also improve the overall gain. An experimental antenna prototype made through a conventional low-cost printed circuit board (PCB) technique operates in RHCP mode covering the frequency range of interest from 58 to 62 GHz. The antenna is compact, showing a good radiation performance.