Low-cost circularly polarized spiral antenna array for 60 GHz applications

A 4 × 4 circularly polarized antenna array with a substrate integrated waveguide feed network is proposed in this paper. The array is fabricated using low-cost printed-circuit-board and plated-through-hole technologies. The wideband single element is a modified spiral antenna with unequal arm lengths. The measured −10-dB reflection coefficient and 3.2-dB axial ratio bandwidths are 15.7% and 15%, respectively, while the measured gain at 60 GHz is 18.7 dBic.