Design of a low-profile 2 to 6 GHz circular polarized single arm hexagonal spiral array antenna

We introduce a low-profile circular polarized, single-arm hexagonal spiral array antenna having a 30° beam scan without grating lobe operating 3:1(2 to 6 GHz) bandwidth placed on a ground plane. The array is composed of regular hexagonal spirals fed by 50 Ohm coaxial cable without Balun. A spurious resonance occurs in the feeding structure due to the periodic structure when the element antennas are arranged, and the resonance can be suppressed by using ferrite. A prototype 8 × 8 array is fabricated and measured. As a result, we implemented a circularly polarized antenna with an axial ratio of 3.5 or less that enables 30° beam steering of 2~6GHz(3:1).