Printed Planar 8 $\times$ 8 Array Antenna With Circular Polarization for Millimeter-Wave Application

A new type of printed millimeter planar antenna with circular polarization for 60-GHz range is proposed. Radiation elements with two open tape rings are arranged in a two-dimensional 8×8 antenna array. Feeding is synphase network with tapered symmetrical (balanced) microstrip in the same plane as the radiation elements. The 8×8 array is fabricated in the conventional technology. To test reproducibility, three samples are fabricated. Measured S₁₁ (VSWR), gain, and axial ratio (AR) are very good and in very good agreement between all three samples: AR<;3 dB about 25% and gain near 20 dBi.