A New Butterfly Radiating Element for Circular Polarized Series Fed Phased Array with Wide Axial Ratio Beamwidth at Millimeter Wave Band

A new wide beamwidth circular polarized radiating element known as the Butterfly antenna is proposed for series fed phased array antenna applications. The unit Butterfly radiating element investigated at millimeter wave band (86 GHz) demonstrates superior performance with axial ratio (AR) beamwidth of 140° and symmetric pattern performance compared to a conventional Herringbone antenna element. A series-fed 8 × 24 planar array has symmetric beam steering capability of ±34° along φ = 0° plane of the array. While a full phased array antenna with its beamforming network is being developed and fabricated, a passive fixed beam aperture prototype of size 32 × 24 is fabricated and experimentally verified for high purity right-hand circular polarized (RHCP) radiation pattern in the broadside direction.