Quad-polarized wideband phased array with reduced sidelobes by interstitial-packing

A quad-polarized wideband phased array antenna system using wideband sinuous antennas is developed and wideband beamforming is demonstrated. The design of wideband sinuous antenna elements as well as the development of the antenna feed network, comprising of a wideband beamformer and polarizer network, is described. To reduce grating lobe effects at higher frequencies, the interstices of the antenna array are filled with smaller antenna elements. For a frequency band of 0.6 GHz to 2.4 GHz, no grating lobes are observed when the beam points at boresight. In comparison, a linear array of sinuous antennas exhibits grating lobes from 1.6 GHz for the same scan angle.