Sequentially rotated arrays with reduced sidelobe levels

The use of sequential rotation in circularly polarised antenna arrays leads to reduced crosspolarisation and input VSWR but also gives rise to significant crosspolarised grating lobes. It is shown that these lobes can be reduced by applying rotation over larger sections of the array. Results are given for configurations where rotation is applied to 2*2 element subarrays and where rotation is applied over an 8*8 element subarray. Off-principal-plane crosspolarised lobes are reduced by up to 10 dB over conventional sequential rotation arrays with lobes of less than -29.5 dB for an array with 4 dB element axial ratio.