Sequentially rotated arrays with reduced sidelobe levels

A companion paper by Smith and Hall (see ibid. vol.141, no.4, p.313-320, 1994) has described the effect of sequential rotation on radiation pattern performance of circularly polarised arrays. Distribution errors result in significant grating lobes that limit bandwidth if resonant elements such as microstrip patches are used. This paper describes the performance of new sequential rotation configurations that reduce grating lobes. Two techniques, rotation of subarrays and large spiral subarrays are discussed. Grating lobe reduction of up to 10 dBs is obtained together with reduction of the pattern frequency dependence