Grating lobes of sequentially rotated antenna arrays

The work described involves theoretical and experimental work on large (up to 256 element) arrays for DBS. In order to maximise the array gain for a given number of elements, an array spacing of approximately 0.9λ is used. (No beam steering is involved.) Sequential rotation groups of 2, 3 or 4 elements are considered, with either square or triangular array grids. A nonisolated array distribution network is used. The nominally circularly polarised elements have two orthogonal feed points fed with a 90° phase difference. Sequential rotation is used to give high boresight cross polar rejection. The measured performance of the 256 element array is presented, with 31 dBic gain across the band 11.75 to 12.1 GHz, and with a boresight ellipticity of 0.5 dB