Design of a triple patch antenna element for double curved conformal antenna arrays

The number of antenna elements on a planar or curved antenna aperture required for high directivity and two-dimensional beam steering can easily become very large, especially if an element spacing around half the free space wave length is required. The present paper describes the design of an antenna sub-array carrying 3 circularly polarized patch antennas at a centre frequency of f = 9.5 GHz and a phase corrected feed network on a common substrate. The sub-array is suited for easy integration into antenna arrays with double curved aperture and can be seen as a trade-off between antenna gain vs. beam granularity. The application of the triple patch antenna to the development of a spherical antenna array with 95 sub-arrays, a diameter of 300 mm and an opening angle of 112° is also shown. Experimental results on antenna matching and radiated far field patterns as well as numerical beam forming results are presented.