Element reduction in phased arrays using dual-mode self-scanning elements

A method for reducing the number of elements in phased arrays that uses dual-mode array elements such as horns or microstrip patches is introduced. It is shown that the excitation of the second mode can be used to locate preferentially a null on the element radiation pattern. In particular, when the null is moved to the array grating lobe location, it causes its cancellation and permits selection of large interelement spacings. The number of array elements can therefore be reduced. The method is then applied to both triangular and rectangular lattice structures having uniform or tapered excitation. It is found that the method can reduce the number of elements by as much as 26% for the triangular lattice and by 45% for the rectangular lattice.