Sequentially rotated phased array consisting of higher order mode elements

A circular or ring microstrip antenna with second or higher order mode excitation can form a conical pattern with the null at broadside and the beam peak at an elevation angle of about 45 degrees, and can be effectively applied as an element of conformal land mobile phased arrays for satellite communication. However, higher order mode microstrip antennas have a serious problem concerning axial ratio characteristics. The author proposes a method of designing a sequentially rotated array consisting of higher order mode elements in order to reduce axial ratio quality. This sequentially rotated array requires different rotation angles for different mode excitation, while the phase shift is independent of the mode excitation. The application of this sequentially rotated array to a phased array consisting of higher order mode elements is described.