Synthesis of optimal sum and difference patterns from time modulated hexagonal planar arrays

An efficient array synthesis technique is developed for the design of optimal monopulse antennas in time modulated planar arrays with triangular lattices and hexagonal boundaries. Major emphasis is laid on the realization of low sidelobe array patterns from uniform amplitude excitations, and the inherent sideband radiations in time modulated arrays are suppressed to a sufficient low level. The synthesis technique implements the differential evolution strategy (DES) as the optimization tool, and a fast computation method based on 2D Fast Fourier Transform (FFT) is employed to speed up the optimization. Numerical results show that with the aid of the time modulation technique, the sum, difference, and double-difference patterns are obtainable from an array with fixed uniform amplitude excitations, thus demonstrating the effectiveness and validity of the proposed technique.