Radiation Optimization for Phased Arrays of Antennas Incorporating the Constraints of Active Reflection Coefficients

High-power radiations from active antenna arrays may result in strong reflected power to cause RF device breakdown by the strong interelement mutual coupling. An excitation weighting synthesis of antenna arrays incorporating the constraint of active reflection/transmission coefficients between antenna elements is presented to optimize the radiation. It may enhance interelement isolation, reducing the effort of using sophisticated hardware-based structures that have difficulty in broad-angle beam steering. In the synthesis, the cost functions incorporate the difference between the optimized and the predefined excitation weightings of radiation patterns with limited reflected power or active reflection coefficients as a constraint. This article first introduces the basic concept to show the operational mechanisms. Practical definitions of cost functions are described to synthesize the radiation pattern considering the mutual coupling effects. The case without setting an initial desired radiation pattern is also examined for comparison. Numerical full-wave simulations are presented to validate the synthesis concepts by examining the characteristics of gain, sidelobe level (SLL), and port reflection coefficients.