A New Method for End-Fire Array Gain Optimization Using Spherical Wave Expansion

This work presents an analysis of the radiating properties of lossy antennas using the Spherical Wave Expansion (SWE) theory. A new formula to predict the gain of uniformly-spaced end-fire arrays based on the dissipation factor is proposed. The latter allows an analytical synthesis of the complex excitation coefficients associated with the array elements to achieve supergain characteristics. Similar studies have been previously dealt with (super)directivity optimization, characterized by high sensitivity and severe gain attenuations, when the dimensions of the array are considerably reduced. In this context, the proposed study shows a significant improvement of the antenna gain and efficiency compared to synthesis procedures having an objective of the directivity maximization.