M. B. Manuilov, B. D. Manuilov
The radiation pattern synthesis methods based on ring harmonics concept are discussed for the case of waveguide-fed axial slot arrays on circular cylinder. Two heuristic methods for single-lobe pattern shaping and the matrix synthesis method are proposed. The first heuristic method is based on exception of some selected ring harmonics from the process of radiation pattern shaping. In the second heuristic technique the radiation pattern shaping is implemented by means of the harmonic weights introduction.
The proposed matrix synthesis technique allows independent controlling the direction, amplitude and phase of each individual main beam of the multi-lobe pattern. The vector of currents on the slots is calculated to maximize the functional that is the physical analogue of directivity in the case of multi-lobe pattern. In accordance with the suggested approach the functional is represented as the Hermitian forms ratio that includes the information about specified orientations, amplitudes and phases of the all main beams of radiation pattern. The optimal vector of current amplitudes on the slots is evaluated analytically using the matrix theory formalism. The suggested matrix synthesis technique combined with 3D electromagnetic model of cylindrical array provides the ability to control the local as well as the total side-lobe level.
It was shown that by implementation of proposed matrix synthesis method the substitution of the ring harmonic radiation patterns instead of array elements (slots) radiation patterns provides the absolutely equal final results. The synthesis techniques based on ring harmonics concept may be appropriate in the case of array excitation by means of Butler matrices.