Antenna modelling and pattern synthesis method for conformal antenna arrays

Abstract

We investigate the influence of inter-element coupling in conformal arrays. Physical parameters are examined as well as possible compensation methods. As a first approach, a simplified antenna model based on the interaction between idealised elements (electrically small dipole and current loop antennas) has been developed. Experimental results show that the coupling influence predicted using this antenna model can be compared to the effects found in practical antenna arrays. Also, a synthesis method for conformal arrays based on Huygens' equivalence principle has been developed. The reference field is composed of cylindrical or spherical sector wave modes which are superposed to produce the desired far field. Array element weights can then be derived by projection of the reference fields onto the element positions. Both the antenna modelling and pattern synthesis method have proved useful for conformal array performance evaluation. Various single and double curved array shapes have been calculated to support the design of antenna arrays. The presented pattern synthesis method using spherical sector wave modes can be used to calculate excitation coefficients for double curved conformal antenna arrays. The resulting modal far fields may also serve as reference fields for other beamforming methods.