Conformal phased array breadboard

Flush mounted slot antenna systems on metallic cones or ogival surfaces can be inertialessly scanned in the required direction. Since scanning over a wide angular region is generally desired, the radiation characteristics, including the effect of mutual coupling on the radiating elements, must be investigated before the more detailed system aspects are considered. To this end, various approximation techniques have been examined for use in pattern calculations and in impedance calculations. These include the approximate asymptotic approach and the equivalence principle technique. The approximation techniques provide simplified computations as compared with the exact technique, and are not applicable to all conditions. A combination of exact and approximation techniques is generally required to design or analyze an array. The approximate asymptotic approach, which allows the separation of the diffracted field and geometrical optics fields, has been examined in detail. It appears that the asymptotic representation of the Legendre function chosen for the analysis leads to divergent expressions as the mode number m is increased, and hence limits the usefulness of the asymptotic approach in the present problem. The divergent nature of the asymptotic expression is verified by computed radiation patterns of several azimuthal modes. A computer program is being developed to apply the equivalence principle technique to a conical surface.