Calculating the mutual coupling between apertures on convex cylinders using a hybrid UTD-MoM method

The problem of radiation from sources in the presence of smooth convex objects is of great interest in the design of antennas on structures, e.g. conformal arrays. Conformal antenna arrays are required whenever on antenna has to conform geometrically to some shaped surface, like that of an aircraft. In the analysis of conformal antennas it is possible to obtain a modal solution to same canonical surfaces, e.g. a circular cylinder or an elliptic cylinder. But for more arbitrarily shaped bodies other methods have to be used. In this paper a hybrid method of UTD and MoM is used to analyse convex cylindrical structures. This method allows higher order modes to enter the calculations, thus receiving better agreement compared to known results. The UTD solution used is the one published by Pathak et al. (1981). The results from the hybrid method have been compared with measured results obtained from a cylindrical test antenna with 54 apertures built at Ericsson Microwave Systems AB in Molndal, Sweden. When higher order modes are included excellent agreement is obtained between measured and calculated results.