Analysis of Circular Arrays on Cylindrical Surfaces

The analysis of conformal arrays has been deeply developed and many authors have proposed either simplified models, based on single mode theory [1]-[4] or more accurate models but at the cost of a long computation time[5]. In this contribution we use the Multimode Equivalent Network (MEN) formulation [6] together with the Unit Cell approach [7], applied to waveguide arrays conformal to cylindrical structures, to obtain an integral equation. The generality and efficiency of this method gives the possibility of developing an eficient and accurate CAD tool for the analysis of complex cylindrical structures including radomes. Furthermore, due to the modularity of the MEN formulation, coaxial excitations and tuning elements can also be easily integrated in the array structure. The formulation starts with the imposition of the boundary conditions and leads to a Multimode Equivalent Network Representation of the basic junction, namely the radiating transition between a rectangular aperture on a curved surface and the free space. The elements of the network representation are specified in terms of an integral equation that is then solved using the method of moments (MoM). The expansion function used in the MoM takes into account the proper field singularity due to presence of the edges on the surface discontinuity [8]. The key feature of the approach proposed is in that the network formalism allows for easy end efficient integration of the radiating transition with additional waveguide discontinuities and transitions thereby allowing for the complete full-wave analysis of very complex integrated array structures.