Analysis of rectangular patches conformed on cylindrical surfaces with the discrete mode matching

Kurzfassung

The research in the field of microstrip antennas and arrays has boomed in the last three decades, due to several improvements made in the fabrication of microwave laminates with low losses. Owing to their favourable aerodynamic profile, low weight and low cost for mass production, the range of applications is now very broad and one can find such antennas installed on mobile platforms, satellites, etc. By using flexible substrates, microstrip antennas may be conformed (installed) on curved surfaces. Typical applications are antennas for sounding and launching rockets, aircraft, etc. Whereas the research on simple microstrip structures with planar cross sections has nearly achieved maturity, the development of effective numerical techniques for conformal antennas is still far behind. Several methods have been proposed to the analysis of such antennas. Volumetric techniques, such as the finite element method (FEM) and the finite-difference time domain (FDTD) use 3D meshes to discretize the computational domain. This leads to the need of large computational memory and long computing times. In this paper, the analysis of rectangular patches conformed on cylindrical surfaces under the application of the discrete mode matching method (DMM) will be discussed. This technique employs the Green’s function in the spectral domain, which is obtained using a full-wave equivalent circuit (FWEC) that models the layered structure, so that fast and accurate analyses can be performed. In the DMM, the computational domain must be bounded by suitable lateral boundary conditions. For the analysis of microstrip antennas, absorbing boundaries are used that will be described in the final version of this paper. To demonstrate the technique, calculations of the resonance frequencies of patch antennas will be shown. In this case, an eigenvalue problem has to be solved. The radiation pattern at the resonance frequency is also computed. Validations of our results have been done with the cavity model and good agreement between the results obtained with both techniques has been achieved.