Using a Higher-Order Basis Function based Method of Moments Analysis for Designing Compact Antenna Test Ranges
Authors: Vince Rodriguez, Anil Tellakula, Daniël Janse van Rensburg, Branko Mrdakovic
Publication: AMTA 2022
Copyright Owner: NSI-MI Technologies, WIPL-D
Abstract — Full wave electromagnetic simulation of a Compact Antenna Test Range (CATR) is not trivial given its electrical size. Typically, the reflector geometry is simulated using asymptotic methods using an assumed feed pattern, while RF absorber and its effects are ignored. A boundary element method of moments (MoM) implementation, using higher-order basis functions (HOBFs) is a good numerical technique for analyzing these ranges since the equations are only solved at the interfaces between different homogeneous regions. There is therefore no need to discretize and solve equations for the fields in the large empty volume portion of the CATR, unlike when using Finite-Difference Time-Domain (FDTD) or Finite Element Methods (FEM). Using HOBFs allows for the mesh size of the discretized CATR geometry to be as large as two wavelengths, reducing the number of unknowns while enabling fast, efficient solutions.
In this paper, a commercial software package that incorporates MoM with HOBFs is used to model a CATR that consists of a blended rolled edge reflector. The results for the reflector and feed model are compared with asymptotic analysis results to show agreement. A realistic feed horn, support structure, and RF absorber is then introduced to the model and its performance is also included to predict field distribution in the CATR test zone. Using this field solution, the Poynting vector is calculated to visualize the flow of energy in the range and from these results proper RF absorber layout can be designed to ensure optimum test zone performance. It is also shown how feed structure absorber treatment impacts CATR test zone performance.View The Paper