Application of macros for automated performance of the same type operations when simulating SIW-based slotted waveguide antennas in Ansys HFSS CAD

Abstract

SIW slotted waveguide antennas contain numerous equidistantly spaced vias and many slots distributed following a particular field distribution. Ansys HFSS CAD user must manually repeat the same type of operations when creating slots or vias. Automating these routine operations is advisable to eliminate design errors and speed up model construction. This paper aims at complete automation of SIW resonant slotted waveguide antenna arrays modelling in CAD Ansys HFSS, including model construction, running simulations and displaying simulation results. There are multiple procedures for slotted waveguide antenna synthesis. For small waveguide antenna arrays with a number of elements less than 15, the internal and external slots coupling consideration is beneficial, while for large waveguide antennas, no mutual coupling assumption can be made (so-called “energy method”). The energy method has been used to determine the coordinates of the longitudinal slots on the broad wall of the SIW based on a given side lobe level. The slot resonant length has been determined using substrate permittivity and operating frequency. The number of slots has been obtained based on the required half-power beamwidth. SIW dimensions have been calculated using the given operating frequency and the dimensions of the filled rectangular waveguide. An IronPython script has been developed to automate the antenna's model construction, automatic simulation and determination of its characteristics. All script commands have been taken from the “HFSS Scripting Guide” document integrated into Ansys HFSS. The tangible outcome of this work is the development of the IronPython script for fully automated modelling of SIW resonant slotted waveguide antennas. The script builds an antenna model from scratch based on a given antenna characteristics, assigns excitation port and radiation boundary conditions, and displays the simulation results – a radiation pattern at a fixed frequency. The script significantly reduces the antenna design time by eliminating the need to repeat the object creation operations.