Surrogate Models for Antenna Placement on Large Platforms: A Case Study

The Institute of High Performance Computing (IHPC) is a Research Institute under the Agency for Science, Technology and Research (A*STAR). Established in 1998, IHPC seeks to power discoveries through advanced methodologies, techniques and new tools in modelling, simulation and visualization. The RF engineering group develops advanced computational electromagnetics and multiphysics algorithms and tools, leveraging vast knowhow in electromagnetic compatibility (EMC) for a wide range of applications covering both small-scale and large scale problems, such as high-speed electronics, urban and space EMC. IHPC has delivered numerous impactful projects in collaboration with companies and government agencies both local and overseas.

The Institute of High Performance Computing (IHPC) was faced with the challenge of developing cost-effective and innovative approaches for modelling, diagnosing and solving electromagnetic compatibility (EMC) problems. The complexity of the electromagnetic (EM) system and environment was ever-increasing, and the institute was tasked with handling electrically-large and multi-scale EM problems such as the antenna placement on large platforms. Additionally, they had to deal with multiphysics problems such as the electrical-thermal-mechanical analysis of composite materials. In a specific project, the institute needed an efficient modelling tool to identify optimum antenna positions and minimize interference between various antennas on electrically large platforms. The geometric model of a proprietary antenna was difficult to obtain from the vendor, necessitating the development of a surrogate model to represent it in the antenna placement simulations on the platform. The antenna-on-platform problem was both electrically-large and multi-scale, and could no longer be practically solved with a fullwave only method.

The team at IHPC successfully developed surrogate models to represent a patch array and slotted waveguide antenna based on the phaseless radiation pattern information, usually available in the antenna data sheet. The surrogate models represented the radiation and scattering performance of the original antennas. The accurate full-wave simulation of FEKO was used during the development to reveal the current distribution on the antenna, which was crucial to identifying the currents that contributed to the radiation. The design parameters of the surrogate models were determined by exploiting FEKO’s powerful optimization function. Once an accurate surrogate model was available, it was mounted on platforms at various locations to compute and compare the installed radiation pattern. For electrically large platforms, FEKO’s hybridized solvers were essential. An area around (and including) the antenna could be solved with MoM/MLFMM, while the remaining platform geometry was solved simultaneously with PO, LE-PO or RL-GO. This true hybridization approach ensured both an accurate and an efficient solution.

• The surrogate models developed by the team at IHPC proved to be effective in representing the original antennas. The models were mounted on an aerial vehicle to validate their capability of representing the original patch antenna array. The radiation patterns of the patch antenna array and its surrogate model were computed and showed good agreement, proving the surrogate model’s capability. Another example of an antenna mounted on an airframe platform, using the surrogate antenna approach, was validated with an in-house code that was developed at IHPC. The FEKO simulation results were validated with this in-house code, further demonstrating the effectiveness of the surrogate models.