This is a continuation of the work presented at the AMTA 2022 symposium to assess the accuracy of on-axis antenna gain with commercially available computational electromagnetic (CEM) solvers [1]. Common practice for computing antenna gain normalization via the gain-transfer technique is to use the on-axis NRL gain curve of a pyramidal standard gain horn (SGH) derived by Schelkunoff and Slayton [2], [3]. Due to approximations in this formulation, Slayton assessed an uncertainty of ±0.3 dB for typical SGHs operating above 2.6 GHz. Since this uncertainty term is often one of the largest terms in the range measurement uncertainty budget for AUT gain, it is highly desirable to reduce it. Many studies in the past have attempted to improve upon Slayton’s expressions for SGH gain, but none have achieved widespread use. The previous investigation demonstrated the use of several commercially available solvers, including HFSS™, CST Studio Suite®, and FEKO® to model the on-axis directivity and gain of a commercial off-the-shelf (COTS) X-band SGH [1]. In that work, the CEM simulation results from multiple solvers in HFSS™, CST Studio Suite®, and FEKO® are shown to be within ±0.0075 dB of each other. This work is an extension to study how closely the simulation models match recent measurements of gain for the same MVG SGH820 horn discussed in previous paper. These measured and modeled results are compared with the international intercomparison results of a similar SGH [4], in conjunction with a best-estimated simulation model of the original dimensions from [4]. To capture the differences of the physical as-built antenna versus the simulation model, a simple tolerance study in simulation is performed based on the build tolerances of the antenna to provide an uncertainty estimate of the simulation results.
