Accuracy of the Finite Element Method for Directivity of Horn Antennas Martin Vogel Ansoft Corporation

Absorbing Boundary Condition reflects for non-normal incidence

SA 12-0.5 Standard Gain Horn test case for directivity in beam center

Quarter model of horn with partly spherical air object, terminated by absorbing boundary condition

Model of horn with box-shaped air object, terminated by Perfectly Matched Layers

Corrugated Horn - test case for angles off boresight

Horn model with partly-spherical air object with ABC

Corrugated horn model with Perfectly Matched Layers

Directivities corrugated horn, E and H Plane

Conclusions Required mesh density on outer faces of air object: lambda/6 Required mesh density in rest of model: 0.4 lambda Use either partly spherical ABC or use default PMLs Accuracy maximum directivity in main beam: 0.1 dB Accuracy directivity at -21 dB level: 0.5 dB Accuracy directivity at -34 dB level: 1 dB Directivity noise floor between -50 dB and -60 dB Return Loss noise floor -70 dB