What the Phase Centre Application Macro Calculates

The phase centre can be calculated in multiple ways since no unique phase centre exists for a real antenna. It is important to understand the difference between the methods to select the most appropriate calculation.

The phase centre calculation utility application macro calculates two phase centres from a set of far field components in a POSTFEKO far field result. It is intended to be run from within the POSTFEKO interface.

The first method calculates the phase centre from any viewing angle within the far field request (centre of the request by default). The result is the phase centre at a single 3D coordinate. The phase of the electric far field should be close to constant in the vicinity of the viewing angle when the far field origin is moved to the calculated phase centre coordinate.

The second method determines the best “nominal” phase centre in the vicinity of the current far field origin. The best “nominal” phase centre is the 3D coordinate where the maximum change in phase over the entire far field request is minimised.

If the source were an isotropic radiator, both methods would return the same result and the viewing angle would not affect the result when using the first method. Please see the example at the end of this document for an illustration of the difference between the two methods.