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Fast and Continuous Far Field Calculations

Antenna designers will no longer have to be concerned about the angle increments that are used to sample far field radiation patterns as FEKO can automatically compute a continuous representation of the radiation pattern.

The new method, based on spherical wave expansion, uses functions to represent the far field that are interpolated and superimposed to obtain the continuous/uniform resolution pattern. The plotting of continuous far field data can then be sampled with any resolution in POSTFEKO. 

The implementation is accurate and efficient, and faster than using a fine angular sampling. Even very narrow nulls or main lobes (e.g. main lobes of reflector antennas) will be accurately represented in this way, and is well suited for the simulation of large gain antennas or RCS of large objects where a fine angular resolution would be required.

sampled vs continuous RCS
 Comparison of the standard sampled RCS (left) and the continuous RCS (right)

The first example shows the bistatic RCS calculation for a missle at 3 GHz. The missile is simulated with curvilinear and HOBF, the continuous RCS is compared to the sampled RCS where 1441 samples were used. In this case the continuous calculation is more than 3.5x faster than the sampled calculation.

missile RCS

Bistatic RCS for a missile at 3 GHz showing the agreement between the highly sampled and the continuous patterns.

The second example shows a horn fed parabolic dish with an 18λ radius. The structure is simulated with a combination of MoM (for the horn feed) and large element PO (for the reflector). The vertical cut of the gain plot is about 2x faster to calculated with the continuous method compared to the sampled approach with 7201 samples. Furthermore, the results for the continuous method are available anywhere on the sphere, while the sampling method would require additional calculations for each cut.

horn fed parabolic reflector

Sampled and continuous gain of a horn fed parabolic reflector (r = 18λ)