This article is a practical guide on how to feed a double-ridged horn.
As an example, we will have a look at a double-ridged horn antenna consisting of a horn and a ridged waveguide solved using the FEM.
The double-ridged horn. Left: Isometric view; Right: Side view with opacity set to 20%.
Since the face that will be used to excite the model is on the boundary of a FEM region, a FEM modal port must be used (see note below).
Note: A waveguide port can only be applied to a single flat face solved using the SEP or a single flat face on the boundary of a FEM region. Only three basic cross-sections are supported for waveguide ports:
A good approximation of the physical model is to place the FEM modal port in the plane where the waveguide would transition into the coaxial adaptor in the physical model.
To excite the model:
A face is selected.
A FEM modal port is added to the face.
A FEM modal source is added to the FEM modal port.
See Ports and sources in Feko for more information on ports, sources as well as practical examples on how to feed typical structures in Feko.