Conical horn antenna used be feed by TE11 mode.Main beam is at θ=0.If we feed
antenna by TM0n mode,the main beam is not at Θ=0. In "Modern Antenna Design".First edition (McGraw.Hall),I find TM01 mode feed horn. But the paper
about this antenna is few.
I want to know, if I feed with other mode (TM02,TM03,....),how to analyse gain,main beam. If i give a main beam direction , how to get a size of concial horn.
usually, ad hoc software simulators will solve the horn analisys for TE11 fed horns.
Advanced and expensive simulators like hfss, cst may take in consideration high order modes.
But generally the fundamental, TE11 mode is looked for and wanted. Higher modes are used to build the monopulse radar but the bottlenek is the very complicate feed system that is required.
When the horn is conical, and corrugated, the whole principle is about how higher modes are managed by the corrugations to produce the desired effect.
We can define the shape. We can put it in a "air box". We can set conductivities for the boundary surfaces. We can define a excitation plane at the waveguide input.
What we need is to discover the right way to offer the polarized feed, and end up with a radiation pattern plot.