Hybrid modes in corrugated conical horns with narrow flare angle and arbitrary length

By comparing the modified field equations of a corrugated conical horn of narrow flare angle (and arbitrary length) with those of a corrugated cylindrical waveguide, a technique to solve the characteristic equation of the horn is developed. It is also shown that the expressions for the far-field radiation pattern of the waveguide are applicable to the horn, except that the propagation constants must be modified.