Radiation from wide-flare corrugated E-plane sectoral horns

An analytical and experimental investigation of the radiation properties of wide-flare corrugatedE-plane sectoral horns (10 < α₀ < 70, whereα₀is the half-flare angle) excited in theHE₁₁mode [1] with improvedE-plane radiation patterns and suppressed side-lobe levels over a broad bandwidth is described in this paper. Given the flare length and half-flare angle of the horn, the far-field radiation pattern is determined by two methods, one of which involves aperture-field integrations based on vector diffraction formula over a constant phase surface at the mouth of the horn and the other of which employs an expansion of the aperture field in terms of free-space cylindrical TE and TM wave functions. Good agreement is obtained between the two methods with measured radiation patterns for several values ofα₀. Given the flare lengthy variation of the on-axis gain withα₀of the horn is analytically investigated, and the design procedure for determining optimumα{0}, in order to obtain maximum on-axis gain, is also indicated. Furthermore, design and experimental studies on wide-flare horns under consideration are also summarized.