CROSS POLARIZATION CAUSED BY PERTURBED CIRCULAR CROSS-SECTIONS OF WAVE-GUIDES AND HORN ANTENNAS

The cross polarization caused by a perturbed cross section of the conical hybrid-mode horn is analyzed. Simple formulas are presented for cross polarization due to slightly elliptical cross sections of smooth-walled waveguides and hybrid-mode horns. The horn formulas are developed for corrugated horns, but they are assumed to represent a good approximation for other types of hybrid-mode horns with similar field distribution. Simple analytical formulas which are sufficiently accurate for small ellipticites of the cross-section ellipse are presented. These show that the tolerances on the waveguide diameter are extremely strong, typically on the order of 2-4 multiplied by 10-**2 mm in the horn throat for typical horn geometries at 12 GHz.