Monopulse antennas with doubly curved reflectors

Calculations of the radiation pattern of a doubly curved reflector antenna are presented showing how the cross-polarized components due to the reflector's curvature do not cancel in the difference pattern. In a one-plane monopulse system, the cross-polarized components fill up the central null in the difference pattern. A method of compensating for this effect consists in the generation of anti-phase cross-polarization with the proper distribution. For doubly curved reflectors, the cross-polarization components vary for the different reflector zones lying one upon the other, and these zones radiate to different elevation angles. Therefore, the compensation must vary in the same manner in the vertical plane. If a group of dipoles is used for feed, compensation can be obtained by inclining the stubs of the difference channel dipoles in such a manner that the upper stubs will generate cross-polarization with antiphase to that of the lower stubs.