Radiation pattern of a parabolic reflector antenna from near field measurements of a coupled reflector

A scheme is proposed that it permits a more direct prediction of the radiation pattern of a parabolic reflector antenna from an experimental plot of the electric field strength over the focal region of a larger parabolic reflector in the near field of the test antenna. In this technique, the second reflector has a large f/D ratio and its aperture is parallel to and faces the aperture of the test antenna at a separation distance nearly equal to the diameter of the test antenna. Under this measurement condition, the distribution of the electric field strength in the focal region of the second reflector is proportional to the Fourier transform of the aperture distribution of the test antenna. After simple graphical rescaling, this yields the desired far-field radiation pattern of the test antenna.<>