Log periodic feeds for lens and reflectors

The application of unidirectional log periodic antennas as feeds for lens or reflectors to cover 10:1 or 20:1 bandwidths is described. Information on the primary patterns, phase center variation, input impedance, and aperture blocking of trapezoidal-tooth sheet structures is given so as to allow the design of feeds for a variety of lens and reflectors. Final results of pattern, gain and impedance measurements on a four-foot dish over the frequency range of 600 to 6000 mc are presented and a discussion of the slight sacrifice in gain to achieve this bandwidth is given.