Accession Number : AD0251531

Title :   CLOSED FORM ANALYSIS FOR THE RADIATION PATTERN OF THE MODULATED ANTENNA

Corporate Author : WASHINGTON UNIV SEATTLE

Personal Author(s) : BERNARD, GARY DALE ; ISHIMARU, AKIRA

Report Date : NOV 1960

Pagination or Media Count : 1

Abstract : A new method of analysis for the far zone radiation pattern of the antenna with modulated aperture field is developed. The type of modulation considered is cosinusoidal amplitude across the aperture, and sinusoidal phase modulation across the aperture. The case of constant amplitude is discussed in detail, and is applied to the modulated slow wave structure. The endfire pattern is considered in detail in terms of fundamental slow wave speed, and the magnitude, sign, and frequency of the phase modulation. It is shown that lower sidelobes and higher gain result if the antenna is excited with the slowest phase velocity, and that the magnitude of the phase modulation must be less than unity. Also, a condition on the magnitude of the phase modulation for minimum first sidelobe is developed. The sidelobe level, beamwidth, gain, and supergain ratio are tabulated vs. the frequency of phase modulation for values of the magnitude of modulation. Also, the relationship between the aperture size and the slow wave velocity and various parameters are clearly presented. A method of realizing a tilted beam with a slow wave structure is also presented, and a brief example is given. (Author)

Descriptors :   *ANTENNA RADIATION PATTERNS, *ANTENNAS, AMPLITUDE MODULATION, ANTENNA LOBES, MATHEMATICAL ANALYSIS, PHASE MODULATION.

Distribution Statement : APPROVED FOR PUBLIC RELEASE