FOUR-DIMENSIONAL ELECTROMAGNETIC RADIATORS

Abstract

This paper describes an entirely new and fundamental technique which has wide application to many fields of the antenna art as well as important system implications. The essence of this philosophy is the utilization of the time domain as an additional variable with which to control antenna radiation characteristics. One way to accomplish this is by periodically time-modulating one or more of the antenna parameters (aperture excitation, aperture shapes, frequency, phase distribution, aperture size, etc.) in a prescribed way. The result of this modulation is a radiation pattern whose characteristics are periodically changing as a function of time. By virtue of the periodic nature of the pattern fluctuations, an infinite number of independent information channels are available corresponding to the harmonic frequency components of the modulated patterns. Since each harmonic will, in general, have a different space factor associated with it, proper data processing can be utilized to provide simultaneous operation of a single antenna in a variety of modes. In addition, this technique allows synthesis of antenna radiation characteristics which might be unobtainable by conventional methods.