Antennas for Nonsinusoidal Waves: Part: III-Arrays

In the previous two papers, we discussed the Hertzian electric dipole and the large-current radiator, used either as radiators or sensors. Several radiators or sensors can be combined into an array. In the case of sinusoidal waves, such an array would yield more power and a directional pattern of the power called the antenna power pattern. For nonsinusoidal waves, one obtains additional patterns. In the particular case of a time variation of the electric and magnetic field strengths equal to that of a rectangular pulse, one obtains an antenna slope pattern caused by the change of the time variation of the field strengths as functions of azimuth and elevation angles. This change is often called a distortion, but in reality it provides us with additional information for the angular resolution. Sinusoidal waves cannot provide this information due to their lack of a bandwidth. This paper investigates both the regular sensor array using the sum of all sensor outputs, and the monopulse array that uses the difference between the sums of the sensor outputs of the right and the left halves of the array. Radiator and sensor arrays for nonsinusoidal waves have been built at least since 1975, but the circuits required for the utilization of the slope patterns are still at the frontier of our technology for pulse durations in the order of 1 to 0.1 ns, which are primarily of interest.