Wave Beams of Short Radio Pulses Generated by Gigawatt Microwave Sources

A rising interest to the generation of short pulses is observed lately [1-3]. In relativistic backward wave oscillators (BWO) operating in superradiance regime the peak power of output radiation may exceed the power of electron beam [1,2]. Such BWOs are effectively synchronized by the leading edge of accelerating voltage pulse so that the multi-channel systems can be built [1,2]. Radiation patterns of these systems consist of overlapping wave beams. The structure of each wave beam is usually close to the fundamental Gaussian beam with linear polarization. Dimensions of the output window of each channel exceed wavelength λ because of microwave breakdown on smaller apertures. It means that the distance between channels d is greater (typically much greater) than wavelength λ  d (1) and far field radiation pattern has many maximums. In the report we analyze theoretically the peculiarities of such multi-channel systems in case of radiating the phase synchronized short pulses. Superposition of 2D scalar Gaussian beams (see Fig. 1) has been considered:  