A. A. Volkov - Chief of the laboratory of the Military Educational-Research Centre of Air Force «Air Force Academy named after professor N.E. Zhukovsky and Y.A. Gagarin» (Voronezh). E-mail: volkov_aa@autorambler.ru

Air break-down acts as a constraint of the basic characteristics of fields radiated. The air break-down must be taken into account when solving a number of applied problems on microwave power oscillators employment. It is necessary to maintain the electric field strength level below the critical value to provide uninterrupted radiation of electromagnetic energy into atmosphere. This condition can be provided by choosing such aerial dimensions the minimum limit of which depends on aperture illumination. The cited literature lacks techniques to estimate the outlined constraints on aerial dimensions. The chief aim of this paper is to derive an analytical expression for defining the minimum dimensions of an aerial to provide uninterrupted radiation of a microwave power pulse chain. To solve the named task a dependence of the break-down level of electric field strength in air on the time parameters of radiated pulse chain is found. Based on the dependence, assuming uniform aperture illumination, an analytical expression for minimum aerial's boundary area for uninterrupted extraction of microwave oscillator's energy is derived. Calculations of dependences of the minimum boundary radius of circular aperture upon microwave pulse chain parameters are made. The characteristic of these dependences is presented. The minimum boundary radius, given the specified microwave pulse power and length, is in agreement with quasi-single-pulse operation. For these conditions the calculation of the dependence of the aperture's minimum boundary radius on microwave oscillator capacity in the GW range with different pulse lengths is performed. It is shown that the aperture radius must comprise tens centimeters to provide uninterrupted radiation of microwave GW pulse chain in the nanosecond range. The article contains 2 figures and 12 bibliographical references.