Study On Multiple-Fed Reflector Antenna For High Power And High Repetition Rate Pulses

High power pulse radiation system has been widely applied in effect experiment, impulse radar and electromagnetic pulse weapon. The peak power and the repetition rate of the output pulses are very important. However, as a result of the inherent characteristic of the fast pulse switch, both the peak power and the repetition rate of a system with single source are difficult to achieve the highest levels simultaneously. And then space synthesis technology is a way to improve the output capability, which will bring higher demands on the UWB antenna. The multi-fed parabolic reflector antenna possesses high directivity and many feeding ports due to the reflector and the multi-feed, which has performed well in CW power synthesis, but the one used in UWB application research has fewer feeds. Hence, in order to enhance the peak power and repetition rate of the output pulses, the reflector antenna with more feeds, applied to pulse synthesis, is studied in this paper.First, based on a simple model of small-angle TEM horns proposed by Everett G. Farr, the radiation mechanism of exponential tapered TEM horn antenna was analyzed, and the waveform non-distortion condition of axial radiation pulse was verified by simulation, thereby avoiding the radiant energy decentralization in time domain. Then, the basic relationship between the bandwidth and the geometry size of the exponential tapered TEM horn antenna was discussed.Subsequently, on the basis of the ellipse’s geometrical properties and the shrinkage of wavelength in a medium, a radome filled with transformer oil was designed to form a new transformer oil lens. Then the exponential tapered TEM horn antenna was sealed in the new transformer oil lens. Due to that the shrinkage of the wavelength in transformer oil enlarges the electrical size of the TEM horn, the low-frequency radiation will be preliminary improved. And due to the focusing effect in one principal plane of the TEM horn antenna offered by the lens, the performance of the TEM horn antenna will be improved further more. The simulation results showed that, after new lens providing focusing effect in the H-plane of the exponential tapered TEM horn antenna, the low boundary point of bandwidth reached0.2GHz from0.28GHz, axial rEpp was increased by38.10%, the power capacity reached30.07GW.Finally, the exponential tapered TEM horn antenna with new transformer oil lens was adopted to form11-element feeding array, and the array was placed in the focal-line of a parabolic cylindrical reflector to illuminate the reflector. With the help of electromagnetic simulation software, the arrangement of feeds, the reflector, offsetting of feeding array, the irradiation angle to the edge of reflector and the length of reflector were discussed around the reflector antenna aperture efficiency. Then the design of offsetting11-element array fed parabolic cylindrical reflector antenna with6.5X9.6m2aperture was finished. When all elements fed simultaneously, the ratio of axial rEpp and feed-in voltage was6.85, and the power-synthesis efficiency reached89.73%. When every element fed at30ns intervals, the ratio of axial rEpp and feed-in voltage was6.90, and the rEpp jitter of the repetition-synthesis pulses is less than2.1%. And the feed-in peak-power of every element in the feeding array reached21.84GW.