Primary Study On Spatial Powers Combining Of High Power Microwave

It is important to study the spatial powers combining of high power microwave, because every high power microwave source has its physical restrict and fabrication difficulties. At present, the high power microwave is a pulse of carrier frequency with a certain bandwidth and the phase is hard to be accurately controlled. In this thesis, some primary studies on spatial powers combining of high power microwaves are carried out through theoretic analyses and numerical calculation.Theoretically, the formulas of the gain and radiation pattern of the antenna arrays are re- derived with a view to the applications. The spatial powers combining of the cross beams is investigated. The formulas of the energy's gridded distribution at the intersection of the cross beams are derived and a simple design for the cross beams case is carried out as an example. With the consideration that the phases are hard to be accurately controlled for the high power microwaves, some primary probability analysis about the influence of the stochastic phases on the total gain is carried out. The formulas for both the mean value and the standard deviation of the gain are derived. The formula of the probability of the gain is also given. The result shows that the more antennas there are, the greater the standard deviation of the gain is when all the antennas have the same stochastic phases distribution; the greater the standard deviation of the stochastic phases is the smaller the mean value of the gain is when the array has the same number of antennas. The spatial powers combining of high power microwave pulses is investigated with the finite-difference time-domain method, and the results show that the space-time distribution of the microwave pulses in the far field is not all the same as that of the monochromatic continuous wave(CW), owing to the periods of interferential time are different in different directions.Numerically, the spatial powers combining of both the parallel beams and the cross beams are investigated. The conclusions are as follows.When a small solid angle adjacent to the main direction in the far field is considered, the parallel beams combining of compact antenna arrays has its priority if the phases can be controlled,and the parallel beams combining of sparse antenna arrays has its priority if the phases can not be controlled; when a small area in the far field is considered, the parallel beams combining of compact antenna arrays has its priority if the phases can be controlled,and the cross beams of sparse antenna arrays has its priority if the phases can not be controlled. On the account of the energy's gridded distribution at the intersection of the cross beams, one should take into account such factors when designing the cross beam antenna arrays, as target size,distance,source power,working frequency and so on. The differences between the pulsed wave fields and the CW fields are also investigated for powers combining, and the results show that the control of the radiation time is very important for the spatial powers combining besides the control of the phases, owing to the coherence in time and the coherence in space.At last, the projects of the spatial powers combining of high power microwave are put forward and discussed.