Analyze Of Near Field Problem In Precision-guided And Fuze-warhead Coordination

The mono-pulse radar is widely used in engineering for angle measurement and precision guided for its high precision. However, near field misses problem has been plagued by academia and engineering. The vast majority of studies use the approximate model and the ideal point model to analysis the problem. Few near field researches are about improving the precision of antenna and decreasing the angular glint. But these studies did not give the response of antenna in the near field and how these affect the precision quantitatively. The principle of the mono-pulse antenna is actually based on the far-field scattering of targets. But at close range measurement, the antenna emitted and received wave cannot be approximate to uniform plane wave, which lead to the distribution of target scattering field’s amplitude and phase become more complex; Moreover, the structure of the antenna itself and the aperture have certain effect on signal response; all these factors should be considered. So the integrated simulation of a mono-pulse antenna(MPA) which considers all the factors has been done. Then through the simulation we deeply understand the near distance miss, and solutions are put forward.In this paper, the integrated simulation of a mono-pulse antenna(MPA) has been done by using the method of moments(Mo M) and corresponding efficient numerical method. There are three steps: First, the antennas with the summation beam are used as the transmitter to illuminate the target. Then, the scattered field produced by the target, as the incidence to the received antenna, is calculated. At last, the electric signals received by the antennas with the difference beams are computed respectively. The steps can undertake multiple iteration to simulation the interaction between target and antenna until the numerical solution is table and convergent. This paper verifies the correctness of the simulation through a numerical example. Then, the response of a target’s scattering are obtained under different distance and exposure conditions. Then, by comparing with approximate model proves that the approximate model can’t calculate the field in the near field and the integrated simulation is necessary. Next, the MPA is used to calculate a missile-like target’s angle. The results show the angle measurement in the near field has remarkable error, and the measurement performs better at the lower frequency. The corresponding physics behind above phenomena has been given and the recommendation of applying the lower frequency、broadband signal and small diameter of aperture for near range measurement has also been presented. The used of high resolution range profile(HRRP) proves that the broadband signal can improve the accuracy. Finally, a logarithmic spiral mono-pulse antenna is designed.