| Stealth technique is playing an important role in the modern war with complicated electromagnetic environment. The stealth performance directly determines its battlefield survival probability and penetration ability. Avionics equipment is an important component of modern combat aircraft; the scattering from an antenna often becomes a bottleneck which restricts the stealth effect of the whole system. The stealth technique involves electromagnetic calculation, electromagnetic materials, machining process, electromagnetic measurement, and so on. Development of the antennas with good radiation and scattering performances relates mainly to the stealth of the aircraft. This dissertation mainly concerns with the antenna scattering analysis and RCS control methods, the author’s major contributions are outlined as follows:1. The antenna scattering mechanism is analyzed, the basic scattering theory of the antenna is illustrated in both the frequency-domain and time-domain clearly. The polarization of detecting antenna, scattering antenna, and receiver antenna are included in the analytical course. The structural mode scattering and the antenna mode scattering are separated. The scattering of antenna array is analyzed including the coupling, which simplifies the analysis and design.2. Take the ultra-wide band planar monopole antenna for example, the scattering mechanism of UWB antennas is studied. Three methods of reducing the RCS of UWB planar monopole antennas are given. They are reducing the area covered, half UWB antenna design, and interdisciplinary design. Radiation and scattering characteristics of the three antennas are studied and compared to those of the reference antennas. The results show that the three antennas have favorable UWB-related performances and lower RCS than the reference antennas.3. Bionics principle is applied to antenna design, especially to the stealth antenna design. To authenticate the method, five novel bionic antennas are proposed by use of the models of insect tentacle, sunflower, and so on. The five bionic antennas have favorable radiation performances at their specified environment. Insect tentacle antenna, fan-shaped antenna, and sunflower antenna demonstrate the feasibility of applying bionics principle to antenna RCS reduction. Octopus antenna and water-wave antenna demonstrate the feasibility of applying bionics principle to other antenna design.4. Based on bionics principle and the model of orientation of the alternate leaves, bionic frequency selective surface is designed. The technique of applying bionics principle to FSS design is valid. FSS is applied in the monopole antenna array RCS control. An antenna array with low RCS is designed and its radiation and scattering characteristics are studied. The validity of the method is proved by simulated and measured results.5. The scattering mechanism and RCS reduction of rectangular cavity body are studied. Serrated process, tilting wall, and chamfering the edge are used to reduce the total RCS. An antenna is placed in the low RCS cavity, and compared with the reference antenna. The RCS reduction of the method is proved by simulated and measured results.6. The relationship of the antenna scattering and element coupling is studied. The coupling of the two-element array is reduced by using the theories of S parameter network. Simulation and measurement results of the proposed antenna and the reference antenna prove that it is advantageous for the RCS reduction of the antenna array.7. Low RCS cylindrical cavity body and circular polarized microstrip antenna are designed. A novel low RCS circular polarized microstrip antenna array is proposed. The simulated and measured results show that compared to the reference antenna, the novel antenna has lower RCS and favorable radiation performances. |
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