Technical Study Of Ceramic-based Single Screen Frequency Selective Surface

With the rapid development of radar antenna system in the the field of national defense, more and more military targets are difficult to escape from radar antenna. In modern military conflicts, in order to hide their military operations, all countries are actively seeking an electromagnetic stealth technology which can evade radar antenna, frequency selective surface(FSS) as a key technology has become a hot research in the world. In practical applications, FSS embedded in the radome turn into FSS radome. FSS radome not only possesses all the functions the radome has, but also has frequency selective characteristics which can effectively reduce the radar cross section, so that aircraft is invisible for electromagnetic wave. In recent years, due to the substantial increase in the speed of aircraft, organic material radome is no longer able to adapt high temperature generated in the process of aircraft flying at high speed. The ceramic FSS radome, which possesses frequency selection performance, good high temperature resistance, good thermal shock resistance and high mechanical strength, as a new generation of stealth radome become a hot topic. This paper studies modified silica ceramic as a kind of candidate radome material. At the same time, we investigate the craft of preparing flat ceramic-based single-screen FSS with the modified silica ceramic as dielectric material. We also do some theoretical simulation research in the field of ceramic-based multi-screen FSS, details are as follows:First, Li2O-K2O-Al2O3 was doped into pure quartz ceramic and then we study the basic properties as radome material must be considered: dielectric, mechanical and thermal properties. In the testing frequency of 14 GHz, the dielectric constant and dissipation factor of modified silica ceramic are 4.37 and 0.0038, respectively. The flexural strength can reach 163 MPa which has greatly improved compared with that of pure silica ceramic. Meanwhile, due to the generation of a large number of glass liquid phase in the process of modified silica ceramic sintering, the densification of ceramic structure is improved make the ceramic possess certain anti rain erosion and sediment erosion capacity.Secondly, the modified silica ceramic is used as a matrix for FSS dielectric material and then we investigate the HTCC preparation process of flat ceramic-based single-screen frequency selective surface. In order to find the suitable binder for roll forming process, We have tested four kinds of binders. Finally, we find that B79 type poly vinyl butyral which is produced by Solutia company of American is the most suitable binder, so that we solve the problem of roll forming and binder removal. Then we investigate the sintering process of three kinds of electrode pastes which are used to print FSS graph, the electrode pastes are molybdenum manganese metal electrode paste, zinc oxide semiconductor electrode paste and molybdenum disilicide electrode paste. We successfully solve delamination, blistering, cracking and other problems of laminated sample and get the physical samples which can be tested.Finally, we make a preliminary study to the simulation design and optimization of X-band bandpass multi-screen ceramic FSS. Based on conventional FSS units, we redesign the unit structure and the loaded way of the dielectric material to get new FSS units. We have introduced four FSS units: five cross FSS, ring five cross FSS, snowflake FSS and antenna- filters- antenna FSS(AFA-FSS). In these four designs, AFA-FSS has the best frequency selection performance.