Transmission And Scattering Characteristics Of Curved Frequency Selective Surface

Since the second World War,radar detection system has developed rapidly,and the stealth technology which can improve the survival and penetration ability of weapon system has attracted the attention of scholars.Because of its unique frequency selective function,frequency selective surface(FSS)technology has become an important part of stealth technology and has broad development prospects.However,most of the existing research results are aimed at the infinite plane structure,and there are few researches on the surface structure which is more suitable for the actual situation.Therefore,this paper will study the transmission and scattering characteristics of curved frequency selective surface from the actual demand.The main work and innovations of this paper mainly include:1.A curved frequency selective surface of narrow band ring element surface is proposed and its transmission and scattering characteristics are analyzed.By analyzing its electromagnetic characteristics,the research shows that this kind of curved frequency selective surface also has stable transmission frequency band,the in-band transmission efficiency is higher than 90%,and the out-of-band scattering reduction effect is very obvious.In the passband,it does not change the radiation pattern of horn antenna and patch antenna array.Compared with planar structure FSS,the proposed curved FSS not only has similar resonant frequency,but also has the same influence law by structural parameters.In order to verify the correctness of the method,a machining test was carried out on the conical frequency selective surface,and the experimental results are in good agreement with the simulation.2.According to the three kinds of planar band-pass unit,this paper puts forward and designs the symmetric double screen surface structure,the antenna-filter-surface structure and surface structure of non-resonant curved frequency selective surfaces,and their electromagnetic characteristics is analyzed.The results show that the they all have passbands,which can keep the antenna radiation characteristics in the band and reduce the scattering outside the band,and the transmission performance is obviously improved with the increase of the radiation source’s exit angle.Different structure are affected differently by the curved surface,among which the symmetric double-screen structure is the most seriously affected,which loses nearly half of the transmission band compared with the flat surface,and the transmission effect in the passband is not so good;the surface of antenna-filter-antenna structure and non-resonant structure is less affected,the passband does not narrow,but the normal transmission loss is about 2d B,indicating that the normal gain of the antenna is affected.3.According to the practical application,the frequency selective surface,antenna and antenna cabin environment of the surface are modeled and analyzed,and the influence of environmental and structural factors on the overall characteristics of the system is studied.The results show that: with the increase of the size,the frequency selection characteristics of the curved frequency selection surface will not change,and the transmission performance will be improved;the ground and the introduction of absorbing material,does not affect the antenna radiation characteristics,but will change the whole structure of the scattering;for the antenna,the influence of the feed structure can be almost ignored;however,the antenna height and tilt angle have certain influence on the radiation and scattering characteristics.