Study And Optimisation Of Conformal Frequency Selective Surface

Radar-cabin has became the three most important scatters in today’s stealth fighter.Radome based on frequency selective surface(FSS)technology can dramatically decrease the monostatic radar cross section(RCS)around the axis direction and maintain the radiation pattern of the antenna at the same time,which has been widely investigated now.In this paper,finite plane FSS and curved FSS are simulated to investigate the influence of limited truncation and conformal process to the transmission characteristic of FSS.At the same time,a new FSS radome based on separation design is given and studied,which can be easily fabricated in practical engineering.Firstly,Floquet theory and equivalent circuit method(ECM)which are theory foundation of this article are introduced in this chapter.A dual-band FSS element with high frequency offset is designed and investigated based on ECM.The given FSS has two passband at 0.65 GHz and 3GHz respectively and suppresses most parasitic passbands within the operation frequency range(0.1GHz~5GHz).What is more,period of the given FSS element is just 1?20 of the wavelength corresponding to the lower resonant frequency.Secondly,a conversion model based on Babinet principle is proposed to study the transmission property of finite planar FSS.Several finite plane FSS models made up of cross aperture units with different scale are simulated though this method.Simulation results illustrate that resonant frequency will shift and the bandwidth of passband will increase because of the effects of limited truncation.Then,cylindrical FSS has been designed and simulated to investigate curved FSS.Simulation results illustrate that bending process will make the passband of FSS shift and increase the bandwidth of passband.Transmission characteristic of cylindrical FSS will be different when the incident wave has different polarization direction.Cylindrical FSS integrated with microstrip antenna is designed and simulated.At last,a new FSS radome based on separation design is given and studied.Simulation results show that the average transmission efficiency of the radome designed in this paper is about 0.8dB higher than the conical FSS radome within 9.5GHz~10.5GHz.Both simulation and measurement results illustrate that the added plane FSS maintains the radiation and matching property of antenna.Bi-static and monostatic RCS of the integration are given to show that the separation design can dramatically reduce the RCS around the axis direction.The average reduction of monostatic RCS within-20°~5° is 12 dB and the monostatic RCS at the axis direction decrease 28 dB.Based on the separation idea,design of FSS can be picked out from radome and integrated with antenna,which can decrease the complexity of radome-design.What is more,the given design can be easily fabricated and repaired in practical engineering.