Design And Analysis Of Frequency Selective Surfaces(FSS) And Electromagnetic Behavior Of Chiral Medium

The Frequency Selective Surfaces(FSS)advent can be traced back to 18th century,American physicist David Rittenhouse who found out that some light colours of light are suppressed when the street light passes through silk handkerchief.It is concluded that non-continuous surfaces exhibit different transmission characteristics for different frequency wave.Therefore,these surfaces get named frequency selective surfaces.The use of these surfaces allows achieving outstanding improvements in several electromagnetic applications.The proper use of FSS started in 20th century when it is used in reflector antennas.Nowadays scientist uses FSS in radomes,jammers,radar absorbing materials,antennas and many more applications.In this thesis,we designed a second order band pass FSS which is suitable for radome applications.The unit cell size is very small compare to traditional FSS.The small size makes it suitable for radome applications due to stable frequency response under different angle of incidence and polarization.In second problem high gain and wide band Fabry Perot(FB)resonator antenna were designed using FSS,dual layer EBG having same dielectric constant and EBG layers with different dielectric constant as their superstrates.The positive phase gradient of the superstrate is exploited to get high gain at wider bandwidth.A ray based technique is used to explain the operation of such type of antenna.In third problem we discussed the electromagnetic behavior of chiral medium.A special class of chiral medium called chiral metamaterials is analyzed.These metallic patterns on both side of substrate were rotated 90~0 with respect to their adjacent equivalent pattern.These patterns exhibit the properties of chiral medium such as optical activity and circular dichroism due to their cross coupling between the electric and magnetic fields.Finally,the focussing systems in association with chiral medium were analyzed in detail.The high frequency electromagnetic(EM)fields in the focal region of focusing system placed in a homogeneous and reciprocal chiral medium have been analyzed using geometrical optics (GO)approximation and Maslov's method.The GO solution became invalid at the focal region due to the unreal singularities.Therefore,an asymptotic method based on Maslov's theory has been applied to derive the high frequency EM fields which were also valid at the focal points.Moreover,the effect of chirality parameter of the background medium on the position of focal points for both Left circularly polarized wave(LCP)and right circularly polarized(RCP)wave are described by plotting the derived expressions numerically using MATLAB.