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  • 1. MICROWAVE RESONATOR TITLEDesign of resonator with split ring resonator and defected ground structure with sharp transition bandAJEET KUMAR

2. TABLE OF CONTENTS S no.TOPICPage no.1.Abstract42.Introduction53.Split ring resonators64.Design Model Specifications75.Design steps in HFSS86.Simulated s-parameter output Graph97.Coupled split Ring Resonator Structure138.Advantage of SRR structure179.Conclusion1910.References20 3. ABSTRACT We present a systematic simulated study of individual and coupled split ring resonators (SRRs) of rectangular ring with one and two gaps. The behavior of the magnetic field, the magnetic resonance frequency and the currents in the SRRs from a single SRR to strongly interacting SRR pairs in different orientations. The coupling of SRRs along the E direction (y) results to shift of the magnetic resonance frequency to lower or higher values, depending on the capacitive or inductive nature of the coupling. The strong SRR coupling along propagation direction (x) results in splitting of the single SRR resonance into two distinct resonances associated with field and current distributions. For the design and simulation, HFSS 3D simulation tool is used. On comparison it is observed that the SRR filter provides improved performance over the conventional type filter designed using insertion loss or stepped impedance methods. Our aim is to design a deep sharp cutoff and compact low-pass filter. 4. INTRODUCTION In modern wireless communication, compact size and high performance filters are required to reduce the cost and enhance system performances. The defected ground structure (DGS) for microstrip lines or coplanar waveguide (CPW) such as various photonic band gap (PBG) structures have become interesting areas of research due to their extensive applicability and use in microwave circuits. DGS, i.e. etching off a defected pattern from the backside metallic Ground-plane has periodic structures provide rejection of certain frequency band, like band gap effects. The resonant elements allow larger attenuation in the stopband and higher harmonic suppressions to be obtained with less number of periodic structures as compared to the conventional DGS. Also, by using the proposed equivalent SRR model, a compact LPF has been optimally designed with very high attenuation at the cut-off frequency. 5. SPLIT RING RESONATORS 6. Design ModelIndividual SRRs Single gap Two gaps Four gaps 7. Design in HFSS 8. Graph for 0.2mm gap in Square SRRXY Plot 1OneGapSRRDGS0.00ANSOFTCurve Info dB(S(1,1)) Setup1 : Sw eep dB(S(2,1)) Setup1 : Sw eep-10.00Y1-20.00-30.00Single gap Plot-40.00-50.00 -56dB at 4.2GHz-60.00 Freq [GHz] 9. Graph for 1.2 times scaled dimension of each objects in the designXY Plot 1OneGapSRRwith1.2timesscale0.00ANSOFTCurve Info dB(S(2,1)) Setup1 : Sw eep dB(S(1,1)) Setup1 : Sw eep-5.00Y1-10.00-15.00 At 3.5GHz -16dB, w hich is no so much significant-20.00-25.00 Freq [GHz] 10. Graph for 0.4mm gap in the Square SRR XY Plot 1OneGapSRRWith.4mmgap0.00ANSOFTCurve Info dB(S(1,1)) Setup1 : Sw eep dB(S(2,1)) Setup1 : Sw eep-5.00-10.00Y1-15.00-20.00-25.00-30.00-35.00 [GHz]It gives very sharp transition band as well as the stopband attenuation (deep) is -31dB which is acceptable for practical purposes.9.0010.00 11. Graph with one gap SRR coupling for the given orientiationXY Plot 1 0.00NameXYm1ANSOFTCurve Info3.9000 -2.4307m3-5.00m34.1000 -11.6820m2m2HFSSDesign14.6000 -2.4335dB(S(P1,P1)) Setup1 : Sw eep dB(S(P2,P1)) Setup1 : Sw eep-10.00m1 At 4.1GHz the attenuation is -11.682dB-15.00Y1-20.00-25.00-30.00-35.00-40.00-45.00 Freq [GHz] 12. COUPLED SPIT RING RESONATOR STRUCTURES Coupling of the SRRs along the E direction results to shift of the magnetic resonance frequency to lower or higher values, depending on the capacitive or inductive nature of the coupling respectively. Capacitive or inductive coupling is determined by the relative orientation of the interacting SRRs. If orientation is associated with strong magnetic field (and negligible electric field) in the area between the SRRs, it indicates strong inductive coupling while if orientation is associated with strong electric field (and negligible magnetic field), it indicates strong capacitive coupling. 13. Different orientations and coupling of SRRs 14. Different orientations and coupling of SRRs with four gapsNote: Our aim is to simulate all the orientations and coupling off SRRs in HFSS and to observe the resultant resonant frequency 15. ADVANTAGES OF DGS(SRR) STRUCTURE It is simple to implement and analyze Practical results are in agreement with simulation It offers a wide range of frequency, since by changing orientation, number of gaps or the gap width, we can decrease or increase the resonant frequency or possibly the filter response as per the requirement. Design is robust and is based on easy principle of inductive and capacitive coupling 16. CONCLUSION From the above design and simulated results, we come to conclusion that any type of filters can be designed just by varying the orientation of coupling of SRRs or by varying the gap width of SRR or by increasing the number of gaps in the SRR. The observed results are as follows: SpecificationCut-off frequencyStop-Band AttenuationGap 0.2mm4.1 GHz-58 dBGap 0.4mm5.0 GHz-37 dBDesigned parameters scaled to 1.2 times3.5 GHz-16 dBCoupling with Gap 0.2mm, d=1mm4.1 GHz-11.68 dBWe also see that the transition band is much more sharp and the stopband attenuation is also very high. The practical implementation of these filters are also easy and the give results approximate to the simulated result. 17. REFERENCES [1] Microwave Engineering by David M Pozar, 3rd edition [2] Multi-gap individual and coupled split-ring resonating structures by R. S. Penciu, K. Aydin, M. Kafesaki,Th. Koschny, E. Ozbay, E. N. Economou, C. M. Soukoulis [3] Effects of a Lumped Element on DGS with Islands by Jonguk Kim, JongSik Lim, Kwangsoo Kim, and Dal Ahn

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