1 Enhancement Cut off Frequency of Microstrip Low pass Chebyshev Filter using DGS

2 Outlines   Objective of the proposed work   Methodology to Achieve the Objective   Filter Designing   Fabrication of Filter   Low pass filter with DGS   Operational Mechanism   Simulation & Measured Results   Conclusion   References

3 To achieve 2.5GHz cut off frequency of microstrip low pass Chebyshev filter using DGS. Objective of the proposed work

4 Methodology To Achieve The Objective   Enhancement cut off frequency in the proposed filter is achieved by using defected ground structure.   DGS is using the structures etched in the microwave substrate ground plane. The DGS resonant characteristics are then used in filter design.   (a)Simulation cut off frequency 2.66 GHz (b)VNA tested cut off frequency GHz.

5 Filter Design 5th order Chebyshev Low pass filter using Insertion loss method

6 Design Specification To design 5th order Chebyshev Low pass filter using Insertion loss method should be as follows   N=5   R s = R L = 50Ω.   Cut-off frequency fc = 2.5GHz   Substrate used: GML 1000   Permittivity of substrate Єr = 3.2   Height h = 0.762mm   Ripple=0.01dB

7 Design Specification  Step 1: – Prototype design: Schematic of LPF filter Where: g o = 1 g 1 = g 2 = g 3 = g 4 = g 5 = g 6 = 1

8 Design Specification Step 2: – Impedance and frequency scaling: For a new load impedance of R o and cut-off frequency of ω o, the original resistance R n,inductance L n and capacitance C n are changed by the following formulae: R= R o R n L= (R 0 L n )/ ω o C= C n /(R o ω o ) Using the transformation with R o = 50Ω and ω o = 2π(2.5 X 10 ) the new values are: Rs = 50Ω C 1 = pf L 2 = nH C 3 = pf L 4 = nH C 5 = pf R L = 50Ω 9

9 Design Specification Step 3: Converting into distributed elements: The relationship between inductance and capacitance to the transmission line length at the cutoff frequency ω c are L 1 = mm,L 2 = mm,L 3 = mm,L 4 = mm L 5 = mm where n=1,3,5. where n=2,4,6 w/d = mm for z 0 = 50Ω w/d = mm for z 0 = 20Ω w/d =.2940mm for z 0 = 120Ω

10 Photolithography steps Photolithography steps The pattern on the mask is transferred on the substrate by means of photolithography Step1. Clean the substrate, dry thoroughly in front of heat blower. Step2. Coat the substrate with photo-resist material. Step3. Preheat the substrate in oven at 98 o C -100 o C for 10 minutes. Step4. Now aligned the mask on substrate. Step5. Exposed the substrate now to Ultra Violet rays for 2 minutes. Fabrication of microstrip filter

11 Step6.Keep the substrate in developer Step7.Now keep the substrate in acetone and then dry in front of heat blower Step8.Apply dye on the substrate and then now posts heat the substance for 10 minutes. Step9.Protect the ground of substrate with tape. Step10.Allow the substrate for Etching in the solution of FeCl 3 and water, and get the desired pattern on thesubstrate Fabrication of microstrip filter cont….

12 Simulated geometry of microstrip filter Photograph of the fabricated filter

13 Simulation Results Simulated result of the filter without DGS

14 Simulation Results cont…. Simulated result of the filter with DGS

15 VNA result of the fabricated filter With DGS

16 Comparison Table of the simulated and tested result of defected ground structure Simulated result of filter without DGS Simulated cut off frequency with DGS VNA tested cut off frequency with DGS GHz2.66 GHz2.715 GHz

17 Final Fabrication Specification: Size of substrate =50.8 X 50.8mm 2 Thickness of Substrate =0.762 mm Dielectric constant of Substrate = 3.2 Width of the Microstrip patch (W) W 1 = mm for z 0 = 50Ω W 2 =.2940mm for z 0 = 120Ω Length of the Microstrip patch (L) L 1 = mm,L 2 = mm, L 3 = mm,L 4 = mm L 5 = mm Dimensions of the DGS slot = 5 x5 mm 2 Ground plane dimensions = x mm 2 Cut-off frequency f c = 2.715GHz

18 Conclusion Design and fabrication of chebyshev low pass filetr is sucessfully done. The method to calculate the cut off frequency of the LPF has been developed based on the modeled equivalent inductance and capacitance, which depends on the dimension of the DGS pattern. Due to presence of DGS in the implemented design, the cut off frequency is improved from 2.362GHz to 2.66GHz and finally 2.715GHz in the realized filter.

19 Conclusion cont….. The fabricated filter show good agreement between the simulated and measured result. Compactness, easy fabrication and cost effective the proposed filter is useful for commercial wireless communication applications.

20 [1] Ahn, D.; Park, J.-S.; Kim, C.-S.; Kim, J.; Qian, Y.; Itoh, T., "A design of the lowpass filter using the novel microstrip defected ground structure," Microwave Theory and Techniques, IEEE Trans. Vol.49, no.1, pp.86-93, Jan [2] C. S. Kim, J. S. Park, D. Ahn, and J. B. Lim, “A novel 1-D periodic defected ground structure for planar circuits,” IEEE Microw. Wireless Compon. Lett., Vol. 10, no. 4, pp. 131–133, Apr [3] Liu, H., Z. Li, and X. Sun, “Compact defected ground structure in microstrip technology,” Electron. Lett., Vol. 41, No. 3, pp. 132–134, [4] Mandal, M. K. and S. Sanyal, “A novel defected ground structure for planar circuits,” IEEE Microwave Compon. Lett., Vol. 16, No. 2, pp. 93–95, [5] J.-S. Lim, C.-S. Kim, Y.-T. Lee, D. Ahn, and S. Nam, “Design of lowpass filters using defected ground structures and compensated microstrip line”, Electron Lett, Vol.38, pp. 1357–1358, [6] Karmakar, N.C.; Roy, S.M.; Balbin, I., "Quasi-static modeling of defected ground structure," Microwave Theory and Techniques, IEEE Transactions on, Vol.54, no.5, pp , May [7] Easter, B., "The Equivalent Circuit of Some Microstrip Discontinuities," Microwave Theory and Techniques, IEEE Transactions on, Vol.23, no.8, pp , Aug References

21References [08] J.-S. Lim, C.-S. Kim, J.-S. Park, D. Ahn, and S. Nam, "Design of 10dB 90 branch line coupler using microstrip line with defected ground structure," IEEE Electronics Letters, vol. 36, no. 21, pp , Oct [09] J. S. Lim, J. S. Park, Y. T. Lee, D. Ahn, and S. Nam, “ Application of defected ground structure in reducing the size of amplifiers,” IEEE Microwave Wireless Compon. Lett., Vol. 12, pp. 261– 263, July [10] Lim J-S, Jeong Y-C, Ahn D, Lee Y-T, Cho H and Nam S, “Size-reduction and harmonic-rejection of microwave amplifier using spiral-defected ground structure,” European Microwave Conf., Vol 3, pp. 1421–4, [11] J. S. Lim, H. S. Kim, J. S. Park, D. Ahn, and S. Nam, “A power amplifier with efficiency improved using defected ground structure,” IEEE Microwave Wireless Compon. Lett., Vol. 11, pp. 170–172, Apr [12] Ortega, A, de Menezes, Soares, L.R.A.X. and Abdalla,H., "Design of low-pass microstrip filters based on defected ground structure,”IEEEMicrowave & Optoelectronics Conference,pp.69,Oct [13]Pirani, Saeid, Nourinia, Javad, Ghobadi and Changiz, “Design of small modified microstrip lowpass filter with folded U-shaped defected ground structure”, ICEE, pp , 2010 [14]Kumar,A,Choudhari,N.P. and Verma,A.K., “Contest-k and m-derived composite lowpass filter using defected ground structure”, IEEE Advanced Computing & Communication Technologies, pp , 2012.

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