International Journal of Innovative and Emerging Research in Engineering
Volume 3, Issue 4, 2016
Available online at www.ijiere.com
e-ISSN: 2394 - 3343 p-ISSN: 2394 - 5494
b
Deep K Chauhan a
and FalguniRaval b a
M.Tech(C.S.E.),Electronics and Communication Engineering, Charotar University of Science and Technology, Changa
Assistant Prof., Electronics and Communication Engineering, Charotar University of Science and Technology, Changa
ABSTRACT :
Chebyshev low pass filter presented based on lumped-network and microstrip line structure suitable for wireless communication purpose. In this paper chebyshev microstrip lowpass filter of order 3 and 1dB pass band ripple is designed on duroid substrate using step-impedance method for 1GHz cut-off frequency using Ansoft Designer and
Ansys HFSS.
Keywords: ANSOFT DESIGNER, ANSOFT HFSS, lumped-element network, Microstrip low pass filter,Duroid.
I.
I NTRODUCTION
Main purpose of filter is to take up frequencies in selected operated range and turn down all other. There are four main types for filter which we known as low pass filter, high pass filter, band pass filter, band stop filter. Each filter can reject and accept the frequencies in different manner. Low pass filter allows only frequencies below cut-off frequencies.
High pass filter allows higher frequencies than cut-off frequencies. Band pass filter will allow frequencies within pass band and band stop filter will reject frequencies for certain band. A filter can allow frequencies called as pass band. In practical it is not possible to achieve perfect filter[1-2-13].
This filter used in microwave systems like as radars, measurement and test systems, satellite communication [3-
13]. This microstrip filter has advantages like low cost, higher selectivity and uncomplicated structure. This microstrip lines are much cheaper and lighter but gives higher losses.
Stepped impedance low pass microstrip filters offer better stop band characteristics and are simpler to design. Such filters are formed, from the series connection of high and low impendence microstrip transmission lines [8-9].Low pass filter consist of lumped-network and microstrip line structure appropriate for wireless communication purpose. Microstrip line is widely used transmission lines and is definitely miniaturized and integrated with both passive and active microwave devices. During this paper design of microstrip lowpass Chebyshev filter is implemeted with order three and 1dB pass band ripple using step-impedance methodology for 1GHz cut-off frequency in Ansoft Designer and Ansoft HFSS. The length of the strip, the height of substrate and the relative permittivity of substrate determine the characteristic impedance of the transmission line. Between 800MHz to 30GHz we can use microstrip RF filters [4]. Microstrip line with two different characteristic impedances combines together to make microstrip lowpass filter.
In this present paper, filter is designed based on stepped impedance method. Calculation based lumped lowpass filter is designed and analyzed in Ansoft Designer. Lumped elements are converted into microstrip line using Ricahrds transformation method. Third order stepped impedance low pass microstripfilter has been designed and analyzed using
Ansoft HFSS software at 1GHz frequency on Duroid substrate.
II. DESIGN OF MICROSTRIP LOPWASS FILTER
The two basic steps to design the stepped impedance lowpass filter are to select an appropriate low pass prototype and find an appropriate microstrip realization that approximates the lumped element filter. For proposed design work,chebyshev approximation is assumed which exhibits the equal ripple pass-band and maximally flat stop-band. The general structure and LC ladder type stepped impedance lowpass microstrip line filter [13].
Third order low pass filter have been designed in microstrip configuration with the following specification.

Passband Ripple = 1dB
Cut off frequency f c
= 1 GHz
Substrate thickness,h =1.6 mm
Characteristic impedance = 50 Ω
0
Highest Line impedance = 93 Ω
0L
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International Journal of Innovative and Emerging Research in Engineering
Volume 3, Issue 4, 2016
Design of Lumped-Element low pass filter is as follow:
For pass-band ripple characteristic having 1 dB ripple the element values for the filter is given in below table.
Table 1 element value for lowpass chebyshev filter prototypes (g0=1,Wc=1 And 1db Ripple) [1] m g1 g2 g3 g4 g5 g6 g7 g8
1 1.0178 1.000
2 1.8220 0.6580 2.6599
3 2.0237 0.9941 2.0237 1.0000
4 2.0991 1.0644 2.8312 0.7892 2.6599
5 2.1350 1.0911 3.0010 1.0911 2.1350 1.0000
6 2.1547 1.1041 3.0635 1.1518 2.9368 0.8101 1.0000
7 2.1666 1.1115 3.0937 1.1735 3.0937 1.1115 2.1666 1.0000
From the table, as order is 3 so prototype element value for the order three are as follow: g1=2.0237 g2=0.9941 g3=2.0237
Now lumped elements like inductor and capacitor value can be calculated by below formula [1]. i z
0
Ω g
0
2Πf
Ω
2Πf
×
C
C
×
C g
Z
C
0
0
×g .........................................(2)
Calculated values for lumped-element network from equation(1)and (2) are as given in below table 2.
Table 2 Lumped parameter values
Prototype element value Correspond L and C value g1=2.0237 g2=0.9941 g3=2.0237
L1=16.1 nH
C1=3.164 pF
L2=16.1 nH
Figure 1 lumped model of filter
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International Journal of Innovative and Emerging Research in Engineering
Volume 3, Issue 4, 2016
We approximated chebyshev filter, the equation set for this particular filter is as below [1]. g m+1
=

1,where m is odd number


ξ cosh( ),where m is even number
4
.............(4) g =
2a x
1
...................................
................................(5)
,where p=2,3....p................................(6) b g

ξ=ln coth



G r
17.37
 
 

................................................(7)
χ=sinh
 ξ 
...........................................................(8)
 2m 


(2p-1)Π
2m


...................
..............................(9)
2
 pΠ

................................................(10)
 m 
Requirement for the dimensions of microstirpline ,assumption of low and high impedance is done. Characteristic impedance of high impedance line value Z oL=
93 Ω and characteristic impedance of low impedance line value Z oC
=17
Ω. We are going to use Duroid as subtract having 2.2 dielectric permittivity, thickness of subtract is h=1.6mm. We can calculate width of microstrip line by equations (11) and (12). Equations [1] for calculation of width and length are as given below which gives result in radian so need to convert it into degree.
  l rad...............................................(11)
Zh
  c R o rad..............................................(12)



377
Z
0L
ε r

Where W h
gives the width of source and load side wherever the length of those front and end is taken as 10mm.
By using the above formula we can have calculated width and length for Microstrip line are which are shown below.
Table 1 Dimensions of microstrip line
Sr
No.
1
2
Impedence(ohm) Width(mm)
50 5.62
Length(mm)
10
93 1.67 38.93
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3
4
5
17
International Journal of Innovative and Emerging Research in Engineering
Volume 3, Issue 4, 2016
19.90 11.27
93
50
1.67
5.62
38.93
10
Figure 2microstrip filter model
The microstrip lowpass filter is shown in figure 2 and figure 3. We have to assume source as well as load impedance length in this case we assume the length as 10mm.
Figure 3microstriplowpass filter 3d geometry design using Ansoft HFSS
III. RESULT AND DISCUSSION
Simulation result for lumped-element low pass filter design using ANSOFT DESIGNER software is as shown in figure 4.Insertion loss is -3 dB at 1.08 GHz for lumped-network low pass filter design with 1dB ripple in passband.
The figure 5 shows result for microstrip low pass filter in ANSOFT HFSS software. The insertion loss is -2.82 dB at
1.0 GHz. For the simulation purpose we have used method of moment based full-wave EM solver Ansoft HFSS.
Simulation result for lumped lowpass model and microstriplowpass filter model is shown in figure 4 and figure 5.
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International Journal of Innovative and Emerging Research in Engineering
Volume 3, Issue 4, 2016
0.00
-10.00
-20.00
-30.00
-40.00
-50.00
-60.00
0.00
Figure 4 simulated result of ANSOFT DESIGNER for lumped-element low pass filter
XY Plot 11 m1
HFSSDesign1
Name X Y m1 1.0000 -2.8230
Curve Info dB(S(1,1))
Setup1 : Sweep dB(S(2,1))
Setup1 : Sweep
0.25
0.50
0.75
Freq [GHz]
1.00
Figure 5 simulated result of ANSOFT HFSS for microstrip low pass filter
1.25
1.50
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International Journal of Innovative and Emerging Research in Engineering
Volume 3, Issue 4, 2016
IV. REFERENCES
[1] Devendra k. misrea, “radio-frequency and microwave communication circutits, analysis and design”, student edition, A wiley-interscience publication
[2] Ian C. Hunter, L. Billonet, B. Jarry, and P. Guillon,”Microwave filters application and tecchnology”,IEEE transaction on vol.50, issue 3,march 2002.
[3] O. Borazjani, A. Reazaee, “Design , simulation and construction a low pass microwave filters on the
Microstrip transmission line”, International Jouranal of computer theory and Engineering, vol. 4, no. 5, october 2012
[4] K. Rajasekaran, J. Jayalakshmi, T. Jayashankar, “Design and analysis of stepped impedance Microstrip low pass filter using ADS simulation tool for wireless application” , International journal of scentific and research publication, Vol. 3, Aug. 2013
[5] P. singh, “Analysis of multilayer Microstrip line of finite conducter thickness using Quasi_static Spectral domain analysis and single layer reduction metod ”, IEEE, p.p 1-4,Dev. 2011
[6] Tehrani, Kiana, and Andrew Michael. “Wearable Technology and Wearable Devices: Everything You Need to Know.” Wearable Devices Magazine, WearableDevices.com, March 2014. Web.
[7] Garvansh, Abhay Singh Kushwaha, Navita Sing, Arun Kumar, “Implementation of Stepped Impedance Low
Pass Microstrip Line Filter for Wireless Communication” , International Journal of Advanced Research in
Computer and Communication Engineering Vol. 3, Issue 7, July 2014
[8] G.L.Mathaei, L.Young& E.M.T. Jones, “Microwave Filter impedance matching networks and coupling structures,” Artech House, Dedham, Mass, 1980.
[9] Sudipta Das, Dr. S.K.Chowdhury, “Design Simulation and Fabrication of Stepped Impedance Microstrip line
Low Pass Filter for S-band Application using IE3D and MATLAB” IJECT Vol. 3, Issue 1, Jan. - March 2012
[10] Jia-Sheng Hong, M. J. Lancaster,” Microstrip Filters for RF/Microwave Applications.”
[11] David M. Pozar ,”Microwave engineering”, 2nd edition
[12] SAMUEL Y.LIAO, “Microwave devices and circuits”, 3rd addition
[13] M.kulkarni, “Microwave and Radar Engineering”, 2nd edition
[14] Patel, Binal, Falguni Raval. "Wearable Textile Microstrip Low Pass Filter using Jeans as Subtrate."
International Journal of Engineering Research and Technology. Vol. 4. No. 04 (April-2015). ESRSA
Publications, 2015.
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