microstrip notch filter

22
EE522 Numerical Methods for EM -Final Project- Microstrip Notch Filter Goksenin Bozdag December 30, 2014

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  • EE522 Numerical Methods for EM

    -Final Project-

    Microstrip Notch Filter

    Goksenin Bozdag

    December 30, 2014

  • Goksenin Bozdag 30 December 2014 2/22

    Outline

    MS Filter Design

    MS Notch Filter Design

    OpenEMS Simulation

    HFSS Simulation

    QUCS Simulation

    Fabrication and Measurement

    Comparison of the Results

  • Goksenin Bozdag 30 December 2014 3/22

    Microstrip Filter Design

    A filter two-port network used to control the frequency response at a certain point

    Low-pass, high-pass, band-pass, and band-reject

    Communication, radar and measurement systems

  • Goksenin Bozdag 30 December 2014 4/22

    The image parameter method in WW II

    Today, CAD packages by the insertion loss method

    The methods lead to circuits using lumped elements

    In RF, distributed elements such as microstrip lines needed to use

    Limited range of lumped inductors and capacitors

    Difficult implementation at microwave frequencies

    Richards Transformation and Kurodas Identities

    Microstrip Filter Design

  • Goksenin Bozdag 30 December 2014 5/22

    Image parameter method

    cascade of simpler two port filter sections

    the procedure is relatively simple

    Iterated many times

    Microstrip Filter Design

    low-pass filter

    half section

    low-pass response,

    single half-section

    low-pass response with

    four (half) sections

  • Goksenin Bozdag 30 December 2014 6/22

    Microstrip Notch Filter Design

    Insertion loss method

    Uses network synthesis techniques

    Ideally, no power loss in the passband

    Bases normalized low-pass filter

    2dB 10log 10log 1 ( )inL

    PIL

    P

    2

    1

    1 ( )LRP

    2

    2

    M( )1

    N( )LRP

    where M and N are

    real polynomials.

  • Goksenin Bozdag 30 December 2014 7/22

    Richards transformation converts lumped elements to transmission lines

    Microstrip Filter Design

    tan( l)LjX jL

    tan( l)CjX jC

    Reactance of

    Inductance Short-stub

    Susceptance

    of Capacitance Open-stub

  • Goksenin Bozdag 30 December 2014 8/22

    Microstrip Filter Design

    Kurodos identities use redundant transmission lines

    Separete transmission line stubs

    Series stubs into shunt stubs, vice versa

    Impractical impedances to practical impedances

    where n2= 1 + Z2/Z1

  • Goksenin Bozdag 30 December 2014 9/22

    Microstrip Filter Design

    Low-pass

    equivalent circuit

    Richards Transf. & Freq. Mapping

    Adding Matched

    Unit Elements

    Applying Kurodas Identities

  • Goksenin Bozdag 30 December 2014 10/22

    Notch filter rejects the band sharply, band-stopping

    Avoiding interference or unwanted signals

    More optimum filter structures

    Employing quarter-wave open and short stubs in series and parallel as resonant circuits

    Microstrip Notch Filter Design

    Lumped element

    band-stop filter

    Equivalent circuit with

    addmittance inverters

  • Goksenin Bozdag 30 December 2014 11/22

    Microstrip Notch Filter Design

    Admittance inverter

    O.C. for LC Res.

    All of the elements represents by distributed elements

    Avoided reduntant elements

    Characteristic impedance of open stubs

    4 oon

    n

    ZZ

    g

    Zo1 = Zo = 50 and = 12.5 mm for g1 = 0.7 and = 1.8 at 3.2 GHz

    where g coefficient of 0.5 dB equal ripple

    and =

  • Goksenin Bozdag 30 December 2014 12/22

    Finite Difference Time Domain (FDTD) Solver

    Open and Free, requires MatLab or Octave

    The code separeted into six parts

    Setup geometrical parameters

    Setup FDTD paramters (e.g. Boundary cond.)

    Setup FDTD mesh (resoulution, thin metal)

    Assiging Substrate Material

    Assisgning ports and open-stub

    Post processing (reading voltages and currents)

    OpenEMS Simulation

  • Goksenin Bozdag 30 December 2014 13/22

    OpenEMS Simulation

  • Goksenin Bozdag 30 December 2014 14/22

    High Frequency Structure Simulator, Ansys Inc.

    Finite Element Method (FEM)

    Frequency Domain Solver

    Filter modeling includes the parts:

    Draw the geometry

    Assigin the materials

    Assign the ports and boundaries

    Setup solution frequency and convergence

    Setup sweep frequencies

    Post Processing

    HFSS Simulation

  • Goksenin Bozdag 30 December 2014 15/22

    HFSS Simulation

    0.50 1.50 2.50 3.50 4.50 5.50Freq [GHz]

    -30.00

    -25.00

    -20.00

    -15.00

    -10.00

    -5.00

    0.00

    Y1

    HFSSDesign1MSL NF HFSS ANSOFT

    m1

    m6 m7

    m2Curve Info

    dB(S(1,1))Setup1 : Sw eep

    dB(S(2,1))Setup1 : Sw eep

    Name X Y

    m1 3.2650 -28.3810

    m2 3.2650 -1.0139

    m6 2.4500 -3.0028

    m7 4.0000 -3.0114

  • Goksenin Bozdag 30 December 2014 16/22

    Quite Universal Circuit Simulator, open and free

    Mathematical formulations for calculation

    Includes many library and tools including

    MS lines, stubs, lumped elements and

    transmission line calculators eg. rectangular wg

    Filter modeled by following the steps

    Draw the circuit diagram using library

    Assigin the substrate

    Setup sweep frequencies

    Post Processing

    QUCS Simulation

  • Goksenin Bozdag 30 December 2014 17/22

    QUCS Simulation

  • Goksenin Bozdag 30 December 2014 18/22

    Fabrication and Measurement

  • Goksenin Bozdag 30 December 2014 19/22

    Mesh Number Duration (sec) Res.Frq. (GHz)

    OpenEMS 55514 150.2 3.217 0.5176

    HFSS 14240 144 3.265 0.4747

    QUCS X 2 3.220 0.5559

    Realized Filter X X 3.250 0.4077

    Comparison of the Results

    Error Rates (%)

    Resonance Freq.

    OpenEMS 1.0154 34.3144

    HFSS 0.4615 16.4337

    QUCS 0.9231 36.3503

    HFSS the most accurrate

    QUCS results almost the same with openEMS

    QUCS the most practical and fast

  • Goksenin Bozdag 30 December 2014 20/22

    References

    Pozar, David M., Microwave Engineering, John Wiley & Sons, USA, 2012.

    Hong, J. S. and Lancaster M. S., Microstrip Filters for RF and Microwave Applications, John Wiley & Sons, New York, 2001.

    Ludwig R. and Bretchko P., RF Circuit Design: Theory and Applications, Prentice-Hall Inc., New Jersey, 2000.

  • Goksenin Bozdag 30 December 2014 21/22

    References for Softwares

    OpenEMS, www.openems.de

    HFSS v13, www.ansys.com/Products

    QUCS, www.qucs.sourceforge.net

  • Goksenin Bozdag 30 December 2014 22/22

    Thanks for your

    participation.

    Questions ?