Microstrip Transmission Line Design with Left-Handed Material Properties

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Microstrip Transmission Line Design with
Left-Handed Material Properties

• Final Presentation
• ECE 445
• Group 39
• Xu Chen Brian Boerman

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Introduction

• Project based on research by C. Caloz and T. Itoh
  at UCLA
• Transmission Line Approach of Left-Handed (LH)
  Materials and Microstrip Implementation of an
  Artificial LH Transmission Line, May 2004, IEEE
  Transactions on Antennas and Propagation

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Metamaterials

• A class of composites that exhibit exceptional
  properties not readily found in nature

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Left-Handed Materials

• A type of metamaterial with simultaneous negative
  permittivity and permeability, and a negative
  index of refraction
• First proposed in 1968 by Veselago
• Left-handed refers to the Left Hand Triad (E, H,
  k) obtained from Maxwell equations
• Science magazine listed LH materials as one of
  the ten greatest scientific breakthroughs in 2003

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Transmission Line Approach to LH Materials
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Transmission Line Approach to LH Materials
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Characteristics of the Line

• Characteristic Impedance
• For regular transmission lines,
• Where Z is the impedance of the series items and
  Y is the admittance of the parallel items

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Characteristics of the Line

• Wavenumber

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Characteristics of the Line

• Velocity of Propagation

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Objective

• To design a microstrip transmission line that
  would exhibit properties of Left-Handed (LH)
  materials
• To simulate the design and prove the LH
  properties
• To test the physical board and verify the results

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Original Design

• Design for 2 GHz
• Calculations show
• Series capacitance 12.8 pF
• Shunt inductance 32 nH
• 5 capacitor/inductor sections
• Assume ideal transmission lines
• Transmission lines are designed to have
  characteristics impedance of 50

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Design Principles

• In order to design the dual of an ordinary
  transmission line, shunt inductance and series
  capacitance must be used
• This is achieved through the use of
  interdigitated capacitors and through loop
  inductors
• Design is done in Sonnet

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Interdigitated Capacitors
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Through Loop Inductors
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Design Process

• To achieve desired values of C and L, dimensions
  of the interdigitated capacitor and through loop
  inductor are varied
• Since the elements cannot be measured up-close at
  high frequencies, two segments of transmission
  lines are added to the sides
• S-parameters of the whole system (line - L/C -
  line) as well as the standalone line is generated
  using Sonnet
• S-parameters of the inductor or capacitor can be
  extracted through de-embedding

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ABCD Parameters

• ABCD parameters were used for deembedding of
  components
• Utilized because ABCD parameters can be cascaded

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Capacitor testing

• Capacitor tested using B element of de-embedded
  ABCD parameters
• The B element of a series element is equal to the
  impedance of that element
• B

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Inductor testing

• Inductor tested using the C element of the
  de-embedded parameters
• The C element is equal to the admittance of a
  parallel element
• C

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Challenges

• Specifications set forth by the circuit board
  manufacturer
• minimum spacing, minimum line width, through
  hole diameter
• Capacitor value fell short of 12.8 pF goal
• Original capacitor design is not good because
  parasitic inductance takes over at high
  frequencies - resonance point

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Review of Design

• Necessary to have 50 ohm characteristic
  impedance, so
• or

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Review of Design

• Cutoff frequency
• High pass network, so cutoff frequency must be
  below some minimum value to have good operation
  over specified range

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New design

• Capacitor value of 2.662pF
• Inductor value of 6.286nH

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New Design

• Characteristic Impedance

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Simulations in HSPICE
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Simulations in HSPICE
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Applications

• New types of beam steerers, modulators, band-pass
  filters, superlenses, microwave components, and
  antennas

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Microwave Applications

• Dual-band Branch-line Coupler
• Zeroth Order Resonator Antenna
• Backfire-to-Endfire Leaky-Wave Antenna
• Planar Negative Refractive Index Lens

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Thanks To

• Professor Cangellaris
• Adam Gustafson
• Professor Swenson
• Jim Wehmer