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Outline Introduction Types of PTL Theoretical framework Area of Application

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IntroductionFunctionally Microwave devices are classified as :

Passive Device

Active Device

Planar transmission lineCoaxial transmission line

Klystron/Magnetron

Traveling wave tube (TWT)Gunn/IMPATT/Tunnel/Varactor diodeBJT ,GaAs ,FETS , HEMTSMasen

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Passive Device

Active Device

Planar transmission lineCoaxial transmission line

Klystron/Magnetron


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IntroductionTransmission line are essential components in microwavedesign .

Used to transmit m-wavesignal from one-point to another

Construct passive m-wave devices such as directionalcouplers ,filters , power divider ,matching networks etc.

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Construct passive m-wave devices such as directionalcouplers,filters , power divider ,matching networks etc.

7/24/2013 9Directional couplers

They couple a defined amount of theelectromagnetic power in transmission

line to a port. Couple power flowing inone direction.

separating transmitted and receivedsignals on telephone lines.

providing a signal sample formeasurement or monitoring

Applications :

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Construct passive m-wave devices such as directionalcouplers ,Filters , power divider ,matching networks etc.

7/24/2013 10Harmonic Filter

A harmonic filter is used to eliminate theharmonic distortion caused by appliances.

Harmonic currents provide power thatcannot be used and also takes up electricalsystem capacity.

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Achieve isolation between the output portswhile maintaining a matched condition onall ports.

split one source into two parts for separate

measurements

providing taps for cable distributedsystems such as cable TV

Applications :

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Passive Device

Active Device

Planar transmission lineNon planar transmission line

Klystron/Magnetron


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Passive Device

Active Device

Planar transmission lineNon planar transmission line

Klystron/Magnetron


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Introduction

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a) Non-planar transmission lineb) Planar transmission line

Classification of transmission line

Depending on the element that characterize the transmission line thetransmission line can be categorized as planar and non planar.

b ) Non planar transmission linea ) Non planar transmission line

= 138 log d D

1

= 12 12 1 12. 0.04 1

= 2 ln 8 0 25

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Introduction

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a) Planar transmission lineb) Non-planar transmission line

Classification of transmission line

Depending on the element that characterize the transmission line thetransmission line can be categorized as planar and non planar.

a ) Non planar transmission line

b ) Non planar transmission line

= 138 log d D

1

= 12 12 1 12. 0.04 1

= 2 ln 8 0 25

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Introduction

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Basic characteristics of Planar-transmission line

PTL has one or more parallel metal strips placed on a dielectric substrateover a conducting ground plane.

PTLs are fabricated using conventional printed circuit boardstechniques. good mechanical tolerances low cost. PTLs transmission lines are preferred for microwave integrated circuits

(MIC)

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Outline Introduction Types of PTL

Theoretical framework Area of Application

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Types of PTLThere are different types of planar transmission lines :

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2. MICROSTRIP LINE1. STRIP LINE 3. SLOT LINE

4. COPLANAR LINES

These are the commonly used planartransmission lines

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Types of PTLThere are also other variety of PTLs :

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SUSPENDED STRIPLINE FIN LINE INVERTED MICROSTRIP LINE

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Types of PTLComparison between PTLs :

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characteristics Micro strip Line Slot Line Coplanar Lines

Impedance range [] 15-120 50-300 25-155Frequency range (GHZ) 0-60 3-60 0-60, 2-20 10-20 2-20Dispersion Small Large Medium

Attenuation loss Low high Medium

High Low Medium

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Theoreticalframework

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Micro strips: Geometrical characteristics

W- the width of the hot conductor

h- the substrate height t- the conductors thickness

Where

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Micro strips: Electric and magnetic field lines

homogeneous structure:

The field lines between strip and ground plane are not contained entirelyin the substrate. Hence mode of propagation is not purely TEM , But quasiTEM

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Micro strips:

Attenuation

Losses

Its finite Conductibility Its finite resistivity of the substrate and its dumping phenomena Its radiation effects

conductor loss constant

= 2

= [mean power dissipated] = [transmitted power ]Where

Dielectric loss constant

= 20ln101

11 1 tan

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Micro strips:

Practical considerations

Lumped inductors and capacitors

Design of inductors

The elements physical dimensions are much smaller than the freespace wavelength of the highest operating frequency .

High-impedance line

Square spiralCircular spiral Meander line

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Micro strips:


Lumped inductors and capacitors

Design of inductors

The elements physical dimensions are much smaller than the freespace wavelength of the highest operating frequency .

High-impedance line

Circuit Model

nH = 2x10l ln lW t 1.1930.2235 W tl k

= 2( ) 1 40 217ln 5 For

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Micro strips:


Design of capacitor

Metal-insulator-metal (MIM) capacitor

Circuit Model =

= ()

Interdigital capacitor Metal-insulator-metal (MIM)capacitor

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Strip line: Geometrical characteristics

W- the width of the hot conductor

h- the substrate height

t- the conductors thickness

Where

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Strip line: Electric and magnetic field lines

The dominant mode is TEM

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Strip line:

Design equations

The characteristics Impedance:

= 30 0.441

-Effective width of the central conductor

Where

The characteristic impedance decreases for increasing values ofthe parameter / bThe effective width is obtained from:

= -

0

0.350.35

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Strip line:

Design equations

= - 0 0.350.35 120

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Strip line: :

Attenuation

conductor loss constant

= .() 120. 120Where

Dielectric loss constant

tan

2

thickness of the strip =t

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Area of ApplicationApplication-1 :

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Microwave resonator : filter circuits that are used in communicationssystems for frequency band selection.

the single shunt micro strip with the quarter-wave stub is a seriesresonant circuit, which means that it blocks the input signal frompassing through to the output at the resonant frequency.

Ana Keef
https://plus.google.com/115073543672878130711https://plus.google.com/115073543672878130711https://plus.google.com/115073543672878130711

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Butterworth Low Pass Filter: is (maximally flat) low pass filter usingstepped-impedance micro strip lines.

These filters were designed to have a 3GHz cutoff frequency and a largeinsertion loss at 6 GHz.

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3dB Wilkinson power divider : is a three port device and it splits theinput signal into two output signals.

Power dividers are passive componentsthat split the input signal into equalamplitude and equal phase outputs.In the 3-dB Wilkinson power divider theoutput signals are 3 dB below the inputsignal and the phase shift between the

outputs is 0.

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Thank you !

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Fitsum Mergia 1096 03