RF and Microwave Circuit Design E-Book

Charles E. Free

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: Microwave and Wireless Technologies Series
• Sprache: Englisch

Seitenzahl: 866

Veröffentlichungsjahr: 2021

Beschreibung

RF and Microwave Circuit Design

Provides up-to-date coverage of the fundamentals of high-frequency microwave technology, written by two leading voices in the field

RF and Microwave Circuit Design: Theory and Applications is an authoritative, highly practical introduction to basic RF and microwave circuits. With an emphasis on real-world examples, the text explains how distributed circuits using microstrip and other planar transmission lines can be designed and fabricated for use in modern high-frequency passive and active circuits and sub-systems. The authors provide clear and accurate guidance on each essential aspect of circuit design, from the theory of transmission lines to the passive and active circuits that form the basis of modern high-frequency circuits and sub-systems.

Assuming a basic grasp of electronic concepts, the book is organized around first principles and includes an extensive set of worked examples to guide student readers with no prior grounding in the subject of high-frequency microwave technology. Throughout the text, detailed coverage of practical design using distributed circuits demonstrates the influence of modern fabrication processes. Filling a significant gap in literature by addressing RF and microwave circuit design with a central theme of planar distributed circuits, this textbook:

• Provides comprehensive discussion of the foundational concepts of RF and microwave transmission lines introduced through an exploration of wave propagation along a typical transmission line
• Describes fabrication processes for RF and microwave circuits, including etched, thick-film, and thin-film RF circuits
• Covers the Smith Chart and its application in circuit design, S-parameters, Mason???s non-touching loop rule, transducer power gain, and stability
• Discusses the influence of noise in high-frequency circuits and low-noise amplifier design
• Features an introduction to the design of high-frequency planar antennas
• Contains supporting chapters on fabrication, circuit parameters, and measurements
• Includes access to a companion website with PowerPoint slides for instructors, as well as supplementary resources

Perfect for senior undergraduate students and first-year graduate students in electrical engineering courses, RF and Microwave Circuit Design: Theory and Applications will also earn a place in the libraries of RF and microwave professionals looking for a useful reference to refresh their understanding of fundamental concepts in the field.

Leseprobe

Table of Contents

Cover

Title Page

Copyright

Preface

About the Companion Website

1 RF Transmission Lines

1.1 Introduction

1.2 Voltage, Current, and Impedance Relationships on a Transmission Line

1.3 Propagation Constant

1.4 Lossless Transmission Lines

1.5 Matched and Mismatched Transmission Lines

1.6 Waves on a Transmission Line

1.7 The Smith Chart

1.8 Stubs

1.9 Distributed Matching Circuits

1.10 Manipulation of Lumped Impedances Using the Smith Chart

1.11 Lumped Impedance Matching

1.12 Equivalent Lumped Circuit of a Lossless Transmission Line

1.13 Supplementary Problems

Appendix 1.A Coaxial Cable

Appendix 1.B Coplanar Waveguide

Appendix 1.C Metal Waveguide

Appendix 1.D Microstrip

Appendix 1.E Equivalent Lumped Circuit Representation of a Transmission Line

References

Notes

2 Planar Circuit Design I

2.1 Introduction

2.2 Electromagnetic Field Distribution Across a Microstrip Line

2.3 Effective Relative Permittivity,

2.4 Microstrip Design Graphs and CAD Software

2.5 Operating Frequency Limitations

2.6 Skin Depth

2.7 Examples of Microstrip Components

2.8 Microstrip Coupled-Line Structures

2.9 Summary

2.10 Supplementary Problems

Appendix 2.A Microstrip Design Graphs

References

Notes

3 Fabrication Processes for RF and Microwave Circuits

3.1 Introduction

3.2 Review of Essential Material Parameters

3.3 Requirements for RF Circuit Materials

3.4 Fabrication of Planar High-Frequency Circuits

3.5 Use of Ink Jet Technology

3.6 Characterization of Materials for RF and Microwave Circuits

3.7 Supplementary Problems

References

Notes

4 Planar Circuit Design II

4.1 Introduction

4.2 Discontinuities in Microstrip

4.3 Microstrip Enclosures

4.4 Packaged Lumped-Element Passive Components

4.5 Miniature Planar Components

Appendix 4.A Insertion Loss Due to a Microstrip Gap

References

Note

5

S

-Parameters

5.1 Introduction

5.2

S

-Parameter Definitions

5.3 Signal Flow Graphs

5.4 Mason's Non-touching Loop Rule

5.5 Reflection Coefficient of a Two-Port Network

5.6 Power Gains of Two-Port Networks

5.7 Stability

5.8 Supplementary Problems

Appendix 5.A Relationships Between Network Parameters

References

Note

6 Microwave Ferrites

6.1 Introduction

6.2 Basic Properties of Ferrite Materials

6.3 Ferrites in Metallic Waveguide

6.4 Ferrites in Planar Circuits

6.5 Self-Biased Ferrites

6.6 Supplementary Problems

References

Note

7 Measurements

7.1 Introduction

7.2 RF and Microwave Connectors

7.3 Microwave Vector Network Analyzers

7.4 On-Wafer Measurements

7.5 Summary

References

Note

8 RF Filters

8.1 Introduction

8.2 Review of Filter Responses

8.3 Filter Parameters

8.4 Design Strategy for RF and Microwave Filters

8.5 Multi-Element Low-Pass Filter

8.6 Practical Filter Responses

8.7 Butterworth (or Maximally Flat) Response

8.8 Chebyshev (Equal Ripple) Response

8.9 Microstrip Low-Pass Filter, Using Stepped Impedances

8.10 Microstrip Low-Pass Filter, Using Stubs

8.11 Microstrip Edge-Coupled Band-Pass Filters

8.12 Microstrip End-Coupled Band-Pass Filters

8.13 Practical Points Associated with Filter Design

8.14 Summary

8.15 Supplementary Problems

Appendix 8.A Equivalent Lumped T-Network Representation of a Transmission Line

References

Note

9 Microwave Small-Signal Amplifiers

9.1 Introduction

9.2 Conditions for Matching

9.3 Distributed (Microstrip) Matching Networks

9.4 DC Biasing Circuits

9.5 Microwave Transistor Packages

9.6 Typical Hybrid Amplifier

9.7 DC Finger Breaks

9.8 Constant Gain Circles

9.9 Stability Circles

9.10 Noise Circles

9.11 Low-Noise Amplifier Design

9.12 Simultaneous Conjugate Match

9.13 Broadband Matching

9.14 Summary

9.15 Supplementary Problems

References

Notes

10 Switches and Phase Shifters

10.1 Introduction

10.2 Switches

10.3 Digital Phase Shifters

10.4 Supplementary Problems

References

Note

11 Oscillators

11.1 Introduction

11.2 Criteria for Oscillation in a Feedback Circuit

11.3 RF (Transistor) Oscillators

11.4 Voltage-Controlled Oscillator

11.5 Crystal-Controlled Oscillators

11.6 Frequency Synthesizers

11.7 Microwave Oscillators

11.8 Oscillator Noise

11.9 Measurement of Oscillator Noise

11.10 Supplementary Problems

References

Notes

12 RF and Microwave Antennas

12.1 Introduction

12.2 Antenna Parameters

12.3 Spherical Polar Coordinates

12.4 Radiation from a Hertzian Dipole

12.5 Radiation from a Half-Wave Dipole

12.6 Antenna Arrays

12.7 Mutual Impedance

12.8 Arrays Containing Parasitic Elements

12.9 Yagi–Uda Antenna

12.10 Log-Periodic Array

12.11 Loop Antenna

12.12 Planar Antennas

12.13 Horn Antennas

12.14 Parabolic Reflector Antennas

12.15 Slot Radiators

12.16 Supplementary Problems

Appendix 12.A Microstrip Design Graphs for Substrates with

ε

r

 = 2.3

References

Note

13 Power Amplifiers and Distributed Amplifiers

13.1 Introduction

13.2 Power Amplifiers

13.3 Load Matching of Power Amplifiers

13.4 Distributed Amplifiers

13.5 Developments in Materials and Packaging for Power Amplifiers

References

14 Receivers and Sub-Systems

14.1 Introduction

14.2 Receiver Noise Sources

14.3 Noise Measures

14.4 Noise Figure of Cascaded Networks

14.5 Antenna Noise Temperature

14.6 System Noise Temperature

14.7 Noise Figure of a Matched Attenuator at Temperature

T

O

14.8 Superhet Receiver

14.9 Mixers

14.10 Supplementary Problems

Appendix 14.A Appendices

References

Notes

Answers to Selected Supplementary Problems

Chapter 1

Chapter 2

Chapter 3

Chapter 5

Chapter 6

Chapter 8

Chapter 9

Chapter 10

Chapter 11

Chapter 12

Chapter 14

Index

End User License Agreement

List of Tables

Chapter 1

Table 1.1 Designations for a rectangular waveguide.

Chapter 3

Table 3.1 Typical data for common ‘hard’ substrates at 10 GHz.

Table 3.2 Typical data for common ‘soft’ substrates at 10 GHz.

Chapter 7

Table 7.1 Data on common RF/microwave connectors.

Chapter 8

Table 8.1 Butterworth normalized parameters.

Table 8.2 Chebyshev normalized parameters (Ripple 0.01 dB).

Chapter 9

Table 9.1

S

-parameter data for a packaged FET at

X

-band.

Table 9.2 Network gains.

Table 9.3 Source gain requirements.

Chapter 10

Table 10.1 Typical equivalent circuit data for a GaAs MESFET.

Table 10.2 Typical performance data for RF switches.

Table 10.3 Transmission phases through a three-bit phase shifter.

Chapter 12

Table 12.1 Data on typical antennae.

Chapter 13

Table 13.1 Frequency components at output of non-linear amplifier.

Chapter 14

Table 14.1 Typical values of noise figure and corresponding noise temperatur...

List of Illustrations

Chapter 1

Figure 1.1 Common types of high-frequency transmission line.

Figure 1.2 Representation of a transmission line in terms of lumped componen...

Figure 1.3 Equivalent circuit of an elemental length,

δz

, of a transmis...

Figure 1.4 Standing voltage wave.

Figure 1.5 Normalized constant resistance circles.

Figure 1.6 Normalized constant reactance circles.

Figure 1.7 The Smith chart.

Figure 1.8 Examples of constant resistance lines (a) and reactance lines (b)...

Figure 1.9 Examples of normalized impedance points.

Figure 1.10 Examples of normalized admittance points.

Figure 1.11 Plot of VSWR circle (

VSWR

Figure 1.12 Plot of reflection coefficient point,

ρ

Figure 1.13 Impedance,

Z

, at a distance

d

in front of a load

Z

L

.

Figure 1.14 Smith chart solution for Example 1.4.

Figure 1.15 Smith chart solution for Example 1.5.

Figure 1.16 Smith chart solution for Example 1.6.

Figure 1.17 Schematic view of a transmission line stub.

Figure 1.18 Smith chart solution for Example 1.8.

Figure 1.19 Matching network between source and load.

Figure 1.20 Single-stub tuner employing a short-circuited, shunt-connected s...

Figure 1.21 Smith chart solution for Example 1.9.

Figure 1.22 Effect of adding reactance to a normalized impedance,

z

1

.

Figure 1.23 Circuit for Example 1.10.

Figure 1.24 Nomenclature for solution for Example 1.10.

Figure 1.25 Smith chart solution for Example 1.10.

Figure 1.26 Lumped-element matching network.

Figure 1.27 First Smith chart solution to Example 1.11.

Figure 1.28 Second Smith chart solution to Example 1.11.

Figure 1.29 Matching networks for Example 1.11.

Figure 1.30 First solution to Example 1.12(i).

Figure 1.31 Second solution to Example 1.12(i).

Figure 1.32 Matching networks for Example 1.12.

Figure 1.33 Solution to Example 1.12(ii).

Figure 1.34 Lumped-element matching network 2.

Figure 1.35 First solution to Example 1.13.

Figure 1.36 Second solution to Example 1.13.

Figure 1.37 Matching networks for Example 1.13.

Figure 1.38 Matching complex impedances.

Figure 1.39 First solution to Example 1.14.

Figure 1.40 Second solution to Example 1.14.

Figure 1.41 Matching networks for Example 1.14

Figure 1.42 Equivalent lumped network of a transmission line: (a) length of ...

Figure 1.43 Circuit for Q1.13.

Figure 1.44 Circuit for Q1.14.

Figure 1.45 Circuit for Q1.15.

Figure 1.46 Circuit for Q1.16.

Figure 1.47 Circuit for Q1.17.

Figure 1.48 Electromagnetic field within a coaxial cable.

Figure 1.49 Nomenclature for a coaxial cable.

Figure 1.50 Coplanar waveguides.

Figure 1.51

E

-field distribution on a coplanar line.

Figure 1.52 Nomenclature for a coplanar waveguide.

Figure 1.53 Cross-section of a rectangular waveguide.

Figure 1.54 Intersection of two plane waves: (a) the individual waves; (b) t...

Figure 1.55 Sketch of electric and magnetic field patterns for TE

10

mode in ...

Figure 1.56 Single loop of magnetic field in a rectangular waveguide.

Figure 1.57 Coordinate system for electromagnetic field components.

Figure 1.58 Variation of attenuation for rectangular waveguide modes.

Figure 1.59 Coordinate system for a circular waveguide.

Figure 1.60 Sketch of electric and magnetic field patterns for TE

01

mode in ...

Figure 1.61 Attenuation curves of typical modes in a circular waveguide.

Figure 1.62 Cross-section of a microstrip line.

Figure 1.63 π-Network of admittances.

Figure 1.64 π-Network representing an electrically short transmission line....

Figure 1.65 Length of a lossless transmission line.

Chapter 2

Figure 2.1 Cross-section of a microstrip line showing key dimensions.

Figure 2.2 Sketch of electric field surrounding a microstrip line.

Figure 2.3 Sketch of the magnitude of the RF current distribution across a c...

Figure 2.4 Microstrip branch-line coupler.

Figure 2.5 Completed design for Example 2.3.

Figure 2.6 Quarter-wave transformer.

Figure 2.7 Completed design for Example 2.4.

Figure 2.8 Microstrip three-step

λ

/4 transformer.

Figure 2.9 Sketch of the reflection coefficient magnitude of a multi-step

λ

...

Figure 2.10 Completed design for Example 2.5.

Figure 2.11 Wilkinson power divider.

Figure 2.12 Completed design for Example 2.7.

Figure 2.13 Coupled microstrip lines.

Figure 2.14 Sketch of electric field distributions for even and odd modes: (...

Figure 2.15 Nomenclature for microstrip coupled lines.

Figure 2.16 Layout of a microstrip directional coupler.

Figure 2.17 Completed design for Example 2.11.

Figure 2.18 Cross-section of microstrip coupled lines with dielectric overla...

Figure 2.19 Coupled microstrip lines, showing the structure of a zig-zag cou...

Figure 2.20 Microstrip DC break.

Figure 2.21 Edge-coupled microstrip band-pass filter.

Figure 2.22 Lange coupler, showing the port designations.

Figure 2.23 Hybrid ring for use with Q2.8.

Figure 2.24 Impedance design graph for a microstrip transmission line.

Figure 2.25 Effective permittivity design graph for a microstrip transmissio...

Chapter 3

Figure 3.1 Parallel-plate capacitor (a), with its equivalent circuit (b) and...

Figure 3.2 Variation of skin depth with frequency for gold (Au), copper (Cu)...

Figure 3.3 Basic steps in etching a microstrip circuit.

Figure 3.4 Magnified view of an etched 30 μm gap in a 10 GHz microstrip DC b...

Figure 3.5 Example of a thick-film screen: (a) thick-film wire mesh screen a...

Figure 3.6 Multilayer microstrip line: (a) microstrip and (b) microstrip wit...

Figure 3.7 Layout of a multilayer DC break: (a) single-layer DC break and (b...

Figure 3.8 Details of coupling in a multilayer DC break [9].

Figure 3.9 Multilayer package.

Figure 3.10 Basic photoimageable thick-film fabrication process.

Figure 3.11 Structure of

surface integrated waveguide

(

SIW

): (a) cross-secti...

Figure 3.12 Schematic view of VIA arrays in a four-cavity SIW filter.

Figure 3.13 Four-cavity filter using a

surface mount waveguide

(SMW)

Figure 3.14 LTCC production process.

Figure 3.15 Features of a typical LTCC (SiP) module.

Figure 3.16 CPW line fabricated using inkjet technology.

Figure 3.17 Dimensions of a rectangular waveguide cavity.

Figure 3.18 Waveguide cavity resonator and its equivalent circuit.

Figure 3.19 Manual tuning of resonant cavities: (a) use of tuning screw and ...

Figure 3.20 Typical structure of a helical waveguide.

Figure 3.21 Sample mounted in a rectangular waveguide cavity: (a) side view ...

Figure 3.22 Non-radiating slits in waveguide cavities: (a) rectangular waveg...

Figure 3.23 Two-layer thick-film test samples: (a) substrate partially coate...

Figure 3.24 Split post dielectric resonator.

Figure 3.25 Planar view of sample in SPDR.

Figure 3.26 Hemispherical open resonator.

Figure 3.27 Free-space millimetre-wave measurement system.

Figure 3.28 Sample-under-test with a conductor backing plate.

Figure 3.29 Microstrip resonant ring.

Figure 3.30 Simple model of a resonant ring coupling gap.

Figure 3.31 Alternative ring resonator formats: (a) Slotline, (b) CPW, and (...

Figure 3.32 Non-resonant test circuit.

Figure 3.33 Mounting of planar test circuits: (a) microstrip test circuit mo...

Figure 3.34 Cross-section of a symmetrical FGCPW line.

Figure 3.35 Microstrip line loss.

Figure 3.36 Constituent components of line loss.

Figure 3.37 Influence of various sources of line loss.

Figure 3.38 Profiles of gold thick-film lines on alumina: (a) profile of a 6...

Figure 3.39 AFM scans of surface of gold conductor: (a) untreated gold surfa...

Chapter 4

Figure 4.1 Electric field surrounding a microstrip open-end discontinuity.

Figure 4.2 Transmission line representation of open-end effect.

Figure 4.3 Symmetrical step in microstrip.

Figure 4.4 T-network representing a microstrip step discontinuity.

Figure 4.5 Design taken from Example 2.5.

Figure 4.6 Final design for Example 4.3.

Figure 4.7 Right-angled bends in microstrip: (a) 90° corner and (b) compensa...

Figure 4.8 Final design for Example 4.4.

Figure 4.9 Microstrip gap and its equivalent circuit: (a) microstrip gap and...

Figure 4.10 Variation of the insertion loss of a gap in a 50 Ω microstrip li...

Figure 4.11 Symmetrical microstrip T-junction and its equivalent circuit: (a...

Figure 4.12 Compensated microstrip T-junctions: (a) Dydyk technique and (b) ...

Figure 4.13 Cross-section of microstrip line surrounded by a metallic enclos...

Figure 4.14 Typical packages for high-frequency passive components: (a) wire...

Figure 4.15 Equivalent circuit representing a packaged high-frequency resist...

Figure 4.16 Equivalent circuits representing capacitors.

Figure 4.17 Equivalent circuit representing an inductor.

Figure 4.18 Spiral inductor.

Figure 4.19 Loop inductor.

Figure 4.20 Interdigitated capacitor.

Figure 4.21 MIM capacitor: (a) plan view and (b) side view.

Figure 4.22

π

-Network of admittances.

Chapter 5

Figure 5.1 Power wave voltage nomenclature for a two-port network.

Figure 5.2 Signal flow graph for a linear two-port network.

Figure 5.3 A linear two-port network.

Figure 5.4 Flow graph for a two-port network terminated with a load having a...

Figure 5.5 Identification of paths and first-order loop for the flow graph o...

Figure 5.6 Two FETs in cascade terminated in load

Z

L

, with reflection coeffi...

Figure 5.7 Flow diagram for two FETs in cascade, terminated in Γ

L

.

Figure 5.8 Identification of paths and first-order loops for the flow diagra...

Figure 5.9 A simplified flow diagram for two FETs in cascade, using modified...

Figure 5.10 A linear active two-port device connected between source,

Z

S

, an...

Figure 5.11 Unilateral device with matching networks.

Figure 5.12 Voltage and current directions for a two-port network.

Chapter 6

Figure 6.1 (a) Spinning electron and (b) equivalent magnetic dipole.

Figure 6.2 Non-linear B-H characteristic of ferrites.

Figure 6.3 Precessional motion of an electron.

Figure 6.4 Forced precession in ferrites: (a) orthogonal AC magnetic field a...

Figure 6.5 Linearly polarized wave decomposed into the sum of two circularly...

Figure 6.6 Linearly polarized wave applied to ferrite.

Figure 6.7 Magnetic field vector rotation in

x

−

y

plane: (a) coordinate syste...

Figure 6.8 Variation of effective permeabilities of CP waves in ferrite as a...

Figure 6.9 Two-port isolator: (a) two-port isolator, (b) ideal

S

-matrix, and...

Figure 6.10 Waveguide isolator.

Figure 6.11 Magnetic field of TE

10

mode in a rectangular waveguide.

Figure 6.12 Circular polarization of an RF magnetic field at point

P

as a fu...

Figure 6.13 View of cross-section of a field displacement isolator in a rect...

Figure 6.14 Three-port circulator: (a) three-port circulator, (b) ideal

S

-ma...

Figure 6.15

Y

-junction waveguide circulator.

Figure 6.16 Standing wave patterns in a ferrite disc: (a) unmagnetized and (...

Figure 6.17 Triangular ferrite in a

Y

-junction circulator.

Figure 6.18

Y

-junction circulator in a microstrip.

Figure 6.19 LTCC ferrite circulator with integrated winding.

Figure 6.20 E-field distribution on a wide microstrip line on a ferrite subs...

Figure 6.21 Edge-guided-mode microstrip isolator.

Figure 6.22 Non-reciprocal edge-mode phase shifter.

Figure 6.23 Non-reciprocal phase shifter using meander lines on ferrite.

Figure 6.24 Circuit for supplementary problem Q6.6.

Chapter 7

Figure 7.1 Common RF/microwave connectors: (a) type-N, (b) APC-7, (c) SMA, a...

Figure 7.2 Two-port universal test fixture.

Figure 7.3 100 GSG coplanar probe.

Figure 7.4 Typical 110 GHz probe station.

Figure 7.5 Modern vector network analyzers © Keysight Technologies, Inc.

Figure 7.6 Functional diagram of a typical VNA.

Figure 7.7 Structure of a typical test set.

Figure 7.8 Basic reflectometer circuit of a VNA.

Figure 7.9 Multiple reflections in a VNA test set.

Figure 7.10 Additional power splitter imperfections.

Figure 7.11 Directional coupler losses.

Figure 7.12 Twelve-term error model for a VNA: (a) forward direction and (b)...

Figure 7.13 Footprints of on-wafer calibration standards: (a) short circuit,...

Figure 7.14 Device embedded within a coplanar line.

Figure 7.15 Embedded device with a mismatched input probe.

Chapter 8

Figure 8.1 Idealized filter responses.

Figure 8.2 Filter as a two-port network.

Figure 8.3 Basic low-pass circuit configuration.

Figure 8.4 Basic low-pass circuit configuration using a π-network.

Figure 8.5 Lumped-element low-pass filter.

Figure 8.6 Sketch of a Butterworth low-pass frequency response.

Figure 8.7 Normalized low-pass filter (

C

1

 ≡ 

g

1

,

L

2

 ≡ 

g

2

, …).

Figure 8.8 Summary of solution to Example 8.3.

Figure 8.9 Basic high-pass circuit configuration.

Figure 8.10 Configuration of a five-element high-pass filter.

Figure 8.11 Summary of solution to Example 8.4.

Figure 8.12 Sketch of Butterworth response of a band-pass filter.

Figure 8.13 Lumped-element, band-pass filter.

Figure 8.14 Summary of solution to Example 8.5.

Figure 8.15 Sketch of Chebyshev low-pass filter response.

Figure 8.16 Summary of solution to Example 8.7.

Figure 8.17 Low-pass filter in microstrip.

Figure 8.18 π-Network representing a narrow transmission line.

Figure 8.19 T-network representing a wide transmission line.

Figure 8.20 Summary of solution to Example 8.8.

Figure 8.21 Richards' transformations.

Figure 8.22 T-network low-pass filter and its stub equivalent.

Figure 8.23 Kuroda identity for transforming a series-connected short-circui...

Figure 8.24 Low-pass filter using shunt-connected, open-circuited stubs.

Figure 8.25 Final microstrip design for Example 8.9.

Figure 8.26 General structure of a microstrip edge-coupled band-pass filter....

Figure 8.27 Final (dimensioned) design for Example 8.10.

Figure 8.28 Layout of an end-coupled microstrip band-pass filter.

Figure 8.29 End-coupling microstrip gap in single and multilayer formats.

Figure 8.30 End-coupling between two overlapping conductors (applies to 50 Ω...

Figure 8.31 Measured response of a multilayer end-coupled band-pass filter....

Figure 8.32 T-network of impedances.

Chapter 9

Figure 9.1 Small-signal matching of amplifiers.

Figure 9.2 Load matching network.

Figure 9.3 Smith chart for source matching (maximum gain).

Figure 9.4 Source matching network for maximum gain (not to scale).

Figure 9.5 Smith chart for load matching (maximum gain).

Figure 9.6 Load matching network for maximum gain (not to scale).

Figure 9.7 Smith chart for source matching (minimum noise).

Figure 9.8 Source matching network for minimum noise (not to scale).

Figure 9.9 Source matching network for maximum gain (not to scale).

Figure 9.10 Source network data at 9 GHz.

Figure 9.11 Load network data at 9 GHz.

Figure 9.12 DC bias connection.

Figure 9.13 Enhanced DC bias connection.

Figure 9.14 DC bias connection using inductive choke.

Figure 9.15 Completed design for Example 9.4 (not to scale).

Figure 9.16 Mounting of a microwave FET in a microstrip circuit. (a) Package...

Figure 9.17 Typical layout of a hybrid microstrip amplifier.

Figure 9.18 Microstrip DC finger break.

Figure 9.19 Plotting a constant gain circle in the input plane.

Figure 9.20 Constant gain circles for Example 9.5.

Figure 9.21 Examples of output stability circles, showing stable regions (sh...

Figure 9.22 Constant noise circles for Example 9.6.

Figure 9.23 Smith chart solution for Example 9.7.

Figure 9.24 Source constant gain circles required for broadband matching.

Chapter 10

Figure 10.1 Microstrip SPST switches: (a) SPST switch and (b) its microstrip...

Figure 10.2 Microstrip SPDT switches: (a) SPDT switch and (b) its microstrip...

Figure 10.3 Structure of a PIN diode.

Figure 10.4 Idealized doping profiles of PIN diode types: (a)

p

-

π

-

n

and...

Figure 10.5 Equivalent circuit of PIN diode in ON state.

Figure 10.6 Equivalent circuit of PIN diode in OFF state.

Figure 10.7 Mounting of beam-lead PIN diodes: (a) beam-lead PIN diode and (b...

Figure 10.8 Equivalent circuits of series-mounted PIN diodes: (a) without ga...

Figure 10.9 Typical I–V characteristics for a PIN diode.

Figure 10.10 Construction of a GaAs MESFET.

Figure 10.11 Comparison of I–V characteristics of Schottky and PN junctions....

Figure 10.12 MESFET depletion layer at pinch-off.

Figure 10.13 Recessed-gate MESFET.

Figure 10.14 Mounting of passive MESFET switches: (a) series and (b) Paralle...

Figure 10.15 Small-signal equivalent circuit of a MESFET.

Figure 10.16 Location of components of a MESFET equivalent circuit.

Figure 10.17 Equivalent circuit for MESFET in ON state.

Figure 10.18 Equivalent circuits for MESFET in OFF state: (a) equivalent cir...

Figure 10.19 Cantilever MEMS switch.

Figure 10.20 Stages in the production of a cantilever MEMS switch.

Figure 10.21 Capacitive MEMS switch.

Figure 10.22 Capacitive MEMS switch mounted across a CPW line.

Figure 10.23 Basic switched-line phase shifter.

Figure 10.24 Switched-line phase shifter in microstrip.

Figure 10.25 Switched-line phase shifter with terminated OFF line.

Figure 10.26 Switched-line phase shifter with terminated OFF line, and throu...

Figure 10.27 Microstrip three-bit phase shifter.

Figure 10.28 Switched loaded-line phase shifter.

Figure 10.29 Microstrip loaded-line phase shifter.

Figure 10.30 Completed design for Example 10.5.

Figure 10.31 Schematic of switched reflection phase shifter.

Figure 10.32 Reflection phase shifter using a 3 dB backward-wave coupler.

Figure 10.33 Reflective phase shifter using a circulator.

Figure 10.34 Microstrip coupled-line phase shifter.

Figure 10.35 Switched microstrip Schiffman phase shifter.

Figure 10.36 Theoretical phase responses for a Schiffman phase shifter (

ρ

...

Figure 10.37 Theoretical phase responses for a Schiffman phase shifter (

ρ

...

Figure 10.38 Single-bit switched phase shifter.

Figure 10.39 Single-bit switched phase shifter in OFF state.

Figure 10.40 Single-bit switched phase shifter in ON state.

Figure 10.41 Loaded-line microstrip phase shifter for Example Q10.7.

Chapter 11

Figure 11.1 Model of an amplifier with feedback.

Figure 11.2 Basic transistor oscillator.

Figure 11.3 Basic Colpitts oscillator.

Figure 11.4 Practical Colpitts oscillator.

Figure 11.5 Feedback configurations for a Hartley oscillator: (a) using two ...

Figure 11.6 Clapp–Gouriet oscillator.

Figure 11.7 Depletion region in a reverse-biased PN junction.

Figure 11.8 Capacitance–voltage variation of a typical hyper-abrupt varactor...

Figure 11.9 Capacitance change in a hyper-abrupt varactor diode, showing lim...

Figure 11.10 Varactor diodes used to tune resonant circuits: (a) using a sin...

Figure 11.11 Circuit for Example 11.5.

Figure 11.12 Circuit for Example 11.6.

Figure 11.13 Equivalent circuits representing a reverse-biased varactor diod...

Figure 11.14 Electronic crystals: (a) basic structure and (b) circuit symbol...

Figure 11.15 AT-cut in quartz crystal.

Figure 11.16 Typical variation of TC with temperature for an AT-cut quartz c...

Figure 11.17 Equivalent circuit of a crystal.

Figure 11.18 Variation of crystal reactance in the vicinity of the fundament...

Figure 11.19 Crystal-controlled oscillator.

Figure 11.20 Comparison between Pierce (a) and Colpitts oscillators (b).

Figure 11.21 Basic PLL circuit.

Figure 11.22 Analogue phase comparator.

Figure 11.23 Response of analogue phase comparator.

Figure 11.24 Idealized voltage–frequency transfer characteristic for a VCO....

Figure 11.25 Typical low-pass loop filter.

Figure 11.26 Phase-locked loop, showing gain blocks.

Figure 11.27 PLL in the Laplace domain.

Figure 11.28 Normalized step responses of a second-order PLL system.

Figure 11.29 Basic indirect frequency synthesizer.

Figure 11.30 Indirect frequency synthesizer, including a pre-scalar.

Figure 11.31 Indirect frequency synthesizer using an offset oscillator.

Figure 11.32 Multi-loop synthesizer.

Figure 11.33 Fractional-

N

synthesizer.

Figure 11.34 Dielectric resonator.

Figure 11.35 Coupling between a DR and a microstrip line.

Figure 11.36 Equivalent circuit of a dielectric resonator.

Figure 11.37 DR located

λ

s

/4 from the end of an open-circuited microstr...

Figure 11.38 Basic DRO configurations: (a) series feedback and (b) parallel ...

Figure 11.39 Dielectric resonator oscillator.

Figure 11.40 Position of DR in load network.

Figure 11.41 Stability circle in Γ

L

plane.

Figure 11.42 Schematic view of termination network.

Figure 11.43 Smith chart solution for termination network.

Figure 11.44 Termination network, showing designed dimensions.

Figure 11.45 Load network, showing designed dimensions.

Figure 11.46 Diagram of a complete oscillator designed in Example 11.12.

Figure 11.47 Delay-line oscillator.

Figure 11.48 Basic SAW delay-line structure.

Figure 11.49 Structure of an interdigitated transducer (IDT).

Figure 11.50 Typical IDT finger widths as a function of frequency.

Figure 11.51 Energy band diagram for GaAs.

Figure 11.52 Voltage distribution across a Gunn diode with

E

 < 

E

TH

.

Figure 11.53 Current density (

J

) as a function of electric field strength (

E

Figure 11.54 Voltage distribution across Gunn diode domain.

Figure 11.55 Current pulses in Gunn diode circuit.

Figure 11.56 Gunn diode mounted in a waveguide cavity.

Figure 11.57 Equivalent circuit of LSA mode oscillator.

Figure 11.58 I–V characteristic showing LSA mode of oscillation.

Figure 11.59 IMPATT diode structure and typical E-field distribution.

Figure 11.60 I–V characteristic for a P–N junction.

Figure 11.61 The three stages of operation of an IMPATT diode.

Figure 11.62 Noise power spectral density at the output of an oscillator.

Figure 11.63 Carrier modulated by a single noise sinusoid.

Figure 11.64 Linearized representation of oscillator output noise power.

Figure 11.65 Delay-line discriminator technique for measuring oscillator pha...

Figure 11.66 Measurement system for oscillator noise using a high-Q resonant...

Figure 11.67 Q-curve of a resonant circuit.

Figure 11.68 Typical LF network analyzer responses. (Trace A) With resonant ...

Figure 11.69 SA readings 5 kHz off carrier.

Figure 11.70 Circuit for Q11.7.

Figure 11.71 Circuit for Q11.8.

Figure 11.72 Circuit for Q11.9.

Figure 11.73 Circuit for Q11.11.

Chapter 12

Figure 12.1 Sketch of typical antenna power radiation pattern.

Figure 12.2 Antenna beamwidth definitions.

Figure 12.3 Spherical polar coordinates.

Figure 12.4 Hertzian dipole.

Figure 12.5 E-field polar diagrams due to a Hertzian dipole.

Figure 12.6 Elemental annular ring on sphere surrounding Hertzian dipole.

Figure 12.7 Current distribution on a half-wave dipole.

Figure 12.8 Electric field radiation from a half-wave dipole.

Figure 12.9 Electric field radiation patterns of a

λ

/2 dipole.

Figure 12.10 Variation of the input impedance of a 100 MHz half-wave dipole,...

Figure 12.11 Linear array of three isotropic sources.

Figure 12.12 Addition of three electric field vectors from three equally sep...

Figure 12.13 Linear array of four isotropic sources.

Figure 12.14 Two parallel dipoles.

Figure 12.15 Graph showing the real (

R

m

) and imaginary (

X

m

) parts of the mut...

Figure 12.16 Collinear array of two dipoles.

Figure 12.17 Dipole array with a single parasitic element.

Figure 12.18 Antenna array for Example 12.7.

Figure 12.19 Reflectors and directors.

Figure 12.20 Antenna array for Example 12.8.

Figure 12.21 A six-element Yagi–Uda array.

Figure 12.22 Folded dipole.

Figure 12.23 Three-element Yagi–Uda array for Example 12.9.

Figure 12.24 Log-periodic array.

Figure 12.25 Log-periodic array with phase reversal between feeds to adjacen...

Figure 12.26 A rectangular loop antenna located in an E-field.

Figure 12.27 Receiving loop antenna with tuning capacitor. (a) Loop with tun...

Figure 12.28 Microstrip patch antenna.

Figure 12.29 Planar view of a microstrip patch showing positions of radiatin...

Figure 12.30 Transmission line model of a microstrip patch antenna.

Figure 12.31 Design dimensions for a simple microstrip patch antenna.

Figure 12.32 Complete design for Example 12.14.

Figure 12.33 Patch antenna with inset feed point.

Figure 12.34 Complete design for Example 12.15.

Figure 12.35 Probe-fed microstrip patch.

Figure 12.36 Patch excitation through coupling aperture.

Figure 12.37 Modified multilayer feed structure.

Figure 12.38 Microstrip patch array.

Figure 12.39 A 77 GHz patch array on a multilayer polymer: (a) details of st...

Figure 12.40 Circular polarization from a single microstrip patch.

Figure 12.41 Circular polarization from probe-fed rectangular patches: (a) l...

Figure 12.42 Circular polarization from front-fed microstrip patches: (a) le...

Figure 12.43 Circular polarization using an array of linearly polarized patc...

Figure 12.44 Travelling-wave-fed patch array producing circular polarization...

Figure 12.45 Photograph of a 5 GHz CP antenna with a travelling-wave feed: (...

Figure 12.46 15 GHz travelling-wave-fed antenna fabricated using LTCC.

Figure 12.47 Slot line fed microstrip patch: (a) schematic view of construct...

Figure 12.48 Waveguide horns: (a)

H-

plane sectorial, (b)

E-

plane sectorial, ...

Figure 12.49 Photograph of a 13–18 GHz pyramidal horn.

Figure 12.50 Axial length,

L

, of a pyramidal horn.

Figure 12.51 Curved wavefront across aperture of pyramidal horn.

Figure 12.52 Ray paths in a convex dielectric lens.

Figure 12.53 Horn dimensions for Example 12.17.

Figure 12.54 Examples of stepped dielectric lenses.

Figure 12.55 Reflection of waves at a parabolic surface.

Figure 12.56 Typical feed arrangements for parabolic reflector antennas: (a)...

Figure 12.57 Offset feed parabolic reflector.

Figure 12.58 Illustration of Babinet's principle.

Figure 12.59 Sketch of current distribution in walls of a rectangular wavegu...

Figure 12.60 Slot antennas in

X

-band waveguide: (a) array of eight slots in ...

Figure 12.61 SIW antenna concept.

Figure 12.62 77 GHz SIW antennas.

Figure 12.63 160 GHz air-filled waveguide antenna fabricated in LTCC: (a) cr...

Figure 12.64 Antenna array for Q12.11.

Figure 12.65 Antenna array for Q12.14.

Figure 12.66 Microstrip design graph showing

Z

O

as a function of

w/h

for

ε

...

Figure 12.67 Microstrip design graph showing

as a function of

w/h

for

ε

...

Chapter 13

Figure 13.1 Power transfer characteristic of a non-linear amplifier showing ...

Figure 13.2 Intercept diagram showing the two-tone third-order intercept poi...

Figure 13.3 Typical non-linearity in power amplifiers.

Figure 13.4 Pre-distortion circuit.

Figure 13.5 Linearizer using envelope feedback technique.

Figure 13.6 Basic feed-forward linearization.

Figure 13.7 Corporate power combiner.

Figure 13.8 Quadrature power combiner.

Figure 13.9 Travelling-wave power combiner.

Figure 13.10 Doherty amplifier.

Figure 13.11 Equivalent circuit of a Doherty amplifier.

Figure 13.12 Illustration of the general principle of the Doherty amplifier....

Figure 13.13 Load-pull measurement system.

Figure 13.14 Typical load-pull contours at 12 GHz for an FET.

Figure 13.15 Basic configuration of a distributed amplifier.

Figure 13.16 Simple equivalent circuit of an FET.

Figure 13.17 Equivalent circuits representing distributed amplifier: (a) Equ...

Figure 13.18 Equivalent circuit of drain line.

Figure 13.19 Plot of the function

(sin

Nφ

/sin 

φ

)

2

, for

N

Figure 13.20 Simple equivalent circuit of FET including resistors to represe...

Figure 13.21 Equivalent circuits representing distributed amplifier, includi...

Figure 13.22 Use of pyrolytic heat spreader: (a) Conventional heat-sinking. ...

Chapter 14

Figure 14.1 Lossless transmission line of characteristic impedance,

R

O

, term...

Figure 14.2 Series equivalent circuit of a noisy resistor

R

, at temperature

Figure 14.3 Shunt equivalent circuit of a noisy conductance at temperature

T

Figure 14.4 Gaussian probability distribution.

Figure 14.5 (a) Simple digital voltage waveform, and (b) Digital waveform wi...

Figure 14.6 Current pulse due to shot noise: (a) PN junction connected to lo...

Figure 14.7 Noise components at the output of a noisy network.

Figure 14.8 Equivalent networks using noise figure and noise temperature: (a...

Figure 14.9 Networks in cascade.

Figure 14.10 Typical variation of sky noise temperature with frequency, for ...

Figure 14.11 Matched attenuator.

Figure 14.12 Receiving system for Example 14.9.

Figure 14.13 Single-conversion superhet receiver.

Figure 14.14 Front-end of superhet receiver modified to include pre-selector...

Figure 14.15 Position of the image frequency.

Figure 14.16 Typical response of pre-selector circuit, showing image suppres...

Figure 14.17 Band-pass filter used as pre-selector circuit.

Figure 14.18 Double-conversion superhet receiver.

Figure 14.19 Noise temperature reference points in a superhet front-end.

Figure 14.20 Signal-to-noise ratio budget graph for Example 14.12.

Figure 14.21 Modified receiver configuration for Example 14.13.

Figure 14.22 Comparison of signal-to-noise ratio budget graphs showing the i...

Figure 14.23 Circuit symbol for a mixer.

Figure 14.24 Single-ended diode mixer.

Figure 14.25 Effective LO waveform for high drive levels.

Figure 14.26 Single-balanced mixer.

Figure 14.27 Double-balanced switching mixer.

Figure 14.28 Equivalent circuit of double-balanced mixer (LO positive).

Figure 14.29 Equivalent circuit of double-balanced mixer (LO negative).

Figure 14.30 Transconductance mixer.

Figure 14.31 Simplified equivalent circuit of an FET.

Figure 14.32 Dual-Gate FET Mixer.

Figure 14.33 Receiver for problem Q14.12.

Figure 14.34 Receiver for problem Q14.13.

Figure 14.35 Measurement of Noise Figure:

Y

-factor method.

Figure 14.36 Measurement of Noise Figure: Noise diode method.

Figure 14.37 Measurement of Noise Figure: Discharge tube method.

Guide

Cover

Table of Contents

Title Page

Copyright

Preface

About the Companion Website

Begin Reading

Answers to Selected Supplementary Problems

Index

End User License Agreement

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Microwave and Wireless Technologies Series

Series Editor: Professor Steven (Shichang) Gao, Chair of RF and Microwave Engineering, and the Director of Postgraduate Research at School of Engineering and Digital Arts, University of Kent, UK.

Microwave and wireless industries have experienced significant development during recent decades. New developments such as 5G mobile communications, broadband satellite communications, high-resolution earth observation, the Internet of Things, the Internet of Space, THz technologies, wearable electronics, 3D printing, autonomous driving, artificial intelligence etc. will enable more innovations in microwave and wireless technologies. The Microwave and Wireless Technologies Book Series aims to publish a number of high-quality books covering topics of areas of antenna theory and technologies, radio propagation, radio frequency, microwave, millimetre-wave and THz devices, circuits and systems, electromagnetic field theory and engineering, electromagnetic compatibility, photonics devices, circuits and systems, microwave photonics, new materials for applications into microwave and photonics, new manufacturing technologies for microwave and photonics applications, wireless systems and networks.

RF and Microwave Circuit Design: Theory and ApplicationsCharles E. Free, Colin S. AitchisonSeptember 2021

Low-cost Smart AntennasQi Luo, Steven (Shichang) Gao, Wei LiuMarch 2019

RF and Microwave Circuit Design

Theory and Applications

Charles E. Free

UK

Colin S. Aitchison

UK

This edition first published 2022© 2022 John Wiley & Sons Ltd

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.

The right of Charles E. Free and Colin S. Aitchison to be identified as the authors of this work has been asserted in accordance with law.

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Library of Congress Cataloging-in-Publication Data

Names: Free, Charles E., author. | Aitchison, Colin S., author.

Title: RF and microwave circuit design : theory and applications / Charles E. Free, UK, Colin S. Aitchison, UK.

Description: Hoboken, NJ, USA : Wiley, 2022. | Series: Microwave and wireless technologies series | Includes bibliographical references and index.

Identifiers: LCCN 2020028781 (print) | LCCN 2020028782 (ebook) | ISBN 9781119114635 (hardback) | ISBN 9781119114673 (adobe pdf) | ISBN 9781119114666 (epub)

Subjects: LCSH: Radio circuits–Design and construction. | Microwave circuits–Design and construction.

Classification: LCC TK6560 .F68 2022 (print) | LCC TK6560 (ebook) | DDC 621.3841/2–dc23

LC record available at https://lccn.loc.gov/2020028781

LC ebook record available at https://lccn.loc.gov/2020028782

Cover Design: WileyCover Images: Circuit board background © Berkah/Getty Images, Inset sketch by Charles Free

Preface

In recent years, the rapid expansion of communication applications at RF and microwave frequencies has created significant interest in this area of high-frequency electronics, both in industry and academia. This textbook provides a rigorous introduction to the theory of modern-day circuits and devices at RF and microwave frequencies, with an emphasis on current practical design.

One of the themes of the book is that of the design of high-frequency hybrid integrated circuits in which individual passive and active components are interconnected within a planar circuit structure. The traditional method of making such circuits is to assemble the components on a low-loss copper-clad printed circuit board, which has been etched with the required interconnection pattern. In recent years, the development of new materials and new fabrication techniques has created greater scope for the circuit designer, with the opportunity to use hybrid circuit structures at much higher frequencies, well into the millimetre-wave region. In particular, the use of a photoimageable thick-film and low-temperature co-fired ceramic (LTCC) materials has enabled low-cost, high-performance multilayer structures to be fabricated. The properties of these materials, and their application to RF and microwave circuits, are discussed in the book.

The book has been organized to provide a cohesive introduction to RF and microwave technology at undergraduate and Master's degree level. It assumes only a basic knowledge of electronics on the part of the reader, with the bulk of the high-frequency material being developed from first principles. Many worked examples have been included in the text to emphasize the key points, and supplementary problems with answers are provided at the end of most chapters.

The material presented in the book is based largely on courses in RF and microwave communications taught by both authors at several UK Universities.

Chapter 1 introduces the theory of RF and microwave transmission lines, which are fundamental to high-frequency circuits. The basic theory is expanded to include the principles and applications of the Smith chart, which is a graphical tool that can be used to represent and solve transmission line problems. This chapter includes summaries of the properties of some common high-frequency transmission lines, namely coaxial cable, microstrip, coplanar waveguide, and hollow metallic waveguide.

Chapter 2 expands on the theory and applications of microstrip, which was introduced in the first chapter. Microstrip is by far the most common type of interconnection used for RF and microwave applications, and the chapter discusses the properties of this transmission medium, and introduces some typical passive microstrip components.

Chapter 3 presents information on modern circuit materials and the associated fabrication techniques. This is an important chapter in that good electrical design of planar circuits at high frequencies requires a good understanding of the properties and capabilities of the circuit materials. In addition to the traditional etched circuit techniques, the chapter discusses newer fabrication approaches using photoimageable thick-film, LTCC, and ink jet printing. The chapter concludes with a discussion of the various methods available for characterizing circuit materials at high frequencies.

Chapter 4 continues the theme of planar circuit design through a discussion of the discontinuities associated with microstrip components. Also in this chapter are the equivalent circuits of packaged lumped-element passive components, as well as miniature planar components that can be used in single layer and multilayer formats.

Chapter 5 introduces the concept of S-parameters. These are network parameters used to characterize RF and microwave devices, and an understanding of their meaning and usage is essential for microwave design. The chapter includes information on power gain definitions, and the use of flow graphs in high-frequency network analysis.

Chapter 6 presents information on microwave ferrites. Ferrite materials have a well-established place in microwave technology, primarily for providing non-reciprocal components. The properties of ferrite materials, as well as their use in traditional metallic waveguide components, are explained. More recent uses of ferrite material in multilayer planar circuits are also discussed.

Chapter 7 is concerned with measurements at RF and microwave frequencies. The chapter focuses in particular on the use of the vector network analyzer (VNA), which is the main item of test instrumentation in all high-frequency laboratories. As well as describing the functions and use of the VNA, the chapter addresses the important issues of calibration and measurement errors.

Chapter 8 provides an introduction to RF filters, which are essential circuits in most high-frequency sub-systems. This chapter commences with a review of the principal filter responses, and then extends the theoretical discussion into practical design detail. A number of worked examples of the design of microstrip filters have been included, and the chapter ends with a brief review of the advantages of multilayer formats for producing high-performance filters at RF and microwave frequencies.

Chapter 9 presents information on the design of hybrid microwave amplifiers in which a packaged transistor, usually a metal semiconductor field effect transistor (MESFET), is positioned between input and output matching networks. The chapter focuses on the design of the matching networks, and considers the effects of these networks on transducer gain, noise, and stability. Worked examples are included to show the design strategies employed for microstrip implementation.

Chapter 10 introduces the function and design of switches and phase shifters in planar circuits. The functions of four devices commonly used as switches in RF and microwave circuits are described, namely PIN diodes, field effect transistors (FETs), microelectromechanical switches (MEMS), and inline phase change switches (IPCS). The use of these switches in various types of phase shifters are described, with supporting worked examples to show how microstrip phase shifters are designed.

Chapter 11 gives information on the various types of oscillators used in high-frequency circuits. Starting with the criteria for oscillation in a feedback circuit, the three main types of transistor oscillators are described, namely the Colpitts, Hartley, and Clapp–Gouriet oscillators. Leading on from the basic oscillators the concept of the voltage-controlled oscillator (VCO) is introduced. Many RF and microwave receivers, and most test instrumentation, derive the required frequency from a very stable low-frequency crystal oscillator, and a frequency synthesizer. The chapter includes a discussion of crystal oscillators, together with a review of the main types of frequency synthesizers using phase-locked loops. Also given are descriptions of several types of oscillators used specifically at microwave frequencies; these include the dielectric resonator oscillator (DRO), and oscillators using the Gunn and Impatt principles. Oscillator noise is a significant issue in many situations, particularly for low-noise receivers, and the chapter concludes with a discussion of oscillator noise, together with a method for measuring this noise.

Chapter 12 presents information on RF and microwave antennas. The chapter commences with a discussion of the theoretical aspects of electromagnetic radiation from simple wire structures, including the half-wave dipole. The analysis is then extended to consider the behaviour of wire arrays. The most notable array used for RF and low microwave frequency communication is the Yagi–Uda array, and this is considered in some detail. The short wavelengths associated with microwave frequencies offer more scope for the antenna designer, and the chapter gives design details of microwave antennas using planar patch structures and also those using radiation from apertures.

Chapter 13 provides an introduction to power amplifiers, and distributed amplifiers. Power amplifiers are commonly positioned in as the last device in a transmitter before the signals are transmitted, and consequently any distortion introduced by the power amplifier cannot be corrected. Distortion is therefore one of the main themes of this chapter. Also described in this chapter are distributed amplifiers, which provide an attractive combination of high available gain and very wide bandwidth at microwave frequencies.

Chapter 14 brings together a number of devices introduced in earlier chapters with a discussion of RF and microwave receivers. Noise is an important issue in any receiver, particularly when the received signal levels are very low, and this chapter includes a discussion of typical sources of noise, and how they affect the performance of a receiver.

About the Companion Website

This book is accompanied by a companion website:

www.wiley.com/go/free/rfandmicrowave

The website includes:

Teaching PDF Slides (by chapter)

Microstrip Design Graphs

1RF Transmission Lines

1.1 Introduction

Transmission lines, in the form of cable and circuit interconnects, are essential components in RF and microwave systems. Furthermore, many distributed planar components rely on transmission line principles for their operation. This chapter will introduce the concepts of RF transmission along guided structures, and provide the foundations for the development of distributed components in subsequent chapters.

Four of the most common forms of RF and microwave transmission line are shown in Figure 1.1.

Coaxial cable

is an example of a shielded transmission line, in which the signal conductor is at the centre of a cylindrical conducting tube, with the intervening space filled with lossless dielectric. The dielectric is normally solid, although for higher-frequency applications it is often in the form of dielectric vanes so as to create a semi-air-spaced medium with lower transmission losses. A typical coaxial cable is flexible with an outer diameter around 5 mm, although much smaller diameters are available with 1 mm diameter cable being used for interconnections within millimetre-wave equipment. Also, for very high-frequency applications, the cable may have a rigid or semi-rigid construction. Further data on coaxial cables are provided in

Appendix 1.A

.

Coplanar waveguide

(

CPW

), in which all the conductors are on the same side of the substrate, is also shown in

Figure 1.1

. This type of structure is very convenient for the mounting of active components, and also for providing isolation between signal tracks. Coplanar lines are widely used in compact integrated circuits for high-frequency applications. Further data on coplanar lines are given in

Appendix 1.B

.

Waveguide

, formed from hollow metal tubes of rectangular or circular cross-section, is a traditional form of transmission line used for microwave frequencies above 1 GHz. For many circuit and interconnection applications, waveguide has been superseded by planar structures, and its use in modern RF and microwave systems is restricted to rather specialized applications. It is the only transmission line that can support the very high powers required in some transmitter applications. Another advantage of an air-filled metal waveguide is that it is a very low loss medium and therefore can be used to make very high-

Q

cavities, and this application is discussed in more detail in

Chapter 3

in relation to dielectric measurements. A more recent application of traditional waveguides is in substrate integrated waveguide (SIW) structures for millimetre-wave applications, and this is explained in more detail in

Chapter 4

in the context of emerging technologies. Further data on the theory of waveguides are given in

Appendix 1.C

.

Microstrip

is the most common form of interconnection used in planar circuits for RF and microwave applications. As shown in

Figure 1.1

, it consists of a low-loss insulating substrate, with one side completely covered with a conductor to form a ground plane, and a signal track on the other side. Further data on microstrip are given in

Appendix 1.D

. This is a particularly important medium for high-frequency circuit design and so

Chapter 2

is devoted to an in-depth discussion of microstrip and the associated design techniques.

1.2 Voltage, Current, and Impedance Relationships on a Transmission Line

In its simplest form, a transmission line can be viewed as a two-conductor structure with a go and return path for the current. For the purpose of analysis we may regard any transmission line as made up of a large number of very short lengths (δz), each of which can be represented by a lumped equivalent circuit, as shown in Figure 1.2. In the equivalent circuits, R and L represent the series resistance and inductance per unit length of the conductors, respectively, C represents the capacitance between the lines per unit length, and G is the parallel conductance per unit length, and represents the very high resistance of the insulating medium between the conductors.

Figure 1.1 Common types of high-frequency transmission line.

Figure 1.2 Representation of a transmission line in terms of lumped components.

It should be noted that it is legitimate to represent a continuous transmission line by the lumped equivalent circuit shown in Figure 1.2 providing that δz is small compared to a wavelength. R, L, G, and C are normally referred to as the primary line constants, and have the units of Ω/m, H/m, S/m, and F/m, respectively.

In order to establish relationships between the voltage and current on a transmission line we need first to specify a line excited by a sinusoidal voltage at the sending end whose angular frequency is ω. If we then let the voltage and current at some arbitrary point on the line be V and I, respectively, we can consider the effect on an elemental length at this point. The voltage drop across the elemental length will be δV and the parallel current will be δI, as shown in Figure 1.3.

Using standard AC circuit theory, we can relate the change in voltage, δV, to the components of the equivalent circuit as

i.e.

Considering the limit, as δz → 0, giving

(1.1)

Figure 1.3 Equivalent circuit of an elemental length, δz, of a transmission line.

Considering the parallel current, δI, we have

i.e.

As δz → 0, giving

(1.2)

Differentiating Eq. (1.1) with respect to time gives