lec.1 introduction to microwave engineering

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Department of Electrical EngineeringAir University

RF & Microwave Engineering

Lecture No. 1

Basit Ali Zeb

Assistant Professor

Microwave EngineeringBETE-Fall 2009

2 Basit Ali ZebDepartment of Electrical Engineering, AU

Lecturer’s Introduction

Basit Ali Zeb

• MSc Telecommunications Engineering 2006

Technical University of Denmark

• BSc Electrical Engineering 2001 University of Engineering and Technology, Lahore

Area of Specialization: Antennas/Microwave Engineering

Industry Experience: Nescom/MTC

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Course Information

• OBJECTIVES– This course will provide a comprehensive introduction to basic RF & microwave engineering, its theory and applications in practical components and systems.

– To encourage students to get involved in this rather complex but highly rewarding field.

• REQUIRED SKILLS– Electromagnetics Waves EE212

– Antennas and Wave Propagation EE313

– Vector Calculus and Basic Circuit Theory



Course Information -1

• Course Coverage– Microwave Transmission Lines

– Microwave Circuit Design Basics

– Microwave Network Analysis

– Scattering Parameters

– Microwave Devices

– Microwave Systems

– Microwave Measurements

– Some Advanced topics in microwave engineering

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Lecture Plan

Introduction of Scattering parameters, definition of S-parameters for n-port networks,

concept and uses of modified S-parameters 7

Microwave network analysis, Introduction to Z and Y matrices, Global characteristics

of Z and Y matrices, Tutorial Example , N-port microwave networks6

Impedance matching and tuning, matching with lumped elements, matching using

microstrip lines, Single stub tuner, quarter wave transformer matching. Problems

solving using analytical methods and smith charts

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Discussion of home assignment, Introduction to Smith Chart, Algebra behind the smith

chart, problems solving, Introduction to Microstrip lines4

Time average power flow, special cases of lossless terminated transmission lines,

Quarter wave Transformer, Generator and load Mismatch, Problem solving 3

Derivations of Transmission line wave equations, definitions of characteristic

impedance, group and phase velocities. Lossless transmission line, Terminated

lossless lines, concept of standing waves , reflection coefficient and VSWR,

calculation of Input Impedance and Return Loss

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Introduction to Microwave Engineering, Overview of Microwave Frequencies, Review

of relevant Electromagnetics and Maxwell’s Equations, Transmission line theory1

TopicsWeek



Lecture Plan

Microwave Receiver design, Microwave measurements (VNA), Introduction to

Anechoic Chamber, Review topics, problems solving and general discussion15

Active devices, Gunn Oscillator, PIN diodes, Microwave Tubes, Introduction to

Microwave antennas and propagation characteristics14

Microwave Resonators , Transmission line resonators, Dielectric Resonator13

Field analysis of rectangular waveguides, TE and TM modes, Microwave connector

types, Problem solving12

Waveguides, developing concepts of waveguides, Energy propagation in waveguides, E

and H fields11

Wilkinson Power dividers (WPD), Even and odd mode analysis, S-parameters of WPD,

Design of 900 Hybrid coupler and 1800 ring coupler10

Discussion of home assignment, Introduction to passive microwave devices, General

properties of 3 and 4-port networks, Operation of and directional coupler9

Scattering parameters and time average power flow, generalized S-parameters,

Transmission ABCD matrix, 8

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Course Information -2

• Grading CriteriaQuizzes (Written) = 10%

Home Assignments = 05%

Midterm Exam = 20%

Lab Work+ Oral Exam = 20%

Final Exam = 45%

Total = 100%

Attitude Counts !!Be in time, not on-time



Reading

• Text & Reference Books:

1: Microwave Engineering(David M. Pozar) 3rd Edition, John Wiley & Sons, 2005

2: Microwave and RF Design of wireless Systems(David M. Pozar)

3: RF Circuit Design-Theory and Applications(R. Ludwig & P. Bretchko) 2nd Edition, Prentice Hall, 2000

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General Requirements

• You are expected to take active part during the lectures, there might be surprise quizzes!!!

• Late attendance will be marked twice during the two hour session

• Frequent movements in the class is not allowed

• Mobile phone must strictly be turned off, there is a penalty of marks deduction if u don’t follow this.

• You are strongly discouraged to enter the lecture room after five minutes of T0



Questions ?

This course is not about the engineering of Microwave Ovens!!

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Introduction to Microwave Engineering



RF & Microwave Frequencies

Police radar, militaryX8 – 12 GHz

Weather radar, Satellite Broadcasting, military Comms.

C4 – 8 GHz

Weather radars, ISM applications, Microwave Oven 2.4 GHz (US), WiMax

S2 – 4 GHz

L-band communication, GPS, WLL, PCS, GSM 1800 / 1900

L1 – 2 GHz

Microwave

Radars, TV channels, GSM 900, Microwave Oven 915 MHz (Europe)

UHF300 – 1 GHz

Radio, TV channels, FM, Police, flight navigation, telephone

VHF30 – 300 MHz

Radio, citizen’s band radio, cordless

telephony, HERTZ ANTENNAHF3 – 30 MHz

RF

ApplicationBandRangeRegion

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Microwave Frequencies

K18 – 27 GHz

Satellite, military, remote sensing, Police radar, Industrial and medical applications

Ku12 – 18 GHz

Micro

wave

Ka27 – 40 GHz

mm110 – 300 GHz

W75 – 110 GHz

Mobile, Satellite and fixed communications, atmospherical radiometry, solid-state spectroscopy, THz Imaging

V40 – 75 GHz

Millim

eter

wave

ApplicationBandRangeRegion



Advantages of Microwave Circuits

• Increased Antenna Gain

• More Bandwidth is achieved

• LOS Communications & Penetration through Ionosphere makes it useful to communicate with satellites

• Atomic, molecular and Nuclear resonances: useful for remote sensing applications

• Preferred in Radar systems

RF, Microwave & millimeter wave circuit design is much more complicated than low frequency work, So why do we do it?

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Difficulties in Microwave Circuits

• Electrical length of the circuit is defined as:

• Voltages and currents are not well defined

• Behavior of lumped components in microwave region is not predictable

• Device fabrication and measurements need extra care, which means cost increases



Applications

• Wireless data networks

– Bluetooth

– WiFi

– WiMax

– ZigBee

• GPS

• Mobile communications

• Satellite Communications

• High Power Microwaves

CAN YOU THINK OF SOME OTHERS?

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Introduction and Review of Relevant Electromagnetics



Electromagnetics Waves

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Electromagnetics Waves



Overview of Maxwell’s Equations

Combination of Gauss’ law for electric and magnetic fields, Ampere’s law for magnetic fields, and the Faraday-Henry law of electromagnetic induction

What are Maxwell’s Equations ?

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Maxwell’s Equations

• Maxwell’s Equations relate the fields (Eand H) and their sources ( and J) to each other

Faraday’s Law

Ampere’s Law with

Maxwell’s addition

Gauss’s Law

Time Harmonic

Representation

Local fields

Differential Form

of Equations



Qualitative Interpretation

• A changing magnetic flux creates an electric field.

• Both a moving charge (current) and a changing electric flux create a magnetic field.

• The distribution of the electric charge determines the electric field.

• The magnetic flux lines are closed; in other words, there are no magnetic charges.

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Features

• Maxwell’s equations form the basis of radio and microwave engineering, in fact, of the whole of electrical engineering.

• These equations cannot be derived from other laws; they are based on empirical research.

• Their validity comes from their capability to predict the electromagnetic phenomena correctly.

• The creation of EM field is easy to understand with Maxwell’s Equations and hence forms the basis of wave propagation.

We will not explicitly be seeing Maxwell’s Equations much in this course



Representation of Microwaves

Classical field theory on Maxwell’s Equations reveals

that TEM Wave has an impedance which is:

Remember how the wavelength changes as the function of frequency!!

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Example

This example conveys an appreciation of how the

wavelength changes as frequency. As the frequency

increases, the wavelength becomes comparable to the

dimensions of circuit board or even to the individual

discrete components!!



Conclusion

• Low frequency circuits are usually very small as compared to the minimum EM wavelength

• Components like inductors, resistors, capacitors, transistors are electrically small at these frequencies and are considered LUMPED

• Because of this, simple circuit analysis like KVL etc. can be applied in terms of voltages and currents

• However, at microwave frequencies, the lumped components may not be electrically small.

• Wave propagation effects have to be considered for propagation delays and phase shifts

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Study

• Chapter 1 of the text book

–Articles 1.1 to 1.5

• Next lecture on “Transmission Lines”

lec.1 introduction to microwave engineering

Documents

microwave antennas

microwave tubes

basic rf microwave engineering

microwave measurements

microwave connector

university of engineering

lossless transmission

transmission line resonators