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Microwave Tutorials
   Overview of pertinent electromagnetics
   Telegrapher equations for transmission lines. Power flow
   Phasor wave solutions to the telegrapher equations. Termination of TLs.
   TL input impedance, time average power, return and insertion losses
   Generator and load mismatches on TLs
   The Smith chart.
   Transmission line matching using lumped L networks
   Single-stub tuning
   Quarter-wave-transformer matching
   TEM, TE, and TM modes for waveguides. Rectangular waveguide
   Dispersion. Stripline and other planar waveguides
   Microstrip. ADS and LineCalc
   Simple quasi-static moment method analysis of a microstrip
   Impedance and admittance matrices.
   S parameters and the scattering matrix
   Properties of S matrices. Shifting reference planes
   S parameters and time average power. Generalized S parameters.
   Vector network analyzer
   Proper microwave laboratory practices
   Transmission (ABCD) matrix
   Signal flow graphs
   Measurement errors. TRL calibration of a VNA.
   Basic properties of dividers and couplers
   T-junction and resistive power divider
   Wilkinson power divider
   Quadrature 90 degree hybrid
   The 180 degree hybrid.
   Coupled line and Lange directional couplers
   Microwave filter design by the insertion loss method
   Scaling of low pass prototype filters. Stepped impedance low pass filters.
   Stub synthesis. Kuroda’s identities. Stub low pass filters
Free Electronics Tutorials
   Diode Tutorials
   BJT Tutorials
   MOSFET Tutorials
   Electronics II Tutorials
   Applied Electromagnetics Tutorials
   Microwave Tutorials
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Introduction Overview of Pertinent Electromagnetics

Introduction Overview of Pertinent Electromagnetics.
In this microwave engineering course, we will focus primarily on electrical circuits operating at frequencies of 1 GHz and higher. In terms of band designations, we will be working with circuits above UHF:

RF, microwave and millimeter wave circuit design and construction is far more complicated than low frequency work. So why do it?
Advantages of microwave circuits:
1. The gain of certain antennas increases (with reference to an isotropic radiator) with its electrical size. Therefore, one can construct high gain antennas at microwave frequencies that are physically small. (DBS, for example.)
2. More bandwidth. A 1% bandwidth, for example, provides more frequency range at microwave frequencies that at HF.
3. Microwave signals travel predominately by line of sight. Plus, they don’t reflect off the ionosphere like HF signals do. Consequently, communication links between (and among) satellites and terrestrial stations are possible.
4. At microwave frequencies, the electromagnetic properties of many materials are changing with frequency. This is due to molecular, atomic and nuclear resonances. This behavior is useful for remote sensing and other applications.
5. There is much less background noise at microwave frequencies than at RF.
Examples of commercial products involving microwave circuits include wireless data networks [Bluetooth, WiFi (IEEE Standard 802.11), WiMax (IEEE Standard 802.16), ZigBee], GPS, cellular telephones, etc. Can you think of some others?
Difficulties
As was mentioned, microwave circuits are much more difficult to analyze than low frequency ones. Why?
1. Voltage is not well defined if the distance between the two points is not electrically small. At microwave frequencies, “electrically large” distances may be just a few millimeters! Moving the probe leads around will also likely affect voltage measurements.
2. One must carefully choose lumped elements (L, C, R, diodes, transistors, etc.) for use in the microwave region. Typical low frequency components do not behave as expected.
3. To “transport” electrical signals from one position to another, one must use special “wires.” It is more common to speak of “guiding” signals at these frequencies.
Electromagnetism
Electricity is an electromagnetic (EM) phenomenon involving forces produced by stationary and moving charge. Low frequency circuits are generally very, very small wrt the smallest EM wavelength present in the circuit. Because of this,
simple lumped element circuit models can be used to describe the EM effects of resistors, inductors, capacitors, voltage and current sources, etc.
Conversely, at microwave frequencies the circuits may not be electrically small. This requires a shift in our approach to the EM analysis. Nevertheless, the electrical signals remain the outcome of EM phenomenon. Perhaps the two most important of the Maxwell equations are

Much of our work in this course will be in the sinusoidal steady state. With an assumed (and suppressed) e j?t time convention, these curl equations become:

where E , B , D, H and J are all vector phasors. Of course, both the differential and integral forms are equally valid. Which of these to use depends on the problem:
• To derive equations to solve for E and H , the differential forms are often better.
• For circuit approximations of devices (or other physical interpretations), the integral forms are often more useful. Rather than using the full-blown Maxwell’s equations in microwave circuit design, approximations are often made to simplify the solutions. Transmission line theory, to be discussed next, is one of these. We will not explicitly be seeing Maxwell’s equations much in this course.


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Discussion on Microwave Engineering
Thread / Thread Starter Last Post Replies Views
microwave
why TEM mode is not possible for hollow waveguide


Posted By :-
 chayanika.josh
Sep 11, 9:56:18 PM 0 28700
microwave
why we use hollow metallic rectangular wave guide for dominant mode operation


Posted By :-
 chayanika.josh
Sep 11, 9:55:20 PM 0 33890
T-junction and power divider
I want to know how to calculate and the design of power divider


Posted By :-
 vannak
Jun 1, 4:16:47 AM 0 28348

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