EE163A Introductory Microwave Circuits

Fall, 2015

Prof. Y. Ethan Wang Electrical Engineering Dept.

UCLA

Lesson 1

Course info. Course organization TEM waveguides Non-TEM waveguides Equivalent Voltage & Currents

Textbook: David Pozar, Microwave Engineering, Ed. 4

EE163A Course Information Instructor: Y. Ethan Wang

7 Homeworks (30%), distributed on Wed. and due on next Wed.

1 Midterm (25%),

1 Final (45%), The finals week

No late submission of homework will be accepted !!!

No copy of homeworks and exams in any form!!!

Office hour: Tuesday, 3:30pm to 5:30pm

Office address: EN IV 56-147K

EE163A Syllabus 1. Review of transmission line& waveguides (4 hours)

2. Microwave network theory (Z/Y/S parameters, ABCD matrices) (4 hours)

3. Smith Chart and CAD design tools (4 hours)

4. Impedance matching and matching network (4 hours)

5. Microwave resonators, power splitters & couplers (6 hours)

6. Equivalent circuits of microwave devices (4 hours)

7. Noise and gain transfer in two-port networks (4 hours)

8. Amplifier gain, stability, VSWR requirements and design methods (4 hours)

9. Transistor amplifier design (6 hours)

Organization of EE163A

Network parameters & Smith Charts

Impedance Matching

Microwave Transistor Amplifier Design

Transmission line theory

Passive components

Active components

Microwave Network Theory

Microwave Passive Components

Microwave Filters

Designs of Microwave Circuits An example of Microwave Monolithic Integrated Circuits (MMIC)

Block Diagram of T/R Module

X-band T/R Module

64.5 x 13.5 x 4.5mm

Flow of Microwave Circuit Development

Waveguides Definition: Guiding structures for Electromagnetics Waves

Features: Infinitely long, transverse cross-sections are the same

Methodology of Analysis: -Assuming longitudinal variation of the field is known as exponential and solve for the transverse variation of the field for given B.C.

-Separate different field components and solve for one of them (longitudinal one) first

-Solve for other field components based on transverse-longitudinal relationship

Waveguide Solutions General waveguide field solutions are propagating in z direction can be written as:

transverse component longitudinal component

longitudinal variation

transverse variation

TEM waves:

TE waves:

TM waves:

Other hybrid waves

TEM Waveguides

TEM Waves (1) TEM waves is defined for the possibility of solution that satisfies:

One can either guess or prove from Maxwells equations that:

(Laplaces equations, classical electrostatic problems)

Conclusion: The field distribution of TEM waves imitate those (1) of electrostatic problems in the cross-section (2) of plane waves in the waveguide direction

The above assumption of the field direction determines that the wave has only z-propagating components

Wave Eq.:

Full solution:

Like in electrostatic problem, we can define potential function , so that

Voltage:

Current:

One can thus define wave Impedance:

TEM Waves (2)

Voltage & current can also be defined like the electrostatic case,

+

-

(conservative field)

(Laplaces equation)

From previously,

(Gausss law)

For TEM waves, this means:

The ratio between voltage & current is called characteristic impedance,

Parallel Plate Waveguides (1)

d

PEC

y

x

z

Dominant mode: TEM

d

W

Boundary conditions:

Assume no variation in x, thus,

Substitute the boundary conditions in the above,

The fields are,

Laplaces equation:

which gives,

The electric field is thus given by,

PMC

Parallel Plate Waveguides (2) Y-Z plane X-Y plane TEM

wave

The voltage is defined as,

The current is,

Then the characteristic impedance of the line is,

The phase velocity is also a constant,

d

PEC

y

x

z

d

W

PMC

(for TEM wave )

Microstrip Line

Compact, light weight Can be fabricated by photolithography Easily Integrated with other passive and active microwave

devices

Most popular type among planar transmission lines

Pros:

Cons: Low power capacity High loss

Microstrip Line

Define effective dielectric constant to represent the fringe field effect,

Approximately is given by:

Characteristic impedance

(why? ) Half air, half dielectric

Compact, light weight Can be fabricated by photolithography Easily Integrated with other passive and active microwave devices Low power capacity High loss

Coplanar Waveguides (CPW)

Empirical formulas can be used to find out the characteristic impedance and phase velocity

Support multiple quasi-TEM modes

Suited for Monolithic Microwave Integrated Circuit (MMIC) applications where vias and through holes to ground are difficult to make

An uni-planar transmission line

Coplanar Waveguide mode

Coplanar Slotline mode