EE 531

Bipin Maharjan

22 Feb, 2011.1

�PCB/PWB

�MPC

�HISTORY

�FLAT STRIP TRANSMISSION LINES

�DESIGN PARAMETERS

�APPLICATION

�REFERENCES

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�PCB/PWB- Printed Circuit Board/Printed Wiring Board

�MPC- Microwave Printed Circuit

�The first known flat strip transmission- during WWII

�Antenna System

�Power Division

�Similar Application: used by John Ruze

�radar power distribution system at the Cambridge Field

Station US Air Force

�Commercial Application of a planar coaxial system

�slotted line by Hewlett – Packard Co.

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Robert M. Barrett:

�Around 1949, while working on “Wullenweber” antenna, realized the flat

strip coaxial line can be put into the PCB resulted into MPC.

�The potential of this technique grew further into

�Filters, power distribution networks , directional couplers,

�Matched loads etc

�Unshielded systems were considered but decided to concentrate fully on

shielded systems.

�The technique became apparent because testing time was reduced significantly.

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For wide, low impedance

strips,

characteristic impendence can

be calculated parallel- plate

capacitance formula.

�Have to consider fringing

effects over 150 ohms.

�Characteristic impedance(Z0)

is given by the formula,

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�The Printed Circuit Power Splitter

�Printed Circuit Filters

�Antennas

�Bridge Circuits or Hybrid Circuits

�Directional Couplers

�Terminations and Attenuators

�Variable Tuners, Junctions and Transitions

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�Power Splitter based on quarter

wave transformers

�The impedances are related by

the formula,

Z0 =√(Z1 Z2)

�Characteristic impedance is the

geometric mean of the end

impedances.

�Power splitter junction in tri-

plate

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�Microwave filters can be designed

by varying strip width, which is the

characteristic impedance.

�Varying width of the strip also

changes the ratio of the capacitance

and inductance of each section

�Sections when arranged in series

represent a low pass filter

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�Power fed on the input

terminals will equally

divide between two

matched load

� no power will appear in

the adjacent or opposite

pair of terminal.

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�The directional coupler is another

form of the hybrid network.

�Parallel – line Coupler

�Two branch coupler

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�Matched loads and

attenuators are often

required in applications of

MPC

�Early matched loads and

attenuators were made with

resistive paint.

�Recent ones have metalized

films of sheet- coated

materials.

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Transition from coaxial to flat-

strip lines

�Practical double stub tuner

�Complex MPC are fabricated in separated

components and joined together to form

complete and working circuit.

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Micro strip

�Most popular transmission line ease in

fabrication

�Ease in connection

�Slightly lossy and dispersive.

Strip line:

�Advantage over micro strip- non dispersive

�Difficult to fabricate and connection than

micro strip

Coplanar Waveguide:

�Newest technology.

�Both ground and conductor on the same

side.

Slot line:

�A dual wire transmission line.

�Not very popular.

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Styles, Jim.

www.ittc.ku.edu/~jstiles/622/handouts/section_3A_Transmissi

on_Lines_package.pdf . 2-22-2010 . University of Kansas,

Department of EECS.

Barrett M. , Robert (1984). Microwave Printed Circuits- The Early Years.

IEEE Transactions on Microwave Theory and Techniques. Vol. MTT-32,

No.9.

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