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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