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Single Stub Matching

This document is a lab assignment on single shunt stub tuning networks. It discusses the theory of how a single stub transmission line can provide impedance matching by acting as a shunt susceptance. The methodology section outlines the tools and procedure used, which involves normalizing the load impedance, drawing VSWR and reactance circles on a Smith chart, and calculating the stub distances and lengths. The results section shows the output graph, with minimum return loss at the 2GHz operating frequency, indicating successful matching.

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Tafadzwa Nyoni
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105 views5 pages

Single Stub Matching

This document is a lab assignment on single shunt stub tuning networks. It discusses the theory of how a single stub transmission line can provide impedance matching by acting as a shunt susceptance. The methodology section outlines the tools and procedure used, which involves normalizing the load impedance, drawing VSWR and reactance circles on a Smith chart, and calculating the stub distances and lengths. The results section shows the output graph, with minimum return loss at the 2GHz operating frequency, indicating successful matching.

Uploaded by

Tafadzwa Nyoni
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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RADIO FREQUENCY MICROWAVE DEVICES AND CIRCUITS

LAB ASSIGNMENT 2

LECTURER: MR MAGIDI

AUTHOR: TAFADZWA V MUBVUMA

REG NUMBER:H150360Q

TOPIC: SINGLE SHUNT STUB TUNING NETWORK


Theory
A single-stub transmission line impedance matching network is composed of a short or open
circuited section of transmission line placed along the main signal line. The short or open
circuited section provides an equivalent shunt susceptance. This short or open circuited section is
attached perpendicular to the main line. The construction of the short circuited section is similar
to the main line. The load impedance is typically dependent on the frequency of operation. The
distance, d, can be moved back and forth to get a wide range of susceptance values. The
distances d1 and d2 can be found in terms of fractions of wavelength of the signal being
transmitted using a Smith chart. When constructing the single-stub tuner, the stub portion must
be tied to ground. This could imply either as hard ground or AC ground.
Methodology
Tools Used
1. AWR Microwave Development Engine.
2. Smith Chart
3. Locus Tools (Compass)

Procedure
1. Normalisation.
ZN = ZL ÷ Z0
2. Locate ZL normalised on the Smith Chart.
3. Draw the VSWR circle.
4. Draw the 1-jX circle.
5. Find the admittance of ZL and name it YL.
6. Find points Y1 and Y2 which are the points of intersection of the circles VSWR and the
1+Jx
7. Using the wavelength towards generator scale find the distances d1 and d2 from the load
8. Using the wavelength towards load scale, find the lengths L1 and L2 of the stub
Results

Using values d1 and l1

Using the values d2 and l2


Output graph

Conclusion

 Frequency of operation
2GHz
 Return loss value in dB.
Using l1 and d1:- 22.31
Using l2 and d2: -44.11

According to the return loss-frequency graph obtained, it shows that the return loss is minimum
at the frequency of operation 2GHz which affirms that the practical was done correctly.
According to theory the return loss for the two graphs should be less the -10db for S11
parameters hence the practical was a success.

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