Transline-SWR-to-Stripline Flashcards
An interference pattern resulting from ZL not being equal to Zo, creating two sets of travelling waves going in opposite directions.
Standing Wave
The first set travels toward the load, and the reflected set travels back to the generator.
What does SWR stand for?
Standing Wave Ratio
It measures the mismatch between the load and the line.
How is SWR mathematically defined?
SWR = Imax / Imin or SWR = Vmax / Vmin
SWR is a scalar quantity.
What condition results in SWR = 1?
When Zo = ZL
This indicates a perfectly matched line.
What happens when SWR > 1?
It indicates a mismatch between the line and the load
SWR > 1 occurs when the line is terminated in a purely resistive load.
What is the range of SWR values?
∞ ≥ SWR ≥ 1
SWR = ∞ occurs when the load is purely reactive.
What does an SWR of 1 indicate?
An ideal value theoretically
It signifies no signal reflection along the line.
What does a Short-circuited Line condition result in?
Total reflection
This occurs when Zo = zero and ZL = infinite.
What is the effect of an Open-circuited Line?
Total reflection
This occurs when Zo = infinite and ZL = infinite.
A quarter-wave section of a transmission line used to match transmission lines to purely resistive loads.
Quarter-wave Transformer
It is used when RL ≠ Zo.
To measure the power being delivered to a load or an antenna through a transmission line.
Directional Coupler
It uses a sampling technique to measure only the forward wave power.
To convert between balanced and unbalanced transmission parallel lines.
Balun
It acts as a simple form of transmission line transformer.
How the complex impedance of a transmission line varies along its length.
Smith Chart
It was invented by Philip Smith in 1939.
Fill in the blank: SWR is a measure of mismatch between the load and the _______.
line
True or False: An SWR of ∞ indicates a matched line.
False
An SWR of ∞ indicates a purely reactive load.
What is the characteristic of incident voltage at an open circuit?
Reflected back without phase reversal
The incident current is reflected back 180 degrees.
What is a Slotted Line used for?
To measure the position and size of the first voltage maximum from the load.
It has a long narrow longitudinal slot in the outer conductor.
What is the first step in stub matching using the Smith Chart?
Normalize the load impedance (z = ZL / Zo) then plot.
Why is admittance used instead of impedance in stub matching?
Because stubs are shunted across the load.
What do the circles and arcs represent when using admittance?
Conductance and susceptance.
What is the process to normalize the admittance?
Rotate the impedance plot 180 degrees.
What is y’ when intersecting ‘y’ to R=1?
y’=1 ± j
What does the distance between y and y’ indicate?
The distance from the load that the stub must be placed.
What is the stub admittance (ys) derived from?
Get the reciprocal of y’ with R=0; ys = 0 ∓ j
