Determine Reflection Coefficient & Load Impedance: Slotted Line 150ohms

In summary, the voltage standing wave ratio is 3 and the distance of the first voltage maximum is 9 cm and the first voltage minimum is 3 cm from the load. To determine the reflection coefficient of the load, you can use the standard transmission line equations and the location of the voltage minimum and maximum. From this, you can also infer that the load has a capacitive reactance.
  • #1
naspek
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A slotted line used on a 150ohm lossless transmission line connected to an unknown load impedance, ZL. The voltage standing wave ration is found to be equal to 3. The distance of the first voltage maximum from the load is found to be 9 cm, and the first voltage minimum is located at 3 cm from the load.Determine the followings:

i) The reflection coefficient of the load
ii) The unknown load impedance, ZL.

First thing first..
it's given dmax and dmin..
how am i going to translate it to smith chart..?
 
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  • #2


You do not need to use a Smith chart for this. Just take a look at your standard set of transmission line equations.

[tex] VSWR = \frac{1+\left| \Gamma \right|}{1-\left| \Gamma \right|}[/tex]

Now you can solve for the magnitude of the reflection coefficient. Next, use the location of the voltage minimum and maximum to derive the wave number and then the reflection coefficient.

Here's a sanity check for you. Since it reaches a minimum first away from the load then we can infer that the load has a capacitive reactance.
 

FAQ: Determine Reflection Coefficient & Load Impedance: Slotted Line 150ohms

What is a reflection coefficient?

A reflection coefficient is a measure of the amount of energy reflected from a transmission line or device. It is represented by the Greek letter rho (ρ) and can range from 0 to 1.

How is reflection coefficient calculated?

The reflection coefficient can be calculated using the formula ρ = (ZL - Z0) / (ZL + Z0), where ZL is the load impedance and Z0 is the characteristic impedance of the transmission line.

What is a slotted line?

A slotted line is a device used to measure the standing wave ratio (SWR) of a transmission line. It consists of a metal tube with evenly spaced slots along its length, which allow for the insertion of probes to measure the voltage at different points along the line.

What is load impedance?

Load impedance, also known as termination impedance, is the impedance of the device or component at the end of a transmission line. It determines how much power is delivered to the load and how much is reflected back.

How is load impedance determined using a slotted line?

To determine the load impedance using a slotted line, the standing wave pattern on the line is observed and the position of the nodes (points of minimum voltage) and antinodes (points of maximum voltage) are measured. These values are then used to calculate the reflection coefficient, which can be used to find the load impedance using the formula ZL = Z0 * (1 + ρ) / (1 - ρ).

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