Determine attenuation of voltage in transmission line

In summary, the conversation discusses a circuit with a square pulse input and varying source and load impedances, connected by a transmission line circuit. The goal is to achieve source matching and calculate the attenuation coefficient. The conversation also mentions the reflected pulse and its relationship to the attenuation calculation. The speaker is new to this topic and is seeking guidance.
  • #1
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Hello,

So I have a circuit where I input a square pulse with a source impedance and load impedance (which are just pure resistors) each of which can be varied and a transmission line circuit connecting them which is made up of resistors, capacitors, inductors in a lumped element model. I set the load impedance to open circuit and vary the source impedance until Vin (the voltage after the source impedance but at the input to the transmission line) shows only a transmitted pulse and single reflected pulse on an oscilloscope.

This is what I believe is source matching where the source impedance is equal to the characteristic impedance. What I am trying to calculate is the attenuation of the voltage from the input to the output and hence the attenuation coefficient. If I say the transmitted pulse is V1 and the reflected pulse is V2 BUT the reflected is a combination of V1 and the backward traveling wave. As I understand it the attenuation is for forward or reverse traveling wave only. So do I just subtract one from the other and use the difference to work out the attenuation coefficient? i.e. V3=V2 - V1 and so attenuation is V3/V1?

I am very new to this so any help or guidance would be appreciated! Thanks!
 
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  • #2
Are you sending a square pulse and can you see the reflected pulse coming back? What do you see?
 

1. What is attenuation of voltage in a transmission line?

Attenuation of voltage in a transmission line refers to the gradual decrease in voltage as a signal travels through the line. It is caused by factors such as resistance, capacitance, and inductance in the line, which can weaken the signal over distance.

2. Why is it important to determine the attenuation of voltage in a transmission line?

Determining the attenuation of voltage in a transmission line is important because it allows us to understand the loss of signal strength in the line. This is crucial for maintaining the quality and reliability of the signal and ensuring efficient transmission of data or electricity.

3. How is the attenuation of voltage calculated in a transmission line?

The attenuation of voltage can be calculated using the formula A = 10log(P1/P2), where A is the attenuation in decibels, P1 is the initial power and P2 is the final power. Alternatively, it can also be calculated using the formula A = 20log(V1/V2), where V1 is the initial voltage and V2 is the final voltage.

4. What factors can affect the attenuation of voltage in a transmission line?

There are several factors that can affect the attenuation of voltage in a transmission line, such as the type of line (e.g. coaxial, twisted pair), the length of the line, the frequency of the signal, and the quality of the materials used in the line.

5. How can the attenuation of voltage be reduced in a transmission line?

The attenuation of voltage can be reduced in a transmission line by using higher quality materials with lower resistivity, increasing the line diameter, and using techniques such as signal boosting or equalization. Additionally, regularly maintaining and repairing the line can also help minimize attenuation.

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