# How to find the reflection coefficient of the load and the unknown load impedance?

1. Jun 20, 2011

### naspek

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..?

2. Jun 24, 2011

### Born2bwire

Re: How to find the reflection coefficient of the load and the unknown load impedance

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

$$VSWR = \frac{1+\left| \Gamma \right|}{1-\left| \Gamma \right|}$$

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.