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This is my first post so I hope that I am doing this correctly. I have put the question below and i am having troubles with numbers 3,5 and 6. Any help would be great.

Cheers

A transmitter with an output power of 200W operates at a frequency of 20MHz. It feed an antenna with an impedance of 30 Ω. The cable has a characteristic impedance of 50 Ω and a velocity factor of .90. Cable loss will be ignored and power rating is adequate for the application.

Load is not matched to the transmission line so there will be some reflection of the incident wave energy when it arrives at the load. The incident wave and the reflected wave will both combine to produce an interference phenomenon known as a stationary wave or standing wave.

1. Calculation the Reflection Coefficient at the load

Г = (Rl-Zo)/(Rl+Zo)

Г = (30-50)/(30+50) = 20/80 =1/4 or 0.25

* How do you convert this to dB??

2. What does the sign mean of the reflection coefficient value

+ve Maximum positive reflection when the line is open circuited

-ve Maximum negative reflection when the line is short circuited

0= perfectly matched

3. Would there be a Maximum or Minimum in the standing wave

4. Calculate the voltage standing wave ratio (VSWR) on the line

VSWR = Zo/Rl = 50/30 = 1.6667

VSWR = (1+ Г)/(1- Г) = (1+0.25) / (1-0.25) = 1.6667

5. What is the distance between adjacent minima in the standing wave pattern.

6. Calculate the actual amount of reflected power and the actual amount of power few to the load.

Г^2 = Pref/Pinc

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# Homework Help: Communication question

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