# Transmission Lines

Discussion in 'Wireless & RF Design' started by Kayne, May 1, 2010.

1. ### Kayne Thread Starter Active Member

Mar 19, 2009
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Hi there,

I am having trouble with one perticular part of the question that is attached the parts are number 1 though to 8 and i am having trouble with number 6 which is calculating the output power from the cabling to the antenna.

If you can help me with how to do this that would be great. If you know any good site with worked question or easy explanations on telecommunication, Antennas, and transmission line losses and formula and could post them i would be much appricated.

kayne

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Apr 5, 2008
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3. ### t_n_k AAC Fanatic!

Mar 6, 2009
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Hi Kayne,

You seem to have gone astray at point 4.

The fractional loss will simply be the cable power loss expressed as a fraction of input power - rather than a dB loss.

You already have the cable loss 10log(Pout/Pin), is 1.85dB.

Hence P_antenna/P_transmitter =10^(-1.85/10)=0.6531 which is the fraction of the transmitter power that reaches the antenna. Which means 0.3469 of the transmitter power is lost in the cable.

Kayne likes this.
4. ### Kayne Thread Starter Active Member

Mar 19, 2009
105
0
Thanks for the reply, i managed to work though the rest of the problem and the answers worked out.