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RE: Coax Attenuation



Hello Bill

> I tried last week to develop (since I couldn't find one)
> a formula for calculating the attenuation of a known
> length of cable given the attenuation per 100 ft.

If 100' has 3dB attenuation, 50' will be 1.5dB.

About six months ago I spent long and hard thinking about this one, but
didn't need to...

Wipe the slate clean and think of it another way.

Say you put 100W into 100' of cable which has 10dB/100' loss. You have 10W
at the end.

Take another 100' of the same coax. Put 10W into it. You have 1W at the end.

Connect the two 100' cables together so that you have 200'. Put 100W into
one end, and you'll have 1W out the other, with 10W at the mid point.

That's 20dB total loss. So you really can just add the dB's. Unless your
coax has suddenly become non-linear.

73 Howard G6LVB


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