[Amps] Input SWR revisited

[Gerald Williamson via Amps]

Don, the swr at the 100 ohm end of the 75 ohm coax is 100/75=1.333.
 
In the case the 75 ohm coax is 1/4 wavelength long the impedance at the  
other end is 75/1.333 or 56.26 ohms.
 
The swr at the 56.26 ohm end of the 75 ohm coax 75/56.26=1.333.
 
The swr anywhere along the 75 ohm coax is 1.333.
 
The swr inside the coax matters because it determines the what the end  
impedance will be with a given source impedance.
 
It is not so much that we "care" what the swr is, but knowing the swr just  
makes it easy to calculate what the load impedance will be with a given 
source  impedance. It gives us a chance to use a little science instead 
observing "the  magic".
 
73,
Gerald K5GW
 
 
 
 
 
In a message dated 1/14/2015 2:12:46 P.M. Pacific Standard Time,  
donroden at hiwaay.net writes:

>  But, the swr inside the 75 ohm coax is still 1.333 at all points along  
the
> cable.

No, not at either end.

Why does the swr  "inside" the coax even matter when we are discussing  
load and source  impedances ?


Don  W4DNR

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