[TowerTalk] RG-149: 50 ohm/70 ohm - does it matter?

[Steve Hunt]

If you feed a perfect 50 Ohm load through a length of 75 Ohm 
transmission line, the SWR(50) at the input of the line will vary from 
1:1 to 2.25:1 depending on the length of the line.

36% of all possible line lengths will cause the input SWR(50) to be 2:1 
or higher.

If it's a multiband antenna it may be difficult to avoid that 36% on all 
bands!

Steve G3TXQ