[TowerTalk] 75 ohm - v - 50 ohm coax

[Steve Hunt]

The SWR on the 75 Ohm line will be 1.5:1, but if the line is a 
quarter-wave or odd multiple long, the 50 Ohm load impedance is 
transformed to 75*1.5 or 112.5 Ohms - that's an SWR(50) of 2.25:1.

In fact any line length between 0.15 wavelength and 0.35 wavelength will 
transform the load impedance to produce an SWR(50) greater than 2:1.

73,
Steve G3TXQ



On 19/02/2013 14:10, Jim Thomson wrote:
>
> If the antenna has an impedance of 50 Ohms, and the coax is close to a
> quarter-wave or odd multiple long, you'll see an SWR(50) of 2.25:1 at
> the shack end instead of 1:1.
>
> 73,
> Steve G3TXQ
>
> ##  I thought it would be just 75/50 =  1.5:1
>
>