[Elecraft] Measuring SWR (Long)

[David Woolley]

A typical transmitter does not reverse terminate the transmission line 
with its characteristic impedance, so most of the reflected power gets 
re-reflected as forward power.  Reflected power isn't necessarily lost 
power.  At least at lower frequencies, it is likely to present a much 
higher impedance.  A final that did accurately terminate the line would 
be rather inefficient.

A more important issue with SWR is high SWRs can cause clipping (you 
need a larger voltage swing if the load is higher (assuming purely 
resistive for the moment), or take it outside the safe operating area of 
the output devices.

Those may cause problems at quite low SWRs, but they actually depend on 
the complex impedance, so on some parts of the Smith chart circle you 
may be completely safe, but on others, you might kill the finals.


On 09/04/2019 22:39, Roger D Johnson wrote:
> For an interesting discussion..."What happens to the power that's 
> reflected?"