View Single Post
  #9   Report Post  
Old June 11th 10, 11:07 AM posted to rec.radio.amateur.antenna
Richard Fry Richard Fry is offline
external usenet poster
 
First recorded activity by RadioBanter: Jun 2006
Posts: 440
Default Where does it go? (mismatched power)

On Jun 9, 2:44*pm, Roy Lewallen wrote:

Consider a 100 watt transmitter connected to a 50 ohm dummy load or
antenna via a half wavelength of 50 ohm lossless transmission line.
...
(clipped)
...
Ok so far? Now replace the transmission line with one having
200 ohm impedance.

The transmitter sees an impedance of 50 ohms resistive.
The transmitter delivers 100 watts to the transmission line.
The transmission line delivers 100 watts to the load.
The load dissipates 100 watts.
The VSWR on the line is 4:1.
The "forward power" in the transmission line is 156.25 watts.
The "reverse power" in the transmission line is 56.25 watts.


Could you or someone please post the same analysis when the electrical
length of the 200 ohm transmission line is 1/4-wave rather than 1/2-
wave, including the physical locations/components where r-f output
power is dissipated?

RF