Thread: Standing waves
View Single Post
  #39   Report Post  
Old September 22nd 09, 12:05 AM posted to rec.radio.amateur.antenna
Dave Dave is offline
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 797
Default Standing waves


"Szczepan Bialek" wrote in message
...

"Dave" wrote
...

"Szczepan Bialek" wrote in message

In the Gas Analogy the monopole antena is exactly like the Kundt's
tube.

Heaviside did the Hydraulic Analogy. All is exactly the same like in the
fluids mechanics.
Next the electrons were discovered. Automatically Heaviside is a history
and the Gas Analogy is in power.

But you, radio people, are very close to waves and should be easy for
you to work out the answer for the Question:
Which Analogy is right?


neither analogy is 'right'. they are useful in limited circumstances to
demonstrate some basic pressure wave physics to young students. but
neither one properly reproduces electromagnetic waves.


"electromagnetic waves" are paper waves. Radio waves are real waves. Now
we must not know what the waves are like. Now we should estabilish from
which part of the radiator radiate the radio waves.
Do you agree with Richard Harisson:
"At the open circuited ends of a resonant antenna there is almost double
the forward voltage but zero total current due to cancellation of the
dorward and reflected currents at the open circuit. At the open circuit
in the wire, all the energy in the wave is transferred to the electric
field."
S*


we know what they are like, you just have to understand the mathematics.
and yes, richard's statements are true, but a bit too restrictive, it
doesn't HAVE to be resonant. Voltage doubles and current=0 at the end of
any wire fed with a time varying current, it doesn't even have to be a sine
wave... note the effect of sending square waves from a time domain
reflectometer down an open circuited wire.