View Single Post
  #2   Report Post  
Old November 13th 06, 02:26 AM posted to rec.radio.amateur.antenna
Wayne Wayne is offline
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 409
Default What is RF ground?


"John Smith" wrote in message
...
Wayne wrote:
"John Smith" wrote in message
...
David wrote:
What would you define RF ground as? There seem to be a lot of different
ideas.
David:

Ground can be a relative thing. What I have always found to be good
advice is that EVERY ground, at some point, be allowed to reach a low
ohmic earth ground (best possible if it all occurs at the exact same
earth ground point--or no current flows and there is no voltage
potential between such grounds.) For example, although a dipole needs
no rf ground directly at the point it connects to the feed-line, the rig
hooked to such an antenna and feed-line should be given a good earth
ground.
snip


Regards,
JS


When you refer to hooking the rig/dipole to a good earth ground, are you
still talking about an rf ground, or a safety ground?
I see no requirement to connect a nicely matched dipole to an earth
ground for rf purposes. For example, a battery operated transmitter
feeding a dummy load wouldn't need one either.


Wayne:

Both. Only a dummy would think he needed an rf ground for a watt burner
of proper impedance.

However, there always is that "special case;" if the nitwit was running a
kw off a forklift battery, he just might want that rf ground.

JS


Well, my question is in the context of rf ground being a function of the
antenna subsystem. It wasn't clear why you recommend use of a transmitter
rf ground, if the antenna system doesn't require it. Yes, I would run some
sort of rf ground at the rig if I were using a random wire fed with a tuner
in the shack, because the antenna system requires it.

My own setup is a ground mounted vertical with a modest 10 foot diameter
ground system. The "rf ground" is at the base of the antenna (as is a
separate lightning ground). The shack is on the second floor, and has only
a safety ground at the rig.