On 2011-12-27, at 8:29 PM, David Gilbert wrote:
#2 Just because steel has lower loss than a wet tree doesn't mean that it
would be smart to built an antenna inside of a steel structure when it would be
better all the way around to put it in the clear. Why would you ever do that?
---I guess you'd do it because, using the logic of "wood" vs. "steel" that's
been utilized here so far that says there are absorptive losses in wood /
trees, whereas RF would simply reflect off of metal---correct? So why not do
it...? The signal would simply "...reflect its way" out of the steel enclosure
with minimal loss, if I understand things so far...in a wood enclosure, it
would be absorbed & lost.
#4 Actually, at least a few people have already answered your questions.
Conductive but mostly lossy structures absorb RF ... conductive but mostly
non-lossy structures deflect or block RF.
---If the structure is conductive and non-lossy, would it not then simply and
efficiently re-direct all that RF directly to ground, creating an even GREATER
loss in our far-distant signal? Think of your OT VFO enclosure: shielded,
bypassed, and GROUNDED. Taking the logic of this a step further, if a
well-grounded low resistance cover over a VFO was ineffective because it'd
merely "deflect" RF, then why not simply place a small wooden apple basket over
top of it...? Surely the lossiness of the wood would "absorb" any RF fields
emanating from the VFO itself, right...?! And a grounded cover would thus be
rendered a moot point!
Nobody is "having it both ways" ... you just don't grasp the difference.
---No Dave, I guess I do not grasp the difference...and I'm glad of it! If I
were to accept such an "ism" as the gospel truth, I would never have gotten my
station on the air 40 years ago...and I would have razed each & every tree in
the immediate field of the tower that I have here now, too. Trees were the
gifts of nature that allowed me to get on the air years before I could even
dream of ever getting a free-standing steel tower...and I think that any
prevailing "...tribal knowledge" that alleges they are bad to the hobby is
anathema to sustained growth in our ranks, too...think "stealth", think
inexpensive aerial supports.
It's your turn to think about it....
---There. I've thought about it! And I remain unconvinced... : >)
~73~ de Eddy VE3CUI - VE3XZ
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