|To:||Jim Lux <email@example.com>|
|Subject:||Re: [TowerTalk] Radials Questions - 270 or 360 degrees.|
|From:||Bill Coleman <firstname.lastname@example.org>|
|Date:||Wed, 5 Jan 2005 22:56:02 -0500|
On Jan 5, 2005, at 7:55 PM, Jim Lux wrote:
The error in the model is probably a lot bigger, as Red said. Upshot is, don't trust the 1.1dB number. You could have 1 dB more gain, or 1 dB less gain, or no change at all.
Somehow, I doubt any of the readily available inexpensive modeling codes would adequately model the effects of your house, which will dominate any directive effects of your asymmetrical radial field.
Definitely, since the house consists of a complex variety of components, some opaque, others transparent to RF.
There you go.. the real useful advice.. put down as many radials as you have time/money/patience for. Don't worry about the length (well... extending past, say, 1/2 wavelength might be a diminishing returns)
I've got down 24 radials of 60 feet (a few are shorter), which is about all I have space for in my 270 degree circle.
Question 2: In looking at option B, is the vertical segment going to have an adverse effect on the pattern in the NW to NE direction? Is the vertical segment going to change the phase of the currents and ultimately destroy any gains by adding the radials?
Option B would have the radials rise 9 feet off the ground, then traverse the basement ceiling, which is alive with house wiring, gas pipes, and aluminized mylar air ducts.
Option A would have the radials cross the basement floor, which is concrete, and much further away from the conductive parts of the house.
I was really asking about the effect of the 9 foot vertical riser within three feet of the shunt fed tower. Other feedback I received indicated this probably isn't a good idea.
Question 3: Is there any coupling or danger associated with having these radials inside the house? Is there a potential for high voltages to appear, or to have the elements radiating RF inside the structure? Is this different from option A or B?
We're talking 80m and 100 watts. Page 9 of OET #65, supplement B is a diagram of the electromagnetic spectrum. Page 3 of the same bulletin indicates that for power levels under 500 watts on 80m, an RF Safety evaluation is not required.
Bottom line - sounds like people are telling me it ain't worth bothering with running radials across the basement floor. Thanks, that's good advice.
Bill Coleman, AA4LR, PP-ASEL Mail: email@example.com Quote: "Not within a thousand years will man ever fly!" -- Wilbur Wright, 1901
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
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