Bob,
Aside from 1/2 wave verticals (or vertical end fed dipoles if you will)
not needing radials as they are as complete as a horizontal dipole
also, with a 1/4 wave vertical, is it not sufficient to have a number of
closely spaced short radials rather than several radials a 1/4 wave
long at the lowest frequency? I thought I had read that radial spacing
may be more important than length and that radials may not have much
effect past the 1/4 wave point. Although the thought of establishing
(consuming the back yard) as a RF base for a vertical antenna is
certainly interesting.
John / WA1JG
On 5/17/2012 7:59 AM, Bob McGraw - K4TAX wrote:
> Just visualize that your 30 ft length of wire from your station to "ground"
> puts your station near the HV point or nearly 1/4 wave above ground for 40M.
> If one has RFI issues on one band and not on others, this could likely be
> the reason.
>
> I agree with Jim on all of this. Many antenna systems require a ground
> reference for radiation efficiency AND lightning protection. And all of
> this should be outside of the structure, NEVER inside!
>
> At the same time, a center fed dipole or a beam is in itself a complete
> radiating system and requires no ground at all to be an efficient radiator.
> On the other hand, antennas such as verticals, end fed wires, slopers to
> name a few do work against earth/ground which serves as the other 1/2 of the
> antenna system. This is the reason radials are typically used with
> verticals be they at the surface of the earth or elevated as in a ground
> plane antennas.
>
> RFI issues are typically the result of wiring within the station, acting as
> an antenna itself, picking up RF as radiated from the transmitting antenna
> or antenna loads that produce a highly reactive condition at the station.
> In both of these cases, grounding is not the solution.
>
> I also don't subscribe to the idea of a tuned ground system or artificial
> ground. For one, tuning will change from band to band and in some cases
> frequency within the wider bands. Also, as one described, radials of
> various lengths spread around the room can have quite high voltage at their
> ends which in itself can produce some nasty RF burns or contribute to
> accidents or fire.
>
> 73
> Bob, K4TAX
>
>
>
> ----- Original Message -----
> From: "Jose F Ballester"<jfballester@gmail.com>
> To:<k9yc@arrl.net>; "Discussion of Ten-Tec Equipment"
> <tentec@contesting.com>
> Sent: Wednesday, May 16, 2012 9:57 PM
> Subject: Re: [TenTec] RFI Issues
>
>
>> I'm 30' from a copper plated ground rod connected with a 10 gauge braided
>> copper wire from my second story shack. Never detected a difference when
>> it has been disconnected. Don't have grounded antennas.
>>
>> Why is it necessary?
>>
>> 73 de Pepe WP3HW
>>
>>
>> On May 16, 2012, at 10:49 PM, Jim Brown wrote:
>>
>> On 5/16/2012 12:22 PM, Stuart Rohre wrote:
>>> Likely with a second floor shack, ONLY the tuned ground lead would help
>>> your RFI.
>> Repeat after me:
>>
>> A CONNECTION TO EARTH HAS NOTHING TO DO WITH RFI.
>>
>> A CONNECTION TO EARTH HAS NOTHING TO DO WITH RFI.
>>
>> A CONNECTION TO EARTH HAS NOTHING TO DO WITH RFI.
>>
>> A CONNECTION TO EARTH HAS NOTHING TO DO WITH RFI.
>>
>> A CONNECTION TO EARTH HAS NOTHING TO DO WITH RFI.
>>
>> A CONNECTION TO EARTH HAS NOTHING TO DO WITH RFI.
>>
>> A CONNECTION TO EARTH HAS NOTHING TO DO WITH RFI.
>>
>> A CONNECTION TO EARTH HAS NOTHING TO DO WITH RFI.
>>
>> A CONNECTION TO EARTH HAS NOTHING TO DO WITH RFI.
>>
>> What matters is proper bonding of cable shields to the chassis of the
>> equipment to which it is connected, and the proper bonding of every
>> equipment chassis to each other.
>>
>> 73, Jim K9YC
>> _______________________________________________
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>
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