Thanks, Carl - it's nice to get one right for a change! <:}
73/72, George
Amateur Radio W5YR - the Yellow Rose of Texas
Fairview, TX 30 mi NE of Dallas in Collin county EM13QE
"In the 57th year and it just keeps getting better!"
<mailto:w5yr@att.net>
----- Original Message -----
From: "Carl Moreschi" <n4py@earthlink.net>
To: "tentec" <tentec@contesting.com>
Sent: Wednesday, April 02, 2003 7:47 PM
Subject: Re: [TenTec] an antenna question
> George,
>
> You could not of said it any clearer. That's exactly my experience also
> with radials.
>
> I have a very unique vertical that I use on 80, 75, 40, and 30 meters. It
> is a 60 foot vertical wire running from the ground to the top of a tree.
I
> have 16 50 foot radials in the ground. I have a relay switched matching
> circuit at the base that tunes the antenna at 3.5, 3.8, 7, and 10.1 mhz
> depending on which relay is activated. This gives me a very good 1/4 wave
> vertical on 80, 1/2 wave vertical on 40, and 5/8 wave vertical on 30. It
is
> a great DX antenna.
>
> Carl Moreschi N4PY
> Franklinton, North Carolina
> n4py@earthlink.net
> ----- Original Message -----
> From: "George, W5YR" <w5yr@att.net>
> To: <tentec@contesting.com>
> Sent: Thursday, April 03, 2003 2:56 AM
> Subject: Re: [TenTec] an antenna question
>
>
> > Let's keep in mind that radials in physical contact with the earth are
> > essentially non-resonant; their length is of importance only to the
extent
> > that collectively they form an effective ground screen to collect return
> or
> > displacement current to the feedline inner braid. Their action is not to
> > serve as a reflector of sorts to provide some for the waves to "bounce
> > against" in the process of being launched. That occurs many wavelengths
> away
> > in the confluence of the Fresnel and far-field zones and defines the
> takeoff
> > angle involved in the vertical radiation pattern.
> >
> > I use eighteen 25 ft radials with a Butternut HF-9V simply because (a)
> that
> > is about the height of the antenna and (b) I made a good buy on 450 feet
> of
> > insulated #12 green wire at Lowe's which translates into 18 twenty-five
> foot
> > radials. The wire size is massive overkill, but it was cheap!
> >
> > Jerry Sevick demonstrated in the 70's that 0.2 wavelength radials are
> > essentially as effective as anything longer and a rule of thumb that
> radials
> > as long as the vertical is high works out pretty well.
> >
> > Elevated radials are an altogether different story. There you want (a)
> > resonance and (b) a balanced configuration so that the radiation among
the
> > radials is cancelled as much as possible. So symmetry is important.
> > Preferably one would tune a pair or two of radials for each band in use.
> >
> > However, ground-mounted radials are largely frequency independent and
the
> > aim there is just to get as much copper in the immediate vicinity of the
> > feedpoint as is feasible. More shorter radials are preferable to fewer
> > longer radials, according to Jerry's extensive experiments. All this is
> > documented in his book on "ununs" and "baluns." As well as in his
original
> > series in QST.
> >
> > 73/72, George
> > Amateur Radio W5YR - the Yellow Rose of Texas
> > Fairview, TX 30 mi NE of Dallas in Collin county EM13QE
> > "In the 57th year and it just keeps getting better!"
> > <mailto:w5yr@att.net>
> >
> >
> >
> >
> >
> > ----- Original Message -----
> > From: "Stuart Rohre" <rohre@arlut.utexas.edu>
> > To: <tentec@contesting.com>
> > Sent: Wednesday, April 02, 2003 3:56 PM
> > Subject: Re: [TenTec] an antenna question
> >
> >
> > > Yes, the transmatch should handle that OK.
> > > The radials are for a lower band and will function as a ground screen
> does
> > > to an extent on higher bands.
> > > 73,
> > > Stuart K5KVH
> > >
> > >
> > > _______________________________________________
> > > TenTec mailing list
> > > TenTec@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/tentec
> >
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>
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