Are you then saying that in order to obtain the same percentage of bandwidth
on 20M the elements should be about 2.5 inches in diameter?
What would it be using realistic diameters?
Geoff
----- Original Message -----
From: "Joe Reisert" <W1JR@arrl.net>
To: <K3BU@aol.com>; <Towertalk@contesting.com>
Sent: Tuesday, January 14, 2003 11:08 AM
Subject: Re: [Towertalk] 100M-long boom Yagi for 20M
> Hi Yuri,
>
> Using the same software that W6TSW used, YO, one can easily scale any Yagi
> from band to band (frequency to frequency) with ease. I have found
> excellent correlation. I have scaled numerous VHF Yagis to HF without
> problems. Obviously the elements have greater diameters and are much
> longer! The present day YO software does an excellent job at frequency
> scaling and is especially powerful when using tapered elements.
>
> I have numerous choices of hundreds of designs that I have already built,
> tested and shipped to customers over the years. Just for a quick check, I
> looked at the design of my 17B2 (17 elements on 144 MHz on a 4.5
wavelength
> boom) that Cushcraft sells. It scales to the exact same boom length of the
> W6TSW antenna. It does have a few more elements but has about 1.0 dB more
> gain, an incredibly clean pattern with high F/B ratio....and over the
> entire 20 meter band, not just at 14.150 MHz.
>
> Another example is a 14 element 4.5 wavelength design that I have built on
> 2-meters that has the almost the same gain (15.53 versus 15.89), a very
> clean wide bandwidth BUT a boom length of only 250 feet....70 feet
shorter.
> For 0.36 dB less gain (I'll challenge you top measure that!), you use two
> less towers, quite a savings!
>
> With all due respect to the W6TSW design, we must remember that this is
the
> year 2003, not 1986, so we must give credit where credit is due. However,
> if this gain is to be done on 20 meters again with a Yagi antenna, it
would
> be foolish to duplicate the same design.
>
> 73,
>
> Joe, W1JR
>
>
> At 09:18 PM 1/13/2003 -0500, K3BU@aol.com wrote:
> >In a message dated 1/13/03 8:57:22 PM Eastern Standard Time,
W1JR@arrl.net
> >writes:
> >
> > >
> > > I have built some VHF designs that can be scaled to 20 meters that
will
> > > match the beamwidth and meet or exceed that gain on a shorter boom
with a
> > > much cleaner, broadband pattern and match directly to 50 Ohms!
> > >
> > > That being said, it sure was a novel idea and a way to configure a
> > long HF
> > > Yagi.
> > >
> >
> >Hi Joe,
> >can you elaborate on agreement between software designs and actual
antennas?
> >
> >VHF antennas allow close verification and measurements.
> >
> >Yuri, K3BU
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> _______________________________________________
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