That's the paper I was referring to earlier. Really useful for 160m folks!
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of DAVID
CUTHBERT
Sent: Wednesday, December 12, 2012 6:14 PM
To: Guy Olinger K2AV
Cc: k6xt@arrl.net; topband@contesting.com; Ashton Lee
Subject: Re: Topband: Fw: GAP VERTICAL QUESTION
Guy, you make it sound like magic.
See the IEEE paper RADIATION EFFICIENCY AND INPUT IMPEDANCE OF MONOPOLE
ELEMENTS WITH RADIAL-WIRE GROUND PLANES IN PROXIMITY TO EARTH
Dave WX7G
On Dec 12, 2012 3:13 PM, "Guy Olinger K2AV" <olinger@bellsouth.net> wrote:
> Not all loss is visible as series resistance in the counterpoise
> system, which is the tack you are taking. Note that a dummy load is
> 50 ohms, and does not radiate worth a hoot.
>
> It takes modeling to identify some situations. One of my favorites in
> NEC4 results in a max gain of -18 dBi or so. This is compared to a
> commercial BC 1/4 wave of plus 1.2 dBi in the same ground. The reason
> for the extreme loss is completely counter-intuitive.
>
> We have a lot of mental simplification devices for thinking about
> antennas. In the end you need something to add up all the induced
> currents, all the losses
>
>
>
> On Wed, Dec 12, 2012 at 3:13 PM, DAVID CUTHBERT
<telegrapher9@gmail.com>wrote:
>
>> 20 dB implies that the ground system loss is 10X the inverted-L
>> radiation resistance.
>>
>> This would result in an input resistance of 250 ohms and a minimum
>> VSWR if 5:1.
>>
>> I don't think that is what the real deal will deliver, do you?
>>
>> Dave WX7G
>> On Dec 12, 2012 12:54 PM, "Guy Olinger K2AV" <olinger@bellsouth.net>
>> wrote:
>>
>> > With the following caveat: The very sparse and short buried radial
>> systems
>> > he is showing are FAR more lossy in practice than shown in his gain
>> tables.
>> > Four twenty foot buried radials beneath a 1/4 wave L on 160, could
>> place
>> > you down 20 dB. You really can't do that as your 160 meter counter
>> poise
>> > and expect decent results. You can end feed the same wire on
>> > 80/40/30 meters (full wave worth of wire in the L on 80m) with four
>> > buried 20
>> foot
>> > radials and it will be an excellent antenna. This is due to the
>> > high Z feed at the ground with current max AWAY from the feed point.
>> >
>> > A quarter wave L on 160 MUST deal with the counterpoise loss
>> > issues, one way or another.
>> >
>> > 73, Guy
>> >
>> > On Wed, Dec 12, 2012 at 2:07 PM, Ashton Lee
>> > <Ashton.R.Lee@hotmail.com
>> > >wrote:
>> >
>> > > This wonderful article written by L.B.Cebic W4RNL sure can make
>> > > you a believer in a simple wire inverted L. It is the last
>> > > antenna
>> discussed.
>> > > http://www.users.on.net/~bcr/files/backyard%20wire%20antennaes.pd
>> > > f
>> > >
>> > > A $3 wire pulled up into a tree will beat just about any
>> > > commercial antenna. because it is longer. So on low bands it has
>> > > increased band
>> > width
>> > > and efficiency, and on higher bands it has gain. Yes, I know ,
>> > > some of
>> > that
>> > > high band gain is horizontally polarized, but that's not all bad.
>> > > Just
>> > get
>> > > the vertical portion 33 feet or so and you'll be happy as Larry.
>> > > The article shows that an extensive radial field may not be
necessary.
>> > >
>> > > And a wire is a lot less visible than a big hunk of aluminum.
>> > > Without trees, just top load a 43 foot (or possibly even shorter)
vertical.
>> The
>> > top
>> > > loading could be a T just as easily as an L. People can argue
>> > > that one
>> > all
>> > > day.
>> > >
>> > >
>> > >
>> > >
>> > > On Dec 12, 2012, at 11:30 AM, k6xt <k6xt@arrl.net> wrote:
>> > >
>> > > > My first antenna, still in use, on moving to CO is a GAP Titan,
>> > > advertised to load up 80 thru 10 including WARC bands. The Titan
>> > > is a
>> bit
>> > > shorter than Voyager, 28 feet or something like it. The
>> > > advertising is correct, it loads up 180 thru 10.
>> > > >
>> > > > But wait. Is it effective on all those bands? No.
>> > > >
>> > > > On 80 its a dummy load. On 40 it works extremely well after I
>> > > > added
>> a
>> > > one foot extension to the bottom wire that encircles the antenna.
>> > > In
>> some
>> > > cases it is the equal of my shorty HyGain 40 at 70 ft - which
>> > > probably
>> > says
>> > > more about the HyGain than the GAP. For the rest its better on
>> > > the traditional bands than the WARC bands. It worked a lot of DX
>> > > for me
>> for
>> > the
>> > > couple years it was my only antenna.
>> > > >
>> > > > Carrying my experience to the few feet taller Voyager, and from
>> > > > what
>> > > I've been told by Voyager users, the ant will meet its spec which
>> > > is
>> to
>> > > load up on the low bands. Expectation wise I'd expect it to be
>> > > like
>> the
>> > > Titan. It loads up but is otherwise a dummy load. Maybe with a
>> > > batch
>> of
>> > > radials it could be made to work as well as any other extremely
>> > > short vertical or GP.
>> > > >
>> > > > Not to say there's anything wrong with GAP. My brother had up
>> > > > an R7
>> > > which he rated about like the GAP on bands both cover. Those
>> > > multiband halfwave short verticals work but you get what you pay for.
>> > > >
>> > > > 73 Art K6XT~~
>> > > > Success is going from failure to failure without a loss of
>> enthusiasm.
>> > > > ARRL, GMCC, CW OPS, NAQCC
>> > > > ARRL TA
>> > > >
>> > > > On 12/12/2012 10:00 AM, topband-request@contesting.com wrote:
>> > > >> With the prospect of downsizing and moving into senior housing
>> > > >> in
>> the
>> > > future
>> > > >> I am starting to look at vertical antennas that will allow me
>> > > >> to
>> > > continue
>> > > >> this wonderful hobby.? I have heard "some" good things about
>> > > >> the
>> GAP
>> > > series
>> > > >> of antennas but the company says they do not need radials on
>> > > >> most
>> of
>> > > them
>> > > >> and that worries me.? Over the years I have become very
>> > > >> skeptical
>> > about
>> > > >> claims and the other BS put out by most companies ( maybe it
>> > > >> is a
>> > > function
>> > > >> of age I dunno) so I wonder if these antennas really work.?
>> > > >> The two
>> > > antennas
>> > > >> that I am interested are the Voyager DX for 160/80/40? and the
>> Eagle
>> > DX
>> > > for
>> > > >> the rest of the bands.
>> > > >>
>> > > >> So my question is.... does anyone have actual experience with
>> > > >> these
>> > > antennas
>> > > >> (especially the voyager) as compared to other antennas for a
>> specific
>> > > >> frequency.? Now guys .. I know you cant really compare a 6
>> > > >> element
>> > beam
>> > > to a
>> > > >> vertical of this kind but I am talking about a comparison that
>> > > >> is realistic.. like how does it hear, tune, match & get out
>> > > >> compared
>> to
>> > > >> something like another vertical or a dipole up some reasonable
>> > distance.
>> > > >>
>> > > >> I sure hope this has not opend another can of worms.. some how
>> > > >> I
>> seem
>> > > to do
>> > > >> that .. private emails are ok..especially it the topic gets
>> > > >> out of
>> > hand
>> > > and
>> > > >> we get a large volume of comments (Tree please dont shoot me
>> > > >> before Christmas my wife will miss me.)
>> > > >
>> > > > _______________________________________________
>> > > > Topband reflector - topband@contesting.com
>> > > >
>> > >
>> > > _______________________________________________
>> > > Topband reflector - topband@contesting.com
>> > >
>> > _______________________________________________
>> > Topband reflector - topband@contesting.com
>> >
>> _______________________________________________
>> Topband reflector - topband@contesting.com
>>
>
>
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