On 8 Jan 2005 18:16:02 -0800, wrote:

What type of verticle are you talking about, like a ground plane? Would
a ground plane be a better antenna for 2meters?

A ¼-wave groundplane, a ½-wave dipole, a J-Pole or 5/8-wave ground
plane in most typical installations according to NEC analysis will not
vary more than a dB at best.

Remember a receiving station can hardly detect a dB difference.

Danny, K6MHE

wrote
Jack Painter wrote:
wrote
One final note: the J-Pole is no miracle antenna. It's has zero gain
when
compared to any vertical antenna, and its entire attraction is it
"fairly"
easy construction, and very inexpensive construction materials. To
get as
*reliable* a vertical antenna for marine use that I required, might
have
cost well over $100. At or above that level the vertical antennas of
5/8
wavelength can normally provide gain of 6-10 dbi, and I do not want
to get
into what that is compared to as it has been hashed over a million
times. I
would leave it at "there will be considerable gain possible in
vertical
designs over the J-Pole". You have to be willing to pay for that.
Most users
are happy with J-Pole performance so it's record stands pretty well
on its
own.

73,
Jack Painter
Virginia Beach, Virginia

What type of verticle are you talking about, like a ground plane? Would
a ground plane be a better antenna for 2meters?


Yes/Yes, and there are a number of verticals with referenced gain far in
excess of the more or less unity-gain J-Pole. The specific ones I mentioned
are Marine. Like a vertical-dipole the J-Pole is a "complete" antenna and
requires no radials, I doubt that it could even benefit from them. And the
gain is referring to transmit, not receive, as all verticals are pretty
equal in reception (and it's not always pretty ;-)

What is your target for 2 meters? General area coverage or specific
directional? Need to null out signals or interference from specific
directions? Look at aYagi. J-Poles are not for anything special, just good
general coverage at about $10 in parts. At that job they have become very
popular antennas!

73,
Jack Painter
Virginia Beach, Virginia

verbositized:


What type of verticle are you talking about, like a ground plane? Would
a ground plane be a better antenna for 2meters?

Check out my Stacked-J for 2 meters. It is a J-Pole on top of a
J-Pole.
I don't know the difference in gain, but in comparison to a regular
J-Pole on the same mast, the Stacked-J outperformed it hands down.

From St. Louis County, MO I could reach both UMR (Rolla) and UofC
(Columbia) repeaters on the Stacked-J at 30 watts, a little noisy on
their end, but I was clear. On a single J-Pole I could not bring up
their repeaters even at 50 watts.

The Stacked-J can be found at http://archimedes.galilei.com/raiar
It's under Antenna's.

TTUL
Gary

wrote:

Eike Lantzsch, ZP6CGE wrote:
wrote:
[snip]

So, does a j pole need to be insulated from the antenna mast?

No. For lightning protection grounding is recommended but it does
nothing to the function of the J-pole.

Kind regards, Eike

Dan Richardson wrote:
On 8 Jan 2005 18:16:02 -0800, wrote:

What type of verticle are you talking about, like a ground plane?
Would
a ground plane be a better antenna for 2meters?

A =BC-wave groundplane, a =BD-wave dipole, a J-Pole or 5/8-wave ground
plane in most typical installations according to NEC analysis will
not
vary more than a dB at best.

Remember a receiving station can hardly detect a dB difference.

Danny, K6MHE

So, about any omni is as good as another? Thanks for yoru info. Are
there any other advantages to building one or another?

Why does this guy say his j po;e have 3 db gain over a ground plane?
http://cgi.ebay.com/ws/eBayISAPI.dll...30959 97&rd=1

On 10 Jan 2005 05:42:53 -0800, wrote:

Why does this guy say his j po;e have 3 db gain over a ground plane?
http://cgi.ebay.com/ws/eBayISAPI.dll...30959 97&rd=1

Why don't you ask him?

wrote:
So, about any omni is as good as another?

Nope, he didn't say that. Stacked phased vertical elements,
as exist in repeater antennas, can offer a tremendous amount
of gain over a 1/4WL ground plane. I have an old Comet 2x4MAX
and the gain over a 1/4WL ground plane is amazing.

The Diamond NR22L for 2m, is 97" long and is two elements of
5/8WL each and thus will have about 3 dB gain over a 1/4WL
ground plane, about the same as an Extended Double Zepp.
--
73, Cecil http://www.qsl.net/w5dxp


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wrote:
Why does this guy say his j pole have 3 db gain over a ground plane?
http://cgi.ebay.com/ws/eBayISAPI.dll...30959 97&rd=1

He might be making the J-Pole one-wavelength long which would
indeed result in about 3 dB of gain but at a relatively useless
take-off-angle.
--
73, Cecil http://www.qsl.net/w5dxp


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http://cgi.ebay.com/ws/eBayISAPI.dll...30959 97&rd=1

He might be making the J-Pole one-wavelength long which would
indeed result in about 3 dB of gain but at a relatively useless
take-off-angle.

I suspect that he's comparing a standard half-wave-radiator J-pole to
a typical "ground plane" antenna (a quarter-wave monopole, with one
set of quarter-wave radials, possibly tilted downwards for an
impedance match).

The latter sort of antenna falls somewhat short of behaving like
a true infinite-ground-plane antenna, as the radials are neither
horizontal nor infinite in extent. If I recall correctly, the
radiation pattern will be tilted upwards from the horizon by
a significant amount.

The J-pole will be close to 0 dBd, while the "ground plane" will
probably fall a few dB short of that figure out at the horizon.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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