wrote:
On 7 Feb 2005 14:06:03 -0800, wrote:

???? That's a long distance
telephone service site...

http://www.andrew.com/products/antennas/

I added an "s" by error. Sheesh.

I figured you'd know their products as they are well known in
broadcast and VHF/UHF ham circles. However that was only one
example.
There is also CellOne who also do antenna products and other useful
items. Of course there are only a few hundred (or more) companies
making antennas many of which are suited for a cartiod pattern work.



I couldn't find anything there that was similar
to this:

http://www.drslick.org/Temp1/yagiplot.jpg


s.

On Tue, 08 Feb 2005 04:20:48 GMT, wrote:

On Mon, 07 Feb 2005 16:54:15 -0700, Wes Stewart
wrote:


I'll admit that I've not followed this thread and don't intend to
punch any tar babies. But I must ask; what the hell is a "180 degree"
front lobe?

What he wants is a cartoid pattern, That is a "D" shaped roughly
pattern that's all from and not so much back.

The easy way to do that is a good colinear and mount it near
the flat face of a tower (usually less than 1/4 wave away) . The net
effect is slightly increased gain away from the tower and a mild null
on the other side of the tower. Most of the time this is not desired
but, there are valid cases where you don't wish to waste power behind
you. The most common is coastal commercial broadcat radio and TV.

Allison


What he really wants is to illegally broadcast on the FM broadcast
band. Look at the original post. 2/3 of his newsgroups are Pirate
Radio.


--
73 for now
Buck
N4PGW

Buck wrote:

What he really wants is to illegally broadcast on the FM broadcast
band. Look at the original post. 2/3 of his newsgroups are Pirate
Radio.


My Goodness! I would never break any
FCC rules! How dare you accuse me.

Even though you can use the Super J-pole
up to 1500 watts or so, i would recommend
not using more than 1 femtoWatt or so.

Good for mowing the lawn with your
walkman....




Slick

wrote:

My Goodness! I would never break any
FCC rules! How dare you accuse me.
. . .

No need for anyone to accuse you, it's all there on the Web:

http://www.talkaboutradioshows.com/g...ages/7526.html

Or try a google search of "dr slick" "pirate radio"

Anyone interested in knowing a bit more about Garvin Yee, aka "Dr.
Slick" can see:

http://www.artwanted.com/webjump.cfm?artid=4990

Roy Lewallen, W7EL

Roy Lewallen wrote:
wrote:

My Goodness! I would never break any
FCC rules! How dare you accuse me.
. . .

No need for anyone to accuse you, it's all there on the Web:


http://www.talkaboutradioshows.com/g...ages/7526.html


Don't be silly Roy! I might sell 100 watt
broadcast band transmitters, but i only encourage
people to use them into 50 Ohm non-radiating dummy
loads!

Hehe! Makes a great bed-warmer!



Or try a google search of "dr slick" "pirate radio"

Anyone interested in knowing a bit more about Garvin Yee, aka "Dr.
Slick" can see:

http://www.artwanted.com/webjump.cfm?artid=4990


Thanks for the free plug!

The art is for sale you know....

www.DrSlick.org


Slick

On 7 Feb 2005 21:27:32 -0800, wrote:


I couldn't find anything there that was similar
to this:

http://www.drslick.org/Temp1/yagiplot.jpg

You can lead a horse to water, still can't get it damp.

You'd have to look at the data sheet. All the commercial people
are aware of this and it's accepted practice.

What you missed is a 2 or 4bay dipole is a really nice antenna
that can offer gain and pattern control. The usual use is a 4 bay
vertically oriented with each of the 4 dipoles spaced 90 degrees
around the mast for 5.6db omnidirectional gain. Now, if you want a
directional pattern, such as cartioid then put all four on one side,
also expect slightly higher gain as well. The commercial version are
expensive but are known for their durability but, the good news is
they can be built using copper pipe and will give the same
perfomance. I might add, the gain numbers I gave are not theory,
they are real numbers from proven designs.

Ok, here are some links one how to build it..
http://www.repeater-builder.com/rbti...seddipole.html
some good info here, the metal used is less desirable than
CU pipe. The general design is proven.

http://www.w4dex.com/kc4fwc/ant.htm
Info on making a phasing harness, needed for a 4bay but not
rocket science.

http://dipole.w4zt.com/ look at the plumbers dipole page.
This can be built as a 1/2/4/8 dipole array. The limit is 4
based mostly on size though I've seen one 8 dipole array
and it's long(nearly 45ft!) but very effective. I might add if the
mast pipe is made with 1" copper it can also serve as the supporing
mast. This is a prefered design and offers good all grounded
construction (lightining avoidance and static noise reduction).

The two dipole array with both on one side of the mast is the same
gain as the super jpole with two differences. the 4 bay will be longer
but offers a real gain increase and slightly better pattern control.
The gain increase for this type antenna is predictable, being 3DB
for each time you double the elements. The single being 0 DBd,
2bays 3Dbd, and 4bays 6Dbd . Thereal world the practical antennas
built as omnidirectional are really 0, 2.8 ,5.6dbd due to small but
measureable losses in the cables. If the elements are lined up
on one side the gain is higher (sme claim 9db) with a cartiod
pattern. It's all copper and no required insulators and can be built
more robustly. The pattern is predictable, less is left to chance.
This type of antenna also works well against the side of a metal
building (less tuning difficulties) though you will get a more
directional pattern from the building shielding the opposing
direction. These designs will you get away from theory and use
practical designs.

A repeater group I work with locally used the DBproducts 4bay and
found it the best antenna they've put on the tower to date. It wasn't
cheap and it was heavy. Experience at that site was anything less
robust would barely stand a year before the SWR went to unacceptable.
I've built the 4bay for UHF and it's a solid performer. The all
copper design weathers very well, is very cheap to build
and performs just as well as the commercial versions which are welded
up from aluminum.

I'm sure your getting results from the Jpole but, I can be certain
from using them myself that your results are part luck and can easily
be attributed to the added height (the 70+inches can really help) and
placement more than the presumed gain. If you compare a yagi or
dipole to a J-pole the radiating element must be the same height.
Since the J-pole is really an end fed dipole it has a 38 inch
advantage. For a yagi the centerpoint is the boom.. In direct
comparisons the yagi you built would have to be minimally 3ft higher
to compete on fair ground.

J-poles in general do not like to be near (less than 1/2wave) metalic
structures as it detunes them. Yagi behavour is also sensitive to
metalic structures close to them. The Yo model is not complete
enough for those cases.


Allison
KB1GMX

wrote:
I challenge anyone else to use
whatever Yagi Optimizers they have
to come up with a 3 element design
(to keep the size down) with a 180 degree
front lobe, and with an 11dB F/B ratio,
that has a greater than 4.5 dBi in the
front lobe.

Why would anyone want such an antenna?
--
73, Cecil http://www.qsl.net/w5dxp


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On Tue, 08 Feb 2005 01:25:45 -0800, Roy Lewallen

You likely pegged it.

Why anyone would use a yagi structure to get a pattern like that,
it's not the forte` of that kind of design. That badly a detuned yagi
would likely not perform as expected as well.

I kinda figured that out between the hacked up beam and the almightly
Jpole claims. Jpoles seem to be the holy grail of the pirates. Not
to put down the Jpole but it's suffered more snakeoil and used car
salesmanship than deserved.

Oh well, if someone wanted to do it right at least the recipie is
there even if Dr Slick doesn't fully appreciate it.

Allison

wrote:
Roy Lewallen wrote:

wrote:

My Goodness! I would never break any
FCC rules! How dare you accuse me.
. . .

No need for anyone to accuse you, it's all there on the Web:



http://www.talkaboutradioshows.com/g...ages/7526.html


Don't be silly Roy! I might sell 100 watt
broadcast band transmitters, but i only encourage
people to use them into 50 Ohm non-radiating dummy
loads!

Hehe! Makes a great bed-warmer!


This is an outright lie. On Ebay and at

http://www.talkaboutradioshows.com/g...ages/7526.html

you say:

"...WHETHER 50 OHM DUMMY LOAD OR A

PROPERLY TUNED ANTENNA..."

An antenna is not in the category of "...non-radiating dummy loads!".

John

On Tue, 08 Feb 2005 15:41:51 GMT, wrote:

On Tue, 08 Feb 2005 01:25:45 -0800, Roy Lewallen

You likely pegged it.

Why anyone would use a yagi structure to get a pattern like that,
it's not the forte` of that kind of design. That badly a detuned yagi
would likely not perform as expected as well.

I kinda figured that out between the hacked up beam and the almightly
Jpole claims. Jpoles seem to be the holy grail of the pirates. Not
to put down the Jpole but it's suffered more snakeoil and used car
salesmanship than deserved.

Oh well, if someone wanted to do it right at least the recipie is
there even if Dr Slick doesn't fully appreciate it.

Allison
maybe he is using the yagi for the dummy load.

--
73 for now
Buck
N4PGW