In , "Leland C. Scott"
wrote:


"Landshark" wrote in message
om...
That all depends on your goals. The typical dual antenna setup, when
done
right, generates maximum signal strength to the front and to the rear.
The
signal strength to the left and right is considerably reduced. The same
applies to your receive signal strength as well.


Um, sorry wrong Leland, it makes the signal more omnidirectional.

If done correctly, spaced - phased - good ground plane, it works as I
described.

http://www.bellscb.com/cb_radio_hobb.../antarray.html



Long hual truckers normaly are concerned with communicating with other
truckers on the road. Those truckers are going to be either in front or
behind them on the highway. Thus it makes sense to maximize the signal
in
those directions, and thus the popularity of the setup.

If your more interested in general communications in any direction then
you
really don't want a dual antenna setup. What you want is an antenna
location
near the center of the truck, which will as nearly as possible, give you
a
uniform signal in all directions. The site you picked, on the tool box,
would be a good one.


Again, wrong Leland.

No. The site above has not only a discussion about antenna patterns, but the
antenna field pattern plots to prove it. I can supply some EZNEC 4.0
simulation files to prove same if you want.


Everyone will think I'm insane for saying this, but Landshark has it
right. In order for co-phased antennas to achieve that ideal figure-8
pattern they must be nearly ideal antennas, which CB antennas are not.
Landshark's link explains why this happens. I wouldn't expect any
significant improvement in the omnidirectional characteristics of
dualies (as the site claims), but I do know they don't provide any
noticable directional gain.






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I agree as well, a properly engineered single 102"
will outperform duals anyday.
Most truckers don't understand how and why antennas radiate RF energy and
they run duals because they give a balanced look, as a bonus co-phased
antennas tend to
supplement each other on vehicles with plastic or fiberglass bodies.
The fact is that the trailer blocks a majority of the RF
that co-phased antennas provide to the rear so they end up with a system
that transceives mainly to the front.
The exception to the rule would be a flatbed trailer.
I use a 102" whip on my T2000 which is mounted to a flat bar attached to the
frame that extends past the edge of the trailer which allows the antenna to
"see" behind the trailer.
The antenna is supported roughly 6' above the mounting point using a custom
made plexiglass bracket.
I have also attached 2 braided steel cables to frame which drag the road
during travel and supply a make-shift earth
ground when parked.
I will be flat honest with you and say that this system gets out farther
then i care for sometimes.
It also works well for sky-wave propagation when conditions permit.
My 4x4 truck uses a pedestal mount 102" whip and a
24" x 24" sheet of stainless, the pedestal is mounted to the floor of the
bed 1.5' behind the cab and cut to length with the top of the bed, the
stainless heet is sandwiched between the top of the pedestal and the bottom
of the antenna.
Very powerful system using a highly tuned 25 LTD
--
Mad-Dog



"Frank Gilliland" wrote in message
...
In , "Leland C. Scott"
wrote:


"Landshark" wrote in message
om...
That all depends on your goals. The typical dual antenna setup, when
done
right, generates maximum signal strength to the front and to the
rear.
The
signal strength to the left and right is considerably reduced. The
same
applies to your receive signal strength as well.


Um, sorry wrong Leland, it makes the signal more omnidirectional.

If done correctly, spaced - phased - good ground plane, it works as I
described.

http://www.bellscb.com/cb_radio_hobb.../antarray.html



Long hual truckers normaly are concerned with communicating with
other
truckers on the road. Those truckers are going to be either in front
or
behind them on the highway. Thus it makes sense to maximize the
signal
in
those directions, and thus the popularity of the setup.

If your more interested in general communications in any direction
then
you
really don't want a dual antenna setup. What you want is an antenna
location
near the center of the truck, which will as nearly as possible, give
you
a
uniform signal in all directions. The site you picked, on the tool
box,
would be a good one.


Again, wrong Leland.

No. The site above has not only a discussion about antenna patterns, but
the
antenna field pattern plots to prove it. I can supply some EZNEC 4.0
simulation files to prove same if you want.


Everyone will think I'm insane for saying this, but Landshark has it
right. In order for co-phased antennas to achieve that ideal figure-8
pattern they must be nearly ideal antennas, which CB antennas are not.
Landshark's link explains why this happens. I wouldn't expect any
significant improvement in the omnidirectional characteristics of
dualies (as the site claims), but I do know they don't provide any
noticable directional gain.






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From: (Mad=A0Dog)
I agree as well, a properly engineered single


102" will outperform duals anyday.


Most truckers don't understand how and why


antennas radiate RF energy and they run


duals because they give a balanced look, as a

bonus co-phased antennas tend to


supplement each other on vehicles with plastic

or fiberglass bodies. The fact is that the trailer


blocks a majority of the RF that co-phased


antennas provide to the rear so they end up


with a system that transceives mainly to the


front.


The exception to the rule would be a flatbed


trailer. I use a 102" whip on my T2000 which is

mounted to a flat bar attached to the frame


that extends past the edge of the trailer which


allows the antenna to "see" behind the trailer.


The antenna is supported roughly 6' above the

mounting point using a custom made


plexiglass bracket.


I have also attached 2 braided steel cables to


frame which drag the road during travel and


supply a make-shift earth


ground when parked.


I will be flat honest with you and say that this


system gets out farther then i care for


sometimes.


It also works well for sky-wave propagation


when conditions permit. My 4x4 truck uses a


pedestal mount 102" whip and a 24" x 24"


sheet of stainless,




Congratulations. The "Richochet Skip Dish" has been used for years on
vehicles around here,,practically standard fare on many pickup trucks
'round here. And you're right, it makes one hell of a difference,,,it
gets up and out,,,,.since you have a 4 X 4, pull that bad boy into some
water, like on the edge of the lake or on a beach. Add a Leece-Neville
or two and you're humming.


_
the pedestal is mounted to the floor of the bed


1.5' behind the cab and cut to length with the


top of the bed, the stainless sheet is


sandwiched between the top of the pedestal


and the bottom of the antenna. Very powerful


system using a highly tuned 25 LTD


Mad-Dog




Nice set up for any eleven meter activity. Attaching the mast and
Richochet dish to a steel toolbox is also another popular method. Copper
strap as a ground is preferred instead of wire because of differing
inductance value.

"Frank Gilliland" wrote in message
...
Everyone will think I'm insane for saying this, but Landshark has it
right.

No he doesn't.

In order for co-phased antennas to achieve that ideal figure-8
pattern they must be nearly ideal antennas, which CB antennas are not.

They don't nessessarly need be to be ideal, but the do need to be installed
the same way. By the way no antenna is ideal, but many people have a lot of
success anyway.

Landshark's link explains why this happens. I wouldn't expect any
significant improvement in the omnidirectional characteristics of
dualies (as the site claims), but I do know they don't provide any
noticable directional gain.

If you check the link I provided you will see there is some gain. The gain
does not become noticeable until you have at least a 1/4 wavelength
separation, and at that it is around 2 db or so. On the site I posted the
link for you will see the figure 8 pattern becomes very noticeable for a
half wavelength between antennas. Getting to that degree of separation is
much easier to do on a semi because of their size, and the fact the antennas
are further apart from being mounted on the side view mirrors. Passenger
vehicles just don't have the size needed.


--
Leland C. Scott
KC8LDO

Wireless Network
Mobile computing
on the go brought
to you by Micro$oft

"Leland C. Scott" wrote in message
...

"Frank Gilliland" wrote in message
...
Everyone will think I'm insane for saying this, but Landshark has it
right.

No he doesn't.

Of course I do Leland, you just don't want me too

In order for co-phased antennas to achieve that ideal figure-8
pattern they must be nearly ideal antennas, which CB antennas are
not.

How would you know Leland? Remember, you don't like
CB, let alone talk or use or own one.

They don't nessessarly need be to be ideal, but the do need to be
installed
the same way. By the way no antenna is ideal, but many people have a lot
of
success anyway.

Landshark's link explains why this happens. I wouldn't expect any
significant improvement in the omnidirectional characteristics of
dualies (as the site claims), but I do know they don't provide any
noticable directional gain.

If you check the link I provided you will see there is some gain. The gain
does not become noticeable until you have at least a 1/4 wavelength
separation, and at that it is around 2 db or so. On the site I posted the
link for you will see the figure 8 pattern becomes very noticeable for a
half wavelength between antennas.

The point was that it was a much better omni-directional pattern
on Dual antenna's, to which that is achieved. You are saying
that Signal Engineering, which soul business is antenna's is wrong,
good luck on trying to convince others of that.


Getting to that degree of separation is
much easier to do on a semi because of their size, and the fact the
antennas
are further apart from being mounted on the side view mirrors. Passenger
vehicles just don't have the size needed.


--
Leland C. Scott
KC8LDO


Landshark


--
The world is good-natured to people
who are good natured.

"Landshark" wrote in message
m...

"Leland C. Scott" wrote in message
...

"Frank Gilliland" wrote in message
...
Everyone will think I'm insane for saying this, but Landshark has it
right.

No he doesn't.

Of course I do Leland, you just don't want me too

Then explain away the the information on the other site. Get a copy of EZNEC
and model it yourself.

http://www.eznec.com/

And if you're to cheap to buy a copy then try the freebee versions at:

http://www.qsl.net/wb6tpu/swindex.html

Then you can check at the site below for antenna modeling tips and
information about many types of antennas from an expert in the area.

http://www.cebik.com/

And another interesting antenna site:

http://www.antennex.com/


In order for co-phased antennas to achieve that ideal figure-8
pattern they must be nearly ideal antennas, which CB antennas are
not.

How would you know Leland? Remember, you don't like
CB, let alone talk or use or own one.

You have been sleeping at the keyboard. I was on CB back in the late 70's
until I got fed up with all of the jerks on the air. Even ran a mobile
AM/SSB system. I used a Midland combo base- mobile radio. At that time the
rigs were 23 channels. I've been there, done that, and gave away the radio
to my nephew some years ago.


They don't nessessarly need be to be ideal, but the do need to be
installed
the same way. By the way no antenna is ideal, but many people have a lot
of
success anyway.

Landshark's link explains why this happens. I wouldn't expect any
significant improvement in the omnidirectional characteristics of
dualies (as the site claims), but I do know they don't provide any
noticable directional gain.

If you check the link I provided you will see there is some gain. The
gain
does not become noticeable until you have at least a 1/4 wavelength
separation, and at that it is around 2 db or so. On the site I posted
the
link for you will see the figure 8 pattern becomes very noticeable for a
half wavelength between antennas.

The point was that it was a much better omni-directional pattern
on Dual antenna's, to which that is achieved. You are saying
that Signal Engineering, which soul business is antenna's is wrong,
good luck on trying to convince others of that.

They also make antennas for money. And when money is involved you have to
suspect the claims they make. It won't be the first nor the last time a
manufacture stretched the truth, i.e. lied. But then again you guys also
believe Class "C" amplifiers are linear, "magic" lenghts of coax to fix
antenna SWR etc. This news group should be named "rec.voodoo.11m.radio" from
all of the crap that's passes for fact.


--
Leland C. Scott
KC8LDO

Wireless Network
Mobile computing
on the go brought
to you by Micro$oft

"Leland C. Scott" wrote in message
...
This news group should be named "rec.voodoo.11m.radio" from
all of the crap that's passes for fact.

Here's a fact................Al Banys says you like men for sex
partners....buttboy.

In , "Leland C. Scott"
wrote:


"Landshark" wrote in message
om...

"Leland C. Scott" wrote in message
...

"Frank Gilliland" wrote in message
...
Everyone will think I'm insane for saying this, but Landshark has it
right.

No he doesn't.

Of course I do Leland, you just don't want me too

Then explain away the the information on the other site. Get a copy of EZNEC
and model it yourself.


Forget about all that antenna-modeling software crap and build a
simple field-strength meter. Then go measure it yourself because
that's how it's done in the real world, and that's how the page at
Landshark's link came up with the radiation pattern for the
bumper-mount antenna. A similar pattern can be found in almost any
radio-communications handbook that covers mobile antennas.






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In , Frank Gilliland
wrote:

snip
... A similar pattern can be found in almost any
radio-communications handbook that covers mobile antennas.


Including Radio Shack's famous tome, "All About CB Two-Way Radio"
which, IMO, should be the rrcb FAQ by proxy.







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"Frank Gilliland" wrote in message
...
Forget about all that antenna-modeling software crap and build a
simple field-strength meter. Then go measure it yourself because
that's how it's done in the real world,

Have you personaly done so for the setup in question?

and that's how the page at
Landshark's link came up with the radiation pattern for the
bumper-mount antenna. A similar pattern can be found in almost any
radio-communications handbook that covers mobile antennas.

The antenna simulation software shows the same thing as single bumper mount
antenna pattern as on the page Landshark posted. That's why I question the
omni pattern for a dual antenna setup. In fact Frank you can look up the
pattern for such a setup, dual antenna, in a copy of the radio engineer's
handbook, and I'm surprised you haven't since you know about it. More than
one Ham has modeled some commercially manufactured antennas and discovered
they don't perform as the ads suggest. When the manufacture was confronted
with the results they modified their claims. The software modeling approach
works or people wouldn't waste their time with it. In fact more antenna
manufactures are doing it since it saves a lot of screwing around making
error prone measurements with a field strength meter, and that's how they
are doing it now in the real world.


--
Leland C. Scott
KC8LDO

Wireless Network
Mobile computing
on the go brought
to you by Micro$oft