"NetWeasel" wrote in message
news
Hi all,
I've got an aluminum tool box in the back of my pickup truck. It's the
usual type that spans the bed right behind the cab.

I'm thinking that it might make a good antenna mounting point. I don't
want
to drill into the body of the truck, but I wouldn't mind putting a couple
holes in the toolbox.

Understandable.

I have two questions. The first is: If I mount brackets to the tool box,
will I need some sort of ground strap to connect it to the frame of the
truck to give me a good ground?

Yes. For a quarter wave antenna the ground plane needs to be at least a
quarter wavelength in size too for the antenna to function correctly. The
truck body forms part of the ground plane while the capacitance of the truck
body to earth ground forming the rest of the ground plane in simple terms.

The second is: Will I see any real world improvement in performance by
using dual antennas?

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.

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.

I like the look of the trucks that I see with antennas on each side of the
bed box. It's nice for a balanced appearance.

You have to make up your mind, good looks, or good performance. Your typical
passenger truck is not wide enough, you need 9 feet, to properly setup a
dual antenna system.

I also understand that it's
a bit trickier to adjust SWR with dual antennas.

It can be.

I wouldn't be against
using one as an antenna and simply using the other one to balance out the
look of the truck (although, I guess some folks might think that's silly).

Your truck. You have to drive it.

Good Luck.

--
Leland C. Scott
KC8LDO

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

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

"NetWeasel" wrote in message
news
Hi all,
I've got an aluminum tool box in the back of my pickup truck. It's the
usual type that spans the bed right behind the cab.

I'm thinking that it might make a good antenna mounting point. I don't
want
to drill into the body of the truck, but I wouldn't mind putting a
couple
holes in the toolbox.

Understandable.

I have two questions. The first is: If I mount brackets to the tool
box,
will I need some sort of ground strap to connect it to the frame of the
truck to give me a good ground?

Yes. For a quarter wave antenna the ground plane needs to be at least a
quarter wavelength in size too for the antenna to function correctly. The
truck body forms part of the ground plane while the capacitance of the
truck
body to earth ground forming the rest of the ground plane in simple terms.

The second is: Will I see any real world improvement in performance by
using dual antennas?

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.

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.

I like the look of the trucks that I see with antennas on each side of
the
bed box. It's nice for a balanced appearance.

If looks is what he wants, fine but I think he wants some sort
of performance.


You have to make up your mind, good looks, or good performance. Your
typical
passenger truck is not wide enough, you need 9 feet, to properly setup a
dual antenna system.

I also understand that it's
a bit trickier to adjust SWR with dual antennas.

Correct, it's a bitch.

It can be.

I wouldn't be against
using one as an antenna and simply using the other one to balance out
the
look of the truck (although, I guess some folks might think that's
silly).

You said it, not I.

Your truck. You have to drive it.

Good Luck.

He'll need it.



--
Leland C. Scott
KC8LDO



If you have stake bed holes, go to your local muffler shop,
have them bend a sort of "roll bar" for the antenna. Make
a mount in the center of the bar for the antenna. Then
mount it in the stake bed holes, drilling through the inner
bed, into the antenna bar for bolting it up.

Here's a pretty good link on how
antenna's work.

http://www.signalengineering.com/ult..._antennas.html

Landshark


--
Treat people as if they were what
they ought to be and you will help
them become what they are capable
of becoming.

"Landshark" wrote in message
m...
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.


--
Leland C. Scott
KC8LDO

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

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

"Landshark" wrote in message
m...
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.


--
Leland C. Scott
KC8LDO

Feel free, but I guess Signal Engineering doesn't
know anything, right?

Landshark


--
That does suck..sometimes you're the
windshield..sometimes you're the bug.

"Landshark" wrote in message
...
Feel free, but I guess Signal Engineering doesn't
know anything, right?

They can't seem to get their facts right. For example:

" The pattern is "pulled" to areas where there is the most vehicle body. The
pattern is the worst in directions where there is no metal body for a
radial."

This is from their comment about mounting an omnidirectional antenna lifted
right off their WEB page. The dual antennas mounted near the mid point of
the vehicle should each have a similar pattern distortion due to mounting
location, for example to the front and rear with some to the side where the
antenna is mounted. Those are the directions where the metal is located,
with more to the front and rear than to the side. Now refer to the antenna
pattern for the site I mentioned you will see the greater field strength is
to the front and rear of the vehicle too for quarter wavelength spaced
antennas fed in phase, and is in the same direction. Both effects are adding
together in the same general direction. However under their comments about a
dual antenna setup they claim just the opposite in a round about manner.

--
Leland C. Scott
KC8LDO

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

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.






-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

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.