help with a marine antenna
 

I am looking to set up a laptop on a boat that will receive wifi
signals. I need to install a twenty foot cable from the antenna to a
Proxim orinoco 8011b/g gold wireless card. I have found the cable but
don't know what antenna to attach to it as I want to minimize loss of
signal and I believe I have to get a certain length antenna to
synchronize with the cable length to do this. Does anyone know what the

right size antenna should be? Also, any suggestions on where to pick
one
up?
I found the cable here
http://sharperconcepts.zoovy.com/pro...C-CA-RSPNMAXXX

wrote in message
oups.com...
I am looking to set up a laptop on a boat that will receive wifi
signals. I need to install a twenty foot cable from the antenna to a
Proxim orinoco 8011b/g gold wireless card. I have found the cable but
don't know what antenna to attach to it as I want to minimize loss of
signal and I believe I have to get a certain length antenna to
synchronize with the cable length to do this. Does anyone know what the

right size antenna should be? Also, any suggestions on where to pick
one
up?
I found the cable here
http://sharperconcepts.zoovy.com/pro...C-CA-RSPNMAXXX


Hi Petercc

I have some interest in a similar project with WiFi. Forgive me if I'm
not understanding what you want to do.

Are you sure that card will fit in your lap top? All the lap top PCMCIA
WiFi cards I've seen, that have a coax connector, use a much smaller
connector.
You didnt indicate if you know from which direction the WiFi signal is
coming from. does the marine antenna need to be omniazimuth?
Are you willing to accept the signal loss associated with the 20 feet of
coax?

My weather conditions are not as extreme as your marine environment. I
have installed a wireless Ethernet bridge at the antenna and connected that
to the computer with CAT 5 to alleviate the line loss problem at 2.4 GHz.

E-mail me if you want any info and/or pictures of what I'm messing with.

Jerry

I am looking to set up a laptop on a boat that will receive wifi
signals. I need to install a twenty foot cable from the antenna to a
Proxim orinoco 8011b/g gold wireless card. I have found the cable but
don't know what antenna to attach to it as I want to minimize loss of
signal and I believe I have to get a certain length antenna to
synchronize with the cable length to do this. Does anyone know what the

right size antenna should be? Also, any suggestions on where to pick
one up?


I'd suggest you post your question to some of the Internet wireless or
networking newsgroups. I've seen questions similar to yours posted on some
of them recently, such as, comp.os.linux.networking . I've also seen
some good antenna sources given in posted responses there.


Ed

Yes I would like an email address so I can see what you are talking
about.

I have the cable connector which connects to the main cable from the
proxim card fine. I am picking up the 20 foot cable and want an antenna
that will minimize loss of the signal. I tried an existing omni antenna
that is aboout 30" long and a long cable and the signal was
nonexistant. With the short cable and that same antenna I was using, I
got some hotspots tuned in.

On 10 Sep 2005 10:42:15 -0700, wrote:

I tried an existing omni antenna
that is aboout 30" long and a long cable and the signal was
nonexistant. With the short cable and that same antenna I was using, I
got some hotspots tuned in.

Hi Peter,

This 30" antenna is easily ten times too long. It will be very
directional, and only if you point it (like a rapier) towards the
transmitter. As it stands, your favored direction is straight up.
This, of course, is strictly counter to your stated desire for "omni."

Take a cue from the products offered for this class of communication.
Their antennas are short for reasons that go beyond aesthetics. Take
heart that you are on the right path. Antenna height (distance above
you, not length) is always an advantage.

73's
Richard Clark, KB7QHC

wrote in message
oups.com...
Yes I would like an email address so I can see what you are talking
about.

I have the cable connector which connects to the main cable from the
proxim card fine. I am picking up the 20 foot cable and want an antenna
that will minimize loss of the signal. I tried an existing omni antenna
that is aboout 30" long and a long cable and the signal was
nonexistant. With the short cable and that same antenna I was using, I
got some hotspots tuned in.


Hi Peter

I sent you an E-mail. Let me know here if it doesnt get to you.

Do you have any specs on the "existing antenna"? I havent seen any
omniazimuth WiFi antennas that long. It is likely that the 30 inch long
antenna is *not* designed for 2.4 GHz use.

Try to get some specs on the loss of the cable you are "picking up".
Since I am not willing to accept the loss associated with coax at this
frequency, I have resorted to either USB or CAT 5 rather than use coax from
the antenna to the computer.

Jerry

Richard Clark wrote:
On 10 Sep 2005 10:42:15 -0700, wrote:


I tried an existing omni antenna
that is aboout 30" long and a long cable and the signal was
nonexistant. With the short cable and that same antenna I was using, I
got some hotspots tuned in.


Hi Peter,

This 30" antenna is easily ten times too long. It will be very
directional, and only if you point it (like a rapier) towards the
transmitter. As it stands, your favored direction is straight up.
This, of course, is strictly counter to your stated desire for "omni."

Take a cue from the products offered for this class of communication.
Their antennas are short for reasons that go beyond aesthetics. Take
heart that you are on the right path. Antenna height (distance above
you, not length) is always an advantage.

73's
Richard Clark, KB7QHC

Which means it was a colinear. It is long for a reason.

Similar antennas are vailable at CompoUSA and most other computer stores.

tom
K0TAR

Tom Ring wrote:

Which means it was a colinear. It is long for a reason.

Similar antennas are vailable at CompoUSA and most other computer stores.

tom
K0TAR

What you should look for is small plasic-encased bumps (each enclosing a
coil) or obvious coiled sections spaced every few inches along the
antenna's length. If it has those, it's probably a collinear like Tom
says, and will be omnidirectional broadside to the antenna. If it
doesn't, and is just a straight piece of wire or rod, it's directional
nearly in the direction of the wire like Richard said.

Any reasonable sized coax will have a lot of loss per unit length at
that frequency, so do everything you can to keep it as short as
possible. Depending on the situation, putting the antenna might or might
not help, if putting it higher necessitates making the feedline longer.

Roy Lewallen, W7EL

"Tom Ring" wrote in message
. ..
Richard Clark wrote:
On 10 Sep 2005 10:42:15 -0700, wrote:


I tried an existing omni antenna
that is aboout 30" long and a long cable and the signal was
nonexistant. With the short cable and that same antenna I was using, I
got some hotspots tuned in.


Hi Peter,

This 30" antenna is easily ten times too long. It will be very
directional, and only if you point it (like a rapier) towards the
transmitter. As it stands, your favored direction is straight up.
This, of course, is strictly counter to your stated desire for "omni."

Take a cue from the products offered for this class of communication.
Their antennas are short for reasons that go beyond aesthetics. Take
heart that you are on the right path. Antenna height (distance above
you, not length) is always an advantage.

73's
Richard Clark, KB7QHC

Which means it was a colinear. It is long for a reason.

Similar antennas are vailable at CompoUSA and most other computer stores.

tom
K0TAR

Hi Tom

Isnt 30 inches a little too long for a colinear at 2.4 GHz? I'd guess
that the antenna that Peter has hooked up is a marine radio whip. I'll be
interested in reading more about what he is doing, and where the 30 inch
long antenna came from.

Jerry

Roy Lewallen wrote:

What you should look for is small plasic-encased bumps (each enclosing a
coil) or obvious coiled sections spaced every few inches along the
antenna's length. If it has those, it's probably a collinear like Tom
says, and will be omnidirectional broadside to the antenna. If it
doesn't, and is just a straight piece of wire or rod, it's directional
nearly in the direction of the wire like Richard said.


You won't see that on these colinears, the radome surrounding them
covers it up. I am thinking they may be the coax style colinears, which
would not have the coils.

tom
K0TAR