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Author Topic:   cellular antenna

Ed Stone posted 04-08-2002 10:02 PM ET (US)
I'm looking into a cellular antenna to
mount on my Outrage.I will probally go with
a 8 footer.Either shakespeare or digatal.
One has a 9db gain and the other has 3db.
My biggest problem is connecting from my
nokia 3390 connection to the antenna bnc
connector.So far the marine stores have
been liile or no help.You would think
the antenna would come with a variety
of connections.
Ed Stone
mbking1 posted 04-08-2002 10:35 PM ET (US)
Big Ed:
Before buying a big antenna, go to a local ham radio store. They can advise you and get you the proper connecter. Keep in mind, the handhelds only put out 200mw max. Mark
triblet posted 04-09-2002 12:20 AM ET (US)
The antenna will have a TNC, not a BNC.
Shake's website lists a lot more adapter
cables than the West catalog, but not for
your phone. Maybe get a different phone?
Or get an old Motorola analog bag phone.
I hear you can get them for like 5 bucks.
3 watts, analog.
Chuck
Dr T posted 04-09-2002 07:40 AM ET (US)
Ed,

Are these antennas designed specifically for cellular telephones? Not all antennas are created equally, nor are they appropriate for all radios (which is what a cellular telephone is).
The descriptions you give of antennas doesn't mesh with what is needed for a cellular telephone.
In general, antenna design is one of the black arts of electrical engineering. There are a couple of basics, however.
The long whip antennas are appropriate for VHF communications which live down around 100 MHz and lower. The whip antennas have an omnidirectional pattern (read round and not direction sensitive) and have no gain per se. The length of the antenna is related to the wave lenght of the radio which for VHF in this case is ~10 ft or more by a fractional multiple (1, 1/2, 1/4) because it has to resonate as a harmonic of the wave length. (This is similar to the way a guitar string will vibrate when a loud sound is made close by). This multiple is related to the antenna loss. This is why VHF radios have long antennas.
Cellular telephones live at about 950 MHz and have a wave lenght of a little more than a foot. This is why you see the little short antennas on cars that look like they have a spring on the bottom.
Bottom line: An antenna that works for VHF may not work at all for a cellular telephone.
One other thing: These are all line of sight radios and the range is related to the power. But the higher you go in frequency, the more power is needed to achieve the same performance. You will have to see a cellular telephone tower for the cell phone to work. Personally, I think you would be better off with an exactly matched cellular radio mounted on top of a long pole (to get it as high as possible) than an antenna tuned for another band.
triblet posted 04-09-2002 09:57 AM ET (US)
I know Shake makes several antennas specifically
for cellular, and Shake seems to know antennas.

Chuck
Dr T posted 04-11-2002 10:05 AM ET (US)
Take a look at the table at
http://www.shakespeare-marine.com/antennas/galaxy/galaxycell.htm
The problem is to determine the exact nature of the radio equipment you want to support out of the same antenna. If you have a tri-mode analog/digital/PCS phone and also want to support a VHF radio from the same antenna, it looks like you can do it. There is even a 17'6" monster that would do wonders for your line of sight
It looks like these have been tuned for cellular. In general, at this frequency, the lenght acts primarily to increase your line of site. The actual antennal element will not be the whip per se (they are calling the whip a radome) but an antenna that is packaged inside the whip (probably in a short segment near the end).
However, since these are omni-directional antennas, I don't buy the notion that any of them have any gain since gain implies directivity. Maybe "not as amuch attenuation" would be a better way to put it.
triblet posted 04-11-2002 11:43 AM ET (US)
They can be omni directional and still have
gain by not wasting energy transmitting to
down to the fishes and up to the stars.

Chuck
Dr T posted 04-12-2002 12:40 AM ET (US)
But, in that case they are not really Omni.
But, to your point, one would suspect that the longer the antenna is, the longer its aperature is in the verticle direction. This would increase its horizontal directivity and attenute its verticle. This would tend to flatten the pattern so that, if viewed from the horizon, it would look like a flattened doughnut.
Ed Stone posted 04-12-2002 11:41 AM ET (US)
I have the 5237XT Shakespeare and a 3390
cellphone with the internal antenna.

I 'm going to call Shakespeare and
find out their reccomendations for a
connector between the two.
With out a antenna I'm good out about
8 to ten miles offshore.I wonder how
far the 8foot shakespeare will improve
my range.
Ed Stone
Ed Stone posted 04-12-2002 12:25 PM ET (US)
I just spoke with Shakespeare and they
said my phone is not currently supported
under their connections but probaly within
a month they will have what he called a
(inductive?) connector for the 3390 with
a internal antenna.
He said as far as distance with the math
it should quadruple but realistically it
will probaly just double.
I still have to install the antenna anyway
and that is a project in itself.I have all
the wiring running down the starborad side
of the t-top into the center console. Maybe
I will drill a hole thru the center console
into the port side of the t-top this time.
Only I don't have any rope pulled thru that
side.
Ed Stone
Dr T posted 04-12-2002 12:36 PM ET (US)
Boy, it has been a long time since I have done that calculation. I remember that one way to do it is the Rice-Longley model but it gets real complicated real fast.
Here is a rule of thumb. Right now you can use the cell phone about 8 to 10 miles off shore (or line of site horizon from eye level plus 1 or 2 miles). You are getting the extra 1 or 2 miles due to the height and location of the nearest cell phone tower (that is why it varies).
The key to the calculation is how high off the deck you mount the base of the antenna. This height + 8 ft will be your new antenna height.
So, How far offshore could you see the beach if your eyes were even with the top of the antenna.
Here is a quick approximation:
Assume that you are about 6 ft tall and stand up while using the cell phone--the height of the antenna is even with the top of your head. Further assume that the top of your brand new antenna is 10 ft off the deck (or 4 ft higher than your head).
then for R the new range in miles (the conversion from miles to feet cancels):
6 ft/8 miles = 10 ft/R miles
So R is about 13 1/3 miles.
THIS IS NOT EXACT AND IS ONLY A SIMPLE RULE OF THUMB APPROXIMATION. Your mileage will vary. The exact calculation is far more complex, but this will get you in the ball park. I would expect you would do better since the external antenna is probably much more efficient.

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Author	Topic: cellular antenna
Ed Stone	posted 04-08-2002 10:02 PM ET (US) I'm looking into a cellular antenna to mount on my Outrage.I will probally go with a 8 footer.Either shakespeare or digatal. One has a 9db gain and the other has 3db. My biggest problem is connecting from my nokia 3390 connection to the antenna bnc connector.So far the marine stores have been liile or no help.You would think the antenna would come with a variety of connections. Ed Stone
mbking1	posted 04-08-2002 10:35 PM ET (US) Big Ed: Before buying a big antenna, go to a local ham radio store. They can advise you and get you the proper connecter. Keep in mind, the handhelds only put out 200mw max. Mark
triblet	posted 04-09-2002 12:20 AM ET (US) The antenna will have a TNC, not a BNC. Shake's website lists a lot more adapter cables than the West catalog, but not for your phone. Maybe get a different phone? Or get an old Motorola analog bag phone. I hear you can get them for like 5 bucks. 3 watts, analog. Chuck
Dr T	posted 04-09-2002 07:40 AM ET (US) Ed, Are these antennas designed specifically for cellular telephones? Not all antennas are created equally, nor are they appropriate for all radios (which is what a cellular telephone is). The descriptions you give of antennas doesn't mesh with what is needed for a cellular telephone. In general, antenna design is one of the black arts of electrical engineering. There are a couple of basics, however. The long whip antennas are appropriate for VHF communications which live down around 100 MHz and lower. The whip antennas have an omnidirectional pattern (read round and not direction sensitive) and have no gain per se. The length of the antenna is related to the wave lenght of the radio which for VHF in this case is ~10 ft or more by a fractional multiple (1, 1/2, 1/4) because it has to resonate as a harmonic of the wave length. (This is similar to the way a guitar string will vibrate when a loud sound is made close by). This multiple is related to the antenna loss. This is why VHF radios have long antennas. Cellular telephones live at about 950 MHz and have a wave lenght of a little more than a foot. This is why you see the little short antennas on cars that look like they have a spring on the bottom. Bottom line: An antenna that works for VHF may not work at all for a cellular telephone. One other thing: These are all line of sight radios and the range is related to the power. But the higher you go in frequency, the more power is needed to achieve the same performance. You will have to see a cellular telephone tower for the cell phone to work. Personally, I think you would be better off with an exactly matched cellular radio mounted on top of a long pole (to get it as high as possible) than an antenna tuned for another band.
triblet	posted 04-09-2002 09:57 AM ET (US) I know Shake makes several antennas specifically for cellular, and Shake seems to know antennas. Chuck
Dr T	posted 04-11-2002 10:05 AM ET (US) Take a look at the table at http://www.shakespeare-marine.com/antennas/galaxy/galaxycell.htm The problem is to determine the exact nature of the radio equipment you want to support out of the same antenna. If you have a tri-mode analog/digital/PCS phone and also want to support a VHF radio from the same antenna, it looks like you can do it. There is even a 17'6" monster that would do wonders for your line of sight It looks like these have been tuned for cellular. In general, at this frequency, the lenght acts primarily to increase your line of site. The actual antennal element will not be the whip per se (they are calling the whip a radome) but an antenna that is packaged inside the whip (probably in a short segment near the end). However, since these are omni-directional antennas, I don't buy the notion that any of them have any gain since gain implies directivity. Maybe "not as amuch attenuation" would be a better way to put it.
triblet	posted 04-11-2002 11:43 AM ET (US) They can be omni directional and still have gain by not wasting energy transmitting to down to the fishes and up to the stars. Chuck
Dr T	posted 04-12-2002 12:40 AM ET (US) But, in that case they are not really Omni. But, to your point, one would suspect that the longer the antenna is, the longer its aperature is in the verticle direction. This would increase its horizontal directivity and attenute its verticle. This would tend to flatten the pattern so that, if viewed from the horizon, it would look like a flattened doughnut.
Ed Stone	posted 04-12-2002 11:41 AM ET (US) I have the 5237XT Shakespeare and a 3390 cellphone with the internal antenna. I 'm going to call Shakespeare and find out their reccomendations for a connector between the two. With out a antenna I'm good out about 8 to ten miles offshore.I wonder how far the 8foot shakespeare will improve my range. Ed Stone
Ed Stone	posted 04-12-2002 12:25 PM ET (US) I just spoke with Shakespeare and they said my phone is not currently supported under their connections but probaly within a month they will have what he called a (inductive?) connector for the 3390 with a internal antenna. He said as far as distance with the math it should quadruple but realistically it will probaly just double. I still have to install the antenna anyway and that is a project in itself.I have all the wiring running down the starborad side of the t-top into the center console. Maybe I will drill a hole thru the center console into the port side of the t-top this time. Only I don't have any rope pulled thru that side. Ed Stone
Dr T	posted 04-12-2002 12:36 PM ET (US) Boy, it has been a long time since I have done that calculation. I remember that one way to do it is the Rice-Longley model but it gets real complicated real fast. Here is a rule of thumb. Right now you can use the cell phone about 8 to 10 miles off shore (or line of site horizon from eye level plus 1 or 2 miles). You are getting the extra 1 or 2 miles due to the height and location of the nearest cell phone tower (that is why it varies). The key to the calculation is how high off the deck you mount the base of the antenna. This height + 8 ft will be your new antenna height. So, How far offshore could you see the beach if your eyes were even with the top of the antenna. Here is a quick approximation: Assume that you are about 6 ft tall and stand up while using the cell phone--the height of the antenna is even with the top of your head. Further assume that the top of your brand new antenna is 10 ft off the deck (or 4 ft higher than your head). then for R the new range in miles (the conversion from miles to feet cancels): 6 ft/8 miles = 10 ft/R miles So R is about 13 1/3 miles. THIS IS NOT EXACT AND IS ONLY A SIMPLE RULE OF THUMB APPROXIMATION. Your mileage will vary. The exact calculation is far more complex, but this will get you in the ball park. I would expect you would do better since the external antenna is probably much more efficient.