Cell boosters and antennas?

[ThirdHatt]

Okay now you guys are making me worry! I ordered the Digital amp TODAY along with their antenna and low-loss cable. Even if the amp is junk, the antennas themselves are high quality (from all accounts and reviews) and I can always go to a shakespeare or wilson amp, RIGHT?? Swapping a $160 amp is one thing, swapping antennas and cables on the radar arch is another thing! I figure there's always someone else willing to take a chance on a Digital amp on Ebay if it doesn't perform properly. A 9db gain antenna connected directly should be enough to show a big improvement without an amplifier I would think.

 

[GJH]

I'd be happy to try and help some of the unsuccessful efforts here, though I must say Chris and Third Hatt are right on and their advice is well taken.

Disclaimer: A division of my company is a wholesale distributor for Digital Antenna and Wilson, amongst others, primarily into the land use market. We sell thousands of both the hard wired amps and wireless repeaters each year. The Digitals are easily the biggest sellers right now out of the pack. We like them because they don't get returned very much. We sell them into resellers who serve pretty rigorous requirements like the oilfield (on and off shore) service markets, government agencies and the like. The Wilson amp is fine as well. I am not soliciting sales here, so on that front, please don't ask.

You must have the wireless repeaters set up right; the problem with boats is that FRP doesn't do much to help attenuate the cross signal between the two antennas. As noted, vertical separation is better than horizontal; some applications do best if the internal antenna is unidirectional pointing across the interior away from the outdoor omni.

I personally carry a hard wired amp and in most cases this is what I would recommend for a boat. We do get perfectly functional wireless repeater kits back due to inability to install, return rates on the hard wired amps is virtually nil.

One benefit of a good antenna (start with that first, by the way) and amp is that they improve data through put speeds for those using the non-voice side of the network.

We have this stuff deployed in a wide variety of applications, so again, if I can be of assitance, let me know. I will be tapping this forum for advice pretty soon (we are intensely shopping for 56/58/61MYs or CMY/YFs), so I had better contribute where I can!

George

 

[Trojan]

I am not a spread spectrum person, that was after my time. That is all computer controlled and uses a voting system to select a clear channel. It is still an RF FM transmitter and receive. But getting back to basics. Antenna, Antenna, Antenna. All the amplifiers in the world for incoming or out going signals won't do any good without a good antenna. Start with a high gain vertical antenna, high in the air. It must be vertical, there is very little signal inversion at that frequency. It to is line of sight signals, worse than the vhf.
Don't blame the amp for a bad antenna. Watch out for bad RF connections. At that frequency they can really mess up the signal strength.


BILL

 

[TedZ]

Cell signals are line of sight.

Period.

Therefore, you need to know what height the tower is at which you're trying to talk to, etc.

The higher your antenna the better, and an amp helps but its not a panacea.

Hate to let these incorrect prognostications go by. Probably correct at the beginning of cell technology.

See for yourselves.
http://findarticles.com/p/articles/mi_m0TLC/is_5_35/ai_74940612

Ted

 

[thoward]

Clear as mud.... ...I have the 7' Shakesphere cell antenna and I can mount it as high as about 25', is it worth the time to mess with it? How is the Shakespere amp? If I am wasting my time with the whole mess I will quit while I am ahead!

 

[bobk]

OK. Question for the experts.

We are at Baltimore Yacht Club in the summer. This is Essex MD. Verizon sucks here and they know it but won't add a tower or antenna to the tower in our back yard. So I need a way to communicate with the world. I use an older Kyocera phone because it will permit Data/Internet with out added charges, just the minutes. QUESTION then is what antenna amp system is guaranteed to work. DA didn't!! We are in a 48MY and can get an antenna up 25-28' if need be. Thanks,

Bob

 

[Trojan]

Granted antenna height is a plus, but be careful because at the higher frequency the longer the antenna cable the more the signal will degrade. Its a little ketch 22. The trick is to try to keep things as close to one another as you can in order to reduce signal loss in the RF connecting cables. Uhf and above is not a user friendly frequency.

BILL

 

[ThirdHatt]

Okay, I cancelled the order for the Digital Amp so I can do more research on the Wilson and Shakespeare. I will still use Digital's antenna and low-loss cable. I would think that a hard-wired system without any amp would most certainly improve the signal strength. The amp should help but could overpower I guess.

 

[Mike53C]

I posted my experience with amp and antenna begining this thread. It works fine. I install it every weekend then take it to my car. I use the support bracket and spring that Wilson provides to attach to side truck mirrors. I fixed it to the hand rail you use walking the sides going to your forward deck. The rail attached to the cabin roof, so it is not mounted at the highest possible point. I keep the whole lenght of the coax cable provided by Wilson even though I could shorten it, but don't want to mess with the connectors. It is cable connect all over, not wireless. Never had a problem. As I mentioned it works so well that I am planning to buy another set so I don't have to move it and can arrange a more decent and permanent installation.
Miguel

 

[Boss Lady]

Hate to let these incorrect prognostications go by. Probably correct at the beginning of cell technology.

See for yourselves.
http://findarticles.com/p/articles/mi_m0TLC/is_5_35/ai_74940612

Ted

Ted, the non-line of sight they are refering to in your article is for built up areas where there are many reflections which cause out of phase signal degredation, their implementation uses multiple antennas and packet filtering to select the best signal, you could say that it is a refinement of sorts compared to just using standard space diversity antennas such as currently used in the cell industry. While this appears to be something new it is not. If this was the panacea to solve multipath fading and would provide better link paths it would be adopted quickly, so if it really works it will be successful in the market place. This system even if it works as advertised, still cannot overcome the curvature of the earth since there is nothing for the signal to reflect off of to return to terra firma.

So Karl's statement is correct. There is a little thing called physics and there is nothing new about RF propagation. Microwave signals are propagated via direct line of sight and by reflection. Some of the lower vhf frequencies can be bent by refraction and tropospheric ducting along thermal layers, but this phenomena ends around 150 mhz, well below the 900 mhz where the first cell phone frequency band begins. The radio horizon is relatively short for ground based transmitters (about 3 miles), to get more range you have to gain height above ground for one or both ends. Generally speaking 35 feet will get you out to 7 miles, to get 14 miles you will need to 110 feet of tower height. Tower height versus distance is not linear, it is exponential. To transmit line of sight 100 miles would take a tower over 1000 feet in height.

I can certainly discuss the merits of the technology cited above, if you like.

 

[GJH]

There is no antenna/amp solution guaranteed to work everywhere, every time. We have sold and tried them all; the Digitals and Wilsons are as good as it gets. The Shakespeare, amongst others, is merely a rehash of Motorola's old cable compensator. If your antenna isn't right, if the connectors are funky or the cable inappropriate, fugeddabout it. If there isn't a signal to amplify delivered to the amp by the antenna and cable, then you will get amplified nothingness.

For the most part, the carriers are not installing towers with the mariner in mind, with the exception of some key shipping lanes; for instance, I was astonished how good the signal was in the middle of the Northumberland Strait between PEI and New Brunswick this summer, especially given the sparsely populated land masses to the north and south. (I was on a 42LRC, just to keep this somewhat Hatteras oriented)

George

 

[Genesis]

My experience off Florida is that I can FREQUENTLY get a good, solid signal simply from the flybridge out to 10-12 miles, and sometimes out to 15ish.

Beyond 20 miles you simply run into height problems with the LAND antenna; they aim 'em "downish" too on purpose to avoid wasting their power and also to avoid cross-tower interference.

Now if you have an amp and a VERY HIGH antenna that helps a LOT, but its just like VHF, really - its all about the height of the antennas on both ends because of the line-of-sight issue.

Also, handheld cells are limited to 600mw transmit power for health and safety reasons. The amps are typically 3w, which is a big difference, but how much of that is used is up to the cell site - the power level if negotiated and there's no point in using more than the site you're talking to needs to get a solid signal.

 

[TedZ]

No need for discussion. I think you are more correct than i am. The issue is that we obviously don't always have a "clear" view of cell towers and the calls stay connected. The technique is antenna arrays and signal processing, not transmission curvature for sure, which is your point and that is right.

Glad you responded.

Ted

 

[Boss Lady]

It can be tough to try and pass on useful information about a highly technical topic, and it always causes some debate when someone speaks in generalities. to try and put things into useful layman's terms. Ted, you are correct about we don't always have line of sight, in radio terms, this is understood. Lay people equate line of sight with visual line of sight and this can cause confusion. Without writing a physics paper, one of the models used is called smoothed earth surface. This model eliminates ground clutter and is used by a lot of antenna manufacturers to show their antenna radiation patterns in a perfect world. These are the models plugged into the computer models that the RF engineers use for system engineering and propagation analysis. From my experience, a lot of RF engineers do not know when the computer is lying to them, so we have a cell system that works less ideally than it should.

The main principle I was trying to get across is that the earth's curvature is actually more dramatic than one would expect. The other factor is the very signal attenuation of air at microwave frequencies, which requires more and more power the longer the distance. Your handheld phone quickly runs out of power, an amp can add considerable range. The other thing is that you have to have tower that is actually transmitting in your direction. The cell tower does not always have an omni directional radiating pattern, they are optimized for bi-directional radiation along highways in less built up areas, so that the cell company can use less towers to cover greater distances. Two arrays will be pointed up and down the highway, and the third array may or maynot be pointed at the water, so getting good signal at sea is hit and miss.

 

[Trojan]

Boss Lady you pretty much summed it up. All antennas are based on a dipole in free space and all calculation are computed from it in a perfect world. Like you said at the frequency the cell phone is at, the signal takes a dump real quick. Even with an amp the signal goes no where. Most towers are pointed up and down the road. So if you get into a tower at sea its on the size or backside of a beam antenna pointed some other direction. So in the most part its a crap shoot if your signal will make it in. With the amount of power you are allowed at cell frequency I'm not to sure that the signal will even travel the line of sight. Your better off with a computer satellite connection and use your computer phone. My kids do it all the time.

BILL

 

[Mike53C]

Chris..BossLady...now you have planted a doubt. How come we can use the cell phones (by themselves, without fancy antennas or amps) inside elevators or bulding basements??????????...how can the "line of sight" that we all refer to, reach us in there?
I'm not trying to make a joke here
Miguel

 

[rswirtz]

speaking of antennas, our TV cable bites at the marina, I hooked up rabbit ears and I get more channels than the cable provides but the most channels are fuzzy. Has anyone used the XiumAir antenna? http://www.goxium.com/xma201.htm

Thanks

 

[GJH]

Many office buildings have in-building repeaters. In some places, it is a safety requirement.

George

 

[Boss Lady]

Chris..BossLady...now you have planted a doubt. How come we can use the cell phones (by themselves, without fancy antennas or amps) inside elevators or bulding basements??????????...how can the "line of sight" that we all refer to, reach us in there?
I'm not trying to make a joke here
Miguel

The reason that they work inside buildings is that microwave signals will come through the window openings and then reflect around inside the building. The reason it works so well today compared to the old analog cell signal is that the new technologies (CDMA) actually take advantage of the multipath signals (reflected), this is also why you don't hear the picket fence effect while driving down the road at 70 mph either. If you recall, if you were in a weak signal area, moving even a couple of feet would cause you call to fade out, and gave birth to the infamous "can you hear me now?", this was due to reflected signals (multipath) arriving at the antenna slightly out of phase with each other and canceling, CDMA technology uses a "COMB" filter and actually uses all the signal paths arriving at the antenna strong enough to provide useable data packets. If you cell phone works inside an elevator then that building more than likely has an indoor repeater. We used to install them only if there were enough clients, but now it is common place since the equipment has become less expensive to do so. Also with the advent of roaming agreements you chances of having more than one provider in a city environment is very high. I have not kept up with E911 legislation but that may have influenced the in-building coverage as well.

Oh yea, I forgot, They will normally put an antenna on each floor of a building. We put several antennas inside of large manufacturing facilities.

 

[Paul45c]

speaking of antennas, our TV cable bites at the marina, I hooked up rabbit ears and I get more channels than the cable provides but the most channels are fuzzy. Has anyone used the XiumAir antenna? http://www.goxium.com/xma201.htm

Thanks

I wouldn't want to have one of those parabolic dish-types with any headway on, myself...hard to imagine it not getting stressed the way it sits up vertically. Look up my thread on fantastic reception I got on a new HDTV just picking up broadcast signals. I'm just using a regular 14" Shakespeare (used to be made by Winegard) flat dish (lays horizontally) mounted on my half tower roof. It has its own little antenna booster, and it's outstanding so far.