A real cell phone booster: no tin foil!

Setting up a cellular base station for distant working

 

Bad reception with your mobile usually means you need a better or better placed antenna. The folks at Criterioncellular.com (external link) do a good job explaining reception problems and then they offer solutions. You should look over their site for interference, gain, and dbi information alone, even if you aren't in the market for an external antenna or other equipment.

I do not get a commission from these people, nor have I done business with them. But I think they are a good resource so I've put some of their graphics and text on this page to let you decide if you want to visit their site:

"Since the introduction of cheaper cellular airtime rates and included long distance the desire for home or office use of cellular phones has greatly increased. Many people are now using these phones in their home office which often times is even down in the basement! If this is you, you're not strange and you're certainly NOT alone."

"In response to this need, antennas have been developed specifically for this use. However, there are some things that you will need to know before you purchase one of these antennas."

"First off, it is important to understand exactly why your phone is not getting the reception it requires to communicate. The diagram below shows some common reasons..."

As the signal from the Cellular Carrier (AT&T, Verizon, Sprint, etc.) is broadcast from the cell site (A) it is met with obstructions such as:

(B) Brick walls, Cement, Stucco

(D) Earth and Cement

(F) The entire house

The cellular phone (E) and (D) and (G) is not visible (or barely visible) to the cell site (A).

If the distance between the cell site (A) and the phone (F) (E) and (D) is increased (as in an urban area), an external antenna (C) of the correct frequency and higher gain can be used to pickup the signal and transfer it to the phone (D) to increase the reception.

Making it better

Does one or more of these obstacles fit your situation? Then it sounds like an external antenna would fix the problem. On the next page we have put together a checklist to enable you to determine exactly the equipment you will need and which parts to order.

Go HERE for our Checklist (this link will take you to their site)

Cell Phone Booster

Need a true booster for your cell phone? Not a stick on piece of foil? Check out JDTECK LTD's web site: http://www.jdteck.com/ (external link) Their amplifier is FCC approved. I haven't used their equipment but the information they supply makes sense. This kind of booster might be just what you need wherever cell coverage is marginal. Prices aren't cheap, from $185 to $245. But your cell phone is worthless if you can't make a connection. By the way, I don't get any money or equipment from these people, I'm just bringing them to your attention.

Setting up a cellular base station for distant working

How do you improve cellular reception if you are out in the country? If you can get service at all, at least a weak signal, you need a better, higher location for your antenna, or perhaps another antenna altogether. Yagi antennas are directional and offer good results if you can point them at the nearest cell site and if you keep antenna line transmission losses low. (More on this below.) Try an amplifier if replacing or relocating the antenna doesn't work. Start with the least expensive solution, you may not need more. Criterion Cellular (external link) has much equipment and good advice for dealing with rural locations. Here's an e-mail asking Mark van der Hoek about the problem:

Q: Mark: I am doing research for a summer camp in the Rocky Mountians. The main buildings are in a valley. People get a few bars of signal at the highest point on the property, which is sometimes enough to dial out, but calls drop easily. We are thinking about putting up a tower, on which we would install a cell antenna and booster (external link to Criterion Cellular). We have heard that if your tower is less than 40 feet, you do not need any special license or permit for the tower. Is this true? If not, do you know where we could look to find this information?

A: Hello! I don't know of any licensing problem with what you are proposing, but I suggest you try it out with some temporary measures before you spend the money and time to erect a tower. I am skeptical of it working very well. With such a small amplifier, the losses in the cable and connectors could lose all of the gain. You'll want to use some decent cable such as RG-213. Using the ususal RG-58 that you get at Radio Trash will get you nowhere fast, methinks. The losses will be too high. For 50 feet of coax, the RG-58 will give you about 10dB of loss, compared with ~3.8 for the RG-213. You'll need to use the correct connectors, and so on. Figure somewhere in the neighborhood of 40-50 cents per foot, and a couple of bucks for connectors at each end.

DO NOT USE SATELLITE OR OTHER VIDEO CABLE. Video cable is 75 ohm cable, whereas communications cable is 50 ohm. Mismatch the cable and your signal losses will be huge.

If you have a good idea of the direction of the nearest cell sites, you can get a directional antenna for the tower top and do a much better job for yourself. But that will run a few more bucks, of course.

BTW, here's the web site for the FCC tower registration.

http://wireless2.fcc.gov/UlsApp/AsrSearch/towairSearch.jsp

Just plug in the latitude, longitude, ground elevation, and height of the tower, and it will tell you if you need to file with the FAA. for structure type, choose "Free standing or guyed structure." If you are clear, then you don't need to file the tower with the FCC, either. If you need to do an FAA app, then you must register the tower with the FCC, EVEN IF THE FAA MAKES A "NO HAZARD" FINDING. Failure to register (when required) and mark the tower can result in fines in the hundreds of thousands. Just ask AT&T Wireless - $6,000,000 last year in fines for towers not being properly registered and marked.

But don't worry - if you are in the boonies, you aren't likely going to need an FAA study. Generally, if you are more than 8 miles from an FAA registered airport, you won't need to. Run the study at the link above, then print the results and file it away. Be aware that local jurisdictions may have some rules about towers if there are private airports nearby. The FAA doesn't care about those little crop duster strips, but your local county might.

You'll want to install the amp near the bottom of the tower, and run the longer coax run to the antenna up top. This will keep your DC power leads down to a reasonable size. I see the unit comes with TNC connectors, which is reasonable for a car kit, but not the best choice for a fixed installation. Still, you can get TNC connectors for RG-213, but I suspect you'll pay about $4-5 for a quality connector. Check the connector type for the tower top antenna, and by the correct connector. Many ham radio shops will make up a cable for you with whatever connectors you specify. Unless you have someone there who knows how to put connectors on, I recommend you take this route. Mess up a connector and you will be wondering why your setup doesn't work.

You will also need to some waterproofing of the connectors. Ham shops will have the material. A common form is a sheet of tar, kept between two pieces of non-stick paper. The best procedure is to make the connection to the antenna, then tightly wrap the connection with good quality electrical tape. Then a turn or two of the same, but not tight. This holds the first layer in place. Wrap the tar sheet over this. Make sure the tar covers the tape COMPLETELY. Then another layer of electrical tape. Done right, I've seen 5 year old connections on mountain tops that were bright and shiny as new when I took them apart. The electrical tape inner layer makes it easy to get the tar off of the connector if you need to take it apart.

Hmmm. I suspect you'll need to make some kind of housing for the amp, too. I doubt it's made for outdoor use. Good luck.

Mark van der Hoek