When a signal passes through a cable, there will always be a reduction in the strength of the signal. This is known as line loss, or attenuation. The amount of line loss that occurs depends on the distance the signal must travel through the cable and the quality of the cable used. The greater the distance traveled, the more signal will be lost.

This loss is also increased by using poor quality cable. A general rule of thumb is to use the best quality cable you can find. The price of good quality cable is not significantly higher than poor cable, and the benefits can be significant. When wiring up the amplifier to the antenna, we suggest using LMR-400 type coaxial cable. This cable provides the lowest line loss and is very easy to find. It is also fairly stiff and difficult to work with, so plan for this in your installation.

LMR-400 coaxial cable is recommended to cut line loss.Our last piece of advice about cabling is to have as few connectors involved as possible. Each connector will cause additional line loss, so a straight cable from your antenna to the amplifier is better than one that has a connector in-between. Make the cabling simple between the amp and the antenna.

Nowhere is line loss more profoundly demonstrated than on some sailboat configurations we have encountered. The typical scenario is that the captain and crew decide they need better mobile phone coverage. They want another emergency communications device and an easy way to access the Internet and email, so they purchase an antenna that promises to double their cell signal. They want to ensure their antenna can see the cell towers "from anywhere," so they decide to put this antenna at the top of their 40 foot mast. The signal coming to that antenna may be enhanced by the antenna, but they also have more than 40 feet of line loss. In addition, a low quality cable has often been used. After all, 40 feet of high quality cable is more expensive and, due to its stiffness, would be difficult to maneuver through the mast. It is quite conceivable that the signal they end up with is less than what they had before using the antenna. They may have had better results by just standing up outside with the phone in their hand!

But all is not lost. The way to remedy the line loss problem is by installing that amplifier we discussed, before the external antenna. Amplifiers are allowed to increase the small 0.3 watt mobile phone signal to a whopping 3 watts of signal output –10 times what the phone itself can put out.

DIY INSTALLATION

This is a good place to point out that doing the installation yourself is not at all unreasonable. It is no more difficult than installing a VHF radio with antenna. Of course, there are also many electronics installers who can do it for you. Make sure they have experience installing this equipment, and that their experience is in the marine environment. If they don't know what LMR-400 is, look for someone else.

In addition to selecting and purchasing the right equipment, you will also need to determine where to place it. There are a few things you should weigh in order to obtain the best possible signal quality.

First, consider placement of the amplifier. You will most likely want it in an out of the way location. It is something you will rarely need to access and, quite frankly, they are pretty unattractive. It will require a typical 12 volt DC power source, and there will be times when you may need to access the unit to check a cable connection or some such thing. Because this is most likely to occur at the most inconvenient time, when access to your mobile signal is critical, it pays to install the unit in an area that is not too painful to reach. So find a place in the ceiling or behind a bulkhead, preferably where you can get to it without unreasonable hassle.

But proximity to the antenna is also very important. If you are looking at several possibilities for the antenna location with similar convenience factors, select the one closest to your antenna location to cut down on line loss. You'll also save money on cable costs. The same goes for the antenna. Placing it at the top of your mast may not be as good a location as on the stern railing. The antenna simply needs to be where it has a clear view of the sky.

Once your project is scoped and the equipment is purchased, be sure to follow all safety procedures associated with proper marine electrical work, and call in a pro if you feel uncertain.

The bottom line, however, is that amplifiers work. Our experience is that they operate wonderfully in most boating situations, even several miles offshore. We've used a smartphone as far as 20 miles off the North Carolina shore when it was connected to our amplifier. We've traveled from the Penobscot Bay in Maine to Key West in Florida while maintaining a continuous Internet connection with the exception of 25 miles on the Pungo-Alligator Canal. An amplifier will give you 3 "bars" when your mobile phone detects no signal on its own.

NEXT WEEK: Navigating with a mobile phone.