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My boat's auxiliary cellphone antenna seems to extend my range in some places but makes little difference in others. How come? C.K., via e-mail
Ahhh... cell service issues are multiple, complex, and wicked hard to nail down. Here are a few factoids I've picked up that might relate to your issue.
· Digital cell areas are pretty tightly controlled. When the tower gives your phone an electronic "handshake" every 30 seconds or so, it checks your transmission power and drops service if it doesn't meet a pretty high threshold (-65 DBi or less, to be technical). Putting a better antenna higher up will help in fringe areas but won't in itself create more transmit power. Analog systems are more forgiving, which may account for the increased range you experienced in some places.
· Many marine cell antennas do attempt to create more power, measured in DBs, by flattening radiated transmissions toward the horizon. That works fine until your boat starts rolling, which can cause what techies call "packet crashing" and loss of service. Hence, more DBs do not necessarily produce better results (and the correct balance is a bone of contention among the marine antenna folks).
· Over-the-water cell service is getting worse in some areas because tower clusters are fully populated and all their ranges are reduced. In other areas service maps are occasionally more wishful than factual. I can testify that some all-digital phones with "nationwide" service plans are useful only as paperweights along the midcoast of Maine.
· Rumors abound that some financially distressed cell providers are quietly reducing the roaming choices available to their clients with free roaming plans. I've spoken to a technically inclined fellow who swears that he's now experiencing dead spots in places where his phone used to happily roam to one of his provider's "partner" services.
· Given the slight power of a modern cellphone, antenna placement and cable quality are critical to performance. NMEA's new Installation Standard, discussed in my column, has extensive guidelines and test procedures for antennas.
I've answered your question rather vaguely, but I do plan to test some of these auxiliary marine cellphone antennas as well as the amplifiers that are increasingly available. Hopefully I'll turn up some more definitive information. --B.E.

Got a marine electronics question? Write to Electronics Q&A, Power & Motoryacht, 260 Madison Ave., 8th Fl., New York, NY 10016. Fax: (917) 256-2282. e-mail: PMYElectronics@primediamags.com. No phone calls please.

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