Hi, Several of you are contemplating installing remote cellular antennas, so I thought I'd jot a few notes down about such things (I work for Motorola). Most of this does not apply to HF radio (i.e., your marine SSB radiotelephone). Only some of it applies to your VHF radiotelephone. First, the physics governing the range of a radio signal is similar to that governing the distance you can see a light, except that when we calculate range for a radio signal, we assume the earth's curvature to have a 4/3 relationship (because light does not bend but radio signals actually do a bit and so go somewhat further). So, you would think, the higher the antenna the better (just like the higher your eye, the farther out you can see. It ain't necessarily so, like the song says. The base stations for cellular systems often have antennas that have the beams "tilted" downward. This is so that they will cover and penetrate within their intended zone and not spill over. What this means to us boaters is that the signals don't often go that far out to sea. Because of this downward beam tilt, the amount of signal not only falls off with distance, but also falls off with height. Now, at the distances we are talking about from the cell site the practical differences between an antenna on a deck and one at the top of a mast are not great, but there is a case where in some instances going up might actually reduce the signal somewhat. So, if you're in the fringe, adding the right sort of external antenna *might* help, but this does not necessarily mean increasing the height. If you are not in the coverage zone, adding an external antenna, either higher up or with "gain" probably won't improve things. Another problem with the higher is better theory is the transmission line (that is the "coax" between the radio and the antenna). Transmission lines have losses. The longer the line the longer the loss will be. The higher the radio frequency, the higher the loss will be. Cellular works at about 800 MHz (the new PCS cellular works at 1900 MHz). At 800 MHz, if you were to take, say 50 feet of RG58x (that is the usual stuff you will find in radio store these days) so that you could run the antenna up the top of a sailboat mast, the signal your cell phone puts into the bottom end would be reduced to less than one quarter its strength by the time it gets to the top end (I'm doing this from memory, so you radio amateurs should give my figures a bit of leeway here). Bear in mind that the inbound signal (the one you want to hear) will be reduced by the same amount. In radio talk, a degradation of this magnitude is referred to as 6 decibels (dB). Now, if you attach a 6 dB antenna to the top, you probably only just broke even. The old adage, "There is no such thing as a free lunch", applies to antennas. When a "gain" antenna amplifies your signal, it has to respect the laws of physics-it can't create more power. To understand this, first understand the little antenna that comes with your radio in theory (and close enough in practice) emits power in nearly all directions. Power heading up to the sky or going down to the deck is wasted, right. So, the designers of gain antennas take this wasted power and focus it outwards (i.e., horizontally). It is just like the difference between a bare flashlight bulb and a flashlight. The bare bulb does not seem to shine very brightly, as the light goes everywhere; put the bulb in a flashlight and the beam is very bright and directional. In the case of our gain antenna, though, the beam radiates all around horizontally (but no longer way up or way down), in a kind of doughnut shape. Now, since the weenie little antenna on the cell phone radiates all around, like our bare flashlight bulb, you can tip the cell phone around with impunity. Not so with the gain antenna. Tip a gain antenna enough and the horizontal beam will be pointed up or down and you will loose signal. The higher the gain of the antenna, the worse this effect will be. If an ordinary antenna has a pattern like a regular doughnut, then a 6 dB gain one will be like a flattened out doughnut and a 9 dB gain one will be flatter still. So, while your boat is level, you may be able to use the cell phone, but if the boat is rolling, the signal may raise and fall in strength. So, what does this all mean for your cellular antenna? Well, assuming your antenna is high enough to "see" the cellular base station antenna, there is no more signal the higher up you go and there may well be a bit less (i.e., due to beam tilting). So, mount your antenna only high enough to get a clear all around shot at the horizon at the distance that cellular stations in your area radiate (the formula you use for seeing a lighthouse will work close enough). Use the lowest loss cable you can find between your radio and the antenna (this is not easy as there are many variables-consult a technician). Cut off any spare and reattach the connector properly (you can't splice this stuff). Forget super high gain antennas; 6 dB should be plenty. On my boat (a KK 48 Whaleback), I would not bother going higher than the pilothouse roof. I hope this is clear (it is to me!) Best, Maurice AKAMA Singapore