Antennas? A column about antennas? The thin white things that stick up in the air and attach to all that other stuff you need to get you where you're going? What's to know about antennas?

Well, aside from the fact that the plural of antenna is antennae (although a plain 's' is acceptable for those of you who flunked Latin I), quite a bit actually; especially since many of today's boaters have more powerful electronics aboard their 20-foot boats than did the average battleship of World War II. And, while there are some general rules regarding all antennae having to do with height and separation, what's good for VHF is bad for an SSB, which won't work for a GPS, and will burn out your SAT-TV. So, take a closer look at that piece of fiberglass and metal that keeps you attached to shore no matter where you are.

SOME ABCs
Antenna technology is actually pretty complicated, but for the purposes of this column, we'll stick to the basics. In antennas ' as in the NBA ' height matters. The taller the antenna ' radio and radar specifically ' the better. The second major consideration is separation ' the distance between transceivers, other antenna, metal, etc. And the third concern is interference, or lack thereof, between antenna and sky ' this is most important with satellite communications.

Other factors include impedance or resistance; i.e., how much a given substance detracts from the power sent out by your appliance ' be it VHF, GPS, SSB, etc. This is expressed in ohms, and the higher the number, the more impedance.

Also of interest, obviously, is cost. Antenna costs can vary from $30 to nearly $2,000, depending on your needs and communication requirements. A cheap antenna is just that ' cheap ' and while it may work 'almost' as well as a more expensive antenna, it certainly won't last as long. VHF antennas ' which all boaters should have ' are made from copper ('the element') enclosed in fiberglass. This copper can be a thin wire (cheap) or a thicker tube (more expensive). Both work, but the thicker version works better and has a longer range ' and a higher price.

GAIN
Another term you'll encounter is 'gain.' Gain is usually defined as an increase in power by the antenna, but what it really does is quantify how the antenna focuses and makes the signal more effective. It's a fixed number. Gain is measured in decibels (dB). In this case, it's a power identifier with three dBs representing a doubling of power. Most recreational antennae are between 3 dB and 9 dB, with 6 dB being the most common for the eight- to 10-foot antennae.

Height matters with VHF antennae because the signal is transmitted out to the horizon, rather than up and down. The higher the antenna, the further the signal reaches (gain is also a factor).

The roll and pitch of a boat can affect signal range. If the antenna is mounted vertically and shooting a signal out to the horizon and the boat rolls to the side, the signal is now angling up ' and the other side angling down. The higher the gain, the more elongated (to the horizon) the radio signal is focused.

POWER
Probably the biggest source of electronic troubles with units using antennae is power loss, and essentially all power losses can be traced to the antenna cabling and connection of the cable to the receiver or transceiver.

Corrosion, bad connections, etc. will cause power loss. Previously, the best means of connection was through a cable soldered to a connector, but since good soldering skills are going the way of good masonry skills, a press-on connector has become popular. Called a 'PL-259 connector,' it's sort of a press-on connector that should be familiar to those of you who have wired a cable television line. Regardless, soldered connections are still best, but if the alternative press-on method is done correctly it will work.

Another trick to good connections is siliconing the threads. Corrosion of any kind means bad reception/sending.

Lastly, long wire runs and 90-degree bends are bad for reception. Every bit of distance between transceiver and antenna results in a power drop, so keep the runs as short as possible. You can alter lengths and add to them with well-spliced connectors (although if you use a CB radio, the wire lengths cannot be cut or extended since they're tuned to the radio).

PLACEMENT
Placement, when it comes to antennae, is as important as the position of the cue ball on a pool table. Bad placement on the table, and chances are you won't hole out; bad antenna placement and you won't be receiving or transmitting any signal anywhere. Here's a breakdown of the proper antenna placement for some key marine electronics:
VHF. Keep antennae at least three feet from the radio and away from any other VHF antenna ' preferably at different ends of the boat. Get it as high as possible.
GPS. This technology doesn't work indoors. (Intel, the computer chip maker, is experimenting with using a non-satellite-based location system utilizing signal triangulation in cell phones to derive location.) Therefore, you'll want your GPS antenna to be mounted with as clear a view of the sky as possible. If you have radar, it's a smart idea to mount the GPS antenna well away from the radome.
Television. This is also a line-of-sight instrument (and a VHF instrument ' very high frequency). Television transmitters are mounted atop mountains, etc., and your receiving antenna should be as high as practical (it's heavier than a whip) and away from your VHF radio antennae. Directional antennae are generally set for one direction at a time, aimed at the best signal; a device to remote-maneuver your 'dish' is a worthy investment. Omni-directional antennae draw in signals from all around and are best used if you do your viewing while underway.
Satellite radio, et al. Similar to GPS receivers, these work best with a clear look at the sky. Height is not as important as a lack of sky-line-of-sight obstruction.
SSB (Single Sideband) . The best thing about this technology is that you can receive and transmit radio signals, faxes, or even e-mails (non-commercial) for more than 1,000 miles if conditions are good. To make it work properly requires more than just simply running up an antenna and connecting it to your transceiver. For starters, you'll need a long antenna for an SSB radio ' at least 23 feet high ' and you'll need a different type of support setup. SSB operates at a lower frequency (3-30 MHz) than VHF marine radio (which falls in the 156-174 MHz range), and requires an antenna tuner, which becomes part of the antenna assembly and needs to be mounted as close to the antenna base as possible. Proper grounding is also more involved with an SSB system, but is beyond the scope of this article.

MOUNTING
GPS and satellite radio antennae are compact and easily mounted on flat surfaces. Neither their size nor weight will necessitate any special load-bearing concerns, but not so with other antennae. Single-whip radio antennae in the eight- to 12-foot range can use the ubiquitous ratchet mount featuring one-handed operation to raise, lower or lock the antennae in any given position. Use a backing plate when mounting the antenna mount. This should match the size of the mount and have a hole of sufficient size in its center to pass the coaxial cable through.

Another option is a rail mount, which might be useful for those of you with center console rigs and T-tops.

With antennae longer than 10 or 12 feet, use a separate support about midway up the antenna's length. If you've got a bridge that you navigate every time you go out, and it requires raising and lowering the antenna, you'll want to consider the type of mounting hardware, the type of antenna (one or two piece), etc.