Calling All Stations: How big a difference does an antenna make?
Ever wonder if an expensive VHF antenna out-performs a cheaper model? And, just how big a difference antenna elevation makes? I did, so I set up a day of testing offshore to put the VHF through its paces.
Test conditions: we were 25 miles off the coast on a blue-bird clear day, with three foot seas. The radios were set to 25-watts.
For an expensive example, I had an eight-foot Galaxy 5225 which costs about $120. Mounted on the T-top, it was elevated about 18’ above the water’s surface. My buddy-boat’s antenna was about the same height. According to line-of-sight limitations as calculated by the math geeks (1.5 x square root of height in feet + 1.5 x square root of height in feet,) our two boats should be able to keep in contact until we were 12 to 14 miles apart. My buddy boat and I moved five miles away from each other, then continued going until we lost contact.
At 12 miles we were still talking, but the communications were no longer loud and clear. So we tried swapping the Galaxy for an eight-foot $35 Shakespeare 5206, which is about as cheap as you can get for a VHF antenna. Surprisingly, our communications were unchanged. Simply put, antennae quality didn’t seem to make a bit of difference. Wait a sec—that doesn’t mean you should cheap out the next time you buy an antennae. Here’s the big difference: the inexpensive version had a nylon ferrule, a 15’ coax lead, and a two year warranty. The 5225, however, had a stainless-steel ferrule, a 20’ coax lead, and a five year warranty. The cheap version matched performance today, but when it comes to tomorrow we wonder if the ferrule will snap or the fiberglass will splinter. Note: I’ve had nylon ferrules break at least twice in the past 10 years, so don’t think this is a long shot—it happens.
How about extension masts? Do they really increase your effective range? I tried a two-foot extension (which costs about $40) and found that it was a little easier to understand each other at 12 miles, but communications deteriorated quickly and after moving one more mile away, conversation was impossible. So I boosted it to a four-foot extension. Again, the results were perceptible but minimal with just a mile or two more range.
So—quality had no discernable effect and extensions had little effect on range. Bummer. How cold we increase VHF range significantly? Boosting power isn’t an option, since the law limits you to 25-watts. But, what if we could extend the antennae more radically? In the interest of boating science, I pieced together two coax wires, lowered a 20’ outrigger, and duct-taped the Shakespeare 5206 to it. Then I raised the rigger back up vertically. Now, that antennae was elevated nearly 43’.
It worked: at 14 miles we were heard clear as a bell. We pushed farther apart, and at 16 miles we could still communicate easily. At 18 miles the voices began to sound garbled, but were still audible. And when my buddy hit the inlet 25 miles away, he could still hear my transmission (though I had lost his, by then.)
Of course, you might not want to drive around the ocean with an antennae duct-taped on the end of your outrigger all the time. But you may want to add a coax extension cable and a roll of the silver stuff to your emergency box. That way, if communications becomes a cry for help and you’re just out of range, you’ll be able to shout a little bit louder.
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