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What’s Out There?

Picking a radar that lets you see it all.

January 1, 2001
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The average boat owner doesn’t have the foggiest notion how to select a radar. Why should he? In truth, that’s what guys like me are for. But you should be armed with a little knowledge so you can make the best choices for your needs. The differences among radars extend beyond range and price. Unfortunately, a unit’s true usefulness is often hidden behind a lot of technobabble. What I will reveal here are which tech specs you need to pay attention to and how to understand them.

How Far Can It See?
Naturally, the farther your radar can see, the greater its value. Prices usually escalate with a radar’s range. But what you may not realize is that range won’t tell you everything you need to know. The same technical attributes that allow a radar to reach out at a greater distance are also the very characteristics that create a more detailed picture with greater resolution. You need to concern yourself with power output, antenna type and size, and horizontal beam width.

Power to the People
The more energy your radar throws out, the more energy will be reflected off the radar target to make its way back to the antenna. The more target energy received, the more defined the resulting picture will be. In other words, the more kilowatts (kW) a radar boasts, the better.

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Size (and Shape) Matter
If you can, learn the internal antenna length. If you can’t, the size of the enclosure is enough to serve as a guide for comparison. A radar’s signal is in the microwave frequency band, so its electrical wavelength is short. What this means is that an antenna that’s just a few inches longer than another will significantly outperform the shorter antenna. People gravitate to the open-array antenna. Why? Because you can see it spinning, so it looks like it’s working. But these antennas take a considerable amount of effort to build, waterproof, and protect from the elements. Housing the antenna inside a fiberglass enclosure – a dome – significantly reduces its cost. So which is better? Provided that the length of each antenna is the same and the antenna element used is similar, there’s no difference.

It’s Elementary
Antenna elements are either metal waveguide (fabricated from a sort of square metal pipe) or printed circuit board (PCB, or microstrip constructed of plastic or fiberglass). Metal waveguide antennas are superior performers. PCB antenna elements are responsible for cutting the cost and overall antenna size. There’s also a hybrid antenna element that’s part waveguide and part PCB. Its performance exceeds that of more economically advantaged radar antennas with PCB elements.

Wider Isn’t Always Better
The most telltale specification for a radar may be its horizontal beam width. This measures the width of the radar beam as it leaves or is transmitted to the antenna. The narrower the beam, the more concentrated the transmitted radar signal and the more detailed the resulting reflected radar echo.

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Picture This
A large screen makes radar target recognition and interpretation easier. But at the same time, available dash or helm space dictates what size radar display your boat can accommodate. Of more significance is the type of display you choose. A CRT (cathode ray tube) is the same glass picture tube used in most TVs and computers. CRTs present a sharp, detailed picture, but they have a long neck that necessitates a deeper housing. LCDs are gaining in viewability every year. They have a flat face and a more slender depth, making them ideal for confined instrument locations. They also have the comparative price advantage. Traditionally, if you plan on using radar where direct sunlight will fall on the screen, monochrome LCDs prove more viewable. But several new units, including Raytheon’s RL70C+ series color LCDs, counter this negative characteristic and perform surprisingly well in direct sunlight.

Color Me Beautiful
Color is nowhere near as important to a radar as it is to a fishfinder – and it costs more. Yet color does make viewing easier and is the wave of the future. Whether it’s worth it is up to you.

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