Luneberg Tri-Lens Reflector
In reading through this thread, I see that it has now been running for more than seven months. Over that time it has received opinions ranging from radar reflectors being useless to their being essential equipment. I see them as essential equipment, and so does Transport Canada:
"Vessels less than 20 m (65’7”) in length or that are constructed primarily of non-metallic materials must have radar reflectors, unless they are not essential to the safety of the vessel, or the small size of the vessel or its operation away from radar navigation makes compliance impractical. If properly positioned, they help larger, less manoeuvrable vessels detect your presence on their radar screens. They should be located above all superstructures and at least 4 m (13”1’) above the water (if possible)."
But selecting just any reflector is not as safe as you might think. Radar systems typically require a minimum of three consecutive "hits" or blips on a ship's radar before it can be acquired as a target. This puts a premium not only on the strength of the return, but also on consistent coverage to maintain a high Radar Cross Section (RCS).
The commonly used three intersecting disk style of reflector has many blind arcs and a rather low return rate. Their manufactures usually refer to RCS in terms of Peak RCS. What they don't tell you is this Peak RCS is rarely obtainable and that it doesn't happen when your boat is pitching or heeling. Neither do they mention angular coverage, which is most important when evaluating a radar reflector. This type of radar reflector's angular coverage is just 35 degrees wide.
In any sea state that offers a radar some sea return, your sailboat's intermittent and weak return signal is either lost in the sea clutter, or ignored as a false echo.
On my last boat I installed a 305mm Rozendal Tri-Lens Luneberg reflector with 330 degrees of coverage that was little impaired by heel or pitch. Everyone that I asked said that my boat painted like a large ship on their X-band radars. For my new boat I have specified the 405mm model, since its larger size shows-up on both X-band and S-band radars much better. I want to be easily seen.
Last edited by Sequitur; 02-21-2007 at 02:52 AM.