About five years ago I got into radar reflectors for sailboats. the result is in an article I have on Duckworks, with additional details two years later in another article. I encourage you to look at them for many of the details…they are relatively easily made from aluminum roof flashing and pop rivets at low cost AND ARE FAR BETTER AT REFLECTING THAN ANY OF THE SMALL REFLECTORS MARKETED FOR SMALL BOATS. In short, size matters, and no passive technology can get around that.
- Finished reflector on mast top
The reflector is quite rigid with just thin flashing because of the angles. It is basically two sets of quadrahedral reflectors spaced inside each other, and gives excellent reflection over a wide horizontal circle. The two reflectors fill in for each other around the circle.
I strongly recommend building one for your boat if you are likely to be out where there is significant commercial traffic or where there are large cruisers with radar. It is also reassuring in fog, althought boats without radar would not “see” you.