Radar reflector proof of concept pic - Page 2 - SailNet Community
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post #11 of 15 Old 11-09-2012 Thread Starter
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Re: Radar reflector proof of concept pic

Finding a way to test is proving to be a problem. I'd thought that there'd be many locals with radar on their boats but I don't know any of them. No way I'm gonna pay $1300 for a radar to test it. It isnt the issue of cost but I simply don't have time to learn to use a radar I will never use again.

Next, I wanted it to stow in a fabric tube about 5" diameter and that is possible with some releasing of 9 velcro tabs

OR

Stowing flat (14" diameter" is easy as if you simply rotate the outer hoops all into one plane it becomes flat and then nearly springs back to shape.

I am willing to do more work to get it to stow into a tube without screwing with velcro tabs but am not sure the effort is worthwhile.

As that test indicated, the "Catch Rain" position is best with the "Double Catch Rain" position often being used because ti gets better as the boat heels. The Catch Rain position is always best if the reflector maintains that orientation even with heeling as mine does. It will hang by a single line going thru the center with weights (right now lead tape) on the bottom hoops holding it in that orientation no matter how much heel.

BTW, just incorporated Gulf Marine Technology, Inc. (S-Corp) for this and for my upcoming lightning ground and my upcoming fabric foldable sat-TV parabolic antenna. Who needs free time?
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post #12 of 15 Old 11-09-2012
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Re: Radar reflector proof of concept pic

I have had a couple of things tested like this. At least in my experience one of the easiest ways is to find a local graduate school, and see if you can find a graduate student working in the field, and see if you can talk them into using the testing as part of a graduate project.

It may take a little longer, but it gets you access to all the testing equipment of a university, the experience of a nominal specalist in the field, and if it does work out well, a reputable test from an institution that has credibility in the field.

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post #13 of 15 Old 11-09-2012
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Re: Radar reflector proof of concept pic

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Originally Posted by Frogwatch View Post
Stowability is important on a smaller sailboat and I do not like having a radar reflector up all the time as it causes windage aloft.
On the way home from the boat today I had my reflector on the front seat and I thought back to this statement for some reason. I picked it up, rolled down my window and while pinching it with two fingers going 30MPH I stuck my arm out the window. I had no trouble holding it with just two pinched fingers...

I have had reflectors up on many sizes of boats for decades and never had the "windage" cause me any issues.. From the sheer number of boats on the foggy Maine Coast who leave them up 100% of the time I'd say it works for a lot more folks than just me...

My old neighbor Gary sailed his O'day Mariner for the 10 years he lived around the corner from me and in that time I never once saw his reflector not hoisted. That's a pretty small boat..

I only say this because as part of your target market who currently own or would buy a reflector "stowability" and "windage" are non issues for me. They might be for some? I just wonder how many people are in the other camp and if this leaves enough "target market"... I am more concerned about how it works than how it stows..

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Last edited by Maine Sail; 11-09-2012 at 09:22 PM.
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post #14 of 15 Old 11-09-2012
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Re: Radar reflector proof of concept pic

You'll need a proper anechoic chamber (like SRI has) to make quantifiable measurements. These chambers are designed to isolate the test object (your foldable reflector) so you are measuring only the reflector and not other "stuff" that is in the test radar beam.

Radio Frequency anechoic chambers, however, are not typically found in universities.

Before you invest in test services from the likes of Scientific-Atlanta, you might develop a flatter reflective surface that your photo indicates. The waviness in your fabric appears to be significant with respect to typical X-band radar wavelength and will reduce the efficiency of the retroreflection process, assuming you've got the reflective planes precisely orthogonal in the first place.

Could you use a springy connection of your fabric to the hoops, instead of velcro? And might you use a fabric substrate that has Spandex or a similar elastic component? This should result in a flatter reflective surface.
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post #15 of 15 Old 11-09-2012
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Re: Radar reflector proof of concept pic

Frogwatch, you might check out the patent here: Patent US4673934 - Inflatable radar reflector - Google Patents. Its already been done!
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