DIY Radar reflectors and which one is best ??

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We see all sorts of Radar Reflectors out there .... rain catching tin plate, Echomax "barrel" type, Firdell Blippers, Plastimo Tube ..... etc. etc.

So which one really is best ... tests performed in mags are so inconclusive as to be laughable. Like many tests it's left to reader to decide what suits him best and I'm sure that most choose based on cosmetics and whether it catches sails etc. Many I believe follow the masses .... they see a certain type is common - OK that must be good cause so many have them ...

A question to me by another prompted my thinking and what really makes a Radar Reflector .... multi-directional metallic face ... sort of crumpled up tin foil or interconnected foil plates ... so that signal is reflected back whatever angle the reflector is .....

So if you took the main widest part of 3 large lemonade bottles 2 with the bottom ends still intact ... 3rd with open both ends ... Connect 1 ended one and the open one ... crumple up plenty of tin foil and stuff the bottles full, as well as the 3rd one ... then fit all together into a closed affair 3 bottles or more long ... cover and paint in nice white gloss ...
Mount high on mast ....

Would that do the job ? Costing just the price of lemonade and roll of foil / paint etc. ?????

So what ideas could you lot think up for this - Let's have a Blue Peter session and see how many different feasable ways we can devise ......

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It wouldn't be much more expensive to knock together an octahedral out of aluminum plate, and they work. No tests with aluminium foil have ever shown good returns. Crumpled foil is just going to bounce the return signal all over the place, so not much use, Octahedrals work for the simple reason they return the signal back to the sender, and do it strongly, due to the design.
 
A hanging basket with a nice mixture of summer flowers would be good. Probably as good as your crumpled foil as a reflector and much prettier.....
 
I would agree with you, Brendan, but for one observation, that a steel fishing boat, with no readar reflector observable but lots of random angles and flat bits gives a great radar return. A sailing or motor yacht often gives little or no return, especially where no radar refelector is observed. The crumpled foil would give a reasonably omnidirectional return, although I've never seen the results of a "bench" test on one.

I do know that an 18" admiralty pattern folding octahedral gives a good, solid return, 'cos someone on the bridge of a ship told me once.
 
Iam a fan of octahedral flat type reflectors because I KNOW they work.

There is an outfall buoy in our area that is a real "stealth buoy" It shows up poorly on radar and has been hit by ships a few times as a result.

While the superstructure of the buoy was being repaired a temporary octahedral radar reflector was lashed to the float. Instant result the buoy was immediately very visible until the buoy was fully reinstated and became almost invisible again.

This observation was made by several vessel;s that noticed the marked improvement.
 
You may Jest .... but got replies ...

I have the octahedral one - so don't need to DIY actually ...

I posted the thread to start a debate hoping to find out why and what people use.

As to Mag tests .... having read a lot of them and also spend many hours on ships navigating English Channel etc. - I can honestly say that yachts have only been good plain targets on radar in reasonable weather ... the moment a moderate sea state starts ... a yacht is generally lost in the clutter ... especially on bigger ships radar where the vertical height of the scanner array is greater.

With regard to scattering the signal ... can someone explein to me how any reflector actually "bounces" back a signal direct to the source ? No way - it will reflect the signal generally back toward but not exact ... it cannot on a moving rolling, pitching mount ... so scatter will occur on any reflector.

Now back to a B&Q one I did earlier ....
 
The octohedral is designed so that it will reflect a signal back to where is came from. It is similar to the red relector lenses you see on cars and bikes. If you look at them closely you will see that they have many small pyramids each designed so that it reflects the light through 180 degrees. The face of an octohedral is just one of those prisms. Maybe if you just got a one meter square flat sheet of aluminium and got someone to hold it up facing the ship that you want to see you. Cheap, apart from the labour costs of employing someone to hold it up all the time facing each different ship.
 
Do you know of any diy how to do it sites for the octahedral.
 
Re: You may Jest .... but got replies ...

If the signal is not returned to the radar, then it wont show as a target. The more signal that gets returned directly to the radar, the better the signal. A ball of foil the has angles everywhere will send the signal off all over the place like a stealth bomber. Basic physics Nige
PS the octahedron returns most of the radar beam back in roughly the direction it came from, by bouncing the wave around the internal plates. Draw a diagram and you'll see the idea. Crumpled foil will direct most of the beam in a scatter pattern
 
No, but if you find someone who has one, you can take the three bits apart (designed to do that) and copy them onto cardboard templates and cut your own.To be honest, they are so cheap to buy it's probably not worth the hassle unless you have some sheet aluminium lying around
 
The octohedral design will only work satisfactorily if the plates are at 90 degrees. Any less and the signal strength falls dramatically - even 3 degrees is enough to make it practically useless. This is the biggest problem with the octohedral. The proper reflectors like the echomax (best return) and the Firdell are also constructed using 90 degree reflectors, however, the bigger the reflector the better the return.

There are one or two other funnies that sometimes work such as the lunneberg lens, but the only way to make them work properly is to be able to receive the signal and motor the lens round to roughly the right angle.
 
An alloy mast is a very good reflector, it curved surface and usual slope from the vertical just reflects the signal everywhere other than back towards the scanner.

The idea behind a radar reflector (as has been discussed above) is to reflect a significant amount of energy back the way it came.

My experience is the bigger the reflector the better, and the further away from the mast the better (see earlier thread).

The first Firdell was the Pentland, quite a big beast, but I have taken it from one boat to the next because I know it works. I have even been illuminated by searchlights which were turned on pointing at me, presumably seen on the radar but not visually. Also we have monitored ships passing exactly one mile off which implies they have been tracking me long enough to calculate the alteration required for a one mile CPA. Most vessels would make this alteration in open water at about three miles or earlier.
 
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