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Old 06-01-2005, 23:22   #1
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Anyone know how to build a radar?

I'd like to try building a radar. Anyone have some pointers to how they work? How they are built and why?

And yes, I have built electronic things before, just nothing quite so useful.

Thanks!

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Old 07-01-2005, 10:04   #2
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Re-inventing the wheel?

No offense, yet if you have to ask the question then you are not technically qualified to understand just when it is working properly (or safely or within FCC specs) and not likely to have access the very expensive lab equipment required to do such a development. There are no "kits" available with which to build a radar. Buy one!
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Old 08-01-2005, 02:03   #3
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Sorry Jim, but Radar is probably the most difficult electronic application you could have chosen. Besides, it would be far far cheaper to go buy than build. Radar uses Microwaves, not unlike your Microwave oven uses. It beams the microwave energy out and looks for reflections of that energy bouncing off objects. It interprets those reflections and places them onto your screen as a visual ID.
Sooooo, firstly you have to create the Microwave energy. It then has to be beamed in a tight and accurate pattern. You need to be able to spin that beam around in a continuose 360 degree pattern. That same unit must also be able to recieve any reflection. The reflected energy then has to be converted to a signal that the electronics can recognise and the reflection is timed against the sent signal, so as the electronics are able to report a placement. That report is then displayed on your screen. They are working on a chip that does all that with out the need of moving components. But it is still a long way off. It is similar to what is used in the car industry for curb and following distance alarms on Vehicles.
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Old 08-01-2005, 11:59   #4
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As a matter of fact, I -do- want to reinvent the wheel. At least on this, it might be fun.

Thanks wheels, I guess I should have been more clear. I'm interested in how the transmitter and recievers are desined. The analog section to be precise. Once I can send and recieve, the rest is just software and that's not a problem.

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Old 08-01-2005, 14:32   #5
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If you are indeed clued up enough to do this, then this is what I suggest. Have a seriouse look at the Transciever devices that are being used on cars. It looks interesting. The negative about the present day radar, is that it is a combnation of mechanical and electronics. The scannar is where the most problems exist and where changes can't be made. The scanner is a metal reflector that is rotated via a motor. It is a clumsy device and one of contention to yachties, when mounted high up a mast. It is weight aloft and a seriuose wind catcher. The other issue, is that it is the size of the scanner, that determins the power and recieving strength of the Radar. The further the radar can operate, the bigger those scanners are. The big Radars, will be seen with a large revolving arrays. Small ones are usually inside a dome. Some really huge ones are also inside a dome for wind proofing, but they are enormouse.
So going back to the solid state devices, these are small and light. No moving parts. I would imagine an array of these things being switch on and off in a 360-pattern is the way to go. I would think that it would be a simple case of controling via software. But the supplier of these devices, should be able to give you the necessary info on what makes them work and what is needed to make them work and recieve the signal.
The Radar of today, is just not simple enough to try and copy. Hence it's price that has never really come down in relation to other electronics that have been around for many years also.
Good luck, and should you be successful, remember me when you become rich and famouse.
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Old 09-01-2005, 08:16   #6
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The other issue, is that it is the size of the scanner, that determins the power and recieving strength of the Radar. The further the radar can operate, the bigger those scanners are.
I am sorry wheels but this is just incorrect!

The size of the scanner is actually a function of two things only. The wavelength of the radar and the required bearing accuracy and elevation capability. You can push lots of power out of a very small scanner, and achieve much worse results than very small amounts of power out of a large scanner. Furthermore the shape of the wave can have a major impact on power, range, and display capabilities, especially if pulse compression technigues are being used.

The longer the range of a radar normally, the lower the wavelength. These lower wavelengths require larger aerials (just as in radio) taken to absurd lengths you achieve the aerials that are kilometers long, and work out to thousands of miles.

To be able to create a radar, you need to decide what sort of range (thus what frequency) this will then dictate the size of scanner. You then need to be able to initiate pulses of Rf energy (hence a magnetron) - these are available from microwaves, but I have no idea if they can be converted. You need to be able to shield yourself and the boat from the Rf energy (unless you want to end up like the sunday roast - not a joke read the documentation on the pioneers of this area) , you also need to be able to send this rf energy up to the scanner. this requires waveguides that are exact scaled to the wavelength of the radar, You then need to be able to receive this data and interpolate the answers. There are some very good textbooks on this subject so it is not impossible but dont minimise the dangers or the difficulties.
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Old 09-01-2005, 12:22   #7
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Thanks for the correction Talbot. Sorry, but it is the English to English translation where the error ocurred. It is my Kiwi accent. What I meant by the "power and receiving strength" was the Radars over all performance. Or in other words, the fact that they are usually greater operating range devices. I wasn't refering to actuall RF transmission power, although that wasn't very clear was it.
Looks like you are a little(or maybe a lot) more clued than I on Radar, so I won't go into a "I know more than you" contest. But I maybe able to answer a point you made about the magnetron part. Usually the magnatron is housed up in the array. And yes, it is reflected and set on it's path via a "wave guide". Micro wave has the distinct ability to flow along the surface of a conductor, not in it. So it is useless to try and create the Microwave energy at the set and then use a wire conductor to get it up the the scanner.
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Old 10-01-2005, 00:14   #8
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Hmm...

Now its getting interesting.
Wheels we're thinking right along the same lines. There's got to be a way to dump the motor and the size.

"Furthermore the shape of the wave can have a major impact on power, range, and display capabilities"

Shape? Can you go g little deeper here? What kinda' shapes are good for what?

"You need to be able to shield yourself and the boat from the Rf energy."

How does one shield for RF? Grounded plates where you don't want it to go?

"via a 'wave guide' " This is how the output beam is focused? Is there any way to "focus" what the reciever sees? For example only look out the front?

As for frequency, what are people typically using today? I mean for pleasure boat radars. What would be the max range? Maybe 60+/- miles?

I used to write s-ware for e-beam metrology machines. They locate and measure really really tiny things on slicon wafers. We did a lot of stuff to get clear picutres out of very poor quality electron beam information. I'm betting that tech could be applied to radar.

Thanks again, this is just the stuff I was looking for!

-jim lee
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Old 10-01-2005, 12:17   #9
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Talbot may have greater understanding than I on this subject. So please Talbot, Jump in and correct me if I am wrong on any point. I won't be offended.
The one beauty of Microwave is it's ability to be "guided" along a path. So a Scanner is actualy a metal array that simply guides and focuses the energy.
But the scanner is the one part that I don't think you want to reinvent the wheel. I recon that part you should buy from a manufacturer. It is all the proccessing you need to reinvent.

But this is were I recon you want to diverge from the current design and look at these chip type devices. You don't have any of this clutter. It is all done on the surface of the chip as I understand it. Now here is the really really interesting and important part. In current Radar systems, the greatest power draw is that magnetron. It is a very power hungry device, as it has heater elements in it to make it work. Thus the standby time for warm up before it will transmit, and the limited No of hours of operation before it needs to be replaced. Going this otherway, may reduce power consumptiopn considerably. Control of the beam is going to be arrayment of the chips. The entire design will be very different and I think easier.

I suggest you start doing some web searches on Radar and read some articles on how it works and blah blah. You are going to get way more info than anyone can dish up here and probably some cool pictures to boot. Plus look at the techynology on some of the new cars, find out who is making the stuff and ask them questions. I am sure someone will have a heap of info if they see a possible new "toy" for their product.
Just to go one step further. In my industry, we get to play with big projection equipment. Most of the older stuff was done with filters and lenses. Now it is all light reflecting off the surface of a small chip. In revolutionised the miniturisation of high output projectors. What once was the size of a suitcase to get the light output, could now be put into your shirt pocket. The only limiting factors in size now, are the Lens and the Lamp. The rest is the size of a Cellph. And now the whole thing is a fraction of the price they used to be.
I see a similar thing happening with the Radar. Far less power consumed, far smaller arrays, and longer operating time and much cheaper.
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Old 11-01-2005, 04:49   #10
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The following link may be of some use Radar Theory
Navigation radar is normally restricted to about 48 miles due to the Rf . lower frequency is used for aircraft detection in order to get longer range. Small boat radar uses the same Rf range as Nav radar, but lower power settings and smaller aerials in order to consume less power and reduce weight. thus a small boat radar is rarely capable of more than 24 miles, but so what, the curvature of the earth means that even that capability is impossible to exploit. Small boat radar also are able to fit the magnetron units on the scanner assembly which reduces the complexity of the installation enormously, but does increase the weight up the mast.
There are alternatives to magnetrons, but are expensive and techniquely complex. I would recommend that rather than me trying to drudge up my radar 101, you invest in some decent radar theory texts
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Old 11-01-2005, 14:58   #11
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RADAR and fishing

I have a handle on the creation of a RADAR. I equate building my own RADAR as being similar to catching my own fish. Going fishing has great appeal to many folks, but I am not one of them. My idea of a perfect day of fishing is getting a good book, sitting on the beach and reading it. On the way home from the beach , stop at the market and select the fish from the counter, pay the bill and cook it at my convenience. This ensures that I get the kind of fish I want the first time at a more than reasonable cost. Building a RADAR is done the same way. Take cash to the chandlery, select the desired unit, pay for it and take it home to be installed at my convenience.
This leaves more time to sit on the boat or beach with a good book and a few
Best of luck to you.
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Old 21-09-2005, 13:40   #12
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By the way, do you have significant electronics background? Or, do you have an EE degree?

Even if you do, and are able to build one, I assume you do realize that the finished unit is going to be huge and heavy. You don't have access to the micro technology to get the size down to something reasonable.
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Old 21-09-2005, 17:39   #13
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If you hope to design and build an Electronically Steerable, or Synthetic Aperture Radar Array, you may be interested in this seminar:
“Phased Array Radar Design” - presented by Robert Hill of PMS Training
This is a 3-day course covering both the principles and technology of the phased array antenna itself and the overall system significance, design and the operation the phased array permits.
November 9-11 in Stockholm (3 days in English) ... $1900 USD
Contact: http://www.pms.se/seminars/phasedarr.htm
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Old 21-09-2005, 22:06   #14
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Antenna theory, now you are talking my language. I played around a bit in the 90's with microwave communications. designed and built some pretty good wave guides for 2.4ghz. I do not consider myself an expert by any means, but I can tell you that the average computer guy, (no offense Jim) has far less understanding of the mechanics of radio technology than is required to make the equipment work efficiently. It is more tha the software.
I will say, that your idea is good, and if you do reinvent small boat radar, kudos to you. I think you may find that it is a bit more complex than it seems. If for no other reason, the equipment and facilities to manufacture equipment like this is out of reach of most of us.
And Rick, I agree with you completely Had to happen sooner or later.
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Old 25-09-2005, 06:51   #15
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Some good general information at the Naval Air Warfare Center Weapons Division (USN): www.nawcwpns.navy.mil
Specifically:
The “ELECTRONIC WARFARE AND RADAR SYSTEMS ENGINEERING HANDBOOK”
https://ewhdbks.mugu.navy.mil/contents.htm
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