Will the Radar Fry his Brain?

I'm certain that this is not a problem but it will take a good deal of work with the correct equipment to actually measure the antenna pattern produced. I remember an episode of Mythbusters that they tried to cook a turkey by hanging the bird directly on top of the radar antenna. It certainly was one of their lamest episodes but they were not successful in getting even the slightest increase in temperature.

The key thing here really is that in a microwave oven, the microwave frequency used is ideal for heating water. So that frequency is a lousy frequency for use in radar. A fog or cloud would block the radar's ability to peer through the mist.

Is that so? Maybe I'm wrong, but I always thought microwave ovens and radar both use wavelength 2 - 3 cm.

Codey

Some radar does operate at the same frequency as a microwave oven. Weather related radar wants to react with water for obvious reasons.

Meant to add to #8 - I read once about a security guy at a radar station who got in the habit of sitting in front of the transmitter all night as it made him nice and warm. What he didn't know was that every so often the power was turned up by a factor about 10 . One morning they came in and noticed a nice smell of roast meat. Can anybody confirm? or rubbish it?

I believe one of the first things to happen is it blinds you, as the fluid in the eye is like egg-white, and goes solid and opaque when heated.

Codey

I heard that WWII radar technicians used to do some calibration on the radar planes standing in front of the antenna, with the radars ON... allegedly some of them might have got a bit roasted. Don´t know if it is true or just a myth!

Better watch out--it sounds as though your brain may already be fried....

Actually, the radar beam scans more or less horizontally, not much down onto your head below.

I suppose you could also worry about swimming beneath the sonar depth finder.

hmmmm, that popping sound between my ears... you say it´s normal?

It use to happen to me, and mama would always say, "shut up"

hundreds of radiofrequencies travel across our bodies all the time, my only concern was standing 30 cm under the RF emitter.... just that. PS; does anyone know why the wine I had in the glass in my hand did evaporate????? hahahahah. In regard to swimming: its just such a low frequency hat I believe it would do no harm...

When I am using the fly bridge, the radar goes OFF.

Fried brains, no worry. I agree with Tornado and Red Fred, but I'd rather take no risks. Gsm, Asbestos, """were also named SAFE""".

It all has to do with exposure, dose. Heat is not the issue.

you say it is safe, i take that. A free ride in front of the operating radar is available.... who is first in the row? Just wanna confirm Mythbuster's theory

As per the mythbusters comment above, they tied the turkey to a naval antenna which is MUCH more powerful then the standard commercial equipment. Due to the rotation of the antenna the temperature of the turkey actually decreased.

For recreational boaters the answer is "no problem" when you are on the bridge below the antenna; however, when you are on the bow at the same level as the antenna make sure it is not rotating...just in case. btw...Myth-Busters blew that one, the radar techs used to remove an access cover on the wave-guides which fed the multi-kW signal up to the rotating horn antenna, I would not want to stare into that!

Spam: This post was deleted because it contained advertising outside the Commercial Space forum. Please review Section 14 of the CR4 Site FAQ about advertising.

Thank you for your LINK! I WILL START STUDYING THIS LANGUAGE TODAY. IF LUCKY IN 6 OR 7 YEARS I´LL KNOW WHAT YOU MEAN!

Here you go, RF shielding suits, gloves hats etc

Doc! This is only a version of the "cellphone causes cancer" nonsense. MIcrowave only causes heating according its AVERAGE power applied to you.

So, relax, do the fishing and barbecuing, etc. I will come to you to get my broken leg fixed. Radar questions get fixed by electrical engineers, like me.

But, if you really worry, please stay off the boat, entirely. I will not even try to stop you from fretting as a pastime.

Leveles, I actually was concerned about RF damages to "vital organs" like mi stomach! never had my brain in mind!

Yeah, I this is too complex for me I´ll burn the boat down!

Very entertaining, and interesting. However, it covers a very wide range powerwise.

A traffic radar you run into any day emits some milliwatts continouos wave.

A boat radar produces a few watts average, 10kiloWatts peak pulse. Type certification is part of it, and properly installed it is claimed to produce less stray radiation, than a cellphone (see below). For comparison with something we are familiar with, a celltower produces a maximum of 60 watts continous power. That power is aimed at the horizon, for maximum coverage. Right below it you experience a few milliWatts.

A fighter plane's main radar is a kilowatt average, many megawatts peak. I would not turn one on in any enclosed space without the proper absorbing panels in place. Reflections from the hangar's metal walls can cause concentrations of power at the oddest spots.

A capital ship's radar is at least ten times more powerful than that. Peak power may reach many 10 MegaWatts.

The Soviet "Woodpecker" over the horizon radar was at the top of the heap for power.

Boat radar

Very entertaining, and interesting link that.

"unlike traditional radar, there is very little radiation (less than 10 per cent of the radiation emitted by a mobile phone). The Simrad ARGUS radar is available in 12kW and 25kW"

Some freaking mobile phone that salesman must have.

As long as you separate average power from peak pulse power, I am on the same wavelength. Example. A microwave oven puts out a kiloWatt continouosly. A radar puts out a few microsecond in every second, peak power. Seeing is with peak power's reflection return. Heating is with average power.

Tom is right. I used to work for Litton ETD building and testing these things and believe me, they can hurt. Just turn it off or move it to a higher position above the deck. Getting cooked doesn't feel like anything at the time, it's later, when your body catches up to what happened to it that you notice you were cooked.
Any frequency near 2.7Ghz is a potential cooker. Wattage determines the cook speed. The closer you are to the feed horn, the more cooking you will get. Period.
As for high power radar, even one operating well above 2.7Ghz can still cause a fry because it will begin to couple with other elements within your body besides the water that is coupled at 2.7GHz. All of the carbon in your body absorbs and couples somewhat to just about any frequency you can name. You will get hotter. What you don't want is to notice!!! Better safe than sorry or dead.

I will recommend my friend to get rid of the new radar and have a crows-nest built on top of the pole!

X band is 8 to 9 GHZ This is probably where it is at. S band is half that.

The difference in power between navigation and fire control, EW is 40 or more db.

As for the airport tech that was TACAN he was using, only the military uses "skin paint" for aircraft.

Hi Tom, thank you for your thorough response! When you say: " fitting a small, shaped metal ground plane/screen under the dish" what metal should I use: 304 SS or aluminum? or does this not matter? The radar´s antenna dish is fixed to a "mounting shelf" attached to a mast. If I got it right, the piece of metal should be placed between this shelf and the base of the dish. Does it have to exceed the the dish´s base perimeter? If yes: how many centimeters / inches would be OK?

Hi, There seems to be a general concensus that the radar on your boat won't cause any health problems and I'm sure the designers have done tests of the installation to confirm this. However the 'trap' in testing a radar is to assume all the RF is coming out of the front at right angles to the dish. When I ran safety tests on the helicopter radar mentioned earlier I found that some of the radiation from the wavegide horn was spilling past the top of the refector and shooting out past the centre pedestal straight into the face of the technician on the test bench. Can't remember the actual RF levels but they were about 5 times the UK safe limit! Your radar is probably inside a radome so you won't be able to see whether the horn is mounted on the bottom pointing up at the reflector or on the top pointing down at an angle. If it is pointing down towards the deck you might have a problem with RF leakage. Your aerial is probably mounted on a metal shelf attached to the mast so my suggestion about fitting a screen/ground plane under the aerial dish is probably redundant, but you would need to run a few tests on the actual installation to be sure.

I use an old RAHAM RadHaz measuring instrument for RF testing, (General Microwave Corp., New York). Looking at the pouring rain outside - I might be willing to vist sunny Argentina to test it all for you.

Incidently, getting a smack on the head from the aerial isn't as far retched as it sounds, my mate on the day shift popped his head through the hatch on the underground radar transmitter room and managed to stick his head into the path of the 11 ton aerial, (driven by two, 40hp motors). Luckily it was a glancing blow and only caused a small fracture. The worst part was filling in the paperwork afterwards!

Dear Tom, you are invited to sail in "Sunny Argentina" whenever you want! Thank you for your advises!

Was that the radar dome or a GPS dome? I cannot see what you refer to in the picture.

The biggest worry for RF radiation is the injurious heating of the human body upon exposure to EM radiation and the induction of voltages in metallic structures and objects which, under optimum conditions, may result in the propagation of RF arcs.

IEEE lists the exposure limits for non-ionizing radiation here:

http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1626482

The installation instructions should place the radar at the appropriate height.

Normally there is a statement for the applicable country of origin affixed to the housing of the antenna in a prominent location.

In general on Marine navigation RADAR the hazard comes from the rotating antenna hitting you. The average power is so low that there is no danger. The only time you might get into difficulty is if you disable the antenna rotation and look down the throat for an extended period. We had 2 Furunos, X and S band, they were the commercial grade, even so there was no problem. Navy FCC and OSHA have all gone over this many times and have found no significant problems. This is not to say that no problem exists, only that none have been detected.

All tests to the contrary, consist of asking a person with brain cancer how much he used his cell phone.

When we tested our HF antennas 1KW max power, the tech had to climb half way up the antenna and grab it before he reached an unacceptable level. It has been determined that 2 meters (150 MHz) is the worst frequency for absorption. As I recall this is because because people are approx 2 meters tall.

In conclusion our FCC/OSHA (Federal Communications Commission/ Occupational Safety and Health, have set various standards. It is ironic that "civilians" (non technical) are allowed to be exposed to less radiation than techs. I guess we are supposed to know better.

As others have pointed out, get the model number and go on-line. You will bee able to find the recommended installation and safety precautions.

If this is too difficult, bring the boat up, I'm on the east coast of PR mid 80s. We can go over the entire boat and verify it is safe. It may take a couple of weeks, I'll provide the beer.

I will dig out the appropriate tests and standards.

Thanks a lot for this info! IN regard to bringing the boat.... it will be probably cheaper to buy a new boat rather than paying for the fuel for such a journey! Just for fun, I calculated it will take about 4,000 hours to sail over there!

This post was deleted because it contained advertising outside the Commercial Space forum. Please review Section 14 of the CR4 Site FAQ about advertising.

-CR4 Admin

About 20 years ago I worked at a place that generated content for satellite tv. The general manger one day after a heavy snow decided to clean the 3 10meter uplink dishes by getting upon them and sweeping the snow off. One problem they were transmitting! The chief engineer came in just about the time he was finishing. He was fit to be tied at the gm.

I saw birds land on the guide rods that held the feed horn in place. They sit there for a little bit. But when they flew away they looked like they were drunk or they go out about a hundred yards and fall.

Another thing we do a few times for the newbies was to heat hotdogs in front of the feed horn.

The transmitters if I remember had the capability of 2 kw contentious power out.

When working in the dish yard we had to be mindful where we work and which dish was running.

Back to the gm, he left work about a year later and a few years later had cancer problems. Was it from cleaning the dishes? I don't know.

I'm curious about the concept of "contentious power"; does it argue a lot?

--Ed. C.

my bad...continuous

I rather liked it.

I've been wondering about the 'continuous' 'contention' for quite a while.

I wonder if "wave guides", or "horns", have any role in this radiation business.

As in; would it be less, or more, harmful to stand in front of a 2kW xenon lamp, or a 2kW pulse laser?

Or perhaps; deluged by 250 lbs of ball from a foot, or shot by one with 250 ft lbs of energy?

Then there is the conundrum of 'height = range'; so why not a few feet higher?

Ha ha... I would say the pulse laser would put a hole in ya. The xenon would just toast ya.

On the ball if I had too I'd take the one from a foot verse the same 250lb fired with 250 ftlb of energy though.

The rest ???? no comment.