I understand they can cause interference with other air radars and devices, and about microwave ovens. but, radar. How can it be "lethal"? It just burn you to death? Why don't cell phone towers that are spread out all over the place hurt you (or can they)?
Mildred's people: Your question undoubtedly comes from here…
Others have given excellent answers here, though you may be missing the broader concept of what electromagnetic radiation is and why it can hurt you. All radars (not just air search), use microwave energy. All microwave energy is only one type of ELECTROMAGNETIC energy. Other examples of electromagnetic energy include natural ELF from the Earth, visible light, infrared rays (the phenomenon we most often feel as heat), radio signals, cell-phone and Wi-fi signals, (also considered radio signals) ultra-violet rays, x-rays, and many more. The sun is the largest producer of natural electromagnetic energy in our solar system! You know what happens when you stay out in the sun too long, or put food in the microwave oven. That's one over-riding characteristic of ALL electromagnetic energy: in the right doses, it heats things up, particularly "soft" substances like tissue and liquid. But an industrial laser uses em energy that can heat and cut through sheet metal! So you can see why it can be dangerous to living things.
A radar that is powerful enough can burn you, and even kill you. The worst would probably be a fire-control radar, such as would be found on a naval warship or military aircraft. It's a concentrated, fixed narrow beam of energy, transmitted in many kilowatts or megawatts, and if you stood directly in front of it, it could burn you to death in a matter of seconds. On the other hand, a small radar such as on a private boat uses very low power, and you may only sense a slight warming, if anything.
Cell phone tower antennae also use microwaves, but they are transmitted at power levels far lower than most radars. The signal also fans out from the antenna, whereas a radar signal can be very narrow and concentrated in power. However, tower climbers will still de-energize the antenna mast before repairing or installing additional antennae. Working that close to an ENERGIZED antenna for 3 hours might not kill a worker outright, but it could raise his body temperature enough to give him symptoms of heat stress… namely fatigue and a fever, and this has happened several times.
It doesn't have to be microwaves, either. There have been telecom workers injured by em radiation while working on plain old FM radio towers. (It turns out VHF radiation is actually worse for humans than microwaves). Anybody who works with medical x-ray equipment knows how dangerous those devices can be if improperly used. It all depends on how much electrical current is used to produce the radiation, what frequency is being used, how close you are to the "thing" radiating it, how long you stand there getting nuked, and how much radiation your body actually absorbs.
Sorry for the rant, but you asked (again), and I love this stuff.
Radar signals spread out as they leave the antenna, just as light spreads out from a flashlight. The signal strength deteriorates by the square of the distance, so as you move away it drops off rapidly Some radar antennas, if you stood right in front of them they would fry you like a microwave oven (actually a lot more powerful!) but from 1/4 mile away the power is almost nothing. I'm not sure about cellphone towers. I don't think they're that powerful since they only cover a relatively small area. But they're mounted in such a way that you never get that close to them.
The signal from a cellphone is really miniscule. Some people believe that if you walk around with a cellphone against your head for an hour or two a day that tiny signal over hours and hours can hurt you, but there's no real evidence of that. The latest warning, apparently based on some real evidence, is that carrying a cellphone in your front pocket for months and months can damage a guy's fertility.
If you stand right in front of a high power radar that's operating you will find yourself being microwaved.
This is why they tend to put them up high and well away from where people might be. The radar dish over on the other side of the air field isn't going to cause any issue because of the inverse square law. As you get further away from the source it gets much weaker. 1 m away it might be dangerous. 100 m away it's dispersed so much that it's safe.
There is a story that microwave ovens were invented after WW2 radar technicians found the chocolate bars in their pickets melted when they walked in front of the radars they were testing.
If you "understand microwave ovens" then why don't you understand radar? Some Doppler Radar operates at 2.4 gig (same as wifi and microwave ovens and other things).
Most Microwave ovens run about 1000-1500 watts .. radar even more! If you are close enough to an active radar antenna, you will get burns! Wifi runs way way less power and you can hold it in your hand with no ill effects because of the POWER level. (most routers are less than 100milliwatts).
Here is a good article so you can learn more… http://www.who.int/peh-emf/publications/…
Most "air radars" are far enough away from people that very little radiation is "aimed" at people. Thus they don't posse a major issue. (Unless you work on them!) Get directly in the aimed front of a live antenna at a couple of feet… you just messed up.
Absolutely they are at least the old types are!
Stand in front of one for a prolonged period and you will get slowly fricasseed. Repeated doses are similar to X-ray, they can cause genetic damage.
For this reason they are coned off if being tested on the ground and are not normally switched on until you line up for take-off, in the final pre-takeoff checklist.
However, the latest radars use a broadband technology, similar to 4G. I don't pretend to know how this works but it has essentially no emissions and is quite safe very close to people.
It has the distinct advantage of showing close objects, without blinding the radar with strong returns, so can, for instance, be used taxing in fog on the ground.
I never used it, but pilots I know who have, reckon it is a great improvement on older types.
As an airplane leaves the runway to taxi back to parking, the radar is placed on standby –
And on departure, it is only operated from the before takeoff checklist –
Pilots do not operate airplane's weather radar near personnel and ground crew –
It is so specified in our operations manuals –
Cell phone towers, electrical lines and even cell phones themselves do harm. The harm is gradual and over many years so it is not noticeable until you get cancer.