Radar Dishes?

Question

Do radar dishes that are for airport turn in different directions every so often? The one out here where I live looks like it, and even up close it changes direction sometimes, and I am not sure if it is just an optical illusion or not.

Answer 1

Most surveilance radars turn continuously. You can't reverse the direction without having specific support for that in the antenna drive, that would require a bigger, tougher gearbox and much stronger motors. Far more importantly the software that renders the images and correlates tracks on the radar screens would have to be able to deal with the random motion. For primary search radar, especially that which has ECCM, you need to know where your returns occurred in time, and if you keep randomly changing the direction the dish moves then you have to have a method for trasking that information along with the pulse returns. For SSR there's just no point in doing anything except go round and round in one direction.

Honza_Urban, you have no clue what a synthetic aperture radar is, do you? A synthetic aperture radar is an airborne radar that accumulates data as it moves along a track so that it can integrate the returns over a long distance to give better range resolution. Read the wikipedia article below.

Phased array radars don't need to move, they steer the beam electrically (electronically if you like) and you can't tell to look at them where they are actually 'looking'. Pave Paws is a good example, they just sit like big pyramids, but the beam is scanning all the time. Some phased arrays turn too, you get best gain normal to the antenna (straight out the front) so squinting sideways doesn't give you best detection range.

Answer 2

The Air Traffic Control Radars rotates 360 deg. But aImost often you can not see how it rotates because it is usally covered in a white, dome shaped environmental protection to protect it against the elements. And if it is not covered, its rotation is really obvious its like a carousel.

Now you may see other dish/ parabolic type antennas that are stationary, these are microwave communication antennas. Which are used to transmit, relay and receive ultra-high frequencies radio signals that carry data and information. UHF and higher signals travel in a line of sight or straight line pattern just like the RADAR signals. Though they are stationary (they don't rotate like a carousel) their orientation are sometimes adjusted. This is done because of the bending of the radio signals due to athmosphere.

Now if you are fond of looking directly at RADAR antennas, I suggest you refrain from doing that. Though it is not yet proven. But it is speculated that looking directly on RADAR antennas can cause cataract. Better be safe than sorry...

Answer 3

there are several types and several technologies of radar dishes.
the modern so called synthetic aperture radars do not move at all, its antenna is fixed and the change in direction of transmitted beam is done electronically, like the beam that is making picture in your TV.

the dish of older radars turns so fast so it is able to cover the designated airspace in a designated sample rate, typically twice a second. this means ,the radar is able to get a position of aircraft twice in the second.
some radars such as Precision Approach radars just scan the designated descent path to the runway and tilt just a 15 degrees vertically and do not move horizontally at all.

Imagine that the radar antenna is a flash light and the radar operator can only see what the flashlight illuminates. when you are in a dark room, zou scan it with the flash light, but you remeber position of static objects, such as tables chairs, etc. try chatching the cat or a rat using a flashlight :)
that's why.

the big antennae are surveillance radars, scanning the airspace around them, so they turn around.

the RPM rate of the antenna influences the radar range, too, but it would need a more detailed description.

Answer 4

The dish your speaking approximately is the standard Radar transmitter. it is the RADAR that shows the Air site visitors Controllers the place an plane is on the concern of the airport. there's a smaller radar transmitter on spectacular of the massive one called the secondary radar. The secondary sends out a request to the plane transponder telling the transponder to respond. whilst the transponder responds to the request it supplies the Squawk or transponder set huge style to the standard radar pc. they are then joined mutually in the desktops so as that the standard objective (BLIP) on the radar has a different code that identity's that plane for ATC. so which you're finding at 2 radar structures on a similar time. the standard radar dish has a curve and the secondary is flat confronted on spectacular of the different one.

Answer 5

Some radars do and some don't

mostly the ones in airports do.
further reading
http://en.wikipedia.org/wiki/Radar

Answer 6

Yes.. How else are controllers gonna get a 360 view on there scope?