dish


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dish

A type of antenna used in radio telescopes and consisting of a large spherical or parabolic metal reflector, usually circular in outline, by means of which radio waves are brought to a focus above the dish center. The waves are collected at the focus by a secondary antenna, called a feed, or are reflected from a curved secondary to be brought to a focus elsewhere (see Cassegrain configuration). At low radio frequencies the feed may be a dipole mounted in front of a small reflector; at high frequencies it is usually a horn antenna (see waveguide). The signals picked up by the feed are transferred by means of the feeder to the receiver for amplification and analysis. Both the angular resolution and the sensitivity of the telescope to a point source increase with the area of the dish.

The dish is usually mounted so that it can be steered to point in different directions and can be made to track a moving object. Some dishes, however, can move in only one coordinate and rely on the Earth's rotation to provide coverage in the other coordinate. The 305-meter dish mounted in a natural hollow in the ground at the Arecibo radio telescope, Puerto Rico, achieves partial beam steering by moving the feed.

dish

[dish]
(electromagnetism)

dish

A parabolic reflector type of radio or radar antenna.

dish

A bowl-shaped antenna that receives signals from a satellite. See DBS and parabolic antenna.
References in classic literature ?
Father Snail could not speak, he was too much affected; and so they gave them as a dowry and inheritance, the whole forest of burdocks, and said--what they had always said--that it was the best in the world; and if they lived honestly and decently, and increased and multiplied, they and their children would once in the course of time come to the manor-house, be boiled black, and laid on silver dishes. After this speech was made, the old ones crept into their shells, and never more came out.
It has taken me nearly six years to prepare these precious grains of dust, but the little heap on that dish is worth the price of a kingdom and many a king would give all he has to possess it.
She answered "All right, Ethan," and he heard her singing over the dishes as he went.
I have selected a few dishes, and made out a little bill of fare, which will go home in the steamer that precedes me, and be hot when I arrive--as follows:
"That big dish that is smoking farther off," said Sancho, "seems to me to be an olla podrida, and out of the diversity of things in such ollas, I can't fail to light upon something tasty and good for me."
The table was comfortably laid - no silver in the service, of course - and at the side of his chair was a capacious dumb-waiter, with a variety of bottles and decanters on it, and four dishes of fruit for dessert.
He looked to see if the dish of beans was still there; the dish of beans had disappeared.
Alice had seated herself on the bank of a little brook, with the great dish on her knees, and was sawing away diligently with the knife.
AND instead of a nice dish of minnows--they had a roasted grasshopper with lady-bird sauce; which frogs consider a beautiful treat; but I think it must have been nasty!
There were several other dishes on the table, all carefully covered, and when the time came to remove these covers they found bread and butter, cakes, cheese, pickles and fruits--including some of the luscious strawberries of Oz.
When the meal was ended Anne came out of her reverie and offered to wash the dishes.
And Natasha began rapidly taking out of the case dishes and plates wrapped in paper.