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 ?
Mine is dishes and dusters, and envying girls with nice pianos, and being afraid of people.
And then there were apple pies, and peach pies, and pumpkin pies; besides slices of ham and smoked beef; and moreover delectable dishes of preserved plums, and peaches, and pears, and quinces; not to mention broiled shad and roasted chickens; together with bowls of milk and cream, all mingled higgledy- pigglely, pretty much as I have enumerated them, with the motherly teapot sending up its clouds of vapor from the midst-- Heaven bless the mark
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:
Dear Jane, how shall we ever recollect half the dishes for grandmama?
One end, indeed, reflected splendidly both light and heat from ranks of immense pewter dishes, interspersed with silver jugs and tankards, towering row after row, on a vast oak dresser, to the very roof.
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.
After ordering a variety of dishes (which never came) to be placed on the table, and discussing the merits of each one, the Barmecide declared that having dined so well, they would now proceed to take their wine.
They then lifted up a fine white cloth covering fruit and a great variety of dishes of different sorts; one who looked like a student said grace, and a page put a laced bib on Sancho, while another who played the part of head carver placed a dish of fruit before him.
It signifies nothing whether you eat much or little -- whether you have ten dishes or one -- it is always the same price.
nor taste those nice little savory dishes which my dearest wife knew how to serve up?
So much for the first course; several other dishes followed it, some of which were positively delicious.
The table-linen was of the most beautiful damask, and the plates and dishes of real china, an article of great luxury at this early period of American commerce.