時間：2011-03-11 23:11來源：藍天飛行翻譯 作者：admin 點擊：次
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Two antennas, arranged so they are at approximately right angles to each other, radiate low-frequency signals in the form of two figure eights. One antenna transmits the Morse code letter A (. –), and the other transmits the letter N (– .). A pilot flying an airplane in the area where the two signals overlap hears a solid tone. As the airplane moves to one side or the other, the letter A or N predominates, and this indicates to the pilot the side to which he has moved. The area of overlapping signals, usually about three degrees wide, is called the “beam.” antenna. A conductor used with a radio transmitter or receiver to radiate or receive electromagnetic energy. antenna coupler (radio equipment). A special transformer used to connect an antenna to a radio receiver or transmitter. The antenna coupler allows the maximum amount of energy to be transferred between the antenna and the receiver and between the transmitter and the antenna. antenna current. The amount of radio-frequency current flowing in a radio antenna. antenna duplexer. A device that allows two transmitters to use a single antenna without either transmitter interfering with the other. antenna lens (microwave antenna component). A device installed near a microwave antenna that focuses the radiated energy in much the same way a glass lens focuses light waves. antenna matching (radio installation). The process of matching the impedance of a radio antenna with the impedance of the transmission line carrying the signal from the transmitter to the antenna. For the maximum amount of energy to be transferred, the impedance of the transmission line must be the same as the impedance of the antenna. Antenna matching is done by the selection of proper components in the antenna system. antenna wire (aircraft radio antenna). A type of wire having a low electrical resistance and a high tensile strength. Copperweld, a form of copper-plated steel wire, is often used for antennas. antiblush thinner (aircraft finishing material). A slow-drying thinner used with certain types of lacquer or dope to slow the evaporation of the solvents. When the solvents evaporate too rapidly, the evaporation drops the temperature of the surrounding air enough to cause moisture to condense out of the air. This moisture causes the dope or lacquer to blush. anticathode (X-ray tube component). The electrode, or target, in an X-ray tube which, when struck by the stream of electrons from the cathode, emits X-rays. anticollision light. A flashing light on the vertical fin or belly of an aircraft. Anticollision lights increase the visibility of the aircraft, especially at night and under conditions of poor visibility. anticollision radar. A radar system installed in an aircraft to warn the pilot of the presence of any targets that could be on a collision course with the aircraft. anticyclone (meteorology). An area of high atmospheric pressure in which the air has a closed circulation. In the northern hemisphere, the circulation of air out of a high-pressure area is clockwise (anticyclonic). In the southern hemisphere, the circulation out of a high is counterclockwise (cyclonic). At the equator, the circulation is indefinite; it can go either way. |
