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Frage |
Antwort |
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Period |
t Time of one full cycle expressed in seconds. 1/f (Hz) = (s) |
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Frequency |
Number of period or cycles per second expressed in Hertz (Hz). 1/period t (S) = (Hz) |
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Amplitude |
maximum positive or negative magnitude of a wave (V, A or W) |
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peak to peak |
max to min amplitude |
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Phase |
current state of a wave in degrees through its 360 degrees cycle |
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Speed |
v Probagation speed, depending of type and medium |
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wavelength |
Landa, realation between propagation speed and period. C/f (Hz) = 300000000 /f = (m) |
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LF and MF Band |
Applications for aviation: radio navigation aid, NDB |
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HF Band |
applications for long range voice and data communication |
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VHF Band |
Applications for Aviation: Voice communications 118-137 Mhz, Nav-aids: VOR, ILS Localizer and markers. Military com: 230-400 Mhz |
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UHF Band |
applications for aviation: NAv-aids: ILS glide path, DME, GPS, PSR SSR |
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SHF Band |
applications for aviation: Radio link, radio altimeter, weather radar, SMR 8surface movement radar) |
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Range of sections of frequency bands |
alwasy from 3-30 or 30-300 (kHz, MHz, GHz) |
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Antenna principle |
transmitter: converting alternating current in radio waves, receiver: converting radio waves in alternating current |
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basict antenna types |
dipole, monopole (or ground plane), loop and slot antenna |
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radiation pattern |
each antenna type has its characteristics radiation pattern depending on size and polarization |
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VHF Voice com antennas |
-ground equipment: vertical half landa =dipole, quarter landa = monopole antenna |
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Cone of silence |
the cone of silence is a region in the spherical radiation pattern of an antenna with weak radiation (TX) or reception (RX). Its effect can be reduced by bending a dipole antenna to a V |
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Antenna directivity |
the directivity of antennas cn be formed in two ways: with passive elements as reflectors and directors, - with antenna arrays |
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gain |
is the increase of range in one dimension compared with a isotropic antenna. Gain = d/R |
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Remme
