AE - "Fyrsti hluti" Flashcards
Electromagnetic wave consists of an oscillating electric fiel (E) an an oscillating magnetic field (H), their propagation speed is the ____.
speed of light.
Hvað af þessu eru “directional antenna?:
a) slotted planar antenna
b) helical antenna
c) dipolar antenna
d) loop antenna
e) slotted planar array antenna
f) sense antenna
g) parabolic antenna
a) slotted planar antenna
b) helical antenna
d) loop antenna
g) parabolic antenna
What is the most suitable length of a dipole antenna?
1/2 wave length
Hver er formúla wave length?
propagation speed / frequency
What kind of antenna does GPS use?
Helical
Why does GPS use a helical antenna?
Signal has circular polarization
Polarization: Orientation of the plane of oscillation of the ____ of the electromagnetic wave.
electrical component (E)
Hvaða antenna hefur þessa lýsingu? “Virtually eliminates lateral lobes and as a consequence concentrates more energy in the main beam”
Slotted antenna
A horizontally polarized electromagnetic wave has the E field ___.
horizontal
The flat plate antenna generates more/less side lobes than the parabolic reflector.
less
Hvernig antenna notar ADF receiver?
Loop antenna
Hvað er propagation speed mikill?
300,000,000 m/sek
What is the most suitable length of a Marconi antenna?
1/4 wave length
E er __ field og H er __ field.
electric, magnetic
Í primary radar system ertu með tvö loftnet (eitt fyrir transmitting og eitt fyrir receiving) eða eitt?
eitt
1 MHz = _ Hz
1.000.000
Farðu með Hz flokkana frá hæsta Hz og að neðsta flokki
EHF, SHF, UHF, VHF, HF, MF, LF, VLF
Hvað kallast einn milljarður Hz?
1 GHz
Hvernig er best að muna töfluna um tíðnir frá þeirri lægstu og upp að þeirri efstu?
Ef þú sérð fyrir þér töfluna þá byrjar hún á VLF (3-30 kHz) svo fer hún bara upp skalann, næsta er 30-300 og svo 300-3000 og svo bara aftur 3-30 og hringurinn. Eina sem þú þarft að passa er að það eru bara þrjú neðstu sem eru kHz, svo þrjú mHz og svo bara tvö Ghz.
Phase modulation is used in __ where the phase of the carrier wave is reversed.
GPS
Skilgreining á hverju er þetta?: The addition of information onto a radio wave during transmission
modulation
UHF waves appear in the frequency spectrum __.
300Mhz - 3000Mhz
Medium waves appear in the frequency spectrum __.
300 Khz - 3000 Khz
Hvað er þetta kallað?: Interrupting the carrier wave to break it into dots and dashes?
“Keying”
Þetta er skilgreiningin á hverju?: A complete series of values of a periodical process.
cycle
Hvað kallast þetta?: The angular difference between the corresponding points of two cycles of equal wavelength, which is measurable in degrees.
Phase difference
Hver er formúla wave length?
Propagation speed (m/s) / Frequency (Hz) (progagation speed er alltaf 300.000.000)
Radio waves travel at the speed of..
light
EHF waves appear in the frequency spectrum..
30 Ghz - 300 Ghz
Frequency is the..
number of cycles per second
Hver er mælieining frequency?
Hz
What term describes maximum deflection in an oscillation?
amplitude
Speed of a radio wave is
a) 300.000 m/s
b) 300.000 km/s
b) 300.000 km/s
Maximum deflection of a wave is called it’s..
amplitude
The first symbol (ITU categorization) indicates the..
type of modulation of the main carrier
Skilgreining á hverju er þetta?: Distance travelled by a radio wave during one cycle of transmission.
Wavelength