NZART Amateur Examination                     page 9          NZARTX07 Security code 249733
- A half wave antenna cut for 7 MHz can be used on this
band without
change:
- 10 metre
- 15 metre
- 20 metre
- 80 metre
- On VHF and UHF bands, polarisation of the receiving
antenna is important
in relation to the transmitting antenna, but on HF it is relatively
unimportant
because:
- the ionosphere can change the polarisation of the signal
from moment to moment
- the ground wave and the sky wave continually shift the
polarisation
- anomalies in the earth's magnetic field profoundly affect
HF polarisation
- improved selectivity in HF receivers makes changes in
polarisation redundant
- The highest frequency that will be reflected back to the
earth at any given
time
is known as the:
- UHF
- MUF
- OWF
- LUF
- The layer of the ionosphere mainly responsible for long
distance
communication is:
- C
- D
- E
- F
- The 80 metre band is useful for working:
- in the summer at midday during high sunspot activity
- long distance during daylight hours when absorption is
not significant
- all points on the earth's surface
- up to several thousand kilometres in darkness but
atmospheric and
man-made noises tend to be high
- The distance travelled by ground waves in air:
- is the same for all frequencies
- is less at higher frequencies
- is more at higher frequencies
- depends on the maximum usable frequency
- VHF or UHF signals transmitted towards a tall building
are often received
at a
more distant point in another direction because:
- these waves are easily bent by the ionosphere
- these waves are easily reflected by objects in their path
- you can never tell in which direction a wave is travelling
- tall buildings have elevators
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