Kenwood R-600 Instruction Manual page 11

Type of Radio Wave Propagation
Frequency Band
Short-distance
Long-distance
Very Low Frequency
{under 30 kHz)
Surface wave lonospheric wave
Low Frequency
(30 ~ 300 kHz)
Surface wave lonospheric wave
Medium Frequency
{300 ~ 3,000 kHz)
Surface wavelonospheric wave
High Frequency
(3 30 MHz)
Table 1.
The state of the ionized layer is closely associated with the
relative positions of the sun and the earth and also with
the activity of the sun. The D and E layers almost disap-
pear at night, while the F layer changes in height and den-
sity depending on daytime or night time, and changes the
upper frequency limit to be reflected. Occasionally,
"clouds" of ions will drift through the E layer, causing
strong signal propagation (called "sporadic E propaga-
tion.") over several hundred miles, usually between 15
MHz and 30 MHz, and sometimes higher in frequency.
Communication satellite
jving antenna
W
Res
lonospheric wave
lonospheric wave
Such a phenomenon also occurs with changes in seasons
or rotation cycle of the sun as well as unusual activities of
the sun (change in the sunspot cycle every 11 years, unex-
pected explosion on the sun, etc.). To cope with this, inter-
national short-wave broadcast stations change their fre-
quencies according to seasons or directions of radio
waves, or use different frequencies at the same time for
broadcasting the same program.
Frequency Distribution in the Broadcast and Amateur
Bands. |
The R-600 receiver covers a wide frequency range extend-
ing from 150 kHz, to 30 MHz, to receive the internationally
determined frequencies assigned to many broadcast and
communications services. .
As shown in the Frequency Allocation' Chart, Fig. 4-2,
broadcast and Amateur radio station frequencies are allo-
cated in specific bands expressed.in megahertz (MHz) or
wavelength in meters (m). Also in Fig. 4-2, the frequencies
of "other stations" are assigned for fixed station business
use, marine mobile, aviation mobile, land mobile, radio bea-
con stations, etc. The following relationship exists bet-
ween frequency and wave length:
300 ;
Frequency (MHz)
300,000
Frequency (kHz)
300
Wave length (m)
As will be seen from this relationship, the 31 m band and
9 MHz band, for example, are the same shortwave broad-
cast band, covering the range of 9,500 kHz to 9,775 kHz.
Wave-length (m) =
Frequency (MHz) =