Q-MAC Electronics Pty Ltd HF90 Manuale Utente
HF-90 Operation & Installation Guide
A
Not to scale
20 km
2,000 km
800 km
D
C
B
The following illustrations show the characteristics of
ground-wave and sky-wave propagation during the day time
and night time. Each illustration clearly shows the level of
the ionosphere.
In both illustrations Station A communicates with Stations B,
C and D. Propagation from Station A to B is via ground-
wave. You will notice how the time of day, and level of the
ionosphere, does not affect ground-wave.
Propagation from Station A to C and D is via sky-wave. You
will notice how the time of day, and level of the ionosphere,
affects sky-wave.
Under each diagram there are recommended working
frequencies listed. Please note that these will vary according
to time of year and other factors. They are intended only as a
guide and are subject to change.
ground-wave and sky-wave propagation during the day time
and night time. Each illustration clearly shows the level of
the ionosphere.
In both illustrations Station A communicates with Stations B,
C and D. Propagation from Station A to B is via ground-
wave. You will notice how the time of day, and level of the
ionosphere, does not affect ground-wave.
Propagation from Station A to C and D is via sky-wave. You
will notice how the time of day, and level of the ionosphere,
affects sky-wave.
Under each diagram there are recommended working
frequencies listed. Please note that these will vary according
to time of year and other factors. They are intended only as a
guide and are subject to change.
8
Section 2.2
Ionosphere
A to B - Recommended working frequency is 3 MHz
A to C - Recommended working frequency is 7 - 9 MHz
A to D - Recommended working frequency is 13 - 16 MHz
A to C - Recommended working frequency is 7 - 9 MHz
A to D - Recommended working frequency is 13 - 16 MHz
DAY TIME:
Sun is higher
Ionosphere is
higher
Optimum working
frequency is
higher
Radio propagation illustrated