Q-Mac HF-90 - Page 10

HF-90 Operation & Installation Guide
Not to scale
D
C B
A
2,000 km 800 km 20 km
Ionosphere
A to B - Recommended working frequency is 3 MHz
A to C - Recommended working frequency is 5 to 7 MHz
A to D - Recommended working frequency is 9 to 12 MHz
NIGHT TIME:
Sun is lower
Ionosphere is
lower
Optimum
working
frequency is
lower
6
Section 2.2