What is a characteristic of skywave signals arriving at your location by both short-path and long-path propagation?
Periodic fading approximately every 10 seconds
Signal strength increased by 3 dB
The signal might be cancelled causing severe attenuation
A slightly delayed echo might be heard✓الإجابة الصحيحة
الشرح
Short path and long path differ by thousands of kilometers of travel, and at 300,000 km per second that difference is tens of milliseconds, which the ear resolves as a distinct echo behind the main signal. Cancellation is not the outcome because the two arrivals are separated in time rather than being coherent equal-amplitude signals.