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A common phenomenon of HF signal propagation is fading. T3A08 What is a likely cause of irregular fading of signals propagated by the ionosphere? A. Frequency shift due to Faraday rotation B. Interference from thunderstorms C. Intermodulation distortion D. Random combining of signals arriving via different paths This is similar to multipath distortion of VHF and UHF signals, but in this case, the signals are bouncing off the ionosphere, and because the ionosphere is constantly changing, signals