Phase interaction in the D layer

Researchers at the Pennsylvania State University are studying the D layer of the ionosphere with a technique that depends on phase interaction of radio signals. Observations are made by comparing two radio pulses of the same frequency that have been reflected from the D layer. One pulse is “disturbed” by interaction in the ionosphere with a signal of a different frequency, and the other is not. What happens in the interaction between the signals is determined by the electrical characteristics of the layer.