Physics Colloquium

Tom Gaussiran, Applied Research Laboratories, UT-Austin

"Radio Frequency Propagation and the Ionosphere"

4:00pm, The John A. Wheeler Lecture Hall (RLM 4.102). Coffee and cookies will be served at 3:45pm in RLM 4.102

Abstract: The ionosphere is a cold plasma which nominally stretches from 60-1000 km altitude. HF radio waves cover the frequency band of 3-30 MHz (10-100 meters). Long distance transmissions of HF radio waves via the ionosphere dates back to 1901 when Marconi sent his famous 's' transmission from Cornwall, England to Newfoundland, Canada. At the time Marconi believed that the transmission was due to a ducting phenomenon. Since that time radio communications via the ionosphere has often been viewed as mysterious and is often explained by folklore. Much of this is actually easily understood if one understands the nature of a birefringent medium such as the ionosphere. In this talk we will consider HF propagation off of the ionosphere, the impact of ionospheric layers, as well as Traveling Ionospheric Disturbances (TIDs).