As Gene will tell us, radio amateurs have inherited the bands that early radars used to detect enemy bombers approaching the British homeland, also the UHF frequencies used by the Germans to track bombers approaching the German homeland. Radar principles are still being used by radio amateurs for communications purposes. Meteor scatter is a form of the forward scatter radar operation. Moon bounce is a back scatter radar mode. Rain propagation at 10 and 24 GHz uses rain as a forward and backscatter scatter reflector medium.
During the "Cold War" around the world propagation was used for classified research that today can be disclosed and discussed in public. The United States used rocket exhaust ionization to detect the launch of ICBM rockets before there were satellites to detect the visible and near visible ICBM signatures. Russia used the HF bands for over-the-horizon backscatter radar operation during the 1960 and 1970 time period to detect missile launches by the United States. Many times the 20 meter amateur band was made useless by the Russian radar operation. There was not one Russian "Woodpecker" but several working in synchronized fashion. Nuclear testing was monitored by the United States and their allies using HF backscatter radar systems.
There is a long history of amateur radio operators sharing the HF bands with defense projects, often without knowing that the defense radars are in operation. The high power radiated by the defense radars produced interesting ionospheric propagation modes that were unknown to early amateurs but are known today. The defense related programs and the HF propagation modes that have been discovered over the past 75 years since radar's inception will be discussed.
A recent observation made by the presenter using a radar sounding technique on the 80 meter CW band was published in QST. There is some question as to what the propagation event was and three theories are prevalent. The first theory to be discussed is that the signals propagated around the world. The second theory is that the propagation delay was caused by the signal being trapped in a plasma tube. The third theory is that the signal went half way around the world and was reflected back by a region of intense ionization.
Gene Greneker was first licensed as a Novice amateur radio operator in 1957 as K4MOG at the age of 15. He still holds that call as an Extra Class license operator. Before FCC License structure change he held a First Class Radio Telephone License with Radar Endorsement and a Second Class Radio Telegraph License. He worked his way through college as a broadcast engineer, but never to sea as a shipboard radio operator.
He received a Masters of Science degree from the Georgia Institute of Technology and went to work for the Georgia Tech Research Institute conducting radar research in 1971. During his 33 year career, he conducted radar related research for all of the armed services and a number of government agencies. He has authored over 90 Conference papers, and Technical reports. He is a Senior member of IEEE and holds six US Patents. He retired as a Principal Research Engineer and Director of the Severe Storms Research Center at Georgia Tech in 2004. He started his own business, RADAR Flashlight, LLC, where he continues research on through-the-wall radar under contract to the Defense Advanced Research Projects Agency.