Naval Applications of High Frequency Over-the-Horizon Radar


  • James M. Headrick,

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      James M. Headrick is the senior scientist for HF OTH Radar at the Naval Research Laboratory. He has a B.S. degree in Electrical Engineering from the University of Texas and an M.S. degree in Electrical Engineering from the University of Maryland. Mr. Headrick has been an instructor at the MIT Radar School and the George Washington University, and is a Commander USNR (retired). For twenty years he was head of the Radar Techniques Branch, responsible for the HF over-the-horizon radar work in the Radar Division of the U.S. Naval Research Laboratory, where nearly all of the fundamental capabilities of OTH radar were first discovered and demonstrated.

  • Joseph F. Thomason

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      Joseph Thomason earned a B.S.E.E. degree with distinction from the University of Mississippi in 1963 and did post graduate work in Electrical Engineering at the University of Maryland. Mr. Thomason began work on high-frequency radar at the Naval Research Laboratory, Washington, D.C. in September 1963 and is currently head of the Systems Section of the Advanced Radar Systems Branch. The work at NRL on HF radar continues and serves as the basis for this paper.


The Navy now has in operation a relatively new sensor, the AN/TPS-71 radar, that can provide wide area surveillance over a more than one million square mile area and out to ranges of 2000 nmi. This radar was procured primarily to support Naval Battle Groups by providing early warning of airborne threats. This radar is called ROTHR for Relocatable Over-The-Horizon Radar. In addition to the primary mission this type of radar has other capabilities including remote sea and weather sensing.

HF radar that employs the ocean surface attached wave offers a means for detection of sea skimming missiles, aircraft, and ships at shorter but beyond line-of-sight ranges with a ship-borne installation. A current Advanced Technology Demonstration will show applicability of this sensor.