Mr. James Milton Headrick has been honored with the 2011 Picard Medal for pioneering the international effort to develop high-frequency over-the-horizon radar, combining extraordinary skills in electronics, antenna theory, electromagnetic wave propagation and hands-on experimentation. Headrick retired from the Naval Research Laboratory Radar Division in 1992, but continued to work part-time as a rehired annuitant, until he passed away in February 2011.
IEEE presents the Dennis J. Picard Medal for Radar Technologies and Applications each year to recognize outstanding accomplishments in advancing the fields of radar technologies and their applications.
Headrick's pioneering work on the international effort to develop high-frequency, over-the-horizon radar, began at NRL in the late1940s with experiments on developing more stable oscillators and measurement of the attenuation through rocket exhausts as a function of altitude.
In the early 1950s Headrick started work on aspects of a program that led to high-frequency, over-the-horizon (OTH) radar. The Radar Techniques Branch where he worked at NRL tackled the problem of trying to significantly increase radar range by employing coherent Doppler processing of several seconds of radar data. By 1956 NRL completed a set of experiments that showed first that VHF and HF radar echoes could be coherently processed and second that the ionosphere is often sufficiently stable for a radar operating in the high-frequency band (3 MHz to 30 MHz) to be capable of detecting and tracking targets beyond the normal microwave radar horizon. Later in 1961 NRL began operation of their single site, over-the-horizon radar located on the shores of the Chesapeake Bay. This radar was called MADRE, for Magnetic Drum Radar Equipment, and with its continued development, NRL first discovered and demonstrated nearly all OTH radar capabilities such as nuclear test detection, ICBM launch detection, aircraft detection and tracking, ship detection and tracking, and utility of the sea echo. For their work in discovering and demonstrating the fundamental capabilities of high-frequency OTH radar, J. M. Headrick, F. M. Gager, and R.M. Page received an NRL 75th Anniversary Award for Innovation in 1998.
The MADRE program involved 20 to 30 NRL engineers, physicists, and technicians, plus important contributions from contractors. Headrick's major contributions to this project included:
- Experimental demonstration of the coherence of aircraft target echoes - Headrick assembled a VHF radar and recorded Washington area aircraft echoes at an intermediate frequency. An analogue crosscorrelator was used to show the echoes to be near identical with what was transmitted. This may seem silly now, but in 1950 people seriously questioned the coherence of the echoes.
- An analysis that predicted success for an achievable size radar - Headrick used the Single Side Band high frequency radio signal strength data furnished by the Strategic Air Command to estimate the antenna gain and transmitter power required for a skywave OTH radar. This along with other analyses were used to specify NRL's MADRE reseach radar.
- Investigation of ballistic missile launch signatures - Headrick led a team that observed a variety of missiles launched from Cape Kennedy, Wallops Island, White Sands, and Vandenburg. The launch signature features were described and their association with events explained.
- Development of computer techniques for planning and managment of skywave OTH radars - Headrick initiated a program with the Institute for Telecommunications Science aimed at achieving a model for analysis and prediction of performance. Starting with ITS propagation programs, OTH radar data was used to show what was needed for a radar model. Great utility has come from its use in new system design and performance studies for different locations.
- Demonstrated that echo from the sea provided a most useful radar reference target - Early on, daily examination of the North Atlantic sea echo with the MADRE radar suggested that the sea scattering coefficent might be nearly constant, and the ratio of sea echo level to noise became widely used as a performance index without a sound justification. Later NRL installed a groundwave radar overlooking the Pacific. This was a well-calibrated system and sea surface scattering coefficient was determined over the HF Band. Don Barrick compared the data with his theory with excellent agreement. The near constant scattering coefficient only exists for a fully developed sea, but with a detailed sea spectrum the scattering coefficient can be calculated.
- Definition of first OTH detection and track of trans-Atlantic ships and clutter limitations - After the MADRE receiver dynamic range capability was increased to more than 60 dB, Headrick and his team conducted experiments that detected and tracked ships. The limitations imposed by the sea echo were exposed.
- First definition of groundwave radar performance capabilities - Headrick installed a vertically polarized antenna so that MADRE could launch a surface attached wave down the Chesapeake Bay. Headrick and his team conducted a series of experiments that described aircraft, ship, and boat detection capabilites. They discovered that tidal currents in the Bay could be measured.
After becoming a radio amateur in 1932 at age 15, Headrick joined the American Institute of Electrical Engineers as an associate member. In 1942, while at Massachusetts Institute of Technology, he joined the Institute of Radio Engineers as a student member, later upgrading to full member in 1946. When the Institute of Radio Engineers merged with the American Institute of Electrical Engineers to form IEEE, Headrick became a member of the IEEE, later upgrading to Life Senior Member in 1983.
Headrick received his bachelor's degree from the University of Texas and his master's degree from the University of Maryland, both in electrical engineering. He was honored with the Superior Civilian Service Award in 1970, the Award of Merit for Group Achievement in 1970, and the NRL 75th Anniversary Award for Innovation in 1998.