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Two outstanding speakers will open the third and fourth day of the conference with one hour plenary talks. This talk will try to briefly review what developments have had an impact on radar (that is, what concepts and technology have made radar of value in the past), what radar concepts and technology were important in the past but might not be so important in the future, what things appear to be of current interest in radar but are not as likely to see lasting utility (that is, ideas that one should examine with caution when exploring potential new directions in radar), and a few new directions in radar that might be of interest to pursue. Among the new directions that might be briefly discussed include: phased arrays that perform multiple function simultaneously rather than in sequence, a different look at the cause of microwave sea echo, and living with a crowded microwave spectrum by use of shared spectrum.

Over-the-horizon (OTH) EIF radar using sky-wave propagation via refraction by the ionosphere is capable of detecting targets at distances an order of magnitude greater than conventional microwave radar limited by the line of sight. Some of the characteristics, capabilities, and limitations of OTH radar based on the erperience of the MADRE radar as developed by the Naval Research Laboratory are described. Also discussed is the application of OTH radar to air-trafEc control and to the remote sensing of sea conditions.

Radar has been highly influenced by the technology of microwaves, and likewise the development of microwaves has been significantly affected by the needs of radar. This paper addresses the relation between the two. It begins by briefly describing the introduction of microwave radar in World War II that was a major factor in the Allies achieving success in air defense and antisubmarine warfare. Microwave radar developments during and after the war are reviewed, along with a listing of current military and civilian applications. The dependence of modern radar on digital processing (with clock rates at microwave frequencies), high-power transmitters, and sophisticated antennas is discussed. The paper concludes by mentioning possible future directions for radar, and briefly describes two examples of future radar system opportunities. These are the ubiquitous radar (one that looks everywhere all the time so as to allow simultaneous rather than sequential performance of multiple functions), and high-power transportable millimeter-wave radar based on the gyroklystron amplifier. The message of this paper is that microwaves and radar have mutually benefited from one another and that radar still offers many opportunities for microwave engineers to demonstrate their ingenuity and creativity.

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