STANFORD UNIVERSITY
EE 350 RADIOSCIENCE SEMINAR
Professor Antony Fraser-Smith

Fall 2000-2001

Date: Wednesday, May 30, 2001
Time: 4:15-5:30 PM; Refreshments at 4:00 PM
Location: Bldg. 200, Rm. 34


HF Radar for Ocean Surface Current and Wave Mapping - How Far Have We Come in 30 Years?

Dr. Donald E. Barrick
CODAR Ocean Sensors, Ltd.

Abstract

HF observations of the sea surface in the U.S. started about 1970 in collaborative programs between Stanford/STAR Lab, Scripps, and NOAA,where I began CODAR and skywave research efforts.The principles and information extraction methods have solidified over the ensuing three decades.An incredible array of unconventional, novel conceptual approaches date back to these early days, including:(1) bistatic geometries (transmitter and receiver separated); (2) synthetic aperture (driving the radar down a runway on Wake Island);(3) a balloon-borne rhombic antenna; (4) direction-finding to determine bearing; (5) multiple-frequency operation to diagnose vertical current shears;(6) minicomputer -- succeeded by Macintosh -- for radar control and real-time processing.These efforts have led to a viable c ommercial product and thriving market for current-mapping radars we manufacture, called SeaSondes.

We examine several new directions of research and development here that include: (1) bistatic augmentation of existing backscatter radars, so that a single receiver can produce vector current maps in place of two complete radars;(2) inexpensive GPS timing synchronization of multiple backscatter and bistatic radars, so that several can operate on the same frequency based on modulation multiplexing;(3) ultra-long-range surface wave systems that achieve ranges beyone 200 km with only 50 watts power; (4) a tiny UHF bistatic system where transmitter and receiver straddle a river to give profiles of flow needed by the USGS for real-time stream gaging;(5) a compact, inexpensive skywave radar approach that eliminates the billion-dollar conventional phased arrays that demand miles of real estate;(6) tiny circular superdirective receive arrays that form and scan narrow beams equivalent to those of much larger phased array antennas. The future indeed continues to be as exciting as the past!