| Oceanography > Issues > Archive > Volume 10 > Issue 2 |
1997, Oceanography 10(2):72–75, http://dx.doi.org/10.5670/oceanog.1997.27
Evolution of Bearing Determination in HF Current Mapping Radars
Authors | First Paragraph | Full Article | Citation
Authors
Donald E. Barrick | CODAR Ocean Sensors, Ltd., Los Altos, CA, USA
Belinda J. Lipa | CODAR Ocean Sensors, Ltd., Los Altos, CA, USA
First Paragraph
Nearly all target detection "radars" in existence operate at microwave frequencies because their wavelengths are small enough that compact antennas provide both good angular resolution and high sensitivity. By contrast, at high frequency (HF) very large antenna arrays are needed to achieve similar results using traditional signal processing techniques. (To form and scan a beam equal in width to that from a 2-m microwave dish demands an HF receive antenna that is 2-3 km in length.) Despite this physical drawback, only at HF is the first and second-order sea echo directly relatable to surface waves and winds and, through the Doppler relation, to surface currents (Crombie, 1955: Barrick, 1972). For example, at microwave frequencies Doppler shifts depend on many scattering properties of the surface in addition to the wave and current speeds.
Full Article
Citation
Barrick, D.E., and B.J. Lipa. 1997. Evolution of bearing determination in HF current mapping radars. Oceanography 10(2):72–75, http://dx.doi.org/10.5670/oceanog.1997.27.