Improving HF Radar Surface Current Measurements with Measured Antenna Beam Patterns

Abstract

A high-frequency (HF) radar system is deployed on the New Jersey continental shelf as part of a coastal ocean observatory. The system includes two remote transmit?receive sites in Brant Beach and Brigantine, New Jersey, and a central processing site in Tuckerton, New Jersey. The system uses radio waves scattered off the ocean to measure the radial velocity, range, and bearing of the scattering surface. Calculation of the bearing for HF radar systems depends on the actual beam pattern of the receive antennas. A series of antenna beam pattern measurements conducted on the New Jersey system shows that these patterns are often distorted when an antenna is deployed in the field. Tests indicate that the local environment, not system hardware, causes the most significant distortion of the pattern from the theoretical shape. Correlation with an in situ acoustic Doppler current profiler (ADCP) indicates that the beam pattern distortion can bias the bearing estimate. It is shown that this bias can be removed if the measured beam patterns are used to estimate the bearing.