Abstract
The compact high-frequency surface wave radar using a crossed-loop/monopole (CLM) antenna as the receiving sensor has been widely used in ocean remote sensing and target monitoring. However, the direction of arrival (DOA) estimation accuracy of a single CLM antenna is the dominant factor that restricts the target monitoring performance of the compact HF radar. Besides, the single CLM antenna can estimate two signals simultaneously at most, but its effectiveness is challenged by the pattern distortion and the existence of coherent sources, which limits the application range of the compact HF radar. In this study, a compact array combining two CLM antennas is proposed to improve the DOA estimation accuracy and solve the multisource DOA estimation problem. The estimation error and multisource DOA estimation performance of a dual CLM antenna array are analyzed by formula derivation and simulation. Furthermore, the field experiment results are given to demonstrate the performance improvement of the dual CLM antenna array.
Highlights
By using the vertical polarization electromagnetic wave that travels along the curvature of ocean surface with low loss, the high-frequency surface wave radar (HFSWR) can be used for real-time ocean remote sensing over the horizon range, including the measurement of ocean surface dynamic parameters [1, 2] and the detection and tracking of targets [3, 4]
Comparison of direction of arrival (DOA) Estimation Accuracy. e constant false-alarm-rate (CFAR) algorithm [24] is used here to detect the targets in the RD spectrum, and the data received by the two CLM antennas are processed separately. e location, velocity, and heading of the vessel reported by the Automatic Identification System (AIS) are converted to range, radial velocity, and azimuth under the radar coordinate. en, the intersection of detection results of the two CLM antennas is matched with the AIS-reported vessels by using an empirical strategy of a two
AIS-reported azimuth dimensional threshold, that is, if the distance between the detected target and the AIS-reported vessels is within a range bin and the velocity difference is less than two Doppler bins, the target pairs are recognized to be matched. e matched targets are used for DOA estimation and the corresponding vessel azimuths calculated from AIS information are used as ground truth information
Summary
By using the vertical polarization electromagnetic wave that travels along the curvature of ocean surface with low loss, the high-frequency surface wave radar (HFSWR) can be used for real-time ocean remote sensing over the horizon range, including the measurement of ocean surface dynamic parameters [1, 2] and the detection and tracking of targets [3, 4]. A single CLM antenna can theoretically distinguish two signal sources, the multisource estimation problem is still difficult to solve due to the antenna pattern distortion and the existence of coherent sources. E estimation results of field experimental data are given to prove that the DOA estimation accuracy of the dual CLM antenna array is higher than that of the single CLM antenna, which is consistent with the theoretical formula. A multisource case of vessel targets in the shore-based HF radar data is studied, the result confirms that it is effective to estimate the DOAs of multisource with dual CLM antenna array.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
