A new multi-frequency HF radar based on small circular antenna array for sea surface current measurement

A new multi-frequency HF (MHF) radar based on small circular antenna array is briefly introduced in this paper. For the purpose of reducing the area of receiving array, Radio Ocean Remote Sensing Laboratory of Wuhan University designed a small receiving array, which consists of 7 elements with a diameter of 5 meters, for MHF radar system in 2014. This new MHF radar system, adopting Frequency Modulated Interrupted Continuous Wave (FMICW) chirp, is capable of simultaneously operating at four frequencies at most in the band of 7.5-25 MHz. Because of the small antenna aperture, phase direction finding mode is utilized to estimate the direction of current signal. The paper investigates the performance of current measurements using this small receiving array by simulation and observation. Simulations not only study the performance of extracting radial current profile, but also involve the ability of estimating multiple current signals at one Doppler shift bin. Some preliminary observations are also shown in this paper. Comparisons between MHF radar and ADCPs demonstrate that MHF radar system with small circular array has the ability to measure currents with a good performance in the East China Sea.