A study on skywave-surfacewave hybrid networking technique for HF oceanography radar

HF over the horizon radar can be divided into sky wave radar and the surface wave radar according to the radio propagation mode. As a new mode, HF hybrid sky-surface wave radar is composed of the ionosphere reflection propagation mode and the surface wave receiving mode. The technique of HF sky wave and surface wave hybrid networking system for HF oceanography radar is presented and analyzed in this paper, which includes two modes: the hybrid sky-surface wave system consisting of a sky wave transmit path and a surface wave receive path, and the surface wave system consisting of a surface transmit path and a surface wave receive path. Based on this hybrid networking technique, the system combines the merits of surface wave HF radar and sky-surface wave radar, which will improve the ability of target detection and enlarge the detection range. Compared with the single mode radar system, this system has advantages of better detection performance at the far ranges and stronger anti-interference ability. The structure of the hybrid networking system is given. Besides receiving the sea echo from the surface wave radar, HF receiving array on the shore also receives the sea echo from the sky wave transmitting station that is reflected from the ionosphere. The sea echo signals from different transmitting stations is obtained and separated by frequency offset or timing delay. Finally, the experimental system and experimental data analysis are provided. The experimental results under different scenarios including hybrid sky-surface propagation mode and hybrid networking mode are presented. Preliminary results from field experiments show the technical feasibility and the good detection performance of the new radar networking system.