China Purchases Russian Radars
In 2004 China bought Russian Podsolnikh-E high-frequency (HF) surface-wave radars for coastal surveillance. These radars use the ionosphere and the conducting surface of the sea as reflectors to form the boundaries of a waveguide. They reach beyond the usual radar horizon, which is four-thirds of the visual horizon. What is special about HF radar is that the wavelength is so long (typically 10 to 150 meters) that it is not greatly affected by the shape of the object it encounters. Stealth shaping would have little or no effect on detection. Maximum range against surface targets, set by the nature of HF propagation, is generally given as 180 nautical miles, and against air targets as 250 nautical miles. Podsolnikh uses two separate antenna fields 500 to 3,500 meters apart, each 100 meters wide, one to transmit and one to receive.