Long microwave delay fiber optic link for radar testing

A unique application of a long fiber-optic delay line as a radar repeater to improve radar testing capabilities is described. It is shown that, with the use of a 1.3- mu m wavelength distributed feedback laser and an external modulator connected to a long (31.6-km) fiber cable to provide long (152- mu s) delays with minimum dispersion at X-band (10 GHz) frequencies, performance measurements can be made on modern Doppler radars utilizing long transmitter pulses. Tests demonstrate that these fiber-optic links can meet the stringent signal/noise ratio and phase linearity and stability requirements for Doppler radar systems that use pulse compression waveforms to obtain long-range operation with high resolution. >