Calibration of wideband arrays using photonic delay lines

A time domain calibration technique was used to check out a 96 element L-band conformal array using photonic time shifters for wideband operation. A 2 ns pulse was injected into each channel with the time shifter cycling through all the states so that the insertion loss and the time delays could be calibrated. The pulse was synthesised with 801 CW frequencies over a wide band (50%) from 850 to 1400 MHz. The network analyser transmitted the CW frequencies one at a time over ~100 ms in each measurement. The measured data were transformed into the time domain with a built-in FFT in the network analyser