Amplitude and phase compensation of RAC-type chirp lines on quartz

A novel method for correction of the amplitude and phase response of RAC (reflecting array pulse compressor)-type chirp lines on quartz is demonstrated. The corrections are obtained through normal or reactive RF sputter etching of the lines through a moving slit. For amplitude correction the material selectivity of reactive sputter etching is used to correct the groove depth after initial fabrication of the lines. A thin Cr film, left in place in the finished line, is used as an etching mask. Phase correction is done by sputtering off gold from a gold line between the two arrays. Using this method a Kaiser-Bessel weighted line with a chirp rate of 0.0576 MHz/μs and 120-μs dispersive delay was made, and weighted RMS (root mean square) amplitude and phase errors of 0.086 dB and 0.45° were obtained