Transmission-mode y.i.g. dispersive filter for wide-band pulse compression

It has recently been reported that yttrium-iron-garnet microwave variable-delay lines can be operated in a transmission mode of operation rather than in the usual reflection mode of operation by optical-contact bonding quarterwave plates to both ends of the y.i.g. rod.1.2 This is a distinct advantage for many delay-line applications, because the undelayed direct feedthrough can be suppressed to a much higher degree when input and output lines are at opposite ends of the y.i.g. rod, which is mounted in a tightly fitting hole in a brass block. One of the most promising applications of the y.i.g. delay line is in wide-band microwave pulse-compression filters. The successful operation of a y.i.g. delay line, to obtain compressed signals in a transmission with large suppression of direct leakage of undelayed signals, is reported.