Save the "THRU" in the A.N.A. calibration

The conventional network analyzer (NWA) two-port calibration procedures require a standard thru line to be connected between the ports. Unfortunately in many applications, for example when measuring MMIC or on-wafer devices with not aligned ports, a custom thru line must be used. The procedure here applied overcomes the difficulty due to the poor knowledge of this thru element since it is based on a generic reciprocal unknown two port structure, provided that its S21 phase shift is roughly known. Some experimental comparisons with other well sound calibration techniques will be here presented where different reciprocal two-port structures were used as unknown thru.