It?s my impression that wideband phase shifters in radar systems are most often implemented as some kind of variable delay line. In one common case, the variable delay is implemented as a binary-length set of switchable delay lines. In another traditional case, the delay element is magnetized ferrite in a waveguide - the speed of propagation in the ferrite varying with magnetic field intensity. In yet another case, the delay is implemented as a lumped-element low pass filter with voltage-variable diode capacitors.
The question is if it is possible to implement a phase shifter that is not ultimately based on some kind of variable delay. Upon what physics principle would this be based?
Joe Gwinn