Precision Variable Waveguide Phase Shifters any type

Microwave Phase Shifter: a dielectric element in the waveguide increases the electrical length. The physical length is maintained.
Advantage: fixed mounting of waveguides.

Disadvantage: usually slightly higher insertion loss than by the mechanical type.

Differs from mechanical Phase Shifters, where by telescopic move the length of both physical and electical dimension is modified.

phase shifting element is metalized glass, moved by the knob shown in photo, total travel of the element on this specific guide is just over .4 inches.

Waveguide material is brass, silver plated.  based on 22X47mm waveguide internal dimesons, the photo shows an S band waveguide in a frequency range used for maritime communications.

Here you find 11 models, 2 with images and 0 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Polytechnic Research & Development Co, Inc. (PRD); Brooklyn, NY