A compact antenna feeder and associated circulator plate are disclosed. The antenna feeder includes: an orthomode transducer (OMT) polarizer, a first circulator and a second circulator. The OMT -polarizer includes a septum, a first port, a second port, and a third port. The first circulator is coupled to the first port of the OMT polarizer to define one orthogonally polarized microwave signal path between the first circulator and the third port of the OMT-polarizer. The second circulator is coupled to the second port of the OMT polarizer to define another orthogonally polarized microwave signal path between the second circulator to the third port of the OMT-polarizer. The OMT polarizer includes a waveguide with the septum located therein separating the two orthogonally polarized microwave signal paths. The septum has a base mounted on the circulator plate and a step-shape body extending from the base and out of the circulator plate.