Rf waveguide twist

A waveguide apparatus, comprising:

• an input port having a rectangular cross-section in a plane perpendicular to a direction of propagation, the rectangular cross-section having a short side and a long side;
• a plurality of resonant cavities coupled with the input port, the plurality of resonant cavities including a first resonant cavity and a second resonant cavity, the first resonant cavity and the second resonant cavity being diagonally disposed with respect to each other in the plane perpendicular to the direction of propagation, each resonant cavity having a square cross-section in the plane perpendicular to the direction of propagation;
• and
• an output port coupled with the plurality of resonant cavities on a side opposite the input port, the output port having a rectangular cross-section with a short side and a long side, wherein the short side of the output port's cross-section is perpendicular to the short side of the input port's cross-section, wherein the input port is configured to receive a TE10 mode and the output port is configured to output a TE10 mode that is rotated with respect to the input port.