Abstract: A multistage depressed collector for collecting spent electrons from an electron beam useful as an element of a microwave tube includes an evacuated region having an entrance at one end for receiving electrons, and means for establishing an essentially two-dimensional hyperbolic electrostatic focusing field within the evacuated region defined by equipotential field lines having the geometry of concave curves as viewed from said electron entrance, and a plurality of electrodes located along equipotential lines, and wherein said entrance is located asymmetrically with respect to the electrodes. The foregoing structure includes a final electrode, a plurality of intermediate electrodes, each of the intermediate electrodes having an electron beam passage therethrough, and all of said electrodes having an essentially concave geometry, as viewed from said entrance.