A New High-Power Variable Attenuator (Correspondence)

This communication describes a design for a variable attenuator which can operate at very high peak and average power levels propagating in any chosen mode in a single or a multimode waveguide. This attenuator offers the desirable characteristics of dissipating energy in external loads rather than within the internal structure and utilizes only one coupling mechanism. The device consists of a coupled wave structure between two modes in adjacent primary and secondary waveguides, and a suitable mechanism for varying the phase constant of the secondary waveguide.