Some ferrite components for isolation and controlled coupling

Microwave power division employing the field-controllable microwave permeability of ferrites has been used as the basis of current-controlled variable attenuators and switches. Three such devices are described:(a) A 4-port device in waveguide, with ferrite phase shift controlling power division between two ports of exit. Its operating range is 2.7-3.3 Gc/s. (b) A 3-port device, in waveguide or stripline, with a similar basis of control. However, its most suitable application is with a fixed field, as a circulator. (c) A cross-polarization waveguide device using a ferrite to control the rotation of polarization, thereby forming a reflective switch. It is simple and has a good bandwidth, but frequency control is difficult. The construction, mode of operation, and performance are given in each case.