Traveling-wave tubes with ferrite attenuators

In order to determine the efficacy of ferrite isolators used as internal attenuators in traveling-wave tubes, two TWT´s incorporating such isolators were developed, one using orthodox magnetic focusing, the other using electrostatic focusing. The results of the experimentation indicate that the ferrite can, in some cases, offer improvement in gain and efficiency over reciprocal attenuators. The limitations of this device are discussed together with some particular advantages it may offer for special applications. Design criteria for such isolators and the effects of the ferrite as a circuit element in TWT´s, are also investigated.