Ferrite Microwave Detector

In treating the behavior of the magnetic moments of unbalanced electron spins in ferromagnetic materials under the action of an rf field, second-order terms in the alternating components are usually neglected. It is shown here that retention of certain second-order terms for one component of the magnetization predicts the possibility of using ferrites to detect an amplitude-modulated microwave signal. The demodulated envelope can be used to magnetostrict a long thin ferrite rod, the vibration of which can be observed by means of a polarized BaTiO3 ceramic rod. The results obtained with an experimental model of this device indicate verification of the theory. Factors which are expected to improve performance are discussed.