Multiplying action of the magnetoresistance effect in semiconductors and its application to power measurements

The paper describes, in theory and practice, a new method of power measurement applicable over a wide frequency range, employing the magnetoresistance effect in an intermetallic semiconductor biased at a relatively high magnetic flux density. A theory has been developed for the multiplying action of the magnetoresistance effect compared with that of the Hall effect. It is shown that the multiplication sensitivity should be practically the same for both effects if the semiconductor element is the same in each case. However, the theory predicts that the sensitivity could be enhanced several times if the magnetoresistance element were suitably designed. Practical arrangements of applying the effect to power measurements are also discussed. Experiments have been carried out on the multiplication characteristics of the effect with InAs and InSb crystals, and satisfactory agreement with the theory has been obtained. Application to power measurements has been demonstrated for d.c. and a.c., and at microwave frequencies; the temperature dependence, and influence of power factor and of instability in the magnetic bias, were also investigated. The results showed excellent performance not only in linearity but also in voltage gain, with some advantages over the Hall effect.