Note on Radio-Frequency Transformer Theory

In the mathematical analysis for radio-frequency amplifiers employing tuned transformer coupling, the effect of the distributed capacitive coupling. existing between the transformer windings has heretofore been neglected. General equations including this effect are here developed. It is shown that with these equations a closer agreement between computed and experimental results can be obtained. The presence of capacitive coupling changes the amount of mutual inductance necessary to obtain optimum amplification at a given frequency, at the same time reducing the optimum voltage gain. The manner of variation with frequeny of the equivalent transformer primary impedance is also altered.