The Single-Layer Solenoid as an RF Transformer

A set of curves is presented which makes it relatively easy to design air-core transformers satisfying a majority of engineering needs. Inductances in the range 0.1 μh to 10 mh, coupling coefficients in the range 0.001 to 1.0, and inductance ratios up to 100:1 are covered directly. Certain arbitrary restrictions are placed upon the proportions in order to obtain a single set of charts, but the available electrical characteristics are not limited thereby. The proportions of the resulting coils are compatible with large values of Q, but this is seldom important because heavy damping must usually be provided by associated resistors. The derivation and use of the curves is explained.