Design of wide-range varactor-tuned microwave tunnel-diode oscillators

The paper describes the application of tunnel diodes to electronically tunable microwave oscillators. The properties of tunnel diodes are described, and oscillators with a wide tuning range are considered in detail. In order to achieve frequency stability, the tunnel diode should be weakly coupled to a relatively high-Q factor resonator, and this principle is applied to the design of electronically tuned oscillators using varactor diodes as tuning elements. Some comparisons are made with mechanically tuned oscillators designed according to similar principles. The form of construction is described and some results are discussed.