Patent GB-1358896-A (GB)
Title: High frequency energy converters
IPC: H03F3/10
Filed: 1971-09-27
Abstract: 1358896 Harmonic generating SPERRY RAJSTD CORP 27 Sept 1971 [7 Oct 1970] 44853/71 Heading H2F [Also in Divisions H1 and H3] A high frequency, i.e. microwave frequency  energy converter comprises a transmission line 1 having first and second conductors 3 and 2, a conductive wall 4 forming a shorting means for high frequency currents so that energy cannot flow out of the transmission line past the conductive wall, a semi-conductor 6 forming a first junction with the conductive wall 4 and a second junction with the second conductor 2, circuit means 10, 11 for applying a bias field across the semi-conductor, a distributed filter 20 co-operating with the first and second conductors 3, 2 and providing an impedance step located adjacent the plane of the second  junction for preventing time delayed triggered operation of the semi-conductor 6, 7 and impedance matching means 12 spaced from the filter 20 and co-operating with the first and second conductors 3, 2. The semi-conductor 6, 7 may be an avalanche transit time diode, a TRAPATT diode, an epitaxial silicon or other PN or step or abrupt junction diode or a P-N-N4 punch through diode. When the converter is used as an amplifier the diode 6 is biased into conduction and a high frequency input signal such as pulses is applied to the transmission line 1 via a circulator. When the input signal attains a sufficient value an avalanche shock wave is excited in the diode 6 producing amplified output power from an output port of the circulator. The filter 20 has first and second impedance sections provided by discs (21, 23, 25, 27 and 22, 24, 26, Fig. 2, not shown). The low pass or band pass filter 20 may be fixed in position or may be adjustable as may be the #/4 tuning or impedance transforming element 12. The filter 20 has a pass band including the operating fundamental frequency fF of the amplifier and a stop band containing at least the second and third harmonics fH so that all harmonic energy is retained in the region about the diode 6. The filter 20 may be placed at the surface 5 of the diode or spaced from it by #/2 so that time delayed triggering of the diode 6 is prevented. Additional matching elements as 12 may be provided and the element 12 may be mounted on the centre conductor 2 (Fig. 1a, not shown) instead of on the dielectric tube 16. As an alternative to the metal tuning element 12 dielectric tuning devices may be provided. In a modification (Figs. 3-7, not shown) the transmission line (50) has an open side boxlike structure and the central conductor 2 is replaced by a conductor or septum (54). The tuning or impedance transforming element 12 and PF20 are provided by U-shaped members (70, 80) and the input and output is obtained by a coaxial transmission line (67). The first and second impedances of the filter 20 are provided by ridges (84, 86, 88 and 90) and depressions (85, 87 and 89) in the U-shaped member (80). In a further modification (Figs. 11-12, not shown) a ridge wave guide transmission line is used including a serrated filter section (107) acting as the LPF 20, a serrated impedance matching structure (108) and a quarter wave transformer (113). Specification 1,339,837 is referred to.