US2781493A

US2781493A - Cavity resonator devices

Info

Publication number: US2781493A
Application number: US637427A
Authority: US
Inventors: Bruce B Cork; Jr Melville Clark
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-12-27
Filing date: 1945-12-27
Publication date: 1957-02-12
Anticipated expiration: 1974-02-12

Description

Feb. 12, 1957 B. B. CORK ET AL CAVITY RESONATOR DEVICES 3 Sheets-Sheet 1 Filed Dec. 2'7, 1945 awe/Whom BRUCE B. CORK MELVILLE' CLARK JR.

Feb. 12, 1957 B. B. CORK EIAL CAVITY RESONATOR DEVICES s Sheets-Sheet 2 Filed Dec. 27, 1945 BRUCE- a. CORK MELVILLE CLARK JR.

3 Sheets-Sheet 3 BRUCE- B. CORK MELVILLE CLARK JR.

menu:

substantially detune that portion of the cavity so that only a small portion of the transmitter energy will be coupled to conductor 27 and thence to the I. F. post 35 and local oscillator 41. The I. F. crystal will thus be protected from burning out at the high level of the transmitter energy.

Energy received by the antenna, when the transmitter is not in operation, will be applied to the cavity through post 15. Some energy will be coupled through iris 14 to the transmitter oscillator but this will be small because the transmitter, when not energized, will be detuned from the frequency of the incoming energy.

Accordingly the greater part of the energy will be coupled from post 15 to conductor 21.

Conductors

21 and 27, comprising double-tuned resonant circuit, will pass the energy with minimum attenuation to the I. F. coupling post 35, where it will be mixed with local oscillator energy coupled through iris 37 and taken out of the cavity for application to an intermediate frequency detector.

If it is desired to operate the transmit-receive assembly in a difierent frequency range, tuning rod 34 may be moved to alter the position along the frequency spectrum of the mid-point of the pass band of the doubletuned resonant

circuit comprising conductors

21 and 27.

In order to adjust the circuit so that the tuning of line 27 will have the desired relation to that of line 21, a hollow screw 42 may be inserted immediately below the end of conductor 27, forming a variable capacitive load, which may be adjusted until proper operating characteristics are obtained.

When the equipment is not in use, the keep-alive voltage will be shut off from the TR tube 22. Under such circumstances, if high level energy should be received by the antenna and applied to coupling post 15, it might be transmitted through the TR to coupling post 35 damaging the I. F. detector and/or local oscillator. Under such conditions, a conducting rod 43 may be slid within hollow screw 42 until it touches the end of conductor 27. This portion of the cavity will then be short-circuited, constituting to an augmented extent, the same type of protection as is provided during operation by the TR tube 22.

The assembly shown in Figs. 2, 3, and 4 is substantially the same as shown in Fig. 1 with the following modifications. In the first place, a special tuning means has been. The.

shown for actuating the tuning rod 34 of Fig. 1. action of this tuning means will be quite obvious by reference to Fig. 2. Additionally,

tuning slugs

31 and 32, shown as homogeneous conducting members in Fig. 1, have been replaced by a single, integral non-conductive member 50 attached in the center to tuning rod 34. At high frequency, current is confined to the surface of a conductor, and it is possible to use a slug in the form of a toroid of non-conductive material coated with a conductive material such as silver. In Fig. 2, tuning member 50 comprises a pair of toroids of non-conductive matter coated with a layer of silver as shown at 51.

With these exceptions the assembly of Figs. 2, 3 and 4 is substantially the same as that of Fig. 1, and the same reference numerals have been applied to corresponding parts.

It has been found that conducting wall 30 of Fig. 1 may be replaced by a screw 60 (Fig. 5) extending upward into the cavity from floor 13. By proper proportioning the screw, it has been found that the desired coupling may be maintained, and at the same time a certain degree of discrimination against an undesired harmonic, such as the third harmonic, may be obtained. If desired, coupling screw 60 may extend inward from either wall or wall 11, instead of upward from floor 13. Also, under certain conditions a plurality of screws may be substituted for wall 30 of Fig. 1.

While the coupling between the several members within the cavity has been shown as a large iris, equal to the cross section of the cavity, it will be understood that, if desired, the coupling between members may be varied by use of a wall such as wall 30, or by coupling screws such as screw 60, or by use of a small iris such as iris 37.

It will be further understood that this invention is not limited to iris coupling between the portions of the circuit; loop coupling or capacitive coupling may be employed where appropriate.

It will be further understood that any form of transmitter, local oscillator, I. F. detector or antenna may be employed in connection with the transmit-receive assembly of this invention.

Although we have shown and described certain specific embodiments of the invention, we are fully aware of the many modifications possible thereof. This invention is not to be restricted except insofar as is necessitated by prior art and the spirit of the disclosure.

What is claimed is:

l. A double-tuned resonant circuit comprising a plurality of conducting walls forming a cavity, a first elongated conductor connected at one end to a first cavity wall and extending into the cavity, a second elongated conductor connected at one end to said first cavity wall and extending into the cavity, an intermediate conductor connected to a cavity wall opposite said first cavity wall and extending into the cavity between said first and said second elongated conductors, a pair of conducting tuning slugs positioned about said first and said second elongated conductor-s respectively and movable along the respective axes of said conductors, and adjustable positioning means attached to said tuning slugs and extending through a wall of the cavity to provide simultaneou adjustment of the position of said tuning slugs.

2. A transmit-receive device comprising a plurality of conducting walls forming a cavity resonator, a first elongated conductor connected to a wall of the cavity and extending into the cavity, input means adjacent said first elongated conductor eifective to apply input energy to said cavity, a second elongated conductor adjacent to said first conductor and connected to said wall of said cavity and extending into the cavity, output means adjacent said second conductor effective to derive output energy from said cavity, a nonlinear impedance connected between one of said conductorsat its end extending into the cavity and the adjacent cavity wall effective to change abruptly in impedance value upon application of high voltage energy thereto,, conducting means connected to one of said cavity walls and between said elongated conductors and extending into said cavity toward an opposite wall for a portion of the distance between said two last-mentioned cavity walls, a pair of conducting tuning slugs positioned about said first and said second elongated conductors respectively and movable along the respective axes of said conductors, and an adjustable positioning means attached to said tuning slugs and extending through a wall of said cavity to provide simultaneous adjustment of the position of said tuning slugs.

References Cited in the file of this patent