JPH0334043Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a high frequency window for inputting and outputting microwaves in an electron tube for microwave amplification such as a traveling wave tube or a high-speed modulation tube.

In electron tubes for microwave amplification that have a vacuum envelope made of metal and ceramic parts, a part of the vacuum vessel of the tube is used to couple microwaves between the external high-frequency circuit and the high-frequency amplification circuit of the tube. A high frequency window is often used, which consists of a coaxial window forming a coaxial line and a high frequency plug connecting this coaxial window to an external high frequency circuit.

This high-frequency window is, for example, the high-frequency window itself.
Since the VSWR has a large influence on the electrical characteristics such as controlling the VSWR of the tube, various ideas are required for the structure of the coaxial window and high frequency plug and the connection between the two.

FIG. 1 shows a partial cross section of a helical traveling wave tube having a conventional high frequency window structure, including the high frequency window. A disc-shaped insulated porcelain 4, a rod-shaped metal coaxial inner conductor 3 passing through a fitting hole provided at the center of the insulated porcelain 4, and a cylindrical metal having an inner circumferential surface that fits with the outer circular surface of the insulated porcelain 4. The coaxial window 1 is formed by brazing the coaxial outer conductor 2 at each connection portion. One end of the coaxial outer conductor 2 is brazed to a metal cylindrical shell 10 that forms a part of the vacuum vessel and holds the helix 9.
Further, one end of the coaxial inner conductor 3 is connected to the helix 9.

The high frequency plug 5 has a screw portion for connecting the inner peripheral surface that fits with the outer peripheral surface of the coaxial outer conductor 2 and the outer conductor (not shown) of the external coaxial high frequency circuit, and the entire high frequency plug 5 as a support. A substantially cylindrical outer conductor 6 having an outer circumferential surface provided with a flange portion for fixing to the coaxial inner conductor 3 and an inner conductor (not shown) of an external coaxial high frequency circuit is fitted at both ends. It is composed of an inner conductor 7 made of a substantially rod-shaped metal provided with a hole, and an insulating tube 8 made of a substantially cylindrical Teflon material that holds the inner conductor 7 coaxially with the outer conductor 6 and insulates the two. In addition, the coaxial window 1 and the high frequency plug 5 are each independently connected to the case board 12.
is fixed.

In the case of the conventional high frequency window structure described above, the outer circumference of the coaxial outer conductor 2 of the coaxial window 1 fits into the inner circumferential surface of the outer conductor 6 of the high frequency plug 5, and at the same time the coaxial inner conductor 3 of the coaxial window 1
The outer circumferential surface of the coaxial window 1 and the high-frequency connector 5 are designed to fit into the inner circumferential surface of the inner conductor 7 of the high-frequency plug 5. Eccentricity occurs between the outer conductor and inner conductor of each plug 5. In this case, since the coaxial window 1 and the high frequency plug 5 are connected based on either the outer conductor or the inner conductor, it is necessary to loosen the fitting dimension of the remaining one. Moreover, even if each part is machined with high precision and eccentricity is reduced, a certain amount of clearance is required to fit the parts together, which increases the processing cost. Furthermore, there are temperature changes in the environment in which the tube is used, and this temperature change causes expansion or contraction of each part, but each part has a different coefficient of thermal expansion and does not deform in a similar manner, so the clearance increases. It also happens. In this case, problems such as high frequency leakage and a change in the VSWR of the high frequency window itself may occur. Conversely, clearance may also be lost; for example, if a force is generated that forces the coaxial outer conductor 2 to spread the outer conductor 6 from the inside, and the coaxial outer conductor 2 cannot withstand this force, the parts may be deformed or the brazed portion may be damaged. Accidents such as these may occur.

An object of the present invention is to provide a high-frequency window that eliminates the drawbacks of conventional high-frequency windows as described above and is structurally simple and inexpensive.

According to the present invention, a part of the vacuum vessel of the tube and a coaxial line for microwave propagation are made of metal and porcelain of the microwave tube, which has a microwave amplification section that amplifies microwaves by the interaction between an electron beam and a microwave. A coaxial window that forms a coaxial window, and a high frequency window that connects the microwave amplification section and an external high frequency circuit by a high frequency plug that connects this coaxial window and an external high frequency circuit. A high frequency window is obtained in which a ring made of an organic material having conductivity and elasticity is disposed at the connection portion of the high frequency plug with the substantially cylindrical coaxial outer conductor.

A specific embodiment of the high frequency window according to the present invention will be described below with reference to FIG.

In FIG. 2, the high frequency window is composed of a coaxial window 1 and a high frequency plug 5, and the structure and assembly method of the coaxial window 1 are the same as those of the prior art. The high-frequency plug 5 has an outer peripheral surface provided with a threaded portion for connection to an external high-frequency circuit (not shown) and a flange portion for fixing the high-frequency plug 5 to the support 11, and is connected to the coaxial window 1. an outer conductor 6 with a groove formed on its inner peripheral surface, a coaxial inner conductor 3, and an inner conductor of an external high-frequency circuit (not shown)
an approximately cylindrical Teflon insulating tube that holds the inner conductor 7 coaxially with the outer conductor 6 and insulates the two; 8. Furthermore, the coaxial window 1 and the high-frequency plug 5 are each independently fixed to the case board 12 as in the past, but the coaxial outer conductor 2 and outer conductor 6 of both are connected by a connecting ring (conductive and elastic). ring consisting of an organic substance with a property) 13
It is carried out by.

The connection ring 13 is required to electrically connect the coaxial outer conductor 2 and the outer conductor 6. For this purpose, elastic silicone rubber with extremely low electrical resistance mixed with conductive metal powder, such as silver powder, is processed into a ring shape. Further, the connecting ring 13 is held by being accommodated in a groove formed in the outer conductor 6. When connecting the coaxial window 1 and the high-frequency plug 5, the tip of the coaxial outer conductor 2 is not simply brought into contact with the connecting ring 13, but is slightly bitten into the connecting ring 13.

In this case, even if the coaxiality of the coaxial window 1 and the high-frequency plug 5 is poor, the connection between the coaxial outer conductor 2 and the outer conductor 6 is not established even if the coaxial inner conductor 3 and inner conductor 7 of both are fitted together as a reference. The ring 13 always maintains a gap without creating a gap. Furthermore, even if thermal expansion or contraction occurs due to environmental temperature changes, the stress can be absorbed due to the elasticity of silicone rubber. Conversely, even if a gap occurs, since the tip of the coaxial outer conductor 2 is bitten into the connection ring 13 as described above, the gap can always be filled by the connection ring 13 due to the elasticity of silicone rubber. Therefore, there is no need to increase the machining accuracy of each part, and the machining cost is low.

Further, the shape of the connection ring 13 is not limited to a ring shape, but can also be made into a substantially cylindrical shape that covers the outer peripheral surface of the coaxial outer conductor 2, as shown in FIG. The connection between the outer coaxial conductor 2 and the outer coaxial conductor 2 becomes even better.

As described above, according to the present invention, by simply using a conductive and elastic connecting ring, it is possible to eliminate the effects of component deformation due to changes in environmental temperature and obtain a low-cost, high-circumference window. can.

In the above explanation, a coaxial line was used as the high frequency plug, but if the external high frequency circuit is a waveguide circuit,
Because the high frequency that is transmitted in coaxial mode as a high frequency plug must be converted to waveguide mode,
Although a so-called coaxial one-waveguide converter is used, the joint between the coaxial window and the high frequency plug is essentially the same, so the present invention can be applied.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional example, FIG. 2 is a sectional view of an embodiment according to the present invention, and FIG. 3 is a sectional view of a high frequency window showing another embodiment according to the present invention. 1... Coaxial window, 2... Coaxial outer conductor, 3... Coaxial inner conductor, 4... Insulating porcelain, 5... High frequency plug, 6... Outer conductor, 7... Inner conductor, 8... Insulating tube, 9... Helix,
DESCRIPTION OF SYMBOLS 10... Shell, 11... Support body, 12... Case board, 13... Connection ring.

Claims (1)

[Scope of utility model registration request] The metal and porcelain of the microwave tube form a part of the vacuum vessel of the tube and a coaxial window that forms a coaxial line for microwave propagation, and a microwave amplification section is formed by a high frequency plug that connects this coaxial window to an external high frequency circuit. and an external high-frequency circuit, the connecting portion between the substantially cylindrical coaxial outer conductor of the coaxial window and the substantially cylindrical coaxial outer conductor of the high frequency plug is made of an organic material having conductivity and elasticity. A high frequency window for a microwave tube, characterized by having a ring arranged therein.