Wave transmission lines and networks – Resonators – With tuning
Reexamination Certificate
1999-02-09
2001-03-06
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Resonators
With tuning
C333S203000, C333S207000, C333S232000
Reexamination Certificate
active
06198366
ABSTRACT:
This application claims priority under 35 U.S.C. §§119 and/or 365 to 9800378-3 filed in Sweden on Feb. 9, 1998; the entire content of which is hereby incorporated by reference.
TECHNICAL FIELD
The present invention refers to a trimming arrangement in a device for tuning and/or adaptation of electromagnetic waves, including a trimming screw galvanically connected to the device and a bushing portion for inserting and securing the screw.
The invention also refers to a method of producing the trimming arrangement and a device including the same.
BACKGROUND
In microwave equipments, such as filters, oscillating circuits, resonators etc., trimming screws are used to tune and adapt the frequency. Generally, the trimming screw is secured with a locknut after the tuning. In an ordinary screw joint, e.g. in a filter or the like, occurs a certain amount of play between the thread and the screw, which effects the trimming of the filter. Moreover, when the locknut is tightened to secure the screw joint, the tuning is effected.
Since the frequency tuning is significant for the function of a microwave filter or the like, an incorrect tuning, even with very small variation, may consequently effect function of it and other devices enclosed in a microwave transmitter/transponder/receiver. It is therefore important that the trimming screw can be screwed so that an exact desired tuned position can be obtained and that the screw maintains its position and it is not influenced by the changes in the temperature, vibrations and so on. Moreover, parts of many devices are made of material, such as plastic, which makes the production of threads of small dimensions difficult in the material.
JP 5-152845 describes an oscillating circuit cover of which is manufactured of plated plastic material. A trimming screw corresponding to the position of a dielectric resonator is arranged in the ceiling of the cover by screwing it in a tubular metallic nut. The nut is cast in one piece with the cover. The screw is not secured.
Securing the trimming screw or device is known, for example through DE-A1-40 26 062, in which a trimming bolt is connected to a screw which dislocates it. The screw is fixed by a clamp nut pressing a conical flexible insert against the screw.
In U.S. Pat. No. 4,794,354 a locking insert of rubber is used to maintain a screw connected to a resonance element by means of a bar.
SUMMARY
The main object of the present invention is to provide a device for insertion of a trimming screw in a microwave device without above-mentioned drawbacks. Another object of the present invention is to provide a trimming arrangement, for example in devices intended for microwave applications, such as filters, resonating circuits and so on, which allows adaption of frequency and prevents unwanted variations of the adapted frequency in a cost-effective and reliable way.
These objects are obtained by means of the trimming arrangement, described in the preamble, featured by the bushing portion including an essentially pervious opening arranged in a part of the device, a part arranged in the opening for receiving the screw and a constriction arranged in the axial direction of the opening and formed relative the screw to firmly but detachably secure the screw.
The galvanic connection is achieved by providing the bushing portion and surface of the device with a conducting coating. In an advantageous embodiment, said part consists of a bushing. Moreover, said part can exhibit essentially conical threads. Preferably, the constriction is arranged with phased edges for cooperation with threads of the screw. To obtain an electric connection with good density, the constriction is particularly arranged with the conducting coating, which can consist of nickel, copper, gold, silver or the like.
The invention also refers to a device for adaptation and/or tuning of electromagnetic frequencies. The device mainly includes a compartment provided with a number of resonators, a cover which closes the compartment, one or more trimming devices arranged in corresponding openings and connection conductors. Each trimming device includes a conducting trimming screw, a threaded part for reception of the screw and a locking member arranged in the axial direction of the opening formed as a collar with an inner diameter, substantially corresponding to the inner diameter of the screw. Advantageously, the device is made of an insulating material coated with a conducting coating. Said insulating material is preferably a polymer material with a metallized surface which allows a cold flow in the material.
Preferably, the thread part is a bushing inserted in the opening. However, the threaded part consists of essentially conical threads arranged in the opening. In a preferred embodiment the collar is a part of the opening. The device can be a filter, resonator or the like and the electromagnetic waves are microwaves.
The method for producing the bushing portion in the device includes the steps of producing at least a part of the device, for example through moulding, casting or milling, arranging at least an essentially pervious opening having varying diameter in a part of the device when producing it, inserting a bushing into the opening, and providing the bushing and the detail with a conducting surface. The bushing is inserted into the opening preferably through force fit, hot pressing or the like.
REFERENCES:
patent: 4035749 (1977-07-01), Slocum et al.
patent: 4794354 (1988-12-01), Dinsmore et al.
patent: 4963841 (1990-10-01), Sparagna
patent: 5712606 (1998-01-01), Sarkka
patent: 5825267 (1998-10-01), Smith
patent: 5847627 (1998-12-01), Radzikowski et al.
patent: 40 26 062 (1992-02-01), None
patent: 5-152845 (1993-06-01), None
Dahl Torbjorn
Nilsson Sten-Åke
Burns Doane Swecker & Mathis L.L.P.
Nguyen Patricia T.
Pascal Robert
Telefonaktiebolaget LM Ericsson (publ)
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