FI89645C - Device for tuning a coaxial resonator - Google Patents

Description

89645

FIELD OF THE INVENTION bidirectionally to its correct resonant frequency.

The coaxial resonator has a center conductor and a sheath with an insulating layer between them. The insulator does not extend right to the end of the resonator, where the uninsulated state causes a load-capacitance between the center conductor of the resonant tube and the sheath. The resonant frequency of a coaxial resonator is determined by the length of the resonant tube and the load capacitance. The resonator thus corresponds to the parallel connection of inductance and capacitance.

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In a known solution, the middle conductor is soldered to the ground foil. The resonator is then tuned by milling the ground foil. This is inaccurate and difficult. Another problem is that the resonator can only be adjusted in one direction.

In known solutions, the resonator is also tuned by means of a tuning capacitor. The disadvantage of using capacitors is that they are relatively expensive.

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The object of the present invention is to provide a preferred resonator structure which would be effortless to tune in both directions. To achieve this, the invention is characterized in that it comprises a connecting piece placed at the end of a resonator having first contacts in contact with the center conductor and second contacts in contact with the sheath, the contacts being in direct galvanic contact with each other, 2 8964b and a body to which the contacts are mechanically fixed, whereby the center conductor and the sheath of the resonator can be short-circuited at the desired position by moving the connector in the direction of the longitudinal axis of the resonator and thus tuning the resonator in both directions to its correct resonant frequency.

The invention will now be described in detail with reference to the accompanying drawings.

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Figure 1 shows the resonator tuning by the sliding contacts, Figure 2 shows the resonator tuning by the external sliding contacts, and Figure 3 shows the resonator tuning by the threaded sleeve.

In Fig. 1, sliding contacts 4 are placed inside the resonator tube between the center conductor 3 and the sheath 2, which cause a short circuit between the center conductor 3 and the sheath 2. By sliding the connector 5 out or in, a change in the resonant frequency is effected by sliding the connector 5. The insulation is marked with the number 1.

In Fig. 2, the sliding contact 7 contacting the sheath 2 is located on the outside and the sliding contact 25 contacting the center conductor 3 on the inside of the chain 6. Sliding the connector 8 out or in causes a change in the resonant frequency.

In Fig. 3, a sleeve 11 with threads on both the inner surface 10 and the outer surface 9 is screwed inside the resonator tube. The threaded contact of the connector attaches to very soft copper. This solution facilitates automation remarkably-35 ti.

In the case that the coaxial resonator is a suitably rigid cable, e.g. semi-rigid cable, even a known type of coaxial connector can be used as the connecting piece. The outlet side of the contacts are short-circuited, for example, by soldering the center conductor pin of the connector shell. The connector is then simply inserted into the end of the re-5 sonator. In this embodiment, it could be determined by measurements that the frequency of a resonator having a center frequency of 850 MHz could be adjusted in the range ± 20 MHz. The phase price was measured to be -121 dBc / Hz and the output power 3.5 dBm.

By means of the invention, the coaxial resonator can be adjusted in both directions. The invention is easily automated and very inexpensive compared to the previous solution.

Claims (5)

An apparatus for tuning a coaxial resonator having a center conductor (3) and a sheath (2) and an insulator (1) therebetween, wherein the center conductor and the sheath extend at one end of the resonator 5 a certain distance past the insulator, characterized in that it comprises a resonator at said end a set of a connector having first contacts in contact with the center conductor (3) and second contacts in contact with the sheath (2) in direct galvanic contact with each other, and a body (5, 8) to which the contacts are mechanically attached, wherein the center conductor of the resonator and the sheath can be short-circuited at the desired location by moving the connector in the direction of the longitudinal axis of the resonator and thus tuning the resonator in both directions to its correct resonant frequency. Device according to claim 1, characterized in that the first contacts and the second contacts comprise sliding contacts (4) inside the resonator tube. Device according to claim 1, characterized in that the first contacts are sliding contacts inside the resonator tube and the second contacts are sliding contacts outside the jacket (2). Device according to claim 1, characterized in that the connecting piece comprises a sleeve (11) wound inside the resonator tube, the threads on the outer surface (9) of which form second contacts and the threads on the inner surface (10) form the first contacts. Device according to Claim 1, characterized in that the connecting piece is a standard coaxial connector with sliding contacts. 5 8 9 6 4 S