1. Technical Field
The present disclosure relates to cavity filters including resonator tubes.
2. Description of Related Art
Cavity filters are the basic circuitry behind a duplexer and are in a sharply tuned resonant circuit that allows only certain frequencies to pass. A typical cavity filter has one or more resonator tubes each in corporation with one tuning adjustment screw. Traditionally, the resonator tubes are fixed in the cavity filter by fixing members, such that the more resonator tubes and tuning adjustment screws, the longer it takes to assemble the cavity filter.
What is needed, therefore, is a cavity filter capable of being assembled quickly.
Many aspects of the present cavity filter can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present resonator tube and cavity filter including the resonator tube. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the views.
Referring to
The unitarily formed piece 10 is made by casting or molding operation. The unitarily formed piece 10 includes a bottom plate portion 141, a resonator tube body portion 20 formed on a center of the bottom plate portion 141, and a sidewall portion 14 extending from the bottom plate portion 141 surrounding the resonator tube body portion 20.
The resonator tube body portion 20 defines a resonating cavity 200 therein. The cap 22 is attached onto a distal end, that is, the top end of the resonator tube body portion 20. The cap 22 and the resonator tube body portion 20 cooperatively form a resonator tube 16. The size and shape of the cap 22 can be varied to effect the frequency of the cavity filter 100.
The sidewall portion 14 is substantially cylindrical in shape. The sidewall portion 14 has a top opening 140. The cover 12 is attached onto the sidewall portion 14 and shade the top opening 140. The cover 12, the sidewall portion 14, and the bottom plate portion 141 cooperatively form a chamber 300. The chamber 300 communicates with the resonating cavity 200.
The tuning adjustment screw 122 extends through the cover 12 by a screw hole 120 formed in a central area of the cover 12. The tuning adjustment screw 122 is threadedly engaged in the screw hole 120 and aligned with the resonator tube 16. The tuning adjustment screw 122 is formed from a conductive material, such as brass, for example. There may be a number of resonator tubes 16 and a number of corresponding tuning adjustment screws in one cavity filter.
Referring to
The top end surface 202 is a flat surface parallel to the bottom plate portion 141. The beveled surface 204 inclines to the interior of the resonating cavity 200 about θ degrees. θ is an acute angle. One step part 2061 of the step surface 206 is parallel to the bottom plate portion 141 and configured to support an inner tube 222 (shown in
There is a bottom surface 201 located on the center of the resonator tube body portion 20. The resonator tube body portion 20 also includes a support 26 below the bottom surface 201 and over the bottom plate portion 141. The support 26 is solid and free of apertures, thus the probability of a third-order harmonic distortion is lowered.
The detail structure of the cap 22 is mainly shown in
Referring to
Refer to
The resonator tube (except the cap), the bottom plate portion, and the sidewall portion are formed unitarily, therefore, the location of the resonator tube is accurate according to the predetermined design, and does not need to be moved or adjusted. The cap also does not need fixing members to be matched with the resonator tube body portion. In all, the time for producing or assembling the cavity filter is minimized.
It is understood that the above-described embodiments are intended to illustrate rather than limit the disclosure. Variations may be made to the embodiments without departing from the spirit of the disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure.
Number | Date | Country | Kind |
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201120070118.3 | Mar 2011 | CN | national |