Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Patent
1993-06-16
1995-02-14
Ham, Seungsook
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
333206, 333207, H01P 1205
Patent
active
053899032
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a high-frequency bandpass filter, comprising several cylindrical conductor rods arranged in a line with predetermined spacings in a continuous space defined by an elongated housing made of an electrically conductive material and closed on all sides, each conductor rod being attached and short-circuited at its first end to the housing and spaced apart from the housing at its second end so that each conductor rod forms a coaxial resonator together with the housing.
In a typical high-frequency bandpass filter of the type described above, the conductor rods in the metal housing are separated from each other by partition walls into separate compartments each forming a coaxial resonator. The coupling between adjacent resonators is accomplished either by means of separate coil structures inductively at the short-circuited end of the resonators or by means of separate capacitor structures at the open end of the resonators. Another common practice is to realize each coaxial resonator by means of a conductor rod positioned in a fully separate metal box. The coupling between the resonators is again accomplished, e.g., by separate coil structures, such as a conductor wire running from one resonator box to another through coupling openings. Prior art filter structures of this type are large in size and complicated, in addition to which they require plenty of manual work and are difficult to tune, as a result of which a sufficiently accurate reproducibility of the desired filter properties is also difficult to achieve in series production. For instance, when using the above-mentioned conductor wire coil, the coupling between the resonators has to be adjusted by bending the conductor wire coil.
Another known filter type is the so-called Comb-Line filter, in which all conductor rods are placed, in place of separate metal boxes or compartments separated from each other by partition walls, in a single continuous space defined by a housing, so that an open filter structure is achieved, in which the couplings between the resonators are formed directly by the couplings between the conductor rods of the resonators. Therefore the filter is smaller in size and simpler than the filters described above. In this type of filter, the couplings between the conductor rods are controlled by means of adjustment screws provided in the cover of the housing and by varying the distances between the conductor rods; such adjustments, however, cannot provide different filter responses by one and the same filter unit for different applications.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a high-frequency bandpass filter which is smaller in size, simpler in structure and easier to tune than previously.
This is achieved by means of a high-frequency bandpass filter of the type described in the introduction, which according to the invention is characterized in that the second end of each conductor rod comprises a portion larger in diameter as compared with the remaining portion of the conductor rod, and that the type of a coupling between any two adjacent coaxial resonators is arranged to be set to be predominantly capacitive or predominantly inductive by adjusting the ratio of a distance between the first ends of the conductor rods of the coaxial resonators to a distance between said portions with a larger diameter.
In the invention, the unconnected end of the conductor rod, that is, its open end, is provided with a knob having a diameter larger than that of the shaft portion of the conductor rod, which strengthens the capacitive coupling between adjacent conductor rods. As the capacitive portion in the coupling of adjacent resonators depends on the distance between the knobs and the inductive portion depends on the distance between the shaft portions, either a capacitive or an inductive coupling can be made predominant by varying the ratio between the two distances. As the type (inductive or capacitive) of couplings between the resonators affects the location of
REFERENCES:
patent: 3496498 (1970-02-01), Kawahashi et al.
patent: 3840828 (1974-10-01), Linn et al.
patent: 4020428 (1977-04-01), Friend et al.
patent: 4059815 (1977-11-01), Makimoto et al.
patent: 4216448 (1980-08-01), Kasuga et al.
patent: 4224587 (1980-09-01), Makimoto et al.
patent: 4283697 (1981-08-01), Masuda et al.
patent: 4284966 (1981-08-01), Wanat
patent: 4292610 (1981-09-01), Makimoto et al.
patent: 4757289 (1988-07-01), Kosugi et al.
Ham Seungsook
Nokia Telecommunications Oy
LandOfFree
Comb-line high-frequency band-pass filter having adjustment for does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Comb-line high-frequency band-pass filter having adjustment for , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Comb-line high-frequency band-pass filter having adjustment for will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-290267