DE1046128B - Capacitively coupled cavity resonator - Google Patents

Description

GERMAN

The invention relates to a capacitive narrow-profile rectangular waveguide coupled cavity resonator.

It is known that in the field of microwaves resonance circuits or their combinations to frequency filters can be constructed from cavity resonators. By choosing the dimensions, the Coordination and the coupling elements of such resonators with each other and with the connecting lines properties similar to those of concentrated element filters can be achieved.

Four essentially different types of coupling are conceivable, namely capacitive (C) or inductive coupling (L) with the resonator current (H) or with the resonator voltage (E). The combinations CE and LH, which are generally used, are relatively easy to implement. However, they have the disadvantage of becoming broader bandwidth when tuning with increasing frequency and result in asymmetrical transmission and delay curves. In addition, it is known that all line resonators have passbands with approximately integral multiples of the fundamental passband. The combinations CE and LH become wider in bandwidth as the octaves increase, so they have very poor harmonic rejection. Another disadvantage of these combinations is that their equivalent circuit is located inside the resonator, which is unfavorable for branch circuits or when using such a filter as a characteristic impedance transformer. The remaining two combinations CH and LE do not have these disadvantages. However, the LE version is practically difficult to implement with resonators with a low relative bandwidth, because large series inductances cannot be clearly represented in the case of microwaves. The CH version also presents similar difficulties, since diaphragm couplings of known construction with a sufficiently large susceptance cannot be controlled.

Thus, a waveguide arrangement acting as a band filter is already known, which has a longitudinal direction extending strips of dielectric material, which in its immersion depth in the waveguide is adjustable, and with a number of capacitive coupling slots extending in the transverse direction is provided. To achieve sufficiently large coupling tolerances, these slots must be very narrow, namely on the order of a few micrometers. But this means for them Manufacture of such an arrangement is a requirement that is very difficult to implement.

The object of the invention is therefore, while maintaining the advantages of a capacitive current coupling to make this so that no too high capacitively coupled cavity resonator

Applicant:
Standard electrical system Lorenz

Corporation,

Stuttgart-Zuffenhausen,

Hellmuth-Hirth-Str. 42

Dr. Martin Müller, Pforzheim,
has been named as the inventor

Requirements are placed on the manufacturing accuracy. With a capacitively coupled cavity resonator, whose feeds are designed as narrow-profile rectangular waveguides and to the cavity resonator Are coupled by means of current coupling, according to the invention at least one in the interior the narrow profile waveguide parallel to. whose, wider side walls a conductive rod is arranged, and a slot-shaped coupling gap is formed between the wide side walls and the conductive rod, which extends essentially uniformly over the entire width of the waveguide.

The cavity resonator can be designed with a rectangular cross section and with the same width α and the same height b as the connecting waveguide. It is particularly useful that its height b is greater than that of the coupled narrow-profile rectangular waveguide and that the resonator in the
is stimulated.

One possible resonator shape in which the width a of the connecting _{waveguide is retained is the circular-cylindrical H m} resonator of the same cylinder height, which is excited from a surface line.

Finally, a modification of the two above-mentioned resonator shapes has been found to be particularly favorable in such a way that the cavity has a cylindrical shape with an oval cross-section, that the narrow-profile conductor is coupled along a surface line on the narrow side of the cylinder and that the resonator is in an H _{111 rnnd} or H _{101 rectangle} mode is excited.

In order to achieve a particularly high coupling susceptibility in which no interfering H _n “waveforms are excited, a coupling is preferably used

H ₁₀ "mode

809 698/341

proposed, which is dimensioned so that the conductive rod has a circular cross-section and that the waveguide interior is widened at the point of coupling by a corresponding hole parallel to the side walls α such that the coupling gaps formed with the conductive rod have a circular segment-shaped cross-section.

A tunable coupling can be, for. B. achieve that the circular cross-section of the conductive rod is flattened on one side or on both sides, so that the coupling column by turning the Have variable width rods.

The coupling rod can be designed so that it can be inserted from the outside. The bandwidth and the gear ratio of the resonator can also be changed within wide limits in that the Coupling rod is optionally interchangeable.

Capacitively coupled cavity resonators according to the invention are particularly suitable for the construction of Frequency filters by using either appropriately pre-adjusted resonators with the interposition of Waveguide pieces are connected to form a 1/4 coupled filter or cavity resonators directly adjacent to the coupling capacitance to form one directly coupled multi-circuit filters are combined.

The invention is explained in more detail using exemplary embodiments with reference to the drawing:

1 shows, in longitudinal section, a cavity resonator 1 with a tuning die 2 and the connected narrow-profile rectangular conductors 3 and 4. In this exemplary embodiment, the _{cavity is designed as an oval H m resonator.} This shape is particularly favorable for a cast production and for the subsequent surface treatment.

With 5 and 6, the coupling rods are referred to, which are free in a slightly widening the waveguide Bore are arranged. The rod 6 is somewhat flattened on one side, so that with its rotation in the bore the gap width can be changed at least on one side within certain limits.

With a resonator of the form shown in FIG. 1, bandwidths can be achieved in the 4000 MHz range Achieve between 10 and 100 MHz and more with the lowest inherent attenuation, with a change of the coupling rods the resonance frequency with an almost constant bandwidth over a range of ÖOOMHz and more can be voted through. If several such resonators are flanged at an appropriate distance (about 1/4 between the coupling rollers) one behind the other, so one can easily convert individual ones Way, appropriately balanced resonators a multi-circuit filter with arbitrarily adjustable within wide limits Establish properties.

In a similar way, a multi-circuit filter can be constructed from several directly coupled resonance circuits, as shown in Fig. 2 as a three-circuit filter, with 1 the three identical cavities, here designed as H ₁₀₁ rectangular resonators, 2 the tuning screws, 3 the coupling rods, the may have different diameters and 4 show the connecting waveguide. A filter constructed in this way can also be largely tuned without any significant change in bandwidth and transmission properties. It has the further advantage of a length that is essentially frequency-independent, since there are no line sections between the individual cavity resonators, the length of which would have to be coordinated.

Claims (9)

.. claims: 1. Capacitively coupled cavity resonator, its feeds as a narrow-profile rectangular waveguide are formed and are coupled to the cavity resonator by means of current coupling, characterized in that at least in the interior one of the narrow-profile waveguides is parallel to the wider side walls of which a conductive rod is arranged and that between the wider side walls and the conductive rod each have a slot-shaped coupling gap, which extends essentially uniformly over the entire width of the waveguide. 2. Cavity resonator according to claim 1 in rectangular shape, characterized in that its height (V) is greater than the corresponding of the coupled narrow-profile rectangular waveguide and that the resonator _{is excited in the H 10} "mode. 3. Cavity resonator. according to claim 1, which encloses a circular cylindrical three-dimensional shape, characterized in that the narrow-profile rectangular waveguide is coupled along a surface line of the cylinder and that the resonator _{is excited in the H 111} mode with energy transport transversely to the cylinder axis. 4. Cavity resonator according to claim 1, characterized in that the cavity has a cylindrical shape with an oval cross-section, that the SchmalprofuTeiter is coupled along a surface line on the narrow side of the cylinder and that the resonator transversely to the axis in a H _lllruna - or H _101recllteck Mode is excited 5. Cavity resonator according to one of the preceding claims, characterized in that the conductive rod has a circular cross-section and that the waveguide interior is expanded at the point of coupling through a corresponding bore parallel to the side walls (a) so that the with the conductive rod coupling gap formed has a circular segment-shaped cross section. 6. Cavity resonator according to claim 5, characterized in that the cross section of the conductive rod is flattened on one side or on both sides, so that the coupling gaps through Rotating the roller has variable width. 7. Cavity resonator according to one of the preceding claims, characterized in that the coupling rod is optionally interchangeable. 8. Cavity resonators according to one of the preceding claims, characterized in that Additional cavity resonators are connected via appropriately adjusted narrow-profile waveguide sections and are connected. 9. Cavity resonators according to one of claims 1 to 7, characterized in that further cavity resonators directly adjoining the coupling capacitance to form a multi-circuit Filters are united. Considered publications:
Swiss Patent No. 305 548;
British Patent No. 714,827;
U.S. Patent No. 2,629,015. 1 sheet of drawings © 8C9 698/341 12.58