JPS6313601B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in directional filters used in microwave bands and millimeter wave bands.

Here, for convenience of explanation, the explanation will be limited to three frequencies, and these three frequencies will be referred to as ₁ , ₂ , and ₃ , and will be explained assuming that they have a relationship of ₁ < ₂ < ₃ .

Here, a case will be described in which _two waves are separated from the waves consisting of the three frequency bands mentioned above.

First, the conventional directional filter shown in FIG. 1 will be briefly described.

In FIG. 1, 1 is a main waveguide, 2 is a sub waveguide, 3 and 4 are cylindrical cavity resonators, 5 to 7 are coupling holes,
, is the terminal of main waveguide 1, , is the terminal of sub waveguide 2
This is the terminal.

Here, the coupling holes 5 and 7 are located at such a position that the wave incident on one end of the main waveguide 1 and the sub waveguide 2 is coupled to the cavity resonator 3 and the cavity resonator 4 in a circularly polarized manner. It shall be provided in the shape.

Now, if waves ₁ , ₂ , and ₃ are introduced into the terminal of main wave tube 1, and the tube axis length of cavity resonators 3 and 4 is selected to be approximately 1/2 of the tube wavelength of frequency ₂ , the coupling hole will be _{The two} waves coupled by circularly polarized wave 5 resonate in the cavity resonator 3. The other waves ₁ and ₃ pass through the cavity resonator 3 without being affected and are taken out to the terminal. The wave ₂ further resonates in the cavity resonator 4 and is coupled to the sub waveguide 2 through the coupling hole 7. At this time, since the wave in the cavity resonator 4 is a circularly polarized wave, the wave ₂ coupled to the sub waveguide 2 has directionality due to its reversibility and is taken out to the terminal.

As described above, such a directional filter has the function of a so-called demultiplexer that demultiplexes or combines waves of different frequencies.

However, in such a directional filter, the coupling holes 5 and 7 need to be provided at positions where the magnitudes of the axial component and the lateral component of the magnetic field in the main waveguide 1 and the sub waveguide 2 are equal. Since this position is close to the narrower wall surface of the main waveguide 1 and the sub waveguide 2, the sizes of the coupling holes 5 and 7 cannot be made large. For this reason, there was a drawback that the amount of coupling between the coupling holes 5 and 7 was small, and the frequency band ₂ to be demultiplexed was narrow.

In order to eliminate these drawbacks, this invention provides a single coupling hole in the center of the end face of the cavity, and also provides an inductive iris in the main waveguide and sub waveguide near the coupling hole. The drawings will be described in detail below.

FIG. 2 shows one embodiment of this invention, 1 to 7,
- are the same as in FIG. 1, 8 and 9 are inductive irises, and 10 is an iris for alignment with the inductive irises 8 and 9.

Here, the inductive irises 8 and 9 are formed by thin conductor plates protruding from the narrower tube wall surfaces of the main waveguide 1 and the sub-waveguide 2, and the coupling holes 5 and 7 are formed of thin conductor plates protruding from the narrower tube wall surfaces of the main waveguide 1 and the sub-waveguide 2, and the coupling holes 5 and 7 are The central portions of the end faces in contact with the main and sub waveguides 1 and 2 are provided close to the inductive irises 8 and 9.

Further, the matching iris 10 is connected to the cavity resonator 3,
For waves that do not resonate with 4, inductive iris 8,
It is assumed that the arrangement and shape are such that the reflection of 9 is canceled.

Next, the function of the inductive irises 8 and 9 will be explained. The inductive iris 8 changes the magnetic field distribution in the cross section of the main waveguide 1 as shown in FIG. In FIG. 3, arrows indicate magnetic fields, and FIG. 3A shows the case without the inductive iris 8, and FIG. 3B shows the case with the inductive iris 8. As is clear from FIG. 3, when the inductive iris 8 is provided,
The tube axis direction component Hz at the center of the main wave tube 1 can be increased. Therefore, when the inductive iris 8 is provided, the coupling hole 5 can be provided at a position away from the narrow wall of the main waveguide 1,
The size of the coupling hole 5 can be increased without being restricted by the narrower tube wall. The function of the inductive iris 9 is exactly the same, and the size of the coupling hole 7 can be increased.

Therefore, in the directional filter of the present invention, the amount of circularly polarized waves coupled through the coupling holes 5 and 7 can be increased by the action of the inductive irises 9 and 8.

Now, if waves ₁ , ₂ , and ₃ are introduced into the terminal of main wave tube 1, and the tube axis length of cavity resonators 3 and 4 is selected to be approximately 1/2 of the tube wavelength of frequency ₂ , the coupling hole will be _{The two} waves coupled by circularly polarized wave 5 resonate in the cavity resonator 3. The other ₁ and ₃ waves are inductive iris 8,
It passes through the cavity resonator 3 as it is without being affected by it, and is taken out to the terminal. The wave No. ₂ further resonates in the cavity resonator 4, couples to the sub waveguide 2 through the coupling hole 7, and is taken out to the terminal.

Therefore, the directional filter of the present invention has a function as a demultiplexer, and can further increase the coupling amount of the coupling holes 5 to 7, so that it is possible to demultiplex ₂ in a wide frequency band. Can be done.

In addition, although the case where the number of cavity resonators is two was described above, the number of cavity resonators is not limited to two. Moreover, although the case where the coupling hole is X-shaped has been described, the shape of the coupling hole is not limited to the X-shape.

As described above, in the directional filter according to the present invention, a single coupling hole is provided in the center of the end face of the cavity resonator, and a single coupling hole is provided in the main waveguide and the sub waveguide in the vicinity of the coupling hole. Providing an inductive iris has the advantage that waves in a wide frequency band can be separated.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional directional filter, FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, and FIG. 3 is a diagram for explaining the operating principle of the directional filter. It is. In the figure, 1 is a main waveguide, 2 is a sub waveguide, 3 and 4 are cavity resonators, 5 to 7 are coupling holes, and 8 and 9 are inductive irises. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

Claims (1)

[Claims] 1. In a directional filter in which a pair of waveguides are provided with coupling holes in opposing parts, and a cavity resonator is provided between the coupling holes, the coupling hole is located in the center of the end face of the cavity resonator. Directional filtering characterized in that the waveguide is provided with an inductive iris protruding from a narrow wall surface of the waveguide toward the center of the coupling hole. vessel.