JPS63158902A - Waveguide type branching filter - Google Patents

Abstract

PURPOSE:To obtain a branching characteristic of wide band area, by connecting a square waveguide that is a band-pass filter orthogonal to the planes confronting with each other of a square main waveguide, and constituting couping holes with parallel elongated holes when the coupling holes are provided at a part coupling with the waveguide orthogonal to the main waveguide. CONSTITUTION:The square waveguide 4 which forms a first band-pass filter 2 and the square waveguide 5 which forms a second band-pass filter 3 on which irises 6a-6c and 7a-7c are provided respectively are mounted orthogonally to the main waveguide 1 on the confronting outer planes of the square main waveguide 1 having a short-circuit plate 10 at its terminating part. In this way, the coupling holes 11 and 12 are drilled respectively on the coupling part of those waveguide paths, but, at this time, the coupling holes 11 and 12 are not drilled as one hole, and they are constituted with elongated coupling holes being set orthogonally to and in parallel with the tube axis of the main waveguide 1. Also, the irises 6a-6c and 7a-7c on the waveguides 4 and 5 are set as pairs interventing paths respectively, and also, those planes are confronted in a direction of branching. Thus, a large magnetic polarential factor can be generated in the hole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a waveguide duplexer used in microwave bands and millimeter wave bands.

[Prior Art] Fig. 3 is a schematic configuration diagram showing a conventional waveguide type duplexer shown in, for example, Material No. MW72-73 (September 1972) of the Microwave Study Group material of the Institute of Electronics and Communication Engineers. In the figure, (1) is the main waveguide made of a rectangular waveguide, and (2) is the first waveguide.
(3) is a second waveguide bandpass filter, (4) and (5) are rectangular waveguides, (6a
) ~ (6c), (7a) ~ (7c) are iris, (
8) Six waveguide bandpass filters (2) and (3), where (9) is the coupling hole and (10) is the shorting plate of the main waveguide (1).
are rectangular waveguides (4) (5), iris (6a) to (6
c) , (7a) to (7c) and binding holes (8) (9)
constitute a plurality of resonators, and are connected so that their tube axes are perpendicular to the tube axis of the main wave tube (1). The coupling holes (8) and (9) are connected to bandpass filters (2) and (3).
) and the main wave tube (1) at approximately the center of the connecting surface. Further, the tip of the main waveguide (1) is short-circuited by a short-circuit plate (10).

Next, the operation will be explained. The first bandpass filter (
The resonance frequency and the size of the irises (6a) to (6c) are adjusted so that the second bandpass filter (3) passes the frequency f1 as the center frequency, and the second bandpass filter (3) resonates so that the second bandpass filter (3) passes the frequency f2 as the center frequency. Frequency and Iris (
The sizes of 7a) to (7c) are adjusted, and the binding holes (
The distance between 8) and (9) and the shorting plate (10) is 1 of the in-tube vibration lengths λg1 and 1g8 for frequencies f1 and f2, respectively.
72, the incident waves of frequencies f□ and f2 from the main waveguide (1) are located at a distance from the shorting plate (lO) that is an integer multiple of 1g0/2 and 1g2/2. When the magnetic field becomes maximum, the coupling holes (8) and (
9) to efficiently pass bandpass filters (2) and (3).
).

Figure 4 shows the junction (hereinafter referred to as T branch) between the main waveguide (1) and the rectangular waveguide (4) of the bandpass filter (2) in this duplexer. ) is a longitudinal sectional view of the T-junction, FIG. 4(b) is a cross-sectional view thereof, and FIG. 4(c)
is its equivalent circuit diagram. Equivalent circuit constants Ba and Bb
is given by the following equation.

Here, Y is the characteristic admittance of the waveguide, a and b are the width and height of the waveguide cross section, respectively, and λ.

λg are the wavelengths in free space and in the tube, P,
M is an electric polarization ratio and a magnetic braid ratio, respectively, taking into account the frequency characteristics of the coupling holes (8) and (9). The magnetic braid ratio M is expressed by the following equation when the thickness of the coupling hole is ignored.

Here, Mo is the magnetic polarization ratio without considering the frequency characteristics of the coupling hole, and Ω is the length of the coupling hole. Q is usually a dimension smaller than λ/2. Using this M, the coupling Qe (external Q) of the main waveguide (1) and bandpass filters (2) and (3)
And the coupling k (interstage coupling amount) between resonators in the bandpass filter is expressed by the following equation.

k:! ! -MH2...(5) Here, h is the magnetic field component in the cross section of the main waveguide (1), H
is the resonant magnetic field component in the cross section of the resonator in the bandpass filter, λg is the tube wavelength of the input/output rectangular waveguides (2a) (2b), and μ is the magnetic permeability.

[Problem to be solved by the invention 1 The conventional waveguide type duplexer configured as above requires a large amount of coupling in order to obtain broadband characteristics, and the length of the coupling hole Ω Alternatively, it was necessary to increase the width W. However, when the length of the coupling hole is increased, the free space wavelength λ at the center frequency f0 of the bandpass filter becomes two. , the rate of change of the magnetic polarization factor M with respect to frequency becomes large.

Figure 5 shows M/M and λ/λ. The relationship is 2Q/λ. is expressed as a parameter, for example, λlλ. = 1, the larger Q is, the λ/λ of M/M. The slope is increasing. For this reason, the amount of coupling changes greatly depending on the frequency change, and the conventional waveguide type duplexer has a problem in that good VSIIR characteristics cannot be obtained in a wide passband. Further, when the width of the coupling hole is increased, the magnetic polarization ratio M increases as shown in FIG. 6, but the electric polarization ratio P also increases as shown in FIG. 7. For this reason, the inductive susceptance shown in FIG. 4(b) becomes large, deteriorating the splitting characteristics, and it is necessary to provide a capacitive post, resulting in a large size. In addition, in FIG. 7, P is an electric polarization rate without considering the frequency characteristics of the coupling hole.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a waveguide duplexer that is small and has broadband pass characteristics.

[Means for Solving the Problems] The waveguide duplexer according to the present invention includes a plurality of elongated coupling holes provided as coupling holes at the junction between the main waveguide and the waveguide bandpass filter. It is something that

[Function] In this invention, a large magnetic polarization ratio can be obtained because a plurality of elongated coupling holes are used. Furthermore, since the electric polarization rate per bonding hole is sufficiently small, the overall electric polarization rate can also be kept small. Therefore, wideband demultiplexing characteristics can be obtained without providing capacitive posts.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a schematic configuration diagram showing an embodiment of the present invention. In figure 1, (1) is a main waveguide made of a rectangular waveguide, (2) is a first waveguide band-pass filter, and (3) is a main waveguide made of a rectangular waveguide. is the second waveguide bandpass filter, (4) and (5) are the rectangular waveguides, (
6a) to (6c) and (7a) to (7c) are iris, and (10) is a shorting plate of the main wave tube (1), which are the same as those shown in FIG. 3. (11) and (12) are both a plurality of elongated coupling holes, which are provided close to each other.

The operation of this embodiment is similar to the conventional waveguide type duplexer shown in FIG.

In this duplexer, for example, elongated coupling holes (11) (12)
When the ratio W/Q of length Q and width W of
” is 0.007. This binding hole (11) (!2)
When three are used, the magnetic polarization rate and electric polarization rate are respectively the magnetic polarization rate and electric polarization rate when there is one coupling hole, respectively.
The multiplied value, that is, M, / jm ” is 0.24, pH
/Q3ha becomes 0.021. However, the width W of the coupling hole
By increasing the value of M,/a'' for one bonding hole, the value is 0.2.
4, it is necessary to set W/fl to 0.9. Then, the value of P, IQ3 becomes 0.072, W/fl
is approximately 3.4 times larger than when three 0.2 binding holes are used. Therefore, in order to obtain the same magnitude of magnetic polarization, it is better to use multiple elongated coupling holes with a small W/Q value to keep the electrical polarization smaller than by making one coupling hole larger. This makes it possible to reduce deterioration in the characteristics of the duplexer. In the duplexer of this embodiment, since there are multiple coupling holes, all of them cannot be arranged at positions that are integral multiples of λg/2 from the shorting plate (10), but since the magnetic field distribution is sinusoidal, the coupling holes in the center If they are arranged at positions that are integral multiples of λg/2, the difference in magnetic field strength between the coupling holes is negligible because the plurality of coupling holes are provided close to each other. Also, the free space wavelength λ at the center frequency f is twice the length of the coupling hole 2Q
.

If it is made shorter, the problem of changes in magnetic polarization due to changes in frequency will also be eliminated. Therefore, good demultiplexing characteristics can be obtained over a wide band.

FIG. 2 is a schematic configuration diagram showing another embodiment of the present invention, in which metal posts (13a) to (13c) are used instead of the iris.
This is the case when (14a) to (14c) are used. In this case as well, broadband demultiplexing characteristics can be obtained as in the embodiment shown in FIG.

In the above embodiment, a case was described in which three coupling holes were provided, but the present invention is not limited to three coupling holes.

Furthermore, although the case where the number of stages of the filter is three has been described, the present invention is not limited to the number of stages of the filter being three.

[Effect of the invention] As mentioned above, this invention! According to the method, since a plurality of elongated coupling holes are provided, it is possible to obtain a waveguide type duplexer having a large amount of coupling and a broadband demultiplexing characteristic.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing one embodiment of the present invention, FIG. 2 is a schematic block diagram showing another embodiment of the present invention, and FIG. 3 is a schematic diagram showing a conventional waveguide type duplexer. 4 is a longitudinal cross-sectional view, a cross-sectional view, and an equivalent circuit diagram of the T-branch, FIG. 5 is a characteristic diagram showing the frequency characteristics of magnetic polarization, and FIG. 6 is a diagram showing the size of the coupling hole and magnetic polarization. A characteristic diagram showing the relationship between the polarization ratio and FIG. 7 is a characteristic diagram showing the relationship between the size of the bonding hole and the electrical polarization ratio. In the figure, (1) is a main waveguide, (2) and (3) are waveguide bandpass filters, (4) and (5) are rectangular waveguides, (
6a) to (6c), (7a) to (7c) are iris, (10) is a short circuit plate, (11) and (12) are both a plurality of elongated coupling holes, (13a) to (13c), (14a)
- (14c) are metal posts. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (6)

[Claims] (1) A main waveguide with one end short-circuited, two or more waveguide bandpass filters coupled to the main waveguide having different pass frequencies, and the main waveguide and the waveguide bandpass filter. A waveguide type duplexer comprising a coupling hole provided in a tube wall on a connection surface with a waveguide type duplexer, characterized in that a plurality of elongated coupling holes are provided as the coupling holes. Wave equipment. (2) The main waveguide and waveguide type bandpass filter described above are:
The waveguide type duplexer according to claim 1, which is constituted by a rectangular waveguide. (3) The waveguide according to claim 1 or 2, wherein the tube axis of the main waveguide and the tube axis of each of the waveguide bandpass filters are arranged to be orthogonal to each other. shape splitter. (4) A plurality of coupling holes between the main waveguide and the first and second waveguide bandpass filters are such that the coupling hole in the center connects each guide to be coupled from the short-circuited end of the main waveguide. The waveguide type according to any one of claims 1 to 3, which is arranged at a position that is an integral multiple of 1/2 of the pipe wavelength of the pass frequency of the wave tube type band-pass filter. Duplexer. (5) The first and second waveguide bandpass filters are:
A waveguide type duplexer according to any one of claims 1 to 4, which comprises a plurality of resonators each having a plurality of irises provided therein. (6) The first and second waveguide bandpass filters are:
The waveguide type duplexer according to any one of claims 1 to 4, which comprises a plurality of resonators each having a plurality of pairs of metal posts provided inside.