JPH0260202A - Directional filter - Google Patents

Abstract

PURPOSE:To obtain a miniaturized, lightweight filter with low reflection loss, and to prevent unnessary resonance from occurring for a wide band by constituting the directional filter by means of small resonators. CONSTITUTION:Adjustment machine screws 10a are plural adjustment members provided at intervals shorter than a quarter of a guide wave length in the resonator frequency of a resonator 2a. Adjustment machine screws 10b are plural adjustment machine screws provided at the intervals shorter than a quarter of the guide wave length in the resonance frequency of a resonator 2d in the resonator 2d connected to an output wave guide 5. When an intervened angle theta of two lines connecting the center axis of the resonator 2a and the center machine screw among the adjustment machine screws 10a satisfies the relation of an expression (I), the position relation of the adjustment machine screws 10a and 10b and the holes in the edge of the connection holes 4a and 4e becomes satisfactory. Thus, the characteristic of low reflection can be realized in the directional filter having small resonators.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a directional filter for separating and combining communication signals of different frequencies in the field of wireless communication, and particularly to a directional filter that is small and lightweight and can be mounted on a satellite in satellite communication. The present invention relates to a directional filter having characteristics suitable for use in communication equipment.

[Prior Art] Conventionally, in the field of wireless communications, directional filters have been used as devices for separating and combining communication signals having different frequencies.

FIG. 3 is an exploded perspective view showing the configuration of a conventional directional filter. 1 is a signal input end on the antenna side, 21 to 2d are resonators, 3 is an input waveguide, 4a to 4e are coupling holes, 5 is an output waveguide, 6 is a branched signal output end, 7 is a passing signal output edge, 8
is the residual signal output terminal, 9 is the non-reflection terminator, 10a, 10b
is an adjustment screw. A large number of frequency-multiplexed communication signals F + ,
When Ft~F,1 is input from the signal input terminal l on the antenna side, the signal F1 of the frequency component resonating at the resonances 52a~2d is transmitted from the input waveguide 3 to the resonator 2 through the coupling hole 4a.
a, a coupling hole 4b, and a resonator 2b.

Coupling hole 4c, resonance 2c, coupling hole 4d, resonator 2d.

After successively passing through the coupling holes 4e, the signals are coupled to the output waveguide 5 and output to the demultiplexed signal output end 6. Signals F, -Fn of frequency components that do not resonate in the resonators 21 to 2d are not coupled to the resonator 2a, but are output to the passing signal output end 7 of the input waveguide 3. A part of the reflected waves generated in the coupling holes 4a to 4C is reflected to the signal input end 1, and the other part is guided to the residual signal output end 8 and absorbed by the non-reflection termination part 9. Ru.

At this time, coupling holes 4a to 4a provided between the resonators 2a to 2d
In order to obtain a directional filter with a desired band characteristic, the dimensions of the coupling hole 4e are designed to obtain the necessary value, but in particular, the coupling holes 4a and 4e require a strong coupling degree, so a multi-slit type filter is required. Since a structure that can easily obtain a strong coupling degree, such as a coupling hole, is used, the structure is likely to cause reflected waves. If the dimensions of the resonators 4a to 4e are large, the coupling holes 4a and 4e in order to obtain the necessary degree of coupling are formed by forming holes with a small amount of coupling at a predetermined interval (1/4 of the waveguide wavelength of the resonator at the resonant frequency). A large number of them can be provided, and since the reflection from one hole is small, the number of reflected waves from the entire coupling hole can be reduced.The no-load Q value of the resonator is also large, and the demultiplexing loss is reduced, so there is no interference between communication signals. A directional filter with less interference can be easily realized. In addition, three adjusting screws 1oa10b are provided in each of the resonators 2a and 2d for the purpose of adjusting the resonant frequency and improving the directivity and reflection characteristics, but by placing them at intervals of 1/4 of the tube wavelength. At a specific frequency, it is possible to cancel any reflected waves generated in the resonator, and the reflected waves generated in the coupling holes 4a and 4e are transferred to the resonator 2a.

It is easy to perform adjustment to cancel at the 2d resonance frequency, and a directional filter with low reflection characteristics can be realized. Therefore, the positions of the coupling holes 4a and 4e and the adjustment screw lo
As for the relative relationship between the positions of a and lob, they were usually placed at symmetrical positions as shown in FIG. 3 without any special consideration.

[Problems to be Solved by the Invention] However, in the directional filter in the above-mentioned conventional technology, unnecessary resonance tends to occur when the dimensions of the resonators 2a to 2d are large, making it difficult to obtain good signal transmission characteristics. As the band becomes narrower, only a directional filter with a narrow usable band can be realized.Therefore, there is a need for duplexers for satellite communications, which require good transmission characteristics over a wider range of frequencies, and which require small size and lightweight characteristics. However, when used as a directional filter on board a satellite, it had the disadvantage of being large and heavy, and limiting the range of use.

Therefore, in order to obtain small size, light weight, and broadband characteristics, a small-sized resonator (a resonator with a resonance order of N = 3 to 4 or less) is required.
However, if a directional filter is constructed using a small resonator, the distance between the coupling holes 4a and 4e is set to the above-mentioned predetermined distance (inside the waveguide of the resonator at the resonant frequency). The number of pores that can be arranged is reduced by 1/4 of the wavelength, and it is necessary to use large pore sizes in order to obtain the required amount of coupling. Therefore, the reflection of the signal at the - number of holes becomes large, and as a result, the reflection of the signal at the coupling holes 4a and 4e becomes large, and the interference between communication signals becomes large, and the reflection loss becomes large. In order to reduce the reflection of the signal, the coupling hole 4a
, 4e is designed in such a way that the degree of coupling is reduced as much as possible, the dimensions of the holes are made small, and a large number of holes are provided. For this reason,
Input waveguide 3. Output waveguide5. The relationship between the resonators 2a, 2d and the coupling holes 4a, 4e is the same for each resonator 2a.

The three input waveguides and the output waveguide 5 overlap over half a circumference of 2d, and the coupling holes 4a, 4e are formed symmetrically with respect to the center of the overlapping part and over almost the entire overlapping part.
will be provided.

Even in such a conventional directional filter having a small resonator, adjusting screws 10a and 10b are used for the purpose of adjusting the resonance frequency and improving reflection characteristics, or adjusting screws I
Oa and IOb are placed in the gap between the input waveguide 3 and output waveguide 5 and inserted into the small resonators 2a and 2d, so the coupling holes 4a and 4e and the 4 adjustment screw loa,
The positional relationship with 10b is uniquely determined. That is, since the gap in which the adjusting screws IOa and IOb are arranged is small, it is impossible to provide a plurality of adjusting screws 10a and 10b at 1/4 wavelength intervals. was placed. Therefore, a directional filter having a small resonator has a problem in that it is difficult to perform sufficient adjustment to reduce reflection.

FIG. 4 is a diagram showing an example of the characteristics of the above-mentioned conventional directional filter having small resonators, in which the number of resonator stages is 4. The figure shows the case where the resonance order is N-3 and the number of coupling holes is 6, where B is the reflection characteristic and C is the demultiplexing characteristic. In conventional directional filters, as shown in the characteristic example above, the value of the reflected wave is as large as about 115 dB, and even when using adjustment screws 10a and 10b, it is small, lightweight, and has low return loss, and has good signal transmission characteristics over a wide band. It has been difficult to realize a directional filter with

The present invention was devised to solve the above-mentioned problems, and provides a means for realizing a directional filter with small reflection loss, which was previously impossible to realize by using a small resonator. The objective is to realize a directional filter that does not generate unnecessary resonance over a wide band due to reflection loss.

[Means for Solving the Problems] The configuration of the directional filter of the present invention for achieving the above object includes: a resonator coupled to the input waveguide through a coupling hole provided in the side wall of the input waveguide; It has a plurality of adjustment members provided therein at intervals shorter than 1/4 of the tube wavelength at the resonant frequency of the resonator, and is coupled to the output waveguide by a coupling hole provided in the side wall of the output waveguide. In the directional filter, the resonator is coupled to the input waveguide, and includes a plurality of adjustment members provided in a resonator at intervals shorter than 1/4 of the wavelength in the tube at the resonant frequency of the resonator. The positional relationship between the center adjustment member provided in the center and the hole at the end of the coupling hole that couples the input waveguide and the resonator, and the adjustment member provided in the resonator coupled to the exit horn waveguide. The positional relationship between the center of the adjustment member and the hole at the end of the coupling hole that connects the output waveguide and the resonator is determined by connecting the center axis of each of the above-mentioned co-Ia devices to the center of the adjustment member. A line and a line connecting the central axis of each resonator and the hole at the end of the coupling hole are provided so that the included angle θ of the two lines satisfies N, the resonance order of the resonator m, and an odd value. shall be.

[Operations] By configuring a directional filter with a small resonator, the present invention achieves reduction in size and weight, and reduces the occurrence of unnecessary resonance over a wide band. By arranging the coupling holes for the corresponding resonators and the center of each adjustment member in the positional relationship described above, the waves reflected by the coupling holes are reflected by the center of the adjustment member. A nearly inverse phase relationship is obtained with respect to the generated reflected waves, and in combination with the canceling effect of the reflected waves from the adjustment members other than the center, low reflection characteristics are achieved.

[Embodiment] Hereinafter, an embodiment of the present invention will be explained in detail based on the drawings. Fig. 1 is an exploded perspective view of a directional filter showing an embodiment of the present invention. In this embodiment, functionally similar members are given the same reference numerals as in the prior art to simplify the explanation. 1
2 is a signal input terminal on the antenna side, 2a to 2d are small-sized resonators, and 3 is an input waveguide. 4a is a coupling hole provided in one side wall of the input waveguide 3, and the resonator 2a is coupled to the input waveguide 3 through this coupling hole 4a. 4b, 4c
, 4d are a plurality of (
A coupling hole 4e is a coupling hole formed in one side wall of the output waveguide 5. The coupling hole 4e is made up of a plurality of holes for coupling between the resonators 2b and 2c (two in the figure). The resonator 2d is coupled to the output waveguide 5 through the coupling hole 4e. The directional filter obtains desired frequency characteristics by using these resonators 2a to 2d and coupling holes 41 to 4e of required values. 6 is a branched signal output end on the output waveguide 5 side, 7 is a passing signal output end on the input waveguide 3 side,
8 is a residual signal output end on the output waveguide 5 side, and 9 is a non-reflection terminator. 10a is a resonator 2 coupled to an input waveguide 3;
A plurality of (three in the figure) provided in a at intervals shorter than 1/4 of the tube wavelength at the resonant frequency of this resonator 2a.
A plurality of adjusting screws 10b, which are adjustment members, are provided in the resonator 2d coupled to the output waveguide 5 at intervals shorter than 1/4 of the tube wavelength at the resonant frequency of the resonator 2d (Fig. Here are the 3 adjustment screws. In the above configuration, in this embodiment, unlike the conventional case, the coupling holes 4a, 4e
By selecting holes with a large degree of coupling per hole and reducing the number of holes, the positions where the coupling holes 4a and 4e can be installed can be made variable. The adjustment screws I
The relative positional relationship between Oa, 10b and the coupling holes 4a, 4e can be adjusted, increasing the degree of freedom in adjustment. In this way, by using holes with a large coupling amount per hole, the number of holes conventionally provided over half the circumference of the resonator can be reduced, and the adjustment screws IOa, IOb and coupling holes 4
a.

As shown in Fig. 1, the positional relationship between the hole at the end of 4e and the center axis of the resonator 2a (or 2d) and the adjustment screw 10a (
or job) (in this case, if the adjustment screw 10a is the connecting hole 4a, illll upper screw 1
The angle θ of the two lines (where 0b is the coupling hole 4b) is arranged so that the relationship N is expressed by the following equation, the resonance order m of the resonator, and the odd value is added by 11ζ.

The operation of the embodiment configured as above will be described.

The reflected waves from the coupling holes 4a and 4e are a combination of the reflected waves from multiple holes, and since there are errors in hole position due to manufacturing errors, etc., the adjustment screw 10a and IOb are completely It is not an inverse relationship. Furthermore, since the adjustment histometers IOa and 10b are not spaced at 1/4 wavelength intervals, they cannot completely cancel out arbitrary reflected waves. However, by selecting the positional relationship between the adjustment screw 10a and Job and the holes at the ends of the coupling holes 4a and 4e as described above, the coupling hole 4
Screw 10a for adjusting the reflected waves by a and 4e.

The relationship between the reflected waves generated by the central one of TAB can be almost in antiphase, and considering the canceling effect of the reflected waves generated by adjusting the screws on both sides, the coupling near the resonant frequencies of resonators 2a and 2d is The waves reflected by the holes 4a and 4e can be set in an inverse relationship to the waves reflected by the adjusting screws 10a and IOb. This makes it possible to achieve low reflection characteristics even in a directional filter having a small resonator.

FIG. 2 shows the directional filter having four stages of resonators according to the above embodiment with N=3. m=3. It is a figure which shows the example of a characteristic when the hole number of coupling holes 4a and 4e is 6, D is a reflection characteristic, and E is a demultiplexing characteristic. According to the configuration of this embodiment, a reflection characteristic of about -23 dB can be achieved, and when compared with the characteristic of the directional filter of the conventional configuration shown in Figure 3 (Figure 4), the reflection characteristic is significantly improved. I know what I can do.

In the above example, the number of resonator stages is 4 and the resonance order N=3. Although the case where m = 3 is shown, there are no particular restrictions on the number of stages of the resonator, the resonance order N, and m, and the line connecting the center adjustment screws and the central axis of the corresponding resonator are connected. It is sufficient that the included angle θ of the two lines connecting the hole at the end of the hole satisfies the relationship N of the following equation, the resonance order m of the resonator, and an odd value. As described above, the present invention can be applied in various ways and can take various embodiments in accordance with its gist.

[Effects of the Invention] As is clear from the above description, according to the directional filter of the present invention, even if a small resonator is used, a directional filter with low reflection loss can be realized, and it is compact.

It is now possible to create a directional filter that is lightweight, has low return loss, and does not generate unnecessary resonance over a wide band, and is ideal for use in satellite communication duplexers that require good transmission characteristics over a wider frequency range, as well as small and lightweight characteristics. It is possible to realize a directional filter suitable for use onboard a satellite, which requires the following.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a directional filter showing an embodiment of the present invention, FIG. 2 is a characteristic diagram showing an example of the characteristics of the above embodiment, and FIG. 3 is an exploded perspective view of a conventional directional filter. FIG. 4 is a characteristic diagram showing an example of the characteristics of the conventional example. ■...Signal input end, 2a-2d...Resonator, 3.Input waveguide, 4a-4e-.Coupling hole, 5..Output waveguide.
6... Branched signal output end, 7... Passing signal output end, 8
...Residual signal output end, 9...Reflection free terminator, 1oa1
0b...Adjustment screw. Number of rewards earned (MHl) Figure 2 Figure 1 Figure 3 Number of wins (MH;z) Figure 4

Claims (1)

[Claims] (1) A plurality of resonators coupled to the input waveguide through coupling holes provided in the side wall of the input waveguide are provided at intervals shorter than 1/4 of the wavelength in the tube at the resonant frequency of the resonator. A resonator having an adjustment member and coupled to the output waveguide by a coupling hole provided in the side wall of the output waveguide, at an interval shorter than 1/4 of the wavelength in the tube at the resonant frequency of the resonator. In a directional filter having a plurality of adjustment members provided, the central one of the adjustment members provided in a resonator coupled to the input waveguide and a coupling hole coupling the input waveguide and the resonator. The positional relationship of the hole at the end, and the center hole of the adjustment member provided in the resonator coupled to the output waveguide and the hole at the end of the coupling hole that couples the output waveguide and the resonator. The positional relationship is determined by the included angle between two lines: a line connecting the central axis of each resonator and the center of the adjustment member, and a line connecting the central axis of each resonator and the hole at the end of the coupling hole. A directional filter characterized in that θ is provided such that θ=(360)/(4N)m N: resonance order of the resonator m: an odd value.