JP3602493B2 - Waveguide bandpass filter - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a waveguide bandpass filter, and more particularly to a waveguide bandpass filter that has a structure in which the inside of a waveguide is divided by a plurality of inductive irises and passes a signal in a set frequency band.
[0002]
[Prior art]
As a typical example of a waveguide bandpass filter, a structure in which the inside of a waveguide is divided by a plurality of inductive irises, and a pass frequency band is determined based on the length of the divided section, the number of sections, the iris width, and the like. There is something. One example of a conventional waveguide bandpass filter having such a structure is shown in FIGS.
[0003]
The waveguide band-pass filter includes an inductive iris 111x having an iris width w1, an inductive iris 112x having an iris width w2, an inductive iris 113x having an iris width w3, and similarly an iris width w4 in the waveguide 100. .., 16 are arranged in such a manner that their mutual intervals are 11, 12,..., 16 respectively.
[0004]
The pass band characteristics of this waveguide band pass filter are determined by the iris widths w1 to w7 and the iris intervals l1 to l6, and an example of the characteristics is shown in FIG.
In FIG. 7, S11 is a reflection coefficient, S21 is a transmission coefficient, a rectangular waveguide WRJ-220 is used as the waveguide 100, and the thicknesses of the inductive irises 111x to 117x are all 0.5 mm. . This waveguide bandpass filter has a pass band width of 1.2%, the insertion loss in this pass band is 1.6 dB or less, and the center frequency ± 1. At a frequency of 6%, an attenuation of about 59 dB is obtained.
[0005]
[Problems to be solved by the invention]
The above-described conventional waveguide bandpass filter includes, in the waveguide 100, an inductive iris 111x having an iris width w1 to an inductive iris 117x having an iris width w7 in order such that their mutual intervals are 11 to 16. The iris widths w1 to w7 and the iris spacings 11 to 16 are selected to obtain desired characteristics. For example, the insertion loss is 1% at a pass bandwidth of 1.2%. Although a characteristic of about 59 dB can be obtained at a frequency of 1.6 dB or less and a center frequency of ± 1.6% outside the pass band, a steeper attenuation characteristic may be required outside the pass band. In such a case, in order to realize a steeper attenuation characteristic, the number of stages of the inductive iris may be increased, or the inductive iris 111x to 117x may be independently provided outside the pass band forming portion. A structure and a structure in which a plurality of band rejection filters, for example, those having a structure in which a coupling hole is formed in an upper surface plate of a waveguide and a cavity is provided outside the filter, are arranged at quarter wavelength intervals. (Refer to page 755 of “Electronic Communication Handbook (Ohm Co., Ltd.), b., Section 3.2.1 of waveguide filter, etc.”), the number of stages of inductive iris. Increases the insertion loss in the pass band, there is a problem that, if a band rejection filter is independently provided outside the pass band forming portion, the entire size of the waveguide band pass filter becomes extremely large. In addition, there is a problem that the reflection outside the attenuation band of the band rejection filter affects the amount of reflection in the pass band of the waveguide band-pass filter, and the characteristics thereof are deteriorated.
[0006]
Therefore, an object of the present invention is to provide a steeper attenuation characteristic outside the pass band and a set frequency without causing an increase in insertion loss and a deterioration in reflection characteristics in the pass band in view of the above-mentioned problems of the related art. It is an object of the present invention to provide a waveguide bandpass filter capable of obtaining a larger attenuation of components and suppressing an increase in the size of the entire filter.
[0007]
[Means for Solving the Problems]
A waveguide bandpass filter according to the present invention has the following configurations.
(A) A plurality of inductive irises each having an iris width set to a set dimension are sequentially arranged in a waveguide at a set mutual interval, and a pass band of a signal passing through the waveguide is provided. (B) The waveguide is installed at a position outside the region where the plurality of inductive iris is provided in the band-pass filter and close to the outermost inductive iris of the waveguide. And an inductive iris having a set iris width provided on the waveguide wall portion, and a cavity having a set length provided outside the waveguide via the inductive iris, A notch portion coupled to the band-pass filter portion to attenuate a set frequency component outside a pass band by the band-pass filter portion
Further, the notch portion is provided near one of both outermost irises of the plurality of inductive irises, and a high-frequency component and a low-frequency component outside a pass band by the band-pass filtering portion. It has a frequency characteristic of attenuating one of the band-side frequency components, or is installed close to each of the outermost irises of the plurality of inductive iris, and one of them is a pass band by the band-pass filtering unit. , And has a frequency characteristic of attenuating the high frequency components outside the pass band and the other low frequency components outside the pass band.
[0009]
In addition, the iris width of each of the plurality of inductive irises and the mutual interval thereof, and the iris width of the inductive iris of the notch portion, and the notch portion of the plurality of inductive irises of the band-pass filtering portion. Of the distance from the outermost iris of the band-pass filter unit and the notch unit are determined as an integrated structure, so that a desired frequency characteristic is obtained. Have.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
In one embodiment of the present invention, a plurality of inductive irises each having an iris width formed to a set size are sequentially arranged in a waveguide at a set mutual interval, and pass through the waveguide. A band-pass filter for determining a pass band of a signal to be transmitted, and a plurality of inductive iris arrangement regions of the waveguide, outside the band-pass filter, and close to the outermost inductive iris. It is installed in the position, the inductive iris of the set iris width deployed on the waveguide wall portion, the cavity of the set length deployed outside the waveguide via this inductive iris, And a notch unit that is coupled to the band-pass filter unit and attenuates a set frequency component outside a pass band of the band-pass filter unit.
[0011]
In addition, the notch portion is installed close to one of both outermost irises of the plurality of inductive irises, and a high-frequency component and a low-frequency component outside a pass band by the band-pass filtering portion. It has a frequency characteristic of attenuating one of the band-side frequency components, and may be configured, and may be installed close to each of the outermost end irises of the plurality of inductive iris, and one of the band It may be configured to have a frequency characteristic of attenuating high-frequency components outside the pass band by the pass filter unit and attenuating low-frequency components outside the pass band on the other side.
[0012]
Then, the iris width of each of the plurality of inductive irises and the mutual interval of the band-pass filtering section, the iris width of the inductive iris of the notch section, and the plurality of inductive iris of the notch section. The distance from the outermost iris, the dimensions of each, the band-pass filter unit and the notch unit are coupled, determined as an integrated structure, so as to obtain the desired frequency characteristics, Has become.
[0013]
By adopting such a configuration and structure, it is possible to suppress an increase in the size of the entire filter, and to reduce the attenuation characteristic outside the pass band without causing an increase in insertion loss and deterioration of the reflection characteristic in the pass band. It is possible to further increase the steepness and increase the amount of attenuation.
[0014]
【Example】
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partial sectional plan view showing an embodiment of the present invention, and FIG. 2 is a perspective view of the embodiment shown in FIG.
In this embodiment, an inductive iris 111 having an iris width W1, an inductive iris 112 having an iris width W2, an inductive iris 113 having an iris width W3, and so on are provided in the waveguide 100. Irises 114 to 117 are sequentially arranged so that their mutual intervals are L1, L2,..., L6, and a band-pass filter 110 that determines a pass band of a signal passing through the waveguide 100. Outside the area where the plurality of inductive irises 111 to 117 are provided on the waveguide 100, and installed at a position close to the inductive iris 111 of one of its outermost irises. inductive iris 211 of the iris width W8 deployed tube wall portion, and comprises a cavity portion 212 of the inductive iris 211 through to length deployed outside waveguide Ln1, A notch section 210 that is coupled to the band-pass filter section 110 and attenuates a set frequency component outside the pass band by the band-pass filter section 110, for example, a set frequency component higher than the pass band. The waveguide 100 is installed at a position outside the region where the plurality of inductive iris 111 to 117 are provided, in the vicinity of the other of the outermost ends and the inductive iris 117, and is provided on the tube wall portion of the waveguide 100. An inductive iris 221 having an iris width W9, and a cavity 222 having a length Ln2 provided outside the inductive iris 221. Notch part 220 for attenuating frequency components set outside the pass band by filtering unit 110, for example, set frequency components lower than the pass band, has a configuration and structure. .
[0015]
As the position of the notch portion 210 close to the inductive iris 111, the dimension between the outer surface of the inductive iris 111 and the end of the iris width W8 of the inductive iris 211 is D1, and the dimension of D1 is derived. The position of the notch 220 is smaller than the guide wavelength of the waveguide 100, and the position of the notch 220 is close to the inductive iris 117, between the outer surface of the inductive iris 117 and the end of the iris width W <b> 9 of the inductive iris 221. Is set to D2, and the size of D2 is set to be smaller than the guide wavelength of the waveguide 100.
[0016]
Then, the iris widths W1 to W7 of the plurality of inductive irises 111 to 117 and their mutual intervals L1 to L6, and the iris widths W8 and W9 of the inductive iris 211 and 221 of the notch portions 210 and 220 and the outermost end inductivity. The dimensions such as the distances D1 and D2 from the irises 111 and 117 are adjusted so that the plurality of inductive irises 111 to 117 and the notch portions 210 and 220 are combined and integrated to obtain an optimal frequency characteristic. And decide. The attenuation pole outside the pass band is determined by the lengths Ln1 and Ln2 of the cavities 212 and 222 of the notches 210 and 220.
[0017]
For example, WRJ-220 is used as the waveguide 100, the thickness of each inductive iris is all 0.5 mm, and the dimensions of each part are W1 = 3.6450, W2 = 1.656, W3 = 1.6168. , W4 = 1.604, W5 = 1.42727, W6 = 1.8260, W7 = 3.4970, W8 = 4.247, W9 = 4.4733, L1 = 6.4576, L2 = 6.99047, L3 = 6.9227, L4 = 6.9207, L5 = 6.8940, L6 = 6.4807, Ln1 = 13.00014, Ln2 = 13.5283, D1 = 1.0690, D2 = 1.0636 (unit mm) FIG. 3 shows the characteristics of the reflection coefficient S11 and the transmission coefficient S21 at this time.
[0018]
In FIG. 3, the characteristics of the solid line are the characteristics of this embodiment, that is, the characteristics of the two notches, and the characteristics of the dotted line are the characteristics without the notch, that is, the characteristics of the conventional example. As described above, in the pass band and the vicinity thereof, almost the same characteristics as in the case without the notch are obtained, and the insertion loss can be suppressed to 1.6 dB or less in the pass band having a bandwidth of 1.2%. Moreover, in an attenuation band of 1.6% or more with respect to the center frequency, an attenuation of 70 dB or more can be obtained.
[0019]
The size of the notches 210 and 220 is set at a position outside the band-pass filter 110 and close to the outermost iris (111, 117) of the plurality of inductive irises 111 to 117. Therefore, it is possible to suppress an increase in size as a whole.
[0020]
In this embodiment, notches 210 and 220 are provided outside the band-pass filter 110 and in close proximity to the two outermost irises (111 and 117), respectively. Is configured to attenuate the high-frequency component and the other to attenuate the low-frequency component. A notch is provided on one of the outermost irises (111, 117). Alternatively, one of the high-frequency component and the low-frequency component, for example, the high-frequency component outside the pass band by the band-pass filter 110 may be further attenuated. FIG. 4 shows the frequency characteristics in this case.
[0021]
【The invention's effect】
As described above, the present invention provides a bandpass filter in which a plurality of inductive irises each having a set iris width are sequentially arranged at a set mutual interval in a waveguide to determine a passband of a signal. A wave portion and an inductive iris having a set iris width disposed outside the band-pass filtering portion and at a position close to the outermost inductive iris and disposed on the waveguide wall portion; And a cavity of a set length disposed outside the waveguide through the inductive iris , and coupled to the band-pass filter, outside the pass band by the band-pass filter. And a notch portion for attenuating the set frequency component, and further, outside the pass band, without causing an increase in insertion loss and deterioration of reflection characteristics in the pass band. Steep attenuation characteristics And it is possible to obtain a more large attenuation of the set frequency components, moreover, may be the entire filter suppressed from increasing in size, there is an effect that.
[Brief description of the drawings]
FIG. 1 is a partial sectional plan view showing one embodiment of the present invention.
FIG. 2 is a partial sectional perspective view of the embodiment shown in FIG.
FIG. 3 is a frequency characteristic diagram of a reflection coefficient S11 and a transmission coefficient S21 of the embodiment shown in FIGS. 1 and 2;
FIG. 4 is a frequency characteristic diagram of a reflection coefficient S11 and a transmission coefficient S21 according to another embodiment of the present invention.
FIG. 5 is a partial sectional plan view showing an example of a conventional waveguide bandpass filter.
FIG. 6 is a partial cross-sectional perspective view of the waveguide bandpass filter shown in FIG. 5;
FIG. 7 is a frequency characteristic diagram of a reflection coefficient S11 and a transmission coefficient S21 of the waveguide band-pass filter shown in FIGS. 5 and 6;
[Explanation of symbols]
REFERENCE SIGNS LIST 100 Waveguide 110 Band-pass filtering sections 111 to 117, 111x to 117x Inductive iris 210 Notch section 211 Inductive iris 212 Cavity section 220 Notch section 221 Inductive iris 222 Cavity section

Claims (4)

A waveguide bandpass filter having the following configurations.
(A) A plurality of inductive irises each having an iris width set to a set dimension are sequentially arranged in a waveguide at a set mutual interval, and a pass band of a signal passing through the waveguide is provided. (B) The waveguide is installed at a position outside the region where the plurality of inductive iris is provided in the band-pass filter and close to the outermost inductive iris of the waveguide. And an inductive iris having a set iris width provided on the waveguide wall portion, and a cavity having a set length provided outside the waveguide via the inductive iris, Notch part which is coupled with the band-pass filter and attenuates a set frequency component outside a pass band by the band-pass filter. The notch portion is installed near one of both outermost irises of the plurality of inductive iris, outside a pass band by the band-pass filtering portion, a high-frequency component and a low-frequency component. The waveguide band pass filter according to claim 1, wherein the filter has a frequency characteristic of attenuating one of the frequency components. The notch portion is installed in proximity to each of both outermost irises of the plurality of inductive iris, one of which attenuates a high-frequency component outside a pass band by the band-pass filtering portion, 2. The waveguide band-pass filter according to claim 1, wherein the other side has a frequency characteristic of attenuating a low-frequency component outside the pass band. The iris width of each of the plurality of inductive irises and the mutual interval thereof, the iris width of the inductive iris of the notch, and the maximum of the plurality of inductive iris of the notch in the band-pass filter. The distance from the outer end iris is determined as a structure in which the band-pass filter unit and the notch unit are combined and integrated so as to obtain a desired frequency characteristic. Waveguide bandpass filter.

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