JP2639874B2 - Variable frequency filter - Google Patents
Variable frequency filterInfo
- Publication number
- JP2639874B2 JP2639874B2 JP23520192A JP23520192A JP2639874B2 JP 2639874 B2 JP2639874 B2 JP 2639874B2 JP 23520192 A JP23520192 A JP 23520192A JP 23520192 A JP23520192 A JP 23520192A JP 2639874 B2 JP2639874 B2 JP 2639874B2
- Authority
- JP
- Japan
- Prior art keywords
- coupling
- frequency
- semi
- input
- short
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Control Of Motors That Do Not Use Commutators (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、ＵＨＦ帯無線機に用い
られる周波数可変フィルタに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable frequency filter used for a UHF band radio.
【０００２】[0002]
【従来の技術】２００〜４００ＭＨｚのＵＨＦ帯無線通
信機の高周波段用バンドパスフィルタとして半同軸空胴
共振器を用いた周波数可変フィルタが用いられている。
このフィルタの次数ｎは一般にｎ≧２である。このよう
な無線機の運用周波数は２００〜４００ＭＨｚの範囲で
周波数を切換えて通信が行われる。従って、高周波段の
フィルタの中心周波数は運用周波数の切換えに応じて切
換えられる。フィルタの中心周波数を切換える方法は、
複数の半同軸空胴共振器の内部導体の空中軸部に金属棒
を挿入し、ガイドに螺合させてステッピングモータによ
り金属棒の挿入度合いを加減することによって行われ
る。また、各共振器間の電磁結合度は、隣接する共振器
の外部導体間に挿入された金属製結合板に設けられた穴
（これを結合窓という）の直径，大きさ，位置によって
設定されている。この結合窓の従来の位置は、共振器の
高さに対して外部導体と内部導体の短絡面（下面）側か
ら高さを７：３の割合に分割した位置に設けられてい
る。2. Description of the Related Art A variable frequency filter using a semi-coaxial cavity resonator has been used as a band-pass filter for a high-frequency stage of a UHF band wireless communication device of 200 to 400 MHz.
The order n of this filter is generally n ≧ 2. Communication is performed by switching the operating frequency of such a wireless device in the range of 200 to 400 MHz. Therefore, the center frequency of the filter of the high frequency stage is switched according to the switching of the operating frequency. To change the center frequency of the filter,
This is performed by inserting a metal rod into the aerial shaft portion of the internal conductor of a plurality of semi-coaxial cavity resonators, screwing it into a guide, and adjusting the degree of insertion of the metal rod by a stepping motor. The degree of electromagnetic coupling between the resonators is set by the diameter, size, and position of a hole (referred to as a coupling window) provided in a metal coupling plate inserted between outer conductors of adjacent resonators. ing. The conventional position of the coupling window is provided at a position where the height is divided at a ratio of 7: 3 from the short-circuit surface (lower surface) of the outer conductor and the inner conductor with respect to the height of the resonator.
【０００３】[0003]
【発明が解決しようとする課題】このような従来の構成
のフィルタは、中心周波数を切換えると通過帯域幅や挿
入損失も変化してしまう。図５は従来のフィルタ特性例
であり、中心周波数を２５０ＭＨｚ〜４００ＭＨｚの範
囲で、切換えたときの帯域特性を中心周波数をｆ0 とし
て重ね書きしたものである。図において、特性は中心
周波数ｆ0 ＝４００ＭＨｚ、特性はｆ0＝３５０ＭＨ
ｚ、特性はｆ0 ＝３００ＭＨｚ、特性はｆ0 ＝２５
０ＭＨｚのときを示す。図から判るように、中心周波数
ｆ0 が４００ＭＨｚの特性に対して、周波数が低くな
るにつれて通過帯域幅が狭くなり、ｆ0 ＝２５０ＭＨｚ
の特性との差が大きい。図示されていないが、帯域幅
が狭くなるにつれて挿入損失も増加する。そこでその対
策として従来は、共振器の無負荷Ｑを高くして欠点を補
っている。無負荷Ｑを高くすることは、すなわち、共振
器径を大きくするか、波長短縮率を小さくすることであ
る。従って、形状が大きくなってしまうという欠点があ
る。In the filter having such a conventional configuration, when the center frequency is changed, the pass band width and the insertion loss also change. FIG. 5 shows an example of a conventional filter characteristic, in which the center frequency is overwritten within the range of 250 MHz to 400 MHz, and the band characteristic when switching is performed with the center frequency f 0 . In the figure, the characteristic is center frequency f 0 = 400 MHz, and the characteristic is f 0 = 350 MH.
z, characteristic f 0 = 300 MHz, characteristic f 0 = 25
The case of 0 MHz is shown. As can be seen from the figure, for a characteristic in which the center frequency f 0 is 400 MHz, the pass band becomes narrower as the frequency becomes lower, and f 0 = 250 MHz
The difference with the characteristic of is large. Although not shown, the insertion loss increases as the bandwidth decreases. Therefore, conventionally, as a countermeasure, the no-load Q of the resonator is increased to compensate for the disadvantage. Increasing the no-load Q means increasing the resonator diameter or decreasing the wavelength shortening rate. Therefore, there is a disadvantage that the shape becomes large.
【０００４】本発明の目的は、上記の従来技術の問題点
である周波数切換に伴う帯域幅，挿入損失の変化を軽減
し、かつ、形状の大型化を排除した周波数可変フィルタ
を提供することにある。It is an object of the present invention to provide a variable frequency filter which reduces the change in bandwidth and insertion loss due to frequency switching, which is a problem of the prior art, and eliminates the increase in size. is there.
【０００５】[0005]
【課題を解決するための手段】本発明の周波数可変フィ
ルタは、一端で外部導体と内部導体が短絡された短絡面
を有する複数の半同軸空胴共振器と、該複数の半同軸空
胴共振器の互いに隣接する外部導体間に電磁結合度を調
節する結合窓を有する結合板と、前記複数の半同軸空胴
共振器の入出力側の半同軸空胴共振器に設けられた入出
力結合ループ付き端子と、前記空胴共振器の他端から前
記内部導体の中空軸部に挿入加減可能の金属棒とを備え
て、該金属棒を挿入加減することにより所望の周波数範
囲にわたって中心周波数を変化設定することのできる周
波数可変フィルタにおいて、前記結合板の結合窓と前記
空胴共振器の入出力結合ループ付き端子の位置が、隣接
する空胴共振器間の結合係数が前記中心周波数の変化に
反比例するように前記空胴共振器の長さに対して前記短
絡面からほぼ７／１０になるような位置に設定されたこ
とを特徴とするものである。図３はフィルタの結合係数
の目標とする周波数特性図である。周波数可変フィルタ
において、周波数の変化に対する各共振器間の結合係数
の変化を図のように反比例するような構成にすれば、周
波数が変わっても通過帯域幅を常に一定にすることがで
きる。上記本発明の構成によって図３に示す目標特性を
達成することができた。以下実施例によって本発明を詳
細に説明する。SUMMARY OF THE INVENTION A frequency tunable filter according to the present invention comprises a plurality of semi-coaxial cavity resonators having a short-circuited surface in which an outer conductor and an inner conductor are short-circuited at one end, and the plurality of semi-coaxial cavity resonators. A coupling plate having a coupling window for adjusting the degree of electromagnetic coupling between adjacent outer conductors of the resonator, and input / output coupling provided on a semi-coaxial cavity on the input / output side of the plurality of semi-coaxial cavities A terminal with a loop, and a metal rod that can be inserted into and retracted from the other end of the cavity resonator into the hollow shaft portion of the inner conductor, and the center frequency can be adjusted over a desired frequency range by inserting and subtracting the metal rod. In the frequency variable filter that can be set to change, the position of the coupling window of the coupling plate and the position of the input / output coupling loop terminal of the cavity resonator is such that the coupling coefficient between adjacent cavity resonators is a change in the center frequency. To be inversely proportional to Kisorado is characterized in that it has been set to a position such that substantially 7/10 from the short side to the length of the resonator. FIG. 3 is a target frequency characteristic diagram of the coupling coefficient of the filter. In the variable frequency filter, if the change of the coupling coefficient between the resonators with respect to the change of the frequency is made to be inversely proportional as shown in the figure, the pass band width can always be kept constant even if the frequency changes. With the configuration of the present invention described above, the target characteristics shown in FIG. 3 could be achieved. Hereinafter, the present invention will be described in detail with reference to examples.
【０００６】[0006]
【実施例】図１は本発明の実施例の要部を示す構造図で
あり、縦断面図（Ａ）とＡ−Ａ横断面図（Ｂ）及び部分
側面図（Ｃ）である。この実施例は次数ｎ＝２の２段フ
ィルタである。図において、１，５は半同軸空胴共振
器、２，６は外部導体、３，７は内部導体、４，８は短
絡面である。９，１０は入出力端子であり、例えば５０
Ωのラインインピーダンスと整合させるコの字状の入出
力結合ループ１６が設けられている。１１，１２は中心
周波数切換設定用の金属棒であり、空胴共振器１，５の
それぞれの内部導体３，７内の中空軸部に挿入され、ガ
イド１３と螺合して挿入度が変えられる。１４は２つの
空胴共振器１と５の間に挟持されている結合板であり、
（Ｂ）図に示すようにねじ止めされ、（Ｃ）図に示すよ
うに結合窓１５が設けられている。従来の結合窓１５は
共振器の長さを３：７（＝ａ：ｂ）に分割した位置に設
けられていたが、本発明ではａ：ｂ＝７：３の位置に設
け、かつ、入出力の結合ループ付き端子９，１０の位置
も結合窓１５の位置と同じ割合の位置に設けたことが重
要な特徴である。尚、図１のガイド１３の保持機構、金
属棒１１，１２の駆動機構、およびフィルタの金属シー
ルドケースは図示を省略した。1 is a structural view showing a main part of an embodiment of the present invention, which is a longitudinal sectional view (A), an AA transverse sectional view (B) and a partial side view (C). This embodiment is a two-stage filter of order n = 2. In the figure, reference numerals 1 and 5 denote semi-coaxial cavity resonators, reference numerals 2 and 6 denote external conductors, reference numerals 3 and 7 denote internal conductors, and reference numerals 4 and 8 denote short-circuit surfaces. Reference numerals 9 and 10 denote input / output terminals.
A U-shaped input / output coupling loop 16 for matching with the line impedance of Ω is provided. Reference numerals 11 and 12 denote metal rods for setting the center frequency switching, which are inserted into hollow shaft portions in the internal conductors 3 and 7 of the cavity resonators 1 and 5, and screwed with the guide 13 to change the insertion degree. Can be A coupling plate 14 is sandwiched between the two cavity resonators 1 and 5,
(B) It is screwed as shown in the figure, and the coupling window 15 is provided as shown in the (C) figure. The conventional coupling window 15 is provided at a position where the length of the resonator is divided into 3: 7 (= a: b). In the present invention, however, the coupling window 15 is provided at a position of a: b = 7: 3. It is an important feature that the positions of the output coupling loop terminals 9 and 10 are provided at the same ratio as the coupling window 15. The illustration of the holding mechanism of the guide 13, the driving mechanism of the metal rods 11 and 12, and the metal shield case of the filter in FIG. 1 are omitted.
【０００７】図２は本発明による周波数可変フィルタの
選択特性例図である。図５同様、中心周波数ｆ0 を４０
０ＭＨｚ〜２５０ＭＨｚにしたときの特性を重ね書きし
てあり、中心周波数ｆ0 を変えても通過帯域幅が変化し
ないことを示している。挿入損失もほぼ一定の値を示す
ことが確認された。FIG. 2 is a diagram showing an example of selection characteristics of the frequency variable filter according to the present invention. As in FIG. 5, the center frequency f 0 is set to 40
The characteristics at 0 MHz to 250 MHz are overwritten, indicating that the pass band width does not change even when the center frequency f 0 is changed. It was confirmed that the insertion loss also showed a substantially constant value.
【０００８】図４は結合窓１５を有する結合板１４によ
る共振器間の結合係数の周波数特性例図であり、結合窓
１５の直径φ＝３０ｍｍ一定として、結合窓１５の位置
ａ：ｂを従来の場合（３：７）と、本発明の場合
（７：３）、及びその中間の場合（５：５）について
比較している。図から判るように、本発明の場合の目
標特性とほぼ一致している。FIG. 4 is a diagram showing an example of the frequency characteristics of the coupling coefficient between the resonators by the coupling plate 14 having the coupling window 15. The diameter a of the coupling window 15 is fixed at 30 mm, and the positions a: b of the coupling window 15 are conventional. (3: 7), the case of the present invention (7: 3), and the intermediate case (5: 5). As can be seen from the figure, it substantially matches the target characteristic in the case of the present invention.
【０００９】[0009]
【発明の効果】以上詳細に説明したように、本発明を実
施することにより、以下の効果を得ることができた。 （１） 必要以上に無負荷Ｑを高くせずに済むので、小
形化できる。 （２） 結合窓と入出力結合ループとを同じ割合（７：
３）の位置に設けることにより、所望の範囲の周波数帯
にわたって一定のバンド幅を実現することができる。 （３） 有極化構成をとる場合、定バンドであるとその
極の位置が全周波数帯で変化せず、均一な特性が得られ
る。As described in detail above, the following effects can be obtained by implementing the present invention. (1) Since the no-load Q need not be increased unnecessarily, the size can be reduced. (2) The ratio between the coupling window and the input / output coupling loop is the same (7:
By providing at the position 3), a constant bandwidth can be realized over a desired range of frequency band. (3) In the case of a polarized configuration, if the band is a constant band, the position of the pole does not change in all frequency bands, and uniform characteristics can be obtained.
【図１】本発明の実施例の要部を示す構造図である。FIG. 1 is a structural view showing a main part of an embodiment of the present invention.
【図２】本発明の選択特性例図である。FIG. 2 is a diagram illustrating an example of selection characteristics according to the present invention.
【図３】結合係数の目標周波数特性例図である。FIG. 3 is a diagram illustrating an example of a target frequency characteristic of a coupling coefficient.
【図４】従来と本発明の結合係数／周波数特性図であ
る。FIG. 4 is a graph showing a coupling coefficient / frequency characteristic according to the related art and the present invention.
【図５】従来の選択特性例図である。FIG. 5 is an example of a conventional selection characteristic.
【符号の説明】 １，５ 半軸空胴共振器 ２，６ 外部導体 ３，７ 内部導体 ４，８ 短絡面 ９，１０ 入出力結合ループ付き端子 １１，１２ 金属棒 １３ ガイド １４ 結合板 １５ 結合窓 １６ 入出力結合ループ[Description of Signs] 1,5 Semi-axial cavity resonator 2,6 Outer conductor 3,7 Inner conductor 4,8 Short-circuit surface 9,10 Terminal with input / output coupling loop 11,12 Metal rod 13 Guide 14 Coupling plate 15 Coupling Window 16 input / output coupling loop
Claims (1)
短絡面を有する複数の半同軸空胴共振器と、該複数の半
同軸空胴共振器の互いに隣接する外部導体間に電磁結合
度を調節する結合窓を有する結合板と、前記複数の半同
軸空胴共振器の入出力側の半同軸空胴共振器に設けられ
た入出力結合ループ付き端子と、前記空胴共振器の他端
から前記内部導体の中空軸部に挿入加減可能の金属棒と
を備えて、該金属棒を挿入加減することにより所望の周
波数範囲にわたって中心周波数を変化設定することので
きる周波数可変フィルタにおいて、 前記結合板の結合窓と前記空胴共振器の入出力結合ルー
プ付き端子の位置が、隣接する空胴共振器間の結合係数
が前記中心周波数の変化に反比例するように前記空胴共
振器の長さに対して前記短絡面からほぼ７／１０になる
ような位置に設定されたことを特徴とする周波数可変フ
ィルタ。1. A plurality of semi-coaxial cavities having a short-circuited surface in which an outer conductor and an inner conductor are short-circuited at one end, and a degree of electromagnetic coupling between adjacent outer conductors of the plurality of semi-coaxial cavities. A coupling plate having a coupling window for adjusting the frequency, a terminal with an input / output coupling loop provided in the semi-coaxial cavity on the input / output side of the plurality of semi-coaxial cavity resonators, A metal rod that can be inserted into the hollow shaft portion of the internal conductor from the end and that can be adjusted by changing the center frequency over a desired frequency range by inserting and adjusting the metal rod; The position of the coupling window of the coupling plate and the position of the input / output coupling loop terminal of the cavity is such that the coupling coefficient between adjacent cavities is inversely proportional to the change in the center frequency. From the short-circuit surface Variable frequency filter, characterized in that set in the made such a position 7/10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23520192A JP2639874B2 (en) | 1992-08-12 | 1992-08-12 | Variable frequency filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23520192A JP2639874B2 (en) | 1992-08-12 | 1992-08-12 | Variable frequency filter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0661706A JPH0661706A (en) | 1994-03-04 |
| JP2639874B2 true JP2639874B2 (en) | 1997-08-13 |
Family
ID=16982579
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23520192A Expired - Fee Related JP2639874B2 (en) | 1992-08-12 | 1992-08-12 | Variable frequency filter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2639874B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE60034978T2 (en) | 1999-03-04 | 2008-01-24 | Max Co. Ltd. | Mechanism of the magazine for a nailing machine |
| JP4178264B2 (en) | 2005-01-11 | 2008-11-12 | 株式会社村田製作所 | Tunable filter |
| JP4827806B2 (en) * | 2007-08-03 | 2011-11-30 | 古河電気工業株式会社 | Non-stop type antenna switching device |
| KR101137438B1 (en) * | 2010-10-26 | 2012-04-20 | 주식회사 이너트론 | Tunable filter comprising conductive plates capable rotating |
-
1992
- 1992-08-12 JP JP23520192A patent/JP2639874B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0661706A (en) | 1994-03-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |