JPS5831777B2 - antenna input circuit - Google Patents
antenna input circuitInfo
- Publication number
- JPS5831777B2 JPS5831777B2 JP9934679A JP9934679A JPS5831777B2 JP S5831777 B2 JPS5831777 B2 JP S5831777B2 JP 9934679 A JP9934679 A JP 9934679A JP 9934679 A JP9934679 A JP 9934679A JP S5831777 B2 JPS5831777 B2 JP S5831777B2
- Authority
- JP
- Japan
- Prior art keywords
- antenna
- circuit
- transformer
- winding
- input circuit
- 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
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/18—Input circuits, e.g. for coupling to an antenna or a transmission line
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
Description
【発明の詳細な説明】
本発明は、車載用電子同調型AM受信機のアンテナ入力
回路に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antenna input circuit for a vehicle-mounted electronically tuned AM receiver.
自動車用アンテナは一般に容量性となり、第1図に示す
ようにアンテナ起電力EA、それと直列なアンテナ容量
Ca、これらと並列なケーブル容量cbで表わされる。Automotive antennas are generally capacitive, and as shown in FIG. 1, they are represented by an antenna electromotive force EA, an antenna capacitance Ca in series with it, and a cable capacitance cb in parallel with these.
ホイップアンテナの場合はCa =15pF、Cb =
65pF程度である。For whip antenna, Ca = 15pF, Cb =
It is about 65 pF.
容量性アンテナであると受信機を電子同調化する場合、
電圧可変容量ダイオード(バラクタダイオード)使用の
同調用可変容量では容量変化範囲が不足する、S/Nが
低いなどの問題がある。When electronically tuning the receiver with a capacitive antenna,
Tuning variable capacitors using voltage variable capacitance diodes (varactor diodes) have problems such as insufficient capacitance variation range and low S/N ratio.
そこで従来の電子同調チューナのアンテナ入力回路では
、(a)アンテナ出力を先ず電界効果トランジスタで受
け、その後同調回路に通す非同調アンテナ入力型にする
、または(b)バラクタダイオードを2個(一方は直列
に、他方は並列に入れる)使用した同調型入力回路とす
る、などの対策をとっている。Therefore, in the antenna input circuit of a conventional electronic tuning tuner, (a) the antenna output is first received by a field effect transistor and then passed through the tuning circuit, using an untuned antenna input type, or (b) two varactor diodes (one is Countermeasures have been taken such as using a tuned input circuit (one connected in series and the other connected in parallel).
しかしくa)の場合はアンテナに入力した各放送局電波
をそのまま増幅し、同調回路で選択して希望電波のみを
増幅するという方法はとれないので混変調を起しやすい
という欠点があり、(b)の場合は同調回路で選択して
増幅するから混変調は生じないが、ダイオードを2個使
用するのでコストアップを招くことと、トラッキング調
整が難しくなるという欠点がある。However, in case a), it is not possible to directly amplify the radio waves of each broadcasting station input to the antenna, select them using a tuning circuit, and amplify only the desired radio waves, so there is a drawback that cross-modulation is likely to occur. In case b), cross-modulation does not occur because the tuning circuit selects and amplifies the signal, but it has the drawbacks of increasing cost and making tracking adjustment difficult because two diodes are used.
本発明はこれらの点を考慮して、バラクタダイオード1
個で同調型アンテナ入力回路を構成しようとするもので
ある。Taking these points into consideration, the present invention has developed a varactor diode 1.
The aim is to construct a tunable antenna input circuit using the two antennas.
該ダイオード1個使用の同調型アンテナ入力回路には第
2図および第3図に示す回路が考えられる。The circuits shown in FIGS. 2 and 3 are conceivable as the tunable antenna input circuit using one diode.
第2図ではトランスTRを用い、巻数の少ないその1次
側をアンテナ回路のケーブル終端P1 に、2次側をバ
ラクタダイオードCに接続する。In FIG. 2, a transformer TR is used, and its primary side with a small number of turns is connected to the cable termination P1 of the antenna circuit, and its secondary side is connected to a varactor diode C.
これで2次側から見た容量は小さくなり、巻数比を適当
に選ぶことによりダイオードCの容量変化比(最大容量
Cmax/最小容量(Cm1n )が15程度で我国の
AM放送の周波数帯である5 30 )G(zから16
00 KHzをカバーできることになる。This reduces the capacitance seen from the secondary side, and by appropriately selecting the turns ratio, the capacitance change ratio of diode C (maximum capacitance Cmax/minimum capacitance (Cm1n)) is approximately 15, which is the frequency band of AM broadcasting in Japan. 5 30 ) G (z to 16
This means that it can cover 0.00 KHz.
しかしこの方式では第9図の曲線C1で示すように周波
数が低い部分、従ってダイオードCの容量が大きい部分
でS/Nが著しく低下するという難がある。However, this method has a problem in that the S/N ratio is significantly lowered in the lower frequency portion, and hence in the portion where the capacitance of the diode C is large, as shown by the curve C1 in FIG.
これはアンテナ起電圧EAを容量Ca、Cb、Cで分割
することにより生じるものである。This is generated by dividing the antenna electromotive voltage EA by the capacitances Ca, Cb, and C.
第3図はバラクタダイオードCを直列に入れ、同調用イ
ンダクタンスLと共に共振させるものであるが、このま
までは上記放送周波数帯をカバーするためにダイオード
Cに要求される最小容量Cm1nが極めて小となり、実
在するバラクタダイオードでは実現困難であるので容量
Cgを付加してCm1nを犬にすることになる。In Figure 3, a varactor diode C is connected in series and resonates with a tuning inductance L. However, if this is done as it is, the minimum capacitance Cm1n required for the diode C to cover the above broadcasting frequency band will be extremely small, and it will not actually exist. Since this is difficult to achieve with a varactor diode, a capacitance Cg is added to make Cm1n a dog.
しかしこの場合は第9図の曲線C2に示すように周波数
の高い部分従ってダイオードCの容量の小さい部分でS
/Nが著しく低下する。However, in this case, as shown by curve C2 in Figure 9, S
/N decreases significantly.
本発明は、これら両回路の特性の良い部分が出る、即ち
周波数が低い部分では第3図の特性がまた周波数の高い
部分では第2図の特性が出るようにしようとするもので
あり、特徴とする所はアン**テナ起電力、該起電力と
直列なアンテナ容量、これらと並列なケーブル容量から
なる等何回路で表わされる容量性アンテナに接続される
車載用電子同調型AM受信機のアンテナ入力回路におい
て、前記アンテナに接続され、トランスの巻線と該巻線
に直列な電圧可変容量ダイオードを有する回路、および
付加コンデンサを備えて該コンチンサラ流れる電流が前
記トランスの巻線の一部を通るように該トランスに接続
された回路とからなる点にある。The present invention aims to bring out the good characteristics of both of these circuits, that is, to make the characteristics shown in Figure 3 appear in the low frequency part and the characteristics shown in Figure 2 in the high frequency part. The circuit of an electronically tuned AM receiver connected to a capacitive antenna is represented by an antenna electromotive force, an antenna capacitance in series with the electromotive force, a cable capacitance in parallel with these, etc. The antenna input circuit includes a circuit connected to the antenna and having a winding of a transformer, a voltage variable capacitance diode in series with the winding, and an additional capacitor, so that the continuous current flows through a part of the winding of the transformer. and a circuit connected to the transformer so as to pass through the transformer.
本発明の基本回路を第4図に示す。第4図でTRは第2
図と同様に1次巻線が2次巻線より巻数が少ないトラン
スであり、その1次巻線を容量Cgに直列に2次巻線を
端子P2 とグランド間に接続する。The basic circuit of the present invention is shown in FIG. In Figure 4, TR is the second
As shown in the figure, the transformer has a primary winding with fewer turns than the secondary winding, and the primary winding is connected in series with the capacitor Cg, and the secondary winding is connected between the terminal P2 and the ground.
この回路は第3図で無駄に流れる付加容量Cgの電流を
有効利用しようとするものである。This circuit is intended to effectively utilize the current of the additional capacitor Cg that flows in vain in FIG.
トランスTRの1.2次巻数をT2.T1、巻数比T2
/T1をm、2次巻線側のインダクタンスをり。The number of 1.2 turns of the transformer TR is T2. T1, turns ratio T2
/T1 is m, and the inductance on the secondary winding side is R.
とすると、この回路の共振周波数f。Then, the resonant frequency f of this circuit.
は次の(1)式で表わされ、その同調容量coは(2)
式で表わされる。is expressed by the following equation (1), and its tuning capacitance co is (2)
It is expressed by the formula.
この回路のS/Nを考えるに、雑音発生源が共振回路の
損失分つまり抵抗の熱雑音であるとすると抵抗rは共振
回路のQから
となる。When considering the S/N ratio of this circuit, if the noise source is the loss of the resonant circuit, that is, the thermal noise of the resistor, then the resistance r is from the Q of the resonant circuit.
ここでω。は共振角周波数、coは(2)式で表わされ
る同調容量である。Here ω. is the resonance angular frequency, and co is the tuning capacitance expressed by equation (2).
そこで、発生雑音※※VNは となる。Therefore, the generated noise※※VN is becomes.
ここでkはボルツマン定数、Tは温度、Bは帯域である
。Here, k is Boltzmann's constant, T is temperature, and B is band.
従って端子P2 における共振時のS/Nは(5)式の
如くなる。Therefore, the S/N ratio at the time of resonance at the terminal P2 is as shown in equation (5).
この(5)式を見ると明らかなようにバラクタダイオー
ドCの容量(これも同じ符号Cで示す)が分母と分子に
入っており、選局のためにCを変えてもS/Nは分母子
が相殺し合って一定になる傾向を有する。As is clear from Equation (5), the capacitance of the varactor diode C (also denoted by the same symbol C) is included in the denominator and numerator, and even if C is changed for channel selection, the S/N will not change. Mother and child tend to cancel each other out and become constant.
事実、Ca、Cb・・・・・・にそれぞれの値を代入し
、Cgとmを適当に選ぶ(例えばCg =1500 p
F、 m=0.15 )と、Cの変化範囲が市販のバラ
クタダイオードで実現可能な値15程度で530〜16
00KHz の放送周波数帯をカバーでき、かつS/N
は第9図の曲線C3に示すようになり、どの周波数でも
著しい落ち込みはなくはg良好をS/N特性が得られる
。In fact, substitute each value for Ca, Cb... and choose Cg and m appropriately (for example, Cg = 1500 p
F, m=0.15), and the variation range of C is 530 to 16, which is a value of about 15 that can be achieved with commercially available varactor diodes.
Can cover the broadcasting frequency band of 00KHz and has a S/N ratio of
is as shown by curve C3 in FIG. 9, and there is no significant drop at any frequency, and a good S/N characteristic can be obtained.
このアンテナ入力回路の次段にはトランジスタ増幅回路
が置かれるので出力インピーダンスは低いことが要求さ
れる。Since a transistor amplifier circuit is placed next to the antenna input circuit, the output impedance is required to be low.
そこで、第4図の端子P2では出力インピーダンスが相
当に高くなるので第5図に示すようにトランスTRの2
次巻線にタップを設け、これを出力端P3 とするとよ
い。Therefore, the output impedance at terminal P2 in FIG. 4 becomes considerably high, so as shown in FIG.
It is preferable to provide a tap in the next winding and use this as the output terminal P3.
また第4図の回路は第6図のようにも変形できる。The circuit shown in FIG. 4 can also be modified as shown in FIG.
これは第7図aに示すように第4図のトランスを単巻ト
ランスTRa に置換え、次に同図すに示すようにアー
ス点を点P1 とし、また共振には関係しない容量の
大きなコンデンサCdを付加し、かかる回路を回路図上
で上、下入れ換えると同図Cの如くなり、これは第6図
の回路に他ならないことから明らかであろう。As shown in Fig. 7a, the transformer in Fig. 4 is replaced with an autotransformer TRa, and then the ground point is set to point P1 as shown in Fig. 7a, and a large capacitance capacitor Cd not related to resonance If the circuit is added and the circuit is rearranged upside down on the circuit diagram, it will look like C in the same diagram, which is obvious from the fact that this is nothing but the circuit in FIG.
この回路の出力はコンデンサCとCdの接続点P4かも
取出すと、付加コンデンサCdにより低出力インピーダ
ンスが得られる。If the output of this circuit is also taken out from the connection point P4 between capacitors C and Cd, a low output impedance can be obtained due to the additional capacitor Cd.
第8図は、第6図のバラクタダイオードCに直流バイア
ス回路を付加した具体的回路を示す。FIG. 8 shows a specific circuit in which a DC bias circuit is added to the varactor diode C shown in FIG.
vBは同調用の該ダイオードバイアス電圧であり、抵抗
R1,R2およびトランスTRの巻線を通してダイオー
ドCに加えられる。vB is the diode bias voltage for tuning, which is applied to diode C through resistors R1, R2 and the winding of transformer TR.
Ceは高周波バイパス用のコンデンサである。Ce is a capacitor for high frequency bypass.
以上説明したようにこの発明によれば、電圧可変容量ダ
イオードは1個だけでAM放送周波数範囲をカバーでき
る同調型アンテナ入力回路を構成でき、しかもS/N特
性は低周波領域から高周波領域まではg平担にすること
ができる。As explained above, according to the present invention, it is possible to configure a tunable antenna input circuit that can cover the AM broadcasting frequency range with only one voltage variable capacitance diode, and the S/N characteristics are excellent from the low frequency region to the high frequency region. g Can be flattened.
第1図は容量アンテナの等価回路図、第2図および第3
図は従来流を示す回路図、第4図は本発明の基本形を示
す回路図、第5図は第4図の回路の出力の取出し方を説
明する回路図、第6図は本発明の変形例を示す回路図、
第7図abcは変形要領を説明する回路図、第8図は第
6図の具体的回路図、第9図はS/Nの特性図である。
図面でEAはアンテナ起電力、Caはアンテナ容量、C
bはケーブル容量、TRTRaはトランス、Cは電圧可
変容量ダイオード、Cgは付加コンデンサである。Figure 1 is an equivalent circuit diagram of a capacitive antenna, Figures 2 and 3
The figure is a circuit diagram showing the conventional flow, Figure 4 is a circuit diagram showing the basic form of the present invention, Figure 5 is a circuit diagram explaining how to take out the output of the circuit in Figure 4, and Figure 6 is a modification of the present invention. Schematic diagram showing an example,
FIG. 7 abc is a circuit diagram explaining the modification procedure, FIG. 8 is a specific circuit diagram of FIG. 6, and FIG. 9 is an S/N characteristic diagram. In the drawing, EA is the antenna electromotive force, Ca is the antenna capacity, and C
b is a cable capacitance, TRTRa is a transformer, C is a voltage variable capacitance diode, and Cg is an additional capacitor.
Claims (1)
これらと並列なケーブル容量からなる等価回路で表わさ
れる容量性アンテナに接続される車載用電子同調型AM
受信機のアンテナ入力回路において、前記アンテナに接
続され、トランスの巻線と該巻線に直列な電圧可変容量
ダイオードを有する回路、および付加コンデンサを備え
て該コンデンサを流れる電流が前記トランスの巻線の一
部を通るように該トランスに接続された回路とからなる
ことを特徴とするアンテナ入力回路。 2 トランスが巻数の少ない1次巻線および巻数の多い
2次巻線を持ち、付加コンデンサと該1次巻線との直列
回路および電圧可変容量ダイオードと該2次巻線との直
列回路が互いに並列な状態で容量性アンテナに接続され
てなることを特徴とする特許請求の範囲第1項記載のア
ンテナ入力回路。 3 トランスがタップを持つ単巻トランスからなり、該
トランスの巻線の両端部のうち該タップとの間の巻数が
少ない方の端部が容量性アンテナに接続され、他方の端
部に電圧可変容量ダイオードがまた該タップに付加コン
デンサが接続されてなることを特徴とする特許請求の範
囲第1項記載のアンテナ入力回路。[Claims] 1. An antenna electromotive force, an antenna capacitance in series with the electromotive force,
In-vehicle electronically tuned AM connected to a capacitive antenna represented by an equivalent circuit consisting of cable capacitance in parallel with these
An antenna input circuit of the receiver includes a circuit connected to the antenna and having a winding of a transformer and a voltage variable capacitance diode in series with the winding, and an additional capacitor so that the current flowing through the capacitor is connected to the winding of the transformer. and a circuit connected to the transformer so as to pass through a part of the antenna input circuit. 2. The transformer has a primary winding with a small number of turns and a secondary winding with a large number of turns, and the series circuit between the additional capacitor and the primary winding and the series circuit between the voltage variable capacitance diode and the secondary winding are connected to each other. The antenna input circuit according to claim 1, wherein the antenna input circuit is connected to a capacitive antenna in parallel. 3. The transformer consists of a single-turn transformer with a tap, and of both ends of the winding of the transformer, the end with fewer turns between it and the tap is connected to the capacitive antenna, and the other end has a variable voltage. An antenna input circuit according to claim 1, characterized in that a capacitive diode is also connected to the tap with an additional capacitor.
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP9934679A JPS5831777B2 (en) | 1979-08-03 | 1979-08-03 | antenna input circuit |
DE3028099A DE3028099C2 (en) | 1979-08-02 | 1980-07-24 | Antenna input circuit |
US06/172,407 US4369446A (en) | 1979-08-02 | 1980-07-25 | Antenna input circuit |
NLAANVRAGE8004346,A NL188259C (en) | 1979-08-02 | 1980-07-29 | AERIAL INPUT CIRCUIT FOR ADAPTING AN AM RECEIVER TO A CAPACITIVE ANTENNA. |
AU60909/80A AU531465B2 (en) | 1979-08-02 | 1980-07-30 | Antenna input circuit |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP9934679A JPS5831777B2 (en) | 1979-08-03 | 1979-08-03 | antenna input circuit |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS5623038A JPS5623038A (en) | 1981-03-04 |
JPS5831777B2 true JPS5831777B2 (en) | 1983-07-08 |
Family
ID=14245044
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP9934679A Expired JPS5831777B2 (en) | 1979-08-02 | 1979-08-03 | antenna input circuit |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5831777B2 (en) |
-
1979
- 1979-08-03 JP JP9934679A patent/JPS5831777B2/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
JPS5623038A (en) | 1981-03-04 |
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