JP2013121129A - Interference wave suppression device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cancel interference waves propagating from a transmission antenna through the space and going around a receiving antenna over a wider frequency band.SOLUTION: A phase frequency characteristic compensation circuit 50 is configured using a distribution constant circuit having a first circuit 51 which is configured so that an inductance 51a and a capacitance 51b are arranged in series between an input terminal for receiving an output signal from a phase-shifter 40 and an output terminal, and a second circuit 52 which is configured so that an inductance 52a and a capacitance 52b are arranged in parallel between the joint of the capacitance 51b and the output terminal and the earth.

Description

  The present invention relates to an interference wave suppressing device that suppresses an interference wave that propagates through a space from a transmitting antenna and wraps around as a disturbing wave in a receiving antenna.

  Conventionally, in a wireless communication apparatus in which a transmission antenna and a reception antenna are connected, an output signal of a transmission unit that outputs a signal to the transmission antenna is branched by a directional coupler, and a radio wave (spatial propagation) Wave) and a signal (interference suppression wave) adjusted to the same amplitude and opposite phase is generated by an attenuator and phase shifter, and inserted on the power supply line of the receiving antenna to cancel the radio wave that wraps around from the transmitting antenna. There is a technology to obtain a good reception performance. Furthermore, in order to correct the difference in the phase-frequency characteristics between the spatial propagation wave and the interference suppression wave, the compensation circuit constituted by the LCR parallel resonance circuit in which the resonance inductance L, the resonance capacitor C and the dump resistor R are connected in parallel is used as the interference suppression wave. A frequency band that is provided in the latter stage and can cancel out the interference wave that propagates through the space from the transmitting antenna and enters the receiving antenna by combining the output signal of this compensation circuit with the received signal of the receiving antenna by a directional coupler. Is enlarged (see, for example, Patent Document 1).

JP 2000-183781 A

  FIG. 11 shows a configuration of an LCR parallel resonance circuit in which an inductance L, a capacitance C, and a dump resistor R are connected in parallel as shown in Patent Document 1. The compensation circuit constituted by such an LCR parallel resonance circuit has a problem that it is difficult to achieve both reduction of the passage loss and optimization of the phase adjustment amount. FIG. 12A shows an inductance L = 0.1 microhenry (μH) and a capacitance C = 489 picofarad (pF) in order to set the phase adjustment amount at 720 megahertz (MHz) and 715-725 megahertz to 50 °. ) Shows a simulation result of the pass loss-frequency characteristic of the compensation circuit when the dump resistor R = 1 megaohm (MΩ). FIG. 12B shows a simulation result of the phase-frequency characteristics of the compensation circuit configured by the LCR parallel resonance circuit.

  The compensation circuit having the above configuration has phase-frequency characteristics as shown in FIG. 12B in a desired frequency band (for example, 715 MHz to 725 MHz), and propagates through the space from the transmission antenna to receive antenna. It is possible to adjust to the interference suppression wave having the opposite phase in the wide frequency range with respect to the spatial propagation wave that wraps around.

  However, in the compensation circuit having the above-described configuration, as shown in FIG. 12 (a), the fluctuation of the pass loss in a desired frequency band (for example, 715 MHz to 725 MMz) is large. There is a problem that the frequency band capable of canceling the interference wave that wraps around cannot be sufficiently widened. In other words, even if the interference suppression wave is adjusted to have the same amplitude and opposite phase at the center frequency of the spatially propagated wave from the transmitting antenna, and the phase-frequency characteristics are compensated for by this LCR parallel resonance circuit, interference suppression Since the amplitude-frequency characteristics in the target band to be matched do not match, there arises a problem that interference cannot be suppressed in a wide frequency range.

  The present invention has been made in view of the above problems, and an object of the present invention is to cancel an interference wave that propagates through a space from a transmitting antenna in a wider frequency band and wraps around the receiving antenna.

  In order to achieve the above object, an invention according to claim 1 is an interference wave suppressing device (50) for suppressing an interference wave that propagates through a space from a transmission antenna and wraps around the reception antenna as an interference wave. 10) a divider (20) for separating the signal to be output, an attenuator (30) for attenuating the signal separated by the divider (20), and a shift for adjusting the phase of the output signal of the attenuator (30). A phase shifter (40), a phase frequency characteristic compensation circuit (50) for compensating the phase and frequency characteristics of an output signal from the phase shifter (40), and an output signal of the phase frequency characteristic compensation circuit (50) as a receiving antenna ( 11), and a phase frequency characteristic compensation circuit (50) between the input terminal and the output terminal for inputting the output signal from the phase shifter (40). , First inductance ( 1a) and a first capacitance (51b) arranged in series, and a second inductance between the connection point of the first capacitance (51b) and the output terminal and the ground (52a) and a second circuit (52) configured to arrange the second capacitance (52b) in parallel.

  Thus, the phase frequency characteristic compensation circuit (50) includes the first inductance (51a) and the first capacitance (between the input terminal and the output terminal for inputting the output signal from the phase shifter (40). 51b) between the connection point of the first circuit (51) arranged in series with the first capacitance (51b) and the output terminal and the ground, and the second inductance (52a) and the second capacitance. (52b) and a second circuit (52) configured to be arranged in parallel.

  The phase frequency characteristic compensation circuit (50) having such a configuration can secure a desired phase compensation amount while reducing fluctuations in the passage loss in a relatively wide frequency band, and therefore in a wider frequency band. The interference wave that propagates through the space from the transmitting antenna and goes around to the receiving antenna can be canceled out.

  In the invention according to claim 2, the phase frequency characteristic compensation circuit (50) further includes a third inductance (53a) and a third capacitance between the first circuit (51) and the output terminal. (53b) is configured using a circuit having a third circuit (53) configured to be arranged in series.

  In this way, a third circuit (a third circuit (53a) and a third capacitance (53b) arranged in series between the first circuit (51) and the output terminal is further provided. The phase frequency characteristic compensation circuit (50) can also be configured using a distributed constant circuit having (53).

  In addition, as in the invention described in claim 3, the inductance and capacitance values of the first to third circuits (51 to 53) can be set so that the phase advances as the frequency increases. As in the invention described in Item 4, the inductance and capacitance values of the first to third circuits (51 to 53) can be set so that the phase is delayed as the frequency increases.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a figure which shows the whole structure of the interference wave suppression apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the circuit structure of the phase frequency characteristic compensation circuit used with the interference wave suppression apparatus which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the omega-beta diagram of a transmission line. It is a figure which shows the simulation result of the passage loss-frequency characteristic of the phase frequency characteristic compensation circuit which concerns on 1st Embodiment. It is a figure which shows the simulation result of the phase-frequency characteristic of the phase frequency characteristic compensation circuit which concerns on 1st Embodiment. It is a figure which shows the circuit structure of the phase frequency characteristic compensation circuit used with the interference wave suppression apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the board | substrate pattern of the phase frequency characteristic compensation circuit used with the interference wave suppression apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the simulation result of the frequency characteristic of the voltage standing wave ratio of the phase frequency characteristic compensation circuit which concerns on 1st Embodiment, and a phase-frequency characteristic. It is a figure for demonstrating a subject. It is a figure which shows the frequency characteristic of the passage loss between the terminal 1 and the terminal 2. FIG. It is a figure for demonstrating a subject. It is a figure for demonstrating a subject.

(First embodiment)
FIG. 1 shows a block configuration of the interference wave suppressing device according to the first embodiment of the present invention. The interference wave suppressing device suppresses an interference wave that propagates through the space from the transmission antenna 10 and wraps around the reception antenna 11 as an interference wave. The interference wave suppressing device includes a directional coupler 20, an attenuator 30, a phase shifter 40, a phase frequency characteristic compensation circuit 50, and a directional coupler 60. In addition, the transmission unit 12 is connected to the interference wave suppressing device via a terminal P1, and the receiving unit 13 is connected via a terminal P2. In addition, the interference wave suppressing device is connected to the matching circuit 10a and the transmission antenna 10 via the terminal P3, and to the matching circuit 11a and the reception antenna 11 via the terminal P4.

  The interference wave suppression device, the transmission unit 12, the reception unit 13, the matching circuit 10a, the transmission antenna 10, the matching circuit 11a, and the reception antenna 11 constitute a wireless communication device.

  The transmission antenna 10 in this embodiment is used as a radio for vehicle-to-vehicle communication that performs data communication between the host vehicle and another vehicle, and the frequency band is 720 ± 5 megahertz (MHz). . The receiving antenna 11 is used as a mobile phone that performs communication between the vehicle and the public line radio base station, and has a frequency band of 730 to 760 megahertz (MHz).

  When the transmission antenna 10 and the reception antenna 11 are arranged close to each other and the frequency of the transmission radio wave of the transmission antenna 10 is close to the frequency of the reception radio wave of the reception antenna 11, the transmission antenna 10 propagates through the space and receives the reception antenna 11. The interference wave wraps around and the S / N ratio (signal-to-noise ratio) decreases.

  The interference wave suppressing apparatus propagates the space from the transmitting antenna 10 to the receiving antenna 11 because the frequency band of the transmitting antenna 10 and the frequency band of the receiving antenna 11 are at least 5 MHz apart. As a result, the interference wave that wraps around is suppressed.

  The directional coupler 20 separates a transmission signal input from a transmission unit (not shown) via the terminal P1. Specifically, a transmission signal input from a transmission unit (not shown) is separated into one that is sent to the transmission antenna 20 via the matching circuit 20a and one that is sent to the attenuator 30.

  The attenuator 30 attenuates the signal separated by the directional coupler 20. In the present embodiment, the amplitude of the signal input from the phase frequency characteristic compensation circuit 50 to the directional coupler 60 is the same as the amplitude of the received signal input from the receiving antenna 11 via the directional coupler 60. Next, the signal separated by the directional coupler 20 is attenuated.

  The phase shifter 40 adjusts the phase of the output signal of the attenuator 30. In the present embodiment, the phase of the output signal of the attenuator 30 is shifted by 180 degrees so that the phase of the signal output from the phase shifter 40 is opposite to the signal separated by the directional coupler 20. Let

  The phase frequency characteristic compensation circuit 50 compensates the phase / frequency characteristic of the output signal of the phase shifter 40. The interference wave propagating from the transmitting antenna 10 to the receiving antenna 11 through the space has a characteristic that the phase is delayed as the frequency increases. The phase frequency characteristic compensation circuit 50 compensates for the phase / frequency characteristics of the output signal of the phase shifter 40 so as to match the phase / frequency characteristics of the interference wave propagating from the transmitting antenna 10 to the receiving antenna 11 through the space. To do.

  The directional coupler 60 combines the reception signal input from the reception antenna 11 via the matching circuit 11a and the signal output from the phase frequency characteristic compensation circuit 50.

  The signal output from the phase frequency characteristic compensation circuit 50 has the same amplitude, opposite phase, and the same phase / frequency characteristics as the interference wave that propagates through the space from the transmission antenna 10 and wraps around the reception antenna 11. .

  The directional coupler 60 synthesizes the reception signal input from the reception antenna 11 via the matching circuit 11a and the signal output from the phase frequency characteristic compensation circuit 50, thereby propagating the space from the transmission antenna 10. Thus, the interference wave that interferes with the reception antenna 11 is suppressed, and the S / N ratio (signal-to-noise ratio) is improved.

  FIG. 2 shows a circuit configuration of the phase frequency characteristic compensation circuit 50. The phase frequency characteristic compensation circuit 50 includes a first circuit 51 formed by connecting a first inductance 51a and a first capacitance 51b in series, and a second circuit formed by connecting a second inductance 52a and a second capacitance 52b in parallel. A distributed constant circuit having two circuits 52 is connected in multiple stages. The phase frequency characteristic compensation circuit 50 in the present embodiment is configured by connecting the five above-described distributed constant circuits in multiple stages. In FIG. 2, details of the distributed constant circuit in the second to fifth stages are omitted, but are the same as the distributed constant circuit in the first stage.

  The distributed constant circuit having such a configuration is called a so-called left-handed transmission line and can arbitrarily adjust the slope of the phase-frequency characteristic. That is, it is possible to delay the phase or advance the phase as the frequency increases. Also, by optimizing the distribution constant, it is possible to achieve both reduction of the passage loss and optimization of the phase compensation amount.

Here, the inductance value of the inductance 51a of the first circuit 51 is _{L R,} a capacitance value of the capacitance 51b and _{C L,} the impedance Z of the first circuit 51 can be expressed as Equation 1.

また、第２の回路５２のインダクタンス５２ａのインダクタンス値をＬ_Ｌ、キャパシタンス５２ｂの容量値をＣ_Ｒとすると、第２の回路５２のアドミタンスＺは、数式２のように表される。

Further, when the inductance value _{L L} of the inductance 52a of the second circuit 52, the capacitance value of the capacitance 52b and _{C R,} admittance Z of the second circuit 52 is expressed by Equation 2.

また、伝搬定数γは、数式３のように表される。

Further, the propagation constant γ is expressed as Equation 3.

ただし、ω_ｓｅは、直列共振周波数であり、数式４のように表される。

However, ω _se is a series resonance frequency and is expressed as Equation 4.

また、ω_ｓｈは、並列共振周波数であり、数式５のように表される。

Further, ω _sh is a parallel resonance frequency and is expressed as Equation 5.

また、ｓ（ω）は、数式６に示す条件に合わせて設定される。

Further, s (ω) is set according to the condition shown in Equation 6.

図３に、伝送線路のω−βダイアグラムを示す。なお、横軸は位相定数βであり、単位距離あたりの位相の変化量を表している。また、縦軸は角周波数ωである。

FIG. 3 shows a ω-β diagram of the transmission line. The horizontal axis is the phase constant β and represents the amount of phase change per unit distance. The vertical axis represents the angular frequency ω.

Further, the characteristic impedance Z ₀ is expressed as Equation 7.

また、入出力インピーダンスＺ_Ｌは、数式８のように表される。

Further, input and output impedance Z _L is expressed as in Equation 8.

ここで、回路定数の設定方法について説明する。まず、左手系伝送路として、入出力インピーダンスＺ_Ｌ＝５０オーム（Ω）となるように、上記数式１〜６を満たすような各定数を決定する。

Here, a method for setting circuit constants will be described. First, constants that satisfy the above mathematical expressions 1 to 6 are determined so that the input / output impedance Z _L = 50 ohms (Ω) as the left-handed transmission line.

  Next, the phase for each frequency is calculated. Specifically, when the real part of the propagation constant γ is real (γ), the imaginary part is imag (γ), and the arc tangent is ATAN, the phase θ can be calculated using Equation 9.

次に、所望の周波数幅（例えば、７１５〜７２５メガヘルツ（ＭＨｚ））の間の位相差を調べ、必要に応じて多段接続する段数を決定する。このようにして、所望の周波数幅における理想的な位相特性を有する位相周波数特性補償回路５０の回路定数を決定することができる。

Next, a phase difference between desired frequency widths (for example, 715 to 725 megahertz (MHz)) is examined, and the number of stages to be connected in multiple stages is determined as necessary. In this way, the circuit constant of the phase frequency characteristic compensation circuit 50 having an ideal phase characteristic in a desired frequency width can be determined.

  In FIG. 4, the inductance value of the inductance 51a is 45 nanohenry (nH), the capacitance value of the capacitance 51b is 82 picofarad (pF), the inductance value of the inductance 52a is 27 nanohenry (nH), and the capacitance value of the capacitance 52b is 4 picofarad. The simulation result of the passage loss-frequency characteristic of the phase frequency characteristic compensation circuit 50 in the case of (pF) is shown. FIG. 5 shows a simulation result of the phase-frequency characteristics of the phase frequency characteristic compensation circuit 50.

  As shown in FIG. 4, while passing loss in the frequency band of 715 to 725 megahertz is less than 1 decibel (0.7 decibel (dB)), in the frequency band of 715 to 725 megahertz as shown in FIG. The phase compensation amount can be set to 50 ° or more (53 °).

  In the configuration described above, when a signal to the transmission antenna 10 is transmitted from the transmission unit, the output signal of the transmission unit that outputs a signal to the transmission antenna 10 is branched by the directional coupler 20. The branched signal is attenuated by the attenuator 30, the phase of the output signal of the attenuator 30 is adjusted by the variable phase shifter 40, and the phase / frequency characteristic of the output signal of the variable phase shifter 40 is compensated for the phase frequency characteristic. Compensated by the circuit 50, the output signal of the phase frequency characteristic compensation circuit 50 is combined with the received signal of the receiving antenna 11 by the directional coupler 60, propagates through the space from the transmitting antenna 10 and wraps around the receiving antenna 11 as an interference wave. The interference wave is canceled.

  According to the configuration described above, in the phase frequency characteristic compensation circuit 50, the first inductance 51a and the first capacitance 51b are arranged in series between the input terminal for inputting the output signal from the phase shifter 40 and the output terminal. The second circuit 52 is configured to be arranged in parallel between the first circuit 51 configured to be connected to the connection point between the first capacitor 51b and the output terminal and the ground. And a distributed constant circuit having two circuits 52.

  Since the phase frequency characteristic compensation circuit 50 having such a configuration can secure a desired phase compensation amount while reducing fluctuations in the passage loss in a relatively wide frequency band, the transmission antenna can be used in a wider frequency band. The interference wave that propagates through the space and travels around the receiving antenna can be canceled out.

(Second Embodiment)
FIG. 6 shows a circuit configuration of the phase frequency characteristic compensation circuit 50 used in the interference wave suppressing device according to the second embodiment of the present invention. The phase frequency characteristic compensation circuit 50 used in the interference wave suppression device according to the present embodiment is further provided between the first circuit 51 and the output terminal used in the first embodiment, and the third inductance 53a and the third The third circuit 53 is different in that the capacitance 53b is connected in series. In addition, about the same part as the said 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted and it demonstrates below centering on a different part.

  FIG. 7 shows a substrate pattern of the phase frequency characteristic compensation circuit 50. Black portions in FIG. 7 are conductive patterns. As shown in the figure, a first circuit 51, a second circuit 52, and a third circuit 53 are formed by each pattern.

  The inductance and capacitance values in the circuits 51 to 53 can be adjusted by the pattern length, the pattern width, the gap, the dielectric constant of the substrate, and the like.

8, 2 nano henry inductance _{L R} of inductance 51a, 10 picofarads capacitance _{C L} capacitance 51b, 24 nano henry inductance _{L R} of inductance 52a, 30 a capacitance _{C L} of the capacitance 51b picofarads, 2 nano-henry inductance _{L R} of inductance 53a, showing the frequency characteristics of the phase frequency characteristic compensating circuit 50 in a case where the capacitance value _{C L} capacitance 53b was 10 picofarads. FIG. 8A shows a frequency characteristic of a voltage standing wave ratio (VSWR), and FIG. 8B shows a phase frequency characteristic.

  As shown in FIG. 8B, the constants of the first to third circuits 51 to 53 are set so that the phase is delayed as the frequency increases.

  Further, as shown in FIG. 8A, a phase frequency characteristic compensation circuit 50 having a phase frequency characteristic as shown in FIG. 8B is configured while reducing the voltage standing wave ratio.

9, the inductance value _{L R} five nanohenries of inductance 51a, capacitance _{C L} of 2 picofarads capacitance 51b, the inductance value _{L R} 2 nanohenries of inductance 52a, capacitance 51b of the capacitance value _{C L} 18 picofarads, 2 nano-henry inductance L _R of inductance 53a, showing the frequency characteristics of the phase frequency characteristic compensating circuit 50 in a case where the capacitance value C _L capacitance 53b was 5 picofarads. FIG. 9A shows a frequency characteristic of a voltage standing wave ratio (VSWR), and FIG. 9B shows a phase frequency characteristic.

  As shown in FIG. 9B, the constants of the first to third circuits 51 to 53 are set so that the phase advances as the frequency increases.

  Further, as shown in FIG. 9A, a phase frequency characteristic compensation circuit 50 having a phase frequency characteristic as shown in FIG. 9B is configured while reducing the voltage standing wave ratio.

  As described above, the slope of the phase-frequency characteristic can be arbitrarily changed by adjusting each parameter of the first to third circuits 51 to 53.

  FIG. 10 shows the frequency characteristics of the passage loss between the terminal 1 and the terminal 2 in FIG. This figure shows the frequency characteristics of the passage loss when there is no phase frequency characteristic compensation circuit 50 (without a phase frequency characteristic compensation circuit) and when there is a phase frequency characteristic compensation circuit 50 (with a phase frequency characteristic compensation circuit). ing. For reference, the case where there is no interference wave suppression device (no interference suppression) is also shown.

  The frequency band in which the passage loss is −30 decibels (dB) or less is 8 megahertz (MHz) when the phase frequency characteristic compensation circuit 50 is not provided, whereas when the phase frequency characteristic compensation circuit 50 is provided. Is 12 megahertz (MHz).

  The phase frequency characteristic compensation circuit 50 configured as described above can secure a desired amount of phase compensation while reducing fluctuations in the passage loss in a relatively wide frequency band. It is possible to cancel the interference wave that propagates through the space and goes around the receiving antenna.

  As described above, the third inductance 53a and the third capacitance 53b are further arranged in series between the first circuit 51 and the output terminal with respect to the phase frequency characteristic compensation circuit 50 shown in the first embodiment. The phase frequency characteristic compensation circuit 50 can also be configured using a distributed constant circuit having the third circuit 53 configured as described above.

  Also, the inductance and capacitance values of the first to third circuits 51 to 53 can be set so that the phase advances as the frequency increases, and conversely, the first and third circuits 51 to 53 can be set so that the phase is delayed as the frequency increases. The inductance and capacitance values of the first to third circuits 51 to 53 can also be set.

(Other embodiments)
In the first and second embodiments, the transmission antenna 10 used as a radio for inter-vehicle communication that performs data communication between the own vehicle and another vehicle, and the own vehicle and the public line radio base station Although the configuration is shown in which the receiving antenna 11 used as a mobile phone for communication between the two is connected, the use and frequency band of each antenna are not limited to those shown in the above embodiment.

  In the first embodiment, the phase frequency characteristic compensation circuit 50 is configured by connecting five stages of distributed constant circuits each having the first circuit 51 and the second circuit 52, but the number of stages is 1 to 4. It is good also as a step or six steps or more. The same applies to the second embodiment.

DESCRIPTION OF SYMBOLS 10 Transmitting antenna 11 Receiving antenna 12 Transmitting part 13 Receiving part 20 Directional coupler 30 Attenuator 40 Attenuator 50 Phase frequency characteristic compensator 51a, 52a, 53a Inductance 51b, 52b, 53b Capacitance 60 Directional coupler

Claims (4)

An interference wave suppression device (50) that suppresses an interference wave that propagates through a space from a transmission antenna and circulates as a disturbance wave to a reception antenna,
A distributor (20) for separating a signal to be output to the transmission antenna (10);
An attenuator (30) for attenuating the signal separated by the distributor (20);
A phase shifter (40) for adjusting the phase of the output signal of the attenuator (30);
A phase frequency characteristic compensation circuit (50) for compensating a phase / frequency characteristic of an output signal from the phase shifter (40);
A coupler (60) for coupling the output signal of the phase frequency characteristic compensation circuit (50) with the received signal of the receiving antenna (11);
The phase frequency characteristic compensation circuit (50) includes a first inductance (51a) and a first capacitance (51b) between an input terminal and an output terminal for inputting an output signal from the phase shifter (40). Between the connection point of the first circuit (51), the first capacitance (51b) and the output terminal and the ground, and the second inductance (52a) and the second capacitance. An interference wave suppressing device comprising: a second circuit (52) configured to arrange (52b) in parallel.   The phase frequency characteristic compensation circuit (50) further includes a third inductance (53a) and a third capacitance (53b) arranged in series between the first circuit (51) and the output terminal. The interference wave suppressing device according to claim 1, wherein the interference wave suppressing device is configured using a circuit having a third circuit (53).   The interference wave suppressing device according to claim 2, wherein the inductance and capacitance values of the first to third circuits (51 to 53) are set so that the phase advances as the frequency increases. .   The interference wave suppressing device according to claim 2, wherein the inductance and capacitance values of the first to third circuits (51 to 53) are set so that the phase is delayed as the frequency becomes higher. .

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