JP2007049212A - Variable reactance apparatus, oscillator, and radar apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a cost in a variable reactance apparatus 1 which is used for an FM-CW radar etc. and generates a modulation wave for modulating a transmission wave into a triangular modulation wave. <P>SOLUTION: There is provided a rotor 2 having a deformed shape in the circumferential direction and arranged in the proximity of a substrate 11 consisting of a coplanar line and a micro-strip line. The rotor 2 also consists of a conductor and a dielectric. Accordingly, by rotating the rotor 2, it is possible to change the position and amount of the capacitance generated between the transmission line and the rotor 2 and at the side of the rotor 2, thereby changing the reactance viewed from the side of the transmission line. Thus, when handling a high-frequency signal such as a millimeter-wave band, it is difficult to change the reactance by an electric method but a reactance change can be realized by a mechanical method, thereby obtaining an excellent linearity and frequency characteristic at a low cost. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable reactance device, an oscillator, and a radar device that are mounted on a vehicle and are preferably used for a so-called FM-CW radar device or the like that is used for measuring an inter-vehicle distance or a relative speed.

  The FM-CW radar uses, for example, a 76 GHz millimeter wave, and can measure the inter-vehicle distance and relative speed relatively accurately without being affected by the weather and day and night. Has begun. The measurement principle is widely known, the 76 GHz triangular modulated wave is transmitted, and the distance can be measured from the time delay of the received wave (the time until the reflected wave from the object returns), The relative velocity can be measured from the frequency shift (Doppler shift amount) between the transmission wave and the reception wave due to the Doppler effect.

Specifically, the received wave causes a time delay (Δt) and a frequency deviation with respect to the transmission wave, the time delay (Δt) represents a distance to the object, and the frequency deviation is a difference from the object. Represents relative speed. The distance R to the object is 2R = Δt × C (C is the speed of light), that is, R = Δt × C / 2 (A)
Can be obtained.

Here, when the relative speed is 0 and the beat frequency is fr, the larger the Δt, the larger the fr. Specifically, Δt = fr / (2 × ΔF × fm)
(ΔF is the modulation width of the transmitted wave, fm is the repetition frequency)
It is known to satisfy the relationship.

Substituting this into (A),
R = C × fr / (4 × ΔF × fm)
Thus, the distance R can be obtained based on the beat frequency fr.

In the above description, the Doppler shift amount is 0 (when the relative speed is 0), but even when the relative speed is not 0,
fr = (fb ₁ + fb ₂ ) / 2
(Fb ₁ is the beat frequency of the upstream section of the triangular modulated wave, and fb ₂ is the downstream beat frequency of the triangular modulated wave)
The above formula can be applied.

Further, the relative velocity V is given by assuming that the carrier frequency of the transmission wave is fo.
fd = (fb ₁ −fb ₂ ) / 2
As
V = C · fd / (2 · fo)
Can be obtained from

  Therefore, it is necessary for such an FM-CW radar to generate and modulate a triangular modulated wave having a linearity with a modulation width of about 100 MHz. Usually, in order to apply modulation, a VCO (voltage controlled oscillator) using a variable reactance element such as a varactor diode as a modulation element is generally used. However, in the millimeter wave region, it is difficult to obtain a VCO that can change the resonance frequency of the resonator using this varactor diode. The reason will be described in detail below.

  That is, the varactor diode changes the depletion layer capacitance by changing the voltage applied to the semiconductor PN junction, thereby obtaining a change in capacitance. As the capacity of the varactor diode used for the VCO, a capacity that normally has an impedance of about −50 jΩ suitable for modulation is selected. When a varactor diode having a capacity sufficiently larger than this impedance value is used, the varactor diode looks almost short-circuited and hardly changes in resonance frequency. On the other hand, when a varactor diode having a capacitance sufficiently smaller than this impedance value is used, the varactor diode appears almost open, and it is difficult for the resonance frequency to change.

  In a millimeter wave, for example, in the 76 GHz band, the capacitance with an impedance of −50 jΩ is 0.042 pF, and when a generally available capacitance value (0.3 pF or more) is used, it appears to be a substantially short circuit as described above. In addition, the parasitic capacitance that exists in parallel and the parasitic inductor that exists in series hide the capacitance change of the varactor diode. Therefore, as described above, in the millimeter wave region, it is extremely difficult to obtain a VCO that changes the resonance frequency of the resonator using a varactor diode.

In order to obtain a triangular modulation wave having excellent linearity for FM-CW radar, the following three methods are conceivable.
1. A VCO having a constant frequency modulation sensitivity is used.
2. As shown in Patent Document 1, the modulation signal is distorted in the reverse direction so that the frequency modulation sensitivity is constant, and a linear modulation wave is obtained.
3. As shown in Patent Document 2, a closed loop is used in which the oscillation frequency is monitored in real time and correction is performed when the frequency is shifted.
JP-A-8-18343 (Publication date: January 19, 1996) JP-A-6-120735 (Publication date: April 28, 1994)

  1 above. In order to realize this method, a VCO having excellent modulation characteristics is required, but it is very difficult to realize such a VCO.

  In addition, 2. This method can obtain good linearity relatively easily using a low-frequency circuit. However, since this method is an open loop correction, there is a problem that the characteristic is shifted when the characteristic variation of the VCO occurs. In addition, the correction circuit is also a factor of high cost.

  Furthermore, in 3. above. A representative example of this method is PLL (phase lock loop). If a PLL is used, a triangular modulation wave having excellent linearity can be obtained relatively easily, and correction can be made even if the VCO characteristic changes with time. However, the PLL requires a reference oscillator and a frequency divider, and has a problem that the configuration is complicated and the cost is high. Further, in the millimeter wave band, it is necessary to down-convert in order to compare with the reference signal, and the circuit for this down-conversion is complicated and more expensive. Although there is a method called FLL (Frequency Locked Loop) similar to this PLL, there is still a problem that a reference oscillator is required and cost is increased.

  Therefore, any of the above methods has technical or cost problems.

  An object of the present invention is to provide a variable reactance device, an oscillator, and a radar device capable of realizing a modulation method that is inexpensive.

  The variable reactance device of the present invention includes a transmission line and a rotor that is disposed in the vicinity of the transmission line and has a shape that changes in the circumferential direction. It is characterized by changing the reactance seen from the above.

  According to the above configuration, when a rotor made of a conductor or a dielectric is placed close to a transmission line made of a coplanar line, a microstrip line, a slot, or the like, when the rotor is a conductor, the rotor A capacitor is formed between the conductor and the transmission line. When the rotor is a dielectric, a capacitor is formed on the dielectric side. The reactance changes when the rotor is rotated by forming the rotor so that its shape changes in the circumferential direction. For example, the reactance changes periodically by forming irregularities that are continuous in the circumferential direction. In this way, variable reactance can be realized.

  When dealing with high-frequency signals such as millimeter waves, it is difficult to change the reactance by an electrical method, but the reactance change is realized by a mechanical method, resulting in excellent linearity and frequency characteristics. Can be obtained at low cost.

  In the variable reactance device of the present invention, at least a portion of the rotor facing the transmission line is conductive, and a capacitance is formed between the transmission line and the rotor. .

  According to the above configuration, a rotor formed by metallizing a metal or an insulator is used, and the rotor is rotated by a change in the shape of the rotor in the circumferential direction, whereby the transmission line, the rotor, The reactance formed during the period changes. Thereby, the variable reactance can be specifically realized.

  Furthermore, in the variable reactance device according to the present invention, the rotor is characterized in that a ridge that is substantially ring-shaped and meanders in the radial direction is formed on the lower surface of the disk portion.

  According to said structure, a protruding item | line is formed in the wall shape of the uniform height which protruded from the lower surface of the said disc part. The ridges are roughly circular, and are formed by meandering periodically in a triangular modulation wave shape or the like. Further, a plurality of ridges may be formed in parallel to each other.

  Therefore, when the rotor rotates, the position of the capacitor on the transmission line changes, and the reactance can be changed by changing the position of the capacitor.

  In the variable reactance device of the present invention, the transmission line is a coplanar line, and the capacitance is between a line conductor of the coplanar line and the rotor, and between a ground conductor of the coplanar line and the rotor. It is characterized by occurring between.

  According to the above configuration, when the transmission line is formed of a coplanar line, the ridge formed on the lower surface of the disk portion of the rotor as described above faces the coplanar line, and the capacitance is the same as that of the coplanar line. It is formed between the line conductor and the rotor, and between the ground conductor of the coplanar line and the rotor. As the rotor rotates as described above, the positions of these capacities change, and the reactance can be changed.

  Furthermore, in the variable reactance device of the present invention, the rotor is provided in a pair so as to sandwich the transmission line, and is driven to rotate in conjunction with each other.

  According to said structure, even if a rotor displaces to an axial direction, the total value of the clearance gap between two rotors and a transmission line becomes always substantially constant.

  Therefore, even if shaft runout occurs, a change in capacitance formed between the transmission line and the rotor can be reduced.

  In the variable reactance device according to the present invention, the rotor is formed by extending an outer wall from the lower surface of the disk portion, and the thickness of the outer wall is periodically changed in the circumferential direction. It is characterized by.

  According to said structure, an outer wall is extended from the lower surface of a disc part, and a rotor is formed. And the thickness of the outer wall is formed by periodically changing in the circumferential direction in the form of a triangular modulation wave or the like.

  Therefore, when the rotor rotates, the electrode area on the transmission line is changed, the capacitance itself is changed, and the reactance can be changed by the change of the capacitance.

  Furthermore, in the variable reactance device of the present invention, the rotor is formed by extending an outer wall from the lower surface of the disc portion, and the height of the outer wall is periodically changed in the circumferential direction. It is characterized by comprising.

  According to said structure, an outer wall is extended from the lower surface of a disc part, and a rotor is formed. Then, the height of the outer wall is periodically changed in a triangular modulation wave shape or the like in the circumferential direction.

  Therefore, when the rotor rotates, the distance to the transmission line is changed, the capacitance itself is changed, and the reactance can be changed by the change of the capacitance.

  In the variable reactance device according to the present invention, the rotor is formed by repeatedly forming irregularities in the circumferential direction on the outer peripheral surface, the transmission line is a microstrip line, and the capacitor is an opening of the microstrip line. It occurs between the end and the outer peripheral surface of the rotor.

  According to the above configuration, the rotor is formed by repeatedly forming irregularities in the circumferential direction on the outer peripheral surface. The unevenness is formed by periodically changing to a triangular modulation wave shape or the like. Meanwhile, the transmission line is formed of a microstrip line, and the capacitance is generated between the open end of the microstrip line and the outer peripheral surface of the rotor.

  Therefore, when the rotor rotates, the distance between the open end and the rotor is changed, the capacity itself is changed, and the reactance can be changed by changing the capacity.

  Furthermore, in the variable reactance device according to the present invention, the rotor is made of a dielectric material having a ring-shaped and ridged meander in the radial direction on the lower surface of the disk portion, and the transmission line. Is composed of a coplanar track.

  According to said structure, a protruding item | line is formed in the wall shape of the uniform height which protruded from the lower surface of the said disc part. The ridges are roughly circular, and are formed by meandering periodically in a triangular modulation wave shape or the like. Further, a plurality of ridges may be formed in parallel to each other.

  Therefore, when the rotor rotates, the position of the capacitor on the transmission line changes, and the reactance can be changed by changing the position of the capacitor.

  In the variable reactance device of the present invention, the rotor is made of a dielectric material, and the transmission line is made of a coplanar line, and the distance between the rotor and the transmission line is changed by the rotation of the rotor. Features.

  According to the above configuration, the rotor is made of a dielectric, and the distance between the rotor and the transmission line is changed by rotating the rotor by changing the circumferential shape of the rotor. If it comprises, the capacity | capacitance generate | occur | produced between the line conductor of the said coplanar line | wire and a ground conductor will change with the said rotation, and the said reactance can be changed. Thereby, the variable reactance can be specifically realized.

  Furthermore, an oscillator according to the present invention includes the variable reactance device and a resonator, and the oscillation frequency is changed by changing a reactance value of the variable reactance device.

  According to the above configuration, as described above, it is possible to realize an oscillator capable of realizing a change in reactance by a mechanical method and obtaining excellent linearity and frequency characteristics at low cost.

  A radar apparatus according to the present invention uses the oscillator described above.

  According to the above configuration, as described above, it is possible to realize a radar apparatus that can realize a change in reactance by a mechanical method and obtain excellent linearity and frequency characteristics at low cost.

  Furthermore, in the radar apparatus of the present invention, the rotor includes a primary radiator, the oscillation frequency of the oscillator is changed by the rotation of the rotor, and the primary radiator is scanned. Features.

  According to said structure, when a primary radiator scans a radiation radar wave, it comprises integrally with the said rotor for implement | achieving the above-mentioned reactance change.

  Therefore, the configuration of the scanning radar apparatus can be simplified.

  As described above, the variable reactance device of the present invention includes a transmission line and a rotor that is disposed in the vicinity of the transmission line and has a shape that changes in the circumferential direction, and by rotating the rotor. The reactance seen from the transmission line side is changed. For example, the reactance changes periodically by forming irregularities that are continuous in the circumferential direction. Thus, variable reactance is realized.

  Therefore, when dealing with high-frequency signals such as the millimeter wave band, it is difficult to change the reactance by an electrical method, but the reactance change is realized by a mechanical method, and excellent linearity and frequency characteristics are achieved. Can be obtained at low cost.

  Further, as described above, the variable reactance device of the present invention uses a rotor formed by metallizing a metal or an insulator, and rotates the rotor by changing the shape of the rotor in the circumferential direction. A reactance formed between the transmission line and the rotor is changed.

  Therefore, the variable reactance can be specifically realized.

  Furthermore, in the variable reactance device of the present invention, as described above, the rotor is configured by forming, on the lower surface of the disk portion, a substantially strip-shaped ridge that is meandering in the radial direction.

  Therefore, when the rotor rotates, the position of the capacitor on the transmission line changes, and the reactance can be changed by changing the position of the capacitor.

  In the variable reactance device of the present invention, the transmission line is formed of a coplanar line as described above.

  Therefore, the ridge formed on the lower surface of the disk portion of the rotor as described above faces the coplanar line, and the capacitance is between the line conductor of the coplanar line and the rotor, and the coplanar line. When the rotor is rotated and formed between the ground conductor and the rotor, the positions of their capacities change, and the reactance can be changed.

  Furthermore, in the variable reactance device of the present invention, as described above, a pair of the rotors are provided so as to sandwich the transmission line, and they are driven to rotate in conjunction with each other.

  Therefore, even if the rotor is displaced in the axial direction, the total value of the gaps between the two rotors and the transmission line is always constant, and even if shaft runout occurs, there is a gap between the transmission line and the rotor. A change in the formed capacitance can be reduced.

  In the variable reactance device of the present invention, as described above, the rotor has a shape in which an outer wall is extended from the lower surface of the disk portion, and the thickness of the outer wall is periodically changed in the circumferential direction. .

  Therefore, when the rotor rotates, the electrode area on the transmission line is changed, the capacitance itself is changed, and the reactance can be changed by changing the capacitance.

  Furthermore, in the variable reactance device of the present invention, as described above, the rotor is formed by extending the outer wall from the lower surface of the disk portion, and the height of the outer wall is periodically changed in the circumferential direction. Change shape.

  Therefore, when the rotor rotates, the distance to the transmission line is changed, the capacitance itself is changed, and the reactance can be changed by changing the capacitance.

  In the variable reactance device of the present invention, as described above, the rotor has a shape in which irregularities are repeatedly formed in the circumferential direction on the outer peripheral surface, the transmission line is a microstrip line, and the capacitor is the microstrip. It is formed between the open end of the strip line and the outer peripheral surface of the rotor.

  Therefore, when the rotor rotates, the distance between the open end and the rotor is changed, the capacity itself is changed, and the reactance can be changed by changing the capacity.

  Furthermore, the variable reactance device of the present invention, as described above, is a dielectric in which the rotor is formed on the lower surface of the disk portion in a generally ring-like shape and convexly striped in the radial direction. The transmission line is a coplanar line.

  Therefore, when the rotor rotates, the position of the capacitor on the transmission line changes, and the reactance can be changed by changing the position of the capacitor.

  In the variable reactance device of the present invention, as described above, the rotor is formed of a dielectric, the transmission line is a coplanar line, and the distance between the rotor and the transmission line is determined by the rotation of the rotor. To change.

  Therefore, with the rotation, the capacitance generated between the line conductor and the ground conductor of the coplanar line changes, and the reactance can be changed. Thereby, the variable reactance can be specifically realized.

  Furthermore, the oscillator according to the present invention includes the variable reactance device and the resonator as described above, and the oscillation frequency changes by changing the reactance value of the variable reactance device.

  Therefore, as described above, it is possible to realize an oscillator capable of realizing a change in reactance by a mechanical method and obtaining excellent linearity and frequency characteristics at a low cost.

  The radar apparatus of the present invention uses the oscillator as described above.

  Therefore, as described above, it is possible to realize a radar apparatus that can realize a change in reactance by a mechanical method and obtain excellent linearity and frequency characteristics at low cost.

  Furthermore, as described above, the radar apparatus of the present invention includes a primary radiator in the rotor, and changes the oscillation frequency of the oscillator by the rotation of the rotor. Scan.

  Therefore, when the primary radiator performs scanning of the radiation radar wave, it is possible to simplify the configuration of the scanning radar apparatus by integrating with the rotor for realizing the reactance change as described above. it can.

  The first embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is a schematic block diagram of a general VCO used in the FM-CW radar. In this VCO, the reactance Xv is changed, and the reactance Xv ′ of the modulation circuit coupled to the resonator is changed, whereby the resonance frequency of the resonance circuit is changed, and frequency modulation of the triangular modulation wave is performed. As described above, conventionally, the reactance Xv is changed by using a variable reactance element such as a varactor diode. On the other hand, in the oscillator according to the present invention, a rotor is used as follows. Done in

  FIG. 2 is a perspective view showing the structure of the variable reactance device 1 according to the first embodiment of the present invention. The variable reactance device 1 includes a rotor 2 that is rotationally driven by a motor (not shown) and a substrate 11 that is capacitively coupled thereto.

  FIG. 3 is a bottom view of the rotor 2, and FIG. 4 is a longitudinal sectional view taken along one diameter line thereof. The rotor 2 is generally configured by forming two substantially concentric ridges 4 and 5 on the lower surface of the disc portion 3. The ridges 4 and 5 are formed in a wall shape having a uniform height protruding from the lower surface of the disc portion 3. The ridges 4 and 5 are generally ring-shaped and periodically meander in the triangular modulation wave shape in the radial direction, and are formed in parallel to each other. As a result of the meandering, as shown in FIG. 5, the positions of the ridges 4 and 5 on the substrate 11 (the trajectory in the radial direction of the rotor 2) are changed, and the reactance Xv is changed by changing the position. It is like that. Therefore, the modulation frequency of the triangular modulation wave is determined by the number of meanders and the rotation speed. The rotor 2 configured as described above is formed by metallizing the surface of metal or resin, or made of a dielectric.

  The substrate 11 has a coplanar line on the rotor 2 side and a microstrip line on the opposite side, and the end on the opposite side is connected to the resonator. Therefore, when the position of the ridges 4 and 5 changes, the distance between them and both ends of the substrate 11 changes, and the reactance Xv changes as described above.

  FIG. 5 is a plan view of a facing portion between the rotor 2 and the substrate 11. When the rotor 2 faces the substrate 11 that is a coplanar line as described above, an equivalent circuit as shown in FIG. 6A is obtained when the rotor 2 is a conductor. Accordingly, when the position of the ridges 4 and 5 is changed by the rotation of the rotor 2, the position of the capacitance in FIG. 6A is changed, thereby changing the reactance Xv ′ of the modulation circuit and resonating. The frequency can be changed.

  When the rotor 2 is a dielectric, an equivalent circuit as shown in FIG. 6B is obtained. Similarly, when the positions of the ridges 4 and 5 are changed by the rotation of the rotor 2, FIG. The position of the capacitor () changes, thereby changing the reactance Xv ′ of the modulation circuit and changing the resonance frequency.

  Then, by making the shape of the ridges 4 and 5 meander in the form of a triangular modulation wave as shown in FIG. 3, the modulation wave becomes substantially the triangular modulation wave, and a modulation characteristic suitable for FM-CW radar can be obtained. it can. Even if the relationship between the change in the position of the capacitance and the resonance frequency is not linear, it can be corrected by the shape of the ridges 4 and 5, and an accurate triangular modulation wave can be obtained at a certain rotational speed or less. It is easy. Furthermore, when an electric element such as the varactor diode is used, the Q is poor and the loss of the modulation circuit increases. On the other hand, in the variable reactance device 1, the loss of the modulation portion can be reduced and the loss is low. A modulation circuit can be easily realized.

  FIG. 7 is a graph showing changes in the phase of the reflection coefficient at 76 GHz when the position (x) of the ridges 4 and 5 is changed. The substrate 11 has a relative dielectric constant of 3.0, a thickness of 0.2 mm, a line width / gap length of the coplanar line of 0.2 mm, and a gap between the ridges 4 and 5 and the substrate 11 of 80 μm. As shown in FIG. 3 and FIG. 4, the convex strips 4 and 5 are provided in two strips, and the positional relationship is as shown in FIG. 8. As can be seen from FIG. 7, the reflection phase changes by 90 ° or more approximately in proportion to the distance x from the tip of the coplanar line to the outer ridge 4, and the oscillation frequency is changed using this change. Can be changed.

  In this variable reactance device 1, the two ridges 4 and 5 are provided to improve the linearity of the phase change. Of course, even one of them changes the phase, and three or more are provided. May be. If a plurality of meanders are performed on the circumference as shown in FIG. 3, triangular modulation is repeated by the number of meanders per rotation of the rotor 2. Of course, the number of meanders is once. It may be reduced to several times to reduce the number of modulations per rotation.

  The second embodiment of the present invention will be described below with reference to FIG.

  FIG. 9 is a perspective view showing the structure of the variable reactance device 21 of the second embodiment of the present invention. The variable reactance device 21 is similar to the variable reactance device 1 described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. It should be noted that in this variable reactance device 21, another rotor 22 is provided together with the rotor 2 with the substrate 11 (transmission line) interposed therebetween.

  Therefore, even if the rotors 2 and 22 are displaced in the axial direction, the total value of the gaps between the rotors 2 and 22 and the substrate 11 is always constant. For example, one rotor 2 is close to the substrate 11 and the capacitance Increases, the other rotor 22 moves away from the substrate and the capacity decreases. In this way, the capacity change with respect to the shaft shake can be reduced.

  A third embodiment of the present invention will be described below with reference to FIGS.

  FIG. 10 is a perspective view showing the structure of the variable reactance device 31 according to the third embodiment of the present invention. The variable reactance device 31 is similar to the variable reactance device 1 described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. Whereas the variable reactance device 1 described above changes the impedance of the transmission line by changing the radial position of the ridges 4 and 5 along with the rotation of the rotor 2, it performs triangular modulation. It should be noted that the variable reactance device 31 performs triangular modulation by changing the capacity as the rotor 32 rotates.

  Specifically, as shown by the rotor 32a in FIG. 11, the electrode area is changed. In this case, the rotor 32a is formed by extending the outer wall 33 from the lower surface of the disc portion 3, and the thickness of the outer wall 33 periodically changes in the circumferential direction. The rotor 32a is also formed by metallizing the surface of metal or resin. On the other hand, a coplanar line is formed on the rotor 32a side of the substrate 41, and a microstrip line is formed on the resonator side.

  Further, as shown by the rotor 32b in FIG. 12, the distance between the electrode and the substrate 41 is changed. In this case, the rotor 32b is formed by extending an outer wall 34 from the lower surface of the disc portion 3, and the outer wall 34 is formed in a triangular modulation wave shape. The rotor 32b is also formed by metallizing the surface of metal or resin. In the case of this rotor 32b, it may be formed of a dielectric. In this case, as shown in FIG. 6B described above, no capacitance is generated between the rotor 32b and the transmission line, and the capacitance between the hot and ground of the transmission line is changed. That is, since the dielectric has a large ε, the hot-ground capacitance increases when the rotor 32b comes close to the substrate 41, and decreases when the rotor 32b moves away.

  FIG. 13 is a graph corresponding to the rotor 32a of FIG. 11 described above and showing the change in the phase of the reflection coefficient of the modulation circuit with respect to the thickness of the outer wall 33, that is, the change in the conductor width. The electrode width of the microstrip line of the substrate 41 is 500 μm, the gap with the substrate 41 is 50 μm, and the frequency is 76 GHz. The advance amount increases as the thickness of the outer wall 33 increases, that is, as the capacity increases.

  FIG. 14 is a graph corresponding to the rotor 32b of FIG. 12 described above and showing a change in the phase of the reflection coefficient of the modulation circuit with respect to a change in the height of the outer wall 34, that is, a protruding amount of the triangular modulation wave. The electrode area of the edge portion of the microstrip line of the substrate 41 is 500 μm × 500 μm, and the frequency is 76 GHz. The smaller the protruding amount of the outer wall 34, the larger the capacity and the larger the advance amount.

  The following describes the fourth embodiment of the present invention with reference to FIGS. 15 and 16. FIG.

  FIG. 15 is a perspective view showing the structure of a variable reactance device 51 according to the fourth embodiment of the present invention. It should be noted that the variable reactance device 51 uses an edge couple of the substrate 41 on which a microstrip line is formed. Specifically, triangular modulation wave-shaped irregularities 53 are repeatedly formed in the circumferential direction on the outer circumferential surface of the rotor 52, and the thickness direction of the substrate 41 corresponding to this is the circumference of the rotor 52. It faces the outer peripheral surface of the rotor 52 so as to be in the direction.

  Accordingly, the capacity increases when the protrusion approaches the open end of the microstrip line, and the capacity decreases when the recess approaches. FIG. 16 shows that the smaller the gap interval indicating the phase change with respect to the gap change when the dielectric constant ε of the substrate 41 is 3, the thickness of the substrate 41 is 0.2 mm, the gap width is 600 μm, and the frequency is 76 GHz. Therefore, the larger the capacitance, the larger the phase advance amount. For example, when the gap interval is 20 μm and 100 μm, the phase of the reflection coefficient of the modulation circuit changes by several tens of degrees, and frequency modulation can be applied. Yes.

  The fifth embodiment of the present invention will be described below with reference to FIGS.

  FIG. 17 is a perspective view showing the overall configuration of a radar apparatus 61 according to the fifth embodiment of the present invention. The radar device 61 is generally configured by mounting a VCO 63 on a RF (high frequency) circuit board 62 and a radar wave primary radiator 64. The rotors 2, 22, 32 and 52 of any of the variable reactance devices 1, 21, 31, and 51 constituting the VCO 63 are shared with the primary radiator 64. An opening 65a for radiating a radar wave is provided on a side surface of the primary radiator 64, and the primary radiator 64 is rotationally driven by a motor 66 to scan the emitted radar wave.

  FIG. 18 is a block diagram showing an electrical configuration of the radar apparatus 61 configured as described above. In this radar device 61, the resonance frequency of the resonator 67 of the VCO 63 is changed by the variable reactance devices 1, 21, 31, 51, and the resonance signal is taken out by the negative resistance circuit 68 and sent to the RF circuit board 62 as a modulation signal. input.

  In the RF circuit board 62, the modulation signal is branched by the coupler 71 and input to the circulator 69 and the mixer 70. The modulated signal input to the circulator 69 is radiated from an antenna 65 built in the primary radiator 64, and the signal received by the antenna 65 propagates to the mixer 70 through the circulator 69. In the mixer 70, the transmission (modulation) signal branched by the coupler 71 and the reception signal from the circulator 69 are mixed, and a beat signal is created and output.

  Thus, the radar device 61 can be configured using the VCO 63 which is an oscillator on which the variable reactance devices 1, 21, 31, 51 are mounted.

  Further, by sharing the rotors 2, 22, 32, and 52 with the primary radiator 64 that scans the radar wave, the configuration of the scanning radar apparatus can be simplified.

It is a schematic block diagram of the general VCO used for FM-CW radar. It is a perspective view which shows the structure of the variable reactance apparatus of 1st Example of this invention. It is a bottom view of the rotor in the variable reactance apparatus shown in FIG. It is a longitudinal cross-sectional view in the diameter line of FIG. It is a figure which shows the locus | trajectory of the protrusion of the said rotor on a board | substrate. It is an equivalent circuit diagram in case the said rotor is a conductor and a dielectric material. It is a graph which shows the change of the phase of a reflection coefficient at the time of changing the position of the said protruding item | line. It is a perspective view for demonstrating the positional relationship of 2 protruding ridges. It is a perspective view which shows the structure of the variable reactance apparatus of the 2nd Example of this invention. It is a perspective view which shows the structure of the variable reactance apparatus of the 3rd Example of this invention. It is a bottom view which shows the example of 1 structure of the rotor in the variable reactance apparatus shown in FIG. It is a perspective view which shows the other structural example of the rotor in the variable reactance apparatus shown in FIG. 12 is a graph showing a change in the phase of the reflection coefficient of the modulation circuit with respect to a change in the thickness of the outer wall of the rotor shown in FIG. 11, that is, the conductor width. 12 is a graph showing changes in the phase of the reflection coefficient of the modulation circuit with respect to changes in the height of the outer wall of the rotor shown in FIG. It is a perspective view which shows the structure of the variable reactance apparatus of the 4th Example of this invention. It is a graph which shows the change of the phase with respect to the change of the gap in the variable reactance apparatus shown in FIG. It is a perspective view which shows the whole structure of the radar apparatus of the 5th Example of this invention. It is a block diagram which shows the electrical structure of the radar apparatus shown in FIG.

Explanation of symbols

1, 21, 31, 51 Variable reactance device 2, 22, 32, 32a, 32b, 52 Rotor 11, 41 Substrate 3 Disk portion 4, 5 Convex 33, 34 Outer wall 53 Concavity 61 Radar device 62 RF (high frequency) Circuit board 63 VCO
64 Primary radiator 65 Antenna (primary radiator)
66 Motor 67 Resonator 68 Negative resistance circuit

Claims (13)

A transmission line;
A rotor arranged near the transmission line and having a shape that changes in the circumferential direction;
A variable reactance device characterized in that reactance as viewed from the transmission line side is changed by rotating the rotor.   The variable reactance device according to claim 1, wherein at least a portion of the rotor that faces the transmission line is conductive, and a capacitance is formed between the transmission line and the rotor.   3. The variable reactance device according to claim 2, wherein the rotor has a substantially ring-shaped protrusion meandering in the radial direction on the lower surface of the disk portion.   The transmission line is a coplanar line, and the capacitance is generated between a line conductor of the coplanar line and the rotor, and between a ground conductor of the coplanar line and the rotor. 3. The variable reactance device according to 3.   5. The variable reactance device according to claim 3, wherein the rotor is provided in a pair so as to sandwich the transmission line, and is driven to rotate in conjunction with each other.   3. The variable according to claim 2, wherein the rotor is formed by extending an outer wall from a lower surface of the disc portion, and a thickness of the outer wall is periodically changed in a circumferential direction. Reactance device.   3. The rotor according to claim 2, wherein an outer wall extends from the lower surface of the disk portion, and the height of the outer wall is periodically changed in the circumferential direction. Variable reactance device. The rotor is formed by repeatedly forming irregularities in the circumferential direction on the outer peripheral surface,
3. The variable reactance device according to claim 2, wherein the transmission line is a microstrip line, and the capacitance is generated between an open end of the microstrip line and an outer peripheral surface of the rotor. The rotor is formed of a dielectric material having a ring-shaped and ridged meander in the radial direction on the lower surface of the disk portion,
The variable reactance device according to claim 1, wherein the transmission line is a coplanar line.   2. The variable reactance according to claim 1, wherein the rotor is made of a dielectric, and the transmission line is made of a coplanar line, and the distance between the rotor and the transmission line is changed by rotation of the rotor. apparatus.   An oscillator comprising the variable reactance device according to any one of claims 1 to 10 and a resonator, wherein an oscillation frequency is changed by changing a reactance value of the variable reactance device.   A radar apparatus using the oscillator according to claim 11. 13. The radar apparatus according to claim 12, wherein the rotor includes a primary radiator, and the oscillation frequency of the oscillator is changed by the rotation of the rotor and the primary radiator is scanned. .

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