JP2005197782A - Antenna system and high frequency sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna system and high frequency sensor capable of obtaining a preset radiation direction (angle) and a preset radiation pattern of a radio wave while maintaining compactness. <P>SOLUTION: A Doppler sensor (1) is provided as the high frequency sensor. The Doppler sensor (1) is provided with: a board (11); and a plurality of laminar antennas (12) located on the front side of the board (11) and for playing at least either part of transmission and reception of a high frequency radio wave. The Doppler sensor (1) is furthermore provided with: at least one metallic member (14k1, 14k2, ...) provided to the board (11) so as to face at least one antenna among a plurality of antennas (12); a GND layer (14) provided to the board (11) so as to face a plurality of the antennas (12); and connection means (18, 17, 19) for electrically interconnecting the GND layer (14) and the metallic member (14k1, 14k2, ...) to establish electric continuity between them. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an antenna device that radiates high-frequency radio waves and obtains movement information and image information of an object from reflection information of the radio waves, and a high-frequency antenna using the antenna device, and in particular, movement having movement of a human body or the like. The present invention relates to an antenna device and a high-frequency sensor suitable as a Doppler sensor, which can detect body information.

  A Doppler sensor is known as an example of a high-frequency sensor that performs measurement and object detection using high-frequency radio waves. This Doppler sensor receives an oscillating unit that oscillates at a predetermined frequency, a transmitting antenna that transmits a high-frequency signal obtained by the oscillating unit as a radio wave, and a radio wave that is reflected back from the object to be measured. Connected to the receiving antenna, the mixer transmitting the radio wave transmitted from the antenna and the phase change of the received radio wave into a low frequency signal, the oscillating unit and the transmitting antenna, the oscillating unit and the mixer unit, and the receiving antenna and the mixer unit, respectively. The transmission line is configured so that these components are disposed on the same substrate. Further, by arranging a plurality of antennas at a predetermined interval, the required detection range and distance can be arbitrarily changed (see, for example, Patent Document 1).

  In recent years, it has been proposed that a Doppler sensor can be arranged on a wall surface or ceiling of a bathroom and used as a human body detection sensor (see, for example, Patent Document 2).

  Since such a Doppler sensor (high frequency sensor) uses a planar antenna, the sensor can be formed thin. For this reason, it is common to radiate radio waves in a direction orthogonal to the sensor substrate. In this case, however, depending on the position where the Doppler sensor is attached (for example, for the purpose of crime prevention, the wall surface or the back surface of the pottery), it may not be possible to attach the sensor in a posture perpendicular to the floor surface. In such a situation, even if you want to radiate radio waves parallel to the floor, you can't do that, or the target you want to detect not only moves along a direction almost perpendicular to the Doppler sensor board, but also on the Doppler sensor board. When moving along a direction other than a substantially vertical direction or when moving in a horizontal direction on the substrate of the Doppler sensor, it becomes difficult to reliably capture a target in such a moving direction. There was a problem that motion information could not be detected accurately.

  Therefore, in order to match the radiation direction of the radio wave with the direction of movement of the target, it is also necessary to incline in a specific direction along the movement direction. In order to realize the inclination of the radiation direction of the radio wave as described above, one method is to arrange a plurality of antennas on the substrate and to provide a phase difference to the high-frequency signal (that is, the radiated high-frequency radio wave) supplied to each antenna. The technique of giving is often used.

  One method of giving this phase difference is the simplest method by changing the length of the transmission line for supplying the high-frequency signal output from the oscillator to each antenna for each antenna. As another method, a phase difference is obtained by inserting a capacitive component (capacitor) in the middle of the transmission line to each antenna and utilizing a wavelength shortening effect based on the dielectric constant of the capacitive component. As an example of this shortening of the wavelength, when the frequency is 10 GHz, it is 30 mm / wavelength in the air, and in the case of alumina (when the dielectric constant is 10), it is 9.5 mm / wavelength. Therefore, in this case, when the line length is the same, the transmission time of alumina is about three times longer. Furthermore, as can be seen from Patent Document 3, a radar apparatus having a structure in which a phase shifter is inserted in a feeding path to each antenna is also known.

When the phase difference is given in this way, the direction in which the radio waves radiated from each antenna are emphasized and the direction in which they are canceled deviate from the radiation direction from a single antenna. Will tilt.
Japanese Patent Laid-Open No. 11-326505 (page 2-3, FIG. 1) Japanese Patent Laid-Open No. 2002-24958 (page 3-4, FIG. 4) Japanese Patent Laid-Open No. 7-128435 (page 3, FIGS. 1 and 3)

  However, among the methods for providing the phase difference described above, the method of changing the length of the transmission line for each antenna requires a sufficient area for the substrate for routing the transmission line, which increases the size of the substrate. The sensor itself is faced with the problem that it must be enlarged. On the other hand, in the method of inserting a capacitor in the middle of the transmission line to each antenna, in addition to the problem that the variation in the capacitance of the capacitor directly affects the variation in the inclination angle of the radio wave, the frequency is The higher the frequency, the higher the loss of high frequency, so that the set phase difference cannot be secured, which makes it difficult to accurately control the radiation direction of radio waves.

  The present invention has been made in order to solve the above-described problems, and is capable of obtaining preset radiation characteristics such as a radio wave radiation direction (angle) and a radiation pattern while maintaining the compactness of the sensor. An object of the present invention is to provide a high-frequency sensor.

  In order to achieve the first object described above, according to the antenna device of the present invention, a substrate and a layered antenna that is arranged on the surface of the substrate and that is responsible for at least one of transmission and reception of high-frequency radio waves, At least one metal member provided on the substrate so as to face at least one antenna of the plurality of antennas, a grounding member provided on the substrate so as to face the plurality of antennas, and the ground And connecting means for electrically connecting the member and the at least one metal member to each other.

  Moreover, a high frequency sensor provided with the antenna apparatus which has this structure is provided.

  According to the antenna device and the high-frequency sensor according to the present invention, the grounding member and at least one metal member are electrically connected by the connecting means, and therefore the antenna facing the connected metal member is interposed via the metal member. Electromagnetically coupled to ground potential. Thereby, the strength of the radio waves is generated between the radio waves radiated from the plurality of antennas, and the direction of the radio waves radiated from the entire high-frequency sensor is shifted from the direction orthogonal to the substrate. That is, the radio wave is radiated with an inclination from the direction orthogonal to the substrate without the on / off control of the power supplied to the antenna. For which direction the electric wave is tilted and what kind of radiation pattern the electric wave is to be used, which of the plurality of antennas formed on the substrate is supplied with a ground potential via a metal member (ie, connected) Which antenna the metal member is facing is connected to the ground member).

  Thereby, unlike the conventional phase control for the inclination of the radiated radio wave, there is no need to route the transmission line or insert a capacitor for the phase control, and thus the sensor can be miniaturized. Further, since the metal member facing the desired antenna may be fixedly connected to the grounding member via the connecting means, on / off control by a high frequency circuit using a high frequency switch element or the like is not required. . For this reason, it is possible to reliably prevent a decrease in the control accuracy of the radio wave radiation characteristics due to the instability of the high-frequency circuit, such as variations in the capacitance of the capacitors inserted in the transmission line, as in the prior art.

  Embodiments of a high-frequency sensor according to the present invention will be described below in detail with reference to the drawings. In addition, the thickness and pattern dimension of each layer differ from an actual shape on account of description.

  With reference to FIGS. 1-10, one Embodiment of the Doppler sensor as a high frequency sensor which concerns on this invention is described. This Doppler sensor has a function of emitting radio waves so as to scan a space to be detected.

  1 and 2, a Doppler sensor 1 according to the present embodiment includes sensor units 2a to 2p arranged in a matrix of, for example, 4 columns and 4 rows, formed on a substrate having electrical insulation.

  As will be described below, the sensor units 2a to 2p include a first unit group A composed of (radiated radio wave: on) type sensor units that are responsible for radiation of high-frequency radio waves when the Doppler sensor 1 is driven. The second unit group B is composed of sensor units of a type (radiation radio wave: off) that does not bear high-frequency radio wave radiation. Specifically, in the present embodiment, among the sensor units 2a to 2p according to the arrangement of 4 columns and 4 rows shown in FIG. On the other hand, the remaining sensor units 2a, 2b,..., 2j, 2m, and 2n constitute the first unit group A. Note that which sensor unit belongs to which unit group is not limited to this example, and can be selectively set before manufacturing.

  The structural difference between the sensor unit belonging to the first unit group A and that belonging to the second unit group B is whether or not the metal layer disposed opposite to the planar antenna is grounded.

  First, a structure common to both unit groups A and B will be described. Each of the sensor units 2a to 2p includes a planar antenna 12a (to 12p) disposed on the substrate 11, and an insulating layer 13 formed on the antenna 12a (to 12p). Further, as shown in FIG. 2, a GND (grounding) layer as a grounding member for grounding the metal layers 14a1, 14a2 (up to 14r1, 14r2) of each sensor unit 2a (up to 2p) is provided inside the substrate 11. 15 is formed. The back surface of the substrate 11 is covered with a cover 21.

  In the following description, the direction from the substrate 11 toward the insulating layer 13 in FIG. 2, that is, the direction along the radio wave radiation direction is referred to as “upward”, and the direction opposite to “upward” is referred to as “downward”. I will decide. Further, in this description, viewing the insulating layer 13 side from the substrate 11 side is referred to as “upward view”.

  The substrate 11 may be made of any material such as a ceramic material mainly composed of alumina, a fluorine-based material, or a glass epoxy material. However, when the frequency to be used is high or the required detection performance is high. It is desirable to use a ceramic material. The substrate 11 will be further described. In order to radiate radio waves to the outside as an antenna, it is better that the electromagnetic coupling with GND (ground) is weak, so that the thickness of the substrate is better. Generally, the thickness of the substrate, that is, the distance from the antenna-substrate interface to the GND antenna-side interface is preferably 0.5 to 1.5 mm, and more preferably 0.8 to 1.0 mm. Further, since loss increases as the thickness of the substrate increases, it is desirable to use a dielectric having a dielectric loss tangent (tan δ) of 0.001 or less, and the above-described materials can be suitably used.

  The thickness of the insulating layer 13 is, for example, 0.5 to 100 μm. As the thickness of the insulating layer 13 increases, the radiation intensity of the radio wave transmitted from the antenna 12 decreases. Therefore, the insulating layer 13 is preferably thin, and is preferably set to a thickness of 0.5 to 100 μm. In addition, when a fluororesin is used for the insulating layer, examples of the forming method include a manufacturing method such as spin coating, spray coating, and dipping. In order to maintain waterproofness, the thickness is 40 μm or more, and a decrease in radiation intensity is considered Then, 100 micrometers or less are preferable. When ceramic material is used, the ceramic pattern is sprayed directly on the substrate 11 to form the insulating layer 13, or the antenna pattern is screen-printed on the surface of the unsintered ceramic sheet to be the substrate 11, and the antenna surface is formed. There is a method of laminating an unsintered ceramic sheet to be the insulating layer 13 and then firing it, and sintering the substrate 11, the antenna 12 as the conductor layer, and the insulating layer 13. However, if it sets to the thickness of 0.5-50 micrometers, waterproofness will be acquired reliably and radiation intensity can be suppressed rather than a fluororesin. In particular, it is preferable to use a ceramic material having a low dielectric loss tangent and set the thickness to 1 to 10 μm in consideration of production efficiency (change in density due to variations during manufacturing) and simplification of antenna design.

  Each of the antennas 12a to 12r is formed as an integrated antenna for transmission and reception so as to serve also as a reception antenna. However, antennas that share functions for transmission and reception may be arranged for each function.

  In the case of the four sensor units 2k, 2l, 2o, and 2p constituting the second unit group B, the metal layers 14k1, 14k2 (˜14p1, 14p2) further formed on the insulating layer 13 described above are provided. . In this embodiment, as can be seen from FIG. 1, the sensor units 2a, 2b,..., 2j, 2m, and 2n constituting the first unit group A are not provided with a metal layer, but are manufactured. From the standpoint of improving the efficiency, the metal layer may be integrally formed in some cases. However, the metal layer in that case is only formed on the insulating layer 13 and is left so as not to be an element involved in electromagnetic waves transmitted and received by the antenna.

  Here, a structure peculiar to the four sensor units 2k, 2l, 2o, and 2p constituting the second unit group B will be described.

  The arrangement of the metal layers 14k1, 14k2 to 14p1, 14p2 in the laminated structure of each of the four sensor units 2k, 2l, 2o, 2p is a method of arranging along the entire opposite sides (see FIG. ))). Since this is a long explanation, it will be explained later.

  Further, transmission lines 17k (171, 17o, 17p) functioning as a part of connection means are formed on the back surface of the substrate 11. The above-described GND layer 15 is connected to the transmission line 17k (171, 17o, 17p) via an internal conductor 18k (181, 18o, 18p). Thereby, the GND layer 15 and each internal conductor 18k (18l, 18o, 18p) are electrically connected, and a ground potential is applied to the metal layers 14k1, 14k2, 14l1, 14l2, 14o1, 14o2, 14p1, 14p2. (Grounded).

  As shown in FIGS. 1 and 2, both end portions of the transmission lines 17k, 17l, 17o, and 17p are conductors 19k1 that are filled in two through holes that are formed through the substrate 11 in the thickness direction. , 19k2 (19l1, 19l2, 19o1, 19o2, 19p1, 19p2) are electrically connected to the metal layers 14k1, 14k2 (14l1, 14l2, 14o1, 14o2, 14p1, 14p2) located on the upper surface of the sensor. Yes. Therefore, as shown in FIG. 1, the conductors 19k1, 19k2 (19l1, 19l2, 19o1, 19o2, 19p2, 19p1, 19p2 in each of the pairs of metal layers 14k1, 14k2 (14l1, 14l2, 14o1, 14o2, 14p1, 14p2) ) (Grounding point) is present at the center of each of the two opposing sides of the antenna 12k (12l, 12o, 12p). As described above, the position of the central portion corresponds to ¼ of the wavelength λg transmitted on the substrate.

  As described above, the ground potential is applied to the metal layers 14k1, 14k2 (14l1, 14l2, 14o1, 14o2, 14p1, 14p2) of the four sensor units 2k, 2l, 2o, 2p belonging to the second unit group B (that is, Grounded). The four sensor units 2k, 2l, 2o, and 2p having the grounded metal layers 14k1, 14k2, 14l1, 14l2, 14o1, 14o2, 14p1, and 14p2 are supplied with the antenna 12k, The emission of radio waves from 12l, 12o, and 12p is stopped (radio emission is off). That is, as in the present embodiment, one or more arbitrary sensor units are designated from among a plurality of sensor units arranged in a matrix, and a metal layer is disposed substantially opposite to the antenna for each sensor unit. By providing a structure for grounding at the time of manufacture, radio wave radiation from a desired sensor unit among a plurality of sensor units constituting the Doppler sensor can be selectively controlled to be off.

  Although not shown in FIG. 1, on the back surface of the substrate 11, an oscillator 31 that outputs a high-frequency signal to drive the antenna 12 and a high-frequency signal of both the transmission radio wave and the reception radio wave are synthesized to obtain a phase difference between the signals. A mixer 32 for converting into a low frequency signal and a controller 33 for calculating information indicating the movement state of the target based on the low frequency signal are arranged (see FIG. 3). The whole is shielded by the cover 21.

  The controller 33 includes an interface 33A that performs processing such as amplification and A / D conversion, a calculation unit 33B that calculates target movement information, and an output control unit 33C that controls output of calculation results. The amplifying unit 33A amplifies the detection signal, converts it into digital data, and passes it to the arithmetic unit 33B. The computing unit 33B is configured to compute the movement information of the target that reflects the radiated radio wave based on the digitized detection data, that is, Doppler data. The output control unit 33 </ b> C passes the movement information calculated in this way to an output device 34 such as an LED display or a buzzer, and displays and / or outputs the movement information via the output device 34.

  In the present embodiment, the controller 33 is built in, but since the received signal is converted into a low frequency signal by the detection circuit, a structure in which the controller 33 is externally attached may be employed. .

  FIG. 3 is a block diagram illustrating the electrical connection relationship with respect to the sensor units 2a to 2p described above. The antennas 12a to 12p, which are integral antennas for transmission and reception of the sensor units 2a to 2p, are electrically connected to the oscillator 31 and the mixer 32, respectively. Among the sensor units 2a to 2p, the four sensor units 2k, 2l, 2o, and 2p of the metal layers 14k, 14l, 14o, and 14p belonging to the second unit group B are electrically connected to the ground member 15. The The oscillation signal of the oscillator 31 is also sent to the mixer 32 as a reference wave signal.

(Metal layer and its grounding structure)
4 to 7, the four sensor units 2k, 2l, 2o, and 2p constituting the second unit group B have their metal layers 14k1, 14k2, 14l1, 14l2, 14o1, 14o2, and 14p1. , 14p2 and its grounding structure. Here, the reference numerals attached to the members are simplified, and the antenna is simply described as 12, the metal layer as simply 14, the internal conductor as simply 18, the transmission line as simply 17, and the conductor as simply 19.

  In the above description, the metal layer (metal member) 14 of each sensor unit 2k (2l, 2o, 2p) is connected to the GND (ground) layer 15 (ground member) via each internal conductor 18, transmission line 17, and conductor 19. The metal layer 14 and its grounding structure are particularly important and will be described again here.

  The metal layer 14 is required to be disposed at a location where the electric field strength of each antenna 12 is high and to be connected to the GND layer 15 in such an arrangement state. Thereby, the radio wave radiated from each antenna 12 is more reliably blocked (the radiated radio wave is turned off).

  According to the present inventor, in order to realize this grounding structure, when described in the example of FIG. 2, when viewed in the direction Z perpendicular to the radio wave radiation surface of the sensor 1 (when the antenna 12 is viewed from above), It is important that the metal layer 14 is positioned so as to cover the antenna 12. This is because when the antenna 12 is used as in the example of FIG. 2, the electric field distribution is concentrated on the edge portion. In other words, it is not necessary to set the size of the metal layer (metal member) 14 so as to cover the entire surface of the antenna 12. The metal layer 14 may be disposed only so as to cover (overlapping) at least the edge portion of the antenna 12, and the metal layer 14 may be disposed on each of the two sides around the antenna 12 facing each other. A more reliable grounding effect can be obtained by installing it at a position corresponding to the central portion.

  Examples of this are shown in FIGS. Each of (a) to (c) in FIG. 2 shows a stacked structure of one sensor unit among the four sensor units 2k, 2l, 2o, and 2p belonging to the second unit group shown in FIG. A sectional structure taken along line A1-A1 'in the figure is shown in FIG.

  As shown in FIG. 4D, the substrate 11 is provided with metal layers 14 and 14, an insulating layer 13, an antenna 12, and an insulating layer in order from the top. An antenna 12 is disposed on the upper surface of the substrate 11 and is covered with an insulating layer 13. A GND (ground) layer 15 constituting a part of the grounding means is embedded in a middle position inside the substrate 11. The GND layer 15 is connected to a transmission line 17 provided on the lower surface of the substrate 11, and the transmission line 17 is connected to the metal layers 14 and 14 through conductors 19 and 19 provided in two through holes. Each is connected. In addition, the part which penetrates the conductors 19 and 19 of the antenna 12 is partly cut out in a rectangular shape so as to avoid the conductors 19 and 19. With this laminated structure, the metal layers 14 and 14 are electrically fixedly connected to the GND layer 15 and, as a result, are always grounded.

  The metal layers 14 and 14 shown in each of FIGS. 4A to 4C do not adopt a structure that covers the entire surface of the antenna 12, and the entire edge portions of two opposing sides of the antenna 12 or It is formed to cover only a part. Of course, the metal layer 14 may be a single layered body covering the entire antenna 13, but as described above, the electric field distribution is concentrated on the edge portion of the antenna 12. Thus, it has a divided structure in which only two sides are arranged. The metal layers 14 and 14 shown in FIG. 4A are laminated so as to cover the entire edge portions of the two opposite sides of the antenna 12. Moreover, the metal layers 14 and 14 shown in FIG. 4B are laminated so as to partially cover the edge portions of the two opposing sides of the antenna 12. Further, the metal layers 14 and 14 shown in FIG. 4C are laminated so as to cover only the central portions of the two opposite sides of the antenna 13 in a spot manner.

  However, any one of the metal layers 14 and 14 shown in FIGS. 4A to 4C is formed so as to overlap (cover) the antenna 12 in a direction (Y-axis direction) perpendicular to each of the opposing sides. Yes. At this time, the amount D of the metal layer 14 protruding from the antenna 13 is preferably at least 0.1 mm in design.

  If there is no overlap described above, even if the metal layer 14 is grounded, the radio wave radiated from the antenna 13 cannot be turned off (radio wave radiation blocking). This has been confirmed by the present inventors. Thus, in the case where there is no overlap (covered portion) (FIGS. 6A and 6B), and even when there is an overlap, the antenna 12 is formed by extending the pattern integrally from the metal layer 14 to the outside. An example in which the metal layer 14 and the GND layer 15 are connected to each other outside (FIG. 6C), that is, an example in which the radiated radio wave cannot be turned off is shown in FIGS. In these drawings, sectional views taken along line B1-B1 'of the plan view shown in the upper part are shown in the lower part, respectively.

  Returning to FIG. 4, the positions of the ground points (that is, the positions of the conductors 19, 19) that connect the metal layers 14, 14 to the GND layer 15 are on the opposing sides that overlap the metal layers 14 of the antenna 12. It is desirable that the center position is in the direction along the direction (X-axis direction). In general, the length L in the direction along the opposite side of the antenna 13 (X-axis direction) is λ / (2√ (εr)) where the wavelength λ of the transmission radio wave and the dielectric constant εr of the substrate. This is because the center position corresponds to λ / (4 (εr)) having the highest amplitude, and grounding at this high amplitude position is particularly effective for grounding.

  By determining the grounding point in this way, it has been verified that the metal layers 14 and 14 can be grounded more reliably against high-frequency radio waves, and therefore radiation of radio waves can be more reliably blocked.

  It has also been verified that the grounding performance does not deteriorate even when the antenna 13 is formed with a cut portion that avoids the conductors 19 and 19.

  Various examples other than the structure shown in FIG. 4 that satisfy the requirements for the arrangement of the metal layer and the position of the grounding point described above are shown in 5 (a) to (f). The arrangement angle and shape of the antenna 13 can be variously set, and the entire periphery of the antenna 13 may be covered with a metal layer or may be partially covered. 4 and 5, the symbol SP indicates a feeding point for the antenna 13.

(Function and effect)
Next, the function and effect of the Doppler sensor 1 according to this embodiment will be described.

  In the Doppler sensor 1, the antennas 12 of the sensor units 2a to 2p are excited by the high-frequency pulse always output from the oscillator 31. In response to this excitation, an electromagnetic field is generated between the antenna 12 and the GND layer 15, whereby radio waves are radiated from each antenna 12.

  However, in the case of this embodiment, among the sensor units 2a to 2p in the matrix arrangement of the whole sensor, four sensor units 2k, 2l, 2o, 2p belonging to the second unit group B located at the right corner in FIG. In this case, the metal layers 14 are connected to the GND layer 15 in advance. For this reason, the potential of the metal layers 14 and 14 becomes the same potential as GND (grounded), the electromagnetic field coupling between the antenna 12 and the metal layers 14 and 14 is strengthened, and electromagnetic field lines leaking to the outside. That is, the emission of radio waves to the space is greatly limited. That is, the radio wave radiation from the four sensor units 2k, 2l, 2o, and 2p is substantially cut off while the power is supplied to these units, and the radio wave radiation is turned off. (See the shaded area in FIG. 7A). On the other hand, the sensor units 2a, 2b,..., 2j, 2m, 2n belonging to the remaining first unit group A can radiate radio waves because they do not have the above-described ground structure with the metal layer (radio wave Radiation: ON).

  Of all the sensor units 2a to 2p, as described above, some of the sensor units are grounded so that the substantial radio wave radiation is turned off, so that radio waves radiated from the entire Doppler sensor 1 (from each sensor unit). The radiation pattern and radiation angle of the synthesized radio wave) can be controlled.

  For example, as shown in FIG. 7A, when radiation waves from the four sensor units 2k, 2l, 2o, and 2p at the right corner are substantially turned off, the radiation pattern of the synthesized radio wave has a predetermined directivity width. And the remaining sensor unit 2a in which the center direction (radiation direction) in which the intensity of the combined radio wave is strongest is radio wave radiation: on (that is, the on / off switch is turned off and the metal layer is not grounded) 2b,..., 2j, 2m, and 2n are inclined by an angle on the side of the first unit group A (the white unit in FIG. 7A).

  FIG. 8 and FIG. 9 explain the qualitative relationship between the number of sensor units that substantially turn off the emission of radio waves and the emission pattern (directivity width) of radio waves emitted from the entire sensor. When the number of sensor units (indicated by hatching in the figure) that substantially turn off the radiation state of the radio wave is reduced as the process proceeds from the state N1 to N4 in FIG. As shown, the directivity width is reduced. In FIG. 9, the horizontal axis indicates the directivity width, and the vertical axis indicates the radiation intensity.

  In general, the absolute gain Ga of an antenna is represented by the following equation, where A is an antenna effective area and λ is a wavelength of a radio wave transmitted from the antenna. The antenna effective area increases as the number of antennas to be transmitted increases. The radiant intensity of the radiated radio wave increases.

[Equation 1]
Ga = A × 4π / (λ × λ)

  Further, there is a relationship of the following equation between the absolute gain Ga of the antenna and the directivity gain Gd, and the absolute gain of the antenna with negligible loss is equal to the directivity gain (gain with respect to the omnidirectional antenna). Determined by shape (directivity angle).

[Equation 2]
Ga = ηrad × Gd

  Therefore, when the area of the antenna emitting radio waves is N4> N3> N2> N1 as shown in FIG. 8, the radiation intensity decreases in the order of N4, N3, N2, and N1, as shown in FIG. Thus, the directivity width, that is, the directivity angle is widened. In addition, when there is a sensor unit that substantially turns off radio wave radiation, the radio wave radiation direction (angle) deviates from the direction perpendicular to the substrate, and the radio wave radiation state (supply of ground potential to the metal layer) : Tilt obliquely toward the sensor unit in the off state. It has been found that the degree of inclination is determined in relation to the number and position of sensor units in a radio wave emission state and sensor units in a radio wave non-radiation state.

  For this reason, depending on the condition that a desired radiation pattern (directivity width) and radiation angle are required, the radio wave from how many sensor units in which part of the entire sensor unit A decision can be made as to whether radiation should be substantially turned off. When this condition is determined, for example, at the manufacturing stage, as described above, for example, the sensor units 2k, 2l, 2o, and 2p are grounded.

  In addition, by setting the second unit group B to a unit position other than the above-described FIG. 7A, radiation directions other than those described above can be obtained. For example, in FIG. 7, in addition to FIG. 7A, the four sensor units 2j, 2k, 2n, and 2o in the central part adjacent to the center can be substantially set to radio wave radiation: off (see FIG. 7B). ). Further, the four sensor units 2i, 2j, 2m, and 2n adjacent to the left end adjacent thereto can be substantially set to radio wave radiation: off (see FIG. 7C). Further, the other four sensor units 2g, 2h, 2k, and 21 may be set to substantially turn off radio wave radiation (see FIG. 7D). In the same manner, the second unit group B of sensor units that are substantially radio-wave radiated: off can be disposed at appropriate positions (see FIGS. 7E to 7I).

  The arrows AR1 to AR9 shown in FIGS. 7A to 7I schematically indicate that the direction of the radiated radio wave is inclined in different directions by setting the second unit group B to be in different positions. Is shown. When the arrangement of the sensor units shown in FIGS. 7A to 7I is compared to the east, west, south, and north directions, the direction of radio wave emission from the Doppler sensor 1 is the oblique northwest direction in the position state of FIG. In the position state of FIG. (B), the direction is diagonally north, in the position state of FIG. (C), the direction is diagonally northeast, in the position state of (D), the direction is diagonally westward, and so on. .

  As described above, radio waves (synthetic radio waves) radiated in a predetermined oblique direction with a predetermined radiation pattern (directivity width) from the Doppler sensor 1 are reflected on various objects including the target, and the reflected waves (high frequency radio waves) are reflected. Arise. Of this reflected wave, the component reflected in the direction of the Doppler sensor 1 returns to the Doppler sensor 1 and reaches the antennas 2a to 2p. At this time, the sensor units 2k, 2l, 2o, and 2p (with the metal layer grounded) belonging to the second unit group B are not involved in the generation of the reception signal, and are not connected to the remaining first unit group A. Received signals are generated by the sensor units 2a, 2b,..., 2j, 2m, 2n to which they belong.

  Therefore, the mixer 32 uses the received signals and reference wave signals from the sensor units 2a, 2b,..., 2j, 2m, 2n to transmit the transmitted high-frequency signal (radiated radio wave) and the received high-frequency signal (received radio wave). And a low frequency detection signal corresponding to the phase difference is generated. This detection signal is sent to the controller 33. In the controller 33, the detection signal is amplified and converted into digital data by the amplifying unit 33A and sent to the arithmetic unit 33B. The calculation unit 33B calculates the movement information of the target reflecting the radiated radio wave based on the digitized detection data, that is, Doppler data. The calculated movement information is sent to the output unit 34 by the output control unit 33C and output as a display or sound.

  The Doppler sensor 1 according to the present embodiment is configured and functions as described above. For this reason, when the radiated radio wave is tilted with respect to the radio wave radiation surface of the Doppler sensor 1 and the radiated radio wave is tilted in a certain direction along the radiation angle other than the front surface of the sensor, the phase difference between the driving high frequency signals supplied to the plurality of antennas Therefore, it is not necessary to adopt a method that has been used in the past. That is, it is not necessary to change the length of the transmission line connected to each antenna, and it is not necessary to insert a capacitor in the middle of the transmission line. It is only necessary to form a layered metal member that hardly affects the size increase of the Doppler sensor 1 only in a desired sensor unit and to ground this metal member. For this reason, it is not necessary to increase the size of the substrate so much. Therefore, the Doppler sensor 1 can also be prevented from being enlarged in size. Further, unlike the capacitor, the variation in the capacitance does not make the angle control of the radiated radio wave unstable, and the high frequency loss is small, so that the radio wave radiation direction can be controlled with high accuracy.

  As described above, since high-frequency radio waves can be reliably radiated in a desired oblique direction other than the front surface of the sensor, the reflected signal moves along a direction other than a direction substantially perpendicular to the substrate 11 (radiation surface) of the Doppler sensor 1. Or movement information of the target that moves in a direction horizontal to the substrate 11 can be accurately detected. As a result, since the scan range of the Doppler sensor 1 can be expanded to a wide range other than the front surface, the Doppler sensor 1 having a desired scan direction (radiation direction of radio waves) can be used. For example, when the surface of the wall to be attached is inclined in a certain direction, by using the Doppler sensor 1 that emits radio waves in an oblique direction that cancels the inclination, the target that moves in the original front direction is surely thinned. Can do. Thereby, there is no restriction on the mounting position of the sensor, and it is possible to provide a sensing device using high-frequency radio waves that is very versatile and easy to use.

  Furthermore, in the case of the Doppler sensor 1 according to the present embodiment, the radiation state of radio waves can be set in each sensor unit without turning on / off the power supplied to the transmitting antenna 12. In other words, the characteristics (radiation pattern and radiation direction) of the radiated radio wave can be easily controlled by using a DC circuit responsible for supplying or not supplying the ground potential to the metal layer 14 without controlling the high frequency circuit. it can.

  The positional relationship among the transmission antenna 12, the metal layer 14, and the GND layer 15 is not necessarily limited to the configuration in which the transmission antenna 12 is disposed on the radio wave radiation surface side of the substrate 11, as shown in FIG. That is, in the high-frequency sensor of the present invention, the on / off operation in the radio wave radiation state is caused by the electromagnetic field coupling degree between the metal layer 14 and the transmission antenna 12, so that the configuration of FIGS. On the other hand, the metal layer 14 may be disposed inside the substrate 11 or on the back surface side opposite to the radio wave radiation surface of the substrate 11, and in combination with examples of positions that the GND layer 15 can take, Positional relationship can be taken. Some of these modifications are shown in FIGS.

  Note that two or more cases representing a plurality of sensor units will be described, and there are some differences in the structure, but the above-described FIG. , 10 used in the description.

<First Modification>
FIGS. 11A and 11B show a Doppler sensor 1 as a high-frequency sensor according to a first modification. The Doppler sensor 1 is provided with means for substantially turning off radio wave radiation only for some of the sensor units 2a and 2b. FIG. 2B schematically shows a cross-sectional structure along the line EE ′ of FIG.

  As can be seen from the figure, a single metal layer (metal member) 14 is disposed only on the upper surface of the insulating layer 13 for the sensor unit 2 b, and this metal layer 14 is connected to the substrate 11 via conductors 19 and 19. Is connected to the GND layer 15 disposed on the back surface of the substrate. For this reason, the metal layer 14 is always grounded. As a result, the radio wave radiation from the sensor unit 2b can be substantially always turned off. As a result, the radiation pattern and radiation direction of the radio wave radiated from the Doppler sensor 1 can be set to a predetermined pattern and direction. The radiation direction is an oblique direction inclined to the side of the other sensor unit 2a not having the structure of radiated radio wave: off.

<Second Modification>
12A and 12B show a Doppler sensor 1 as a high-frequency sensor according to a second modification. As in the first modification, the Doppler sensor 1 is provided with means for substantially turning off radio wave radiation only for a part of the sensor units 2a and 2b. is there. FIG. 2B schematically shows a cross-sectional structure along the line AX-AX ′ in FIG.

  As can be seen from the figure, only for the sensor unit 2b, a single metal layer (metal member) 14 is arranged inside the insulating layer 13 so that the corresponding antenna 12b is viewed from above, and this metal layer 14 The conductor 18 is connected to the GND layer 15 disposed on the back surface of the substrate 11. For this reason, the metal layer 14 is always grounded. As a result, the radio wave radiation from the sensor unit 2b can be substantially always turned off, and the same effect as that of the first modification can be exhibited.

<Third Modification>
FIGS. 13A and 13B show a Doppler sensor 1 as a high-frequency sensor according to a third modification. As in the first and second modifications, the Doppler sensor 1 is provided with means for substantially turning off radio wave radiation only for some of the sensor units 2a and 2b. It is a thing. FIG. 2B schematically shows a cross-sectional structure along the line AY-AY ′ in FIG.

  The difference from the second modification is that the positional relationship between the metal layer 14 and the GND layer 15 is opposite. That is, the GND layer 15 is embedded in the substrate 11, while the metal layer 14 is disposed on the back surface of the substrate 11. Also by this, the metal layer 14 is always grounded. As a result, the radio wave radiation from the sensor unit 2b can be substantially always turned off, and the same effect as the first and second modifications can be exhibited. Can do.

<Fourth Modification>
14A to 14C show a Doppler sensor 1 as a high-frequency sensor according to a fourth modification. This Doppler sensor 1 is provided with means for substantially turning off radio wave emission only for a part of the sensor units 2b among the plurality of sensor units 2a and 2b, as in the above-described modifications. is there. FIG. 5B is a schematic cross-sectional structure taken along line CC ′ of FIG. 6A, and FIG. 5C is a schematic cross-sectional structure taken along line DD ′ of FIG. It shows. The main difference from the laminated structure of the first modification is that the metal layer 14 is provided in the substrate 11 at a position below the GND layer 15 where the antenna 12 of one sensor unit 2b is viewed. That is. The metal layer 14 is connected to the GND layer 15 through the internal conductor 18a, the transmission line 17, and the internal conductor 18b. This also makes it possible to exhibit the same operation as that of each of the modified examples described above.

<Fifth Modification>
FIGS. 15A and 15B show a Doppler sensor 1 as a high-frequency sensor according to a fifth modification. This Doppler sensor 1 is provided with means for substantially turning off radio wave emission only for a part of the sensor units 2b among the plurality of sensor units 2a and 2b, as in the above-described modifications. is there. FIG. 2B schematically shows a cross-sectional structure along the line CC ′ of FIG. The main difference from the laminated structure of the fourth modified example is that the metal layer 14 is provided in the substrate 11 at a position above the GND layer 15 where the antenna 12 of one sensor unit 2b is viewed. That is. The metal layer 14 is connected to the GND layer 15 through the internal conductor 18a, the transmission line 17, and the internal conductor 18b. This also makes it possible to exhibit the same operation as that of each of the modified examples described above.

<Sixth Modification>
16A to 16C show a Doppler sensor 1 as a high-frequency sensor according to a sixth modification. The Doppler sensor 1 is provided with means for substantially turning off radio wave radiation for two sensor units 2a, 2b among the three or more sensor units 2a, 2b,..., 2n. FIG. 5B is a schematic cross-sectional structure taken along line GG ′ of FIG. 6A, and FIG. 5C is a schematic cross-sectional structure taken along line H-H ′ of FIG. It shows. The main difference from the laminated structure according to the fifth modification is that the metal layers 14a and 14b are provided at positions where the antennas 12a and 12b of both sensor units 2a and 2b are respectively viewed from above. The metal layers 14a and 14b are connected to the GND layer 15 through the internal conductors 18a and 18b, the transmission line 17, and another internal conductor 18c. Also by this, the same operation as the first to fifth modifications described above can be exhibited.

  Further, the metal members 14a and 14b are formed so that the metal members 14a and 14b have different sizes relative to the antenna surface when the antennas (integrated antennas) 12a and 12b are viewed from above. As a result, although the thickness is controlled by the thickness of the ceramic (member) in manufacturing, it cannot be finely controlled. However, since the pattern area has a large degree of design freedom, the electromagnetic coupling state between the antenna and GND is fine. Since it can be set, it is possible to obtain a further effect that the direction of the radio wave can be set according to a request.

<Seventh Modification>
17A and 17B show a Doppler sensor 1 as a high-frequency sensor according to a seventh modification. This Doppler sensor 1 substantially turns off radio wave radiation for two sensor units 2a, 2b out of three or more sensor units 2a, 2b,. Means are provided. FIG. 4B schematically shows a cross-sectional structure along the line JJ ′ of FIG. The main difference from the laminated structure according to the sixth modification is that the metal members 14a and 14b are provided at different positions in the thickness direction inside the substrate 11. Also by this, the same operation as the first to sixth modifications described above can be exhibited.

  In particular, the position in the substrate thickness direction of the other metal member 14b is deeper than the one metal member 14a by the distance d. As a result, it is possible to obtain further operational effects such as increasing the degree of freedom in designing the degree of inclination of radio waves.

  In general, as the dielectric constant εr of the substrate increases, the electromagnetic coupling between the antenna and GND becomes stronger. Therefore, the larger the dielectric constant of the substrate, the more prominent the effects related to the design of the above-described inclination of the radio wave. For this reason, since the dielectric constant of a ceramic substrate is generally larger than that of a resin substrate, it is preferable to use a ceramic material for the substrate. The advantage of using this ceramic material for the substrate is also true for the second and fifth modifications described above.

  In each of the above-described modifications, the structure of the grounding position of the metal layer is not particularly mentioned, but the structure of any one of the grounding positions described with reference to FIGS. It is what is done.

  In the case where a metal layer is also provided in a sensor unit that does not substantially turn off radiated radio waves (that is, in the case of a sensor unit that does not apply a ground potential to the metal layer), the metal layer 14 is used as a part of the antenna. In order to work, it is desirable to form the metal layer smaller than the antenna.

  Furthermore, the present invention can be implemented when the number of sensor units that substantially turn off radio wave radiation is smaller than the total number of sensor units that constitute the high-frequency sensor.

  Further, in the high-frequency sensor according to the above-described embodiment and its modification, as shown in FIGS. 1 to 3, the stacked body in which the sensor units 2 a to 2 p are formed, the oscillator 31, the mixer 32, and the controller 33 are integrally formed. However, the high-frequency sensor according to the present invention is not necessarily limited to this structure. For example, at least a part of these components and the remaining components may be formed separately from each other so that electrical signals can be transmitted and received.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment or embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in various aspects. It is. In the present embodiment, the antenna shape is described as a quadrangle. However, the shape may be a rhombus or a circle, and various forms such as a similar effect can be considered.

  Furthermore, in the present embodiment, the substrate shape is described as a flat plate shape, but the shape may be a curved surface or a cylindrical shape. And the shape of the antenna arrange | positioned through the smooth layer on the surface of a base material should just be made into a curved-surface shape or a cylindrical shape according to the shape of a base material.

The top view which shows schematic structure of one Embodiment of the Doppler sensor as a high frequency sensor which concerns on this invention. The schematic sectional drawing in alignment with the B1-B1 'line of the Doppler sensor shown in FIG. The block diagram which shows the electric constitution of the Doppler sensor of 1st Embodiment. The figure explaining the suitable aspect of the grounding structure of a metal layer (metal member). The figure explaining the suitable example of the grounding structure of a metal layer (metal member). The figure explaining the example unsuitable as a grounding structure of a metal layer (metal member) for reference. The figure explaining the concept of control of the radiation direction of the electromagnetic wave using the Doppler sensor which concerns on embodiment. The figure explaining the state which set the sensor unit to OFF in various modes (antenna area). The figure explaining the radiation pattern qualitatively according to various aspects of the antenna area shown in FIG. The figure which illustrates typically the state of the electromagnetic wave radiated | emitted from the electric wave radiation surface of a Doppler sensor. The figure which illustrates typically the 1st modification of the laminated structure of a board | substrate, a planar antenna, a metal layer (metal member), and a GND layer which can be implemented as a Doppler sensor. The figure which illustrates typically the 2nd modification of the laminated structure mentioned above which can be implemented as a Doppler sensor. The figure which illustrates typically the 3rd modification of the laminated structure mentioned above which can be implemented as a Doppler sensor. The figure which illustrates typically the 4th modification of the laminated structure mentioned above which can be implemented as a Doppler sensor. The figure which illustrates typically the 5th modification of the laminated structure mentioned above which can be implemented as a Doppler sensor. The figure which illustrates typically the 6th modification of the laminated structure mentioned above which can be implemented as a Doppler sensor. The figure explaining typically the 7th modification of the laminated structure mentioned above which can be implemented as a Doppler sensor.

Explanation of symbols

1 Doppler sensors 2a, 2b,... 2n as high-frequency sensors Sensor unit 11 Insulating substrate 12, 12a, 12b Antenna (integrated antenna)
13 Insulating layers 14, 14a, 14b, 14a1, 14a2, ... 14p1, 14p2 Metal layer (metal member)
15 GND (grounding) layer (grounding member)
18, 18a, 18b, 18c, 19 conductor (connection means)
17 Transmission line (connection means)
31 Oscillator 32 Mixer 33 Controller

Claims (7)

A substrate,
A plurality of layered antennas disposed on the surface of the substrate, and responsible for at least one of transmission and reception of high-frequency radio waves,
At least one metal member provided on the substrate so as to face at least one of the plurality of antennas;
A grounding member provided on the substrate so as to face the plurality of antennas;
An antenna device comprising: a connecting means for electrically connecting and grounding the ground member and the at least one metal member. The antenna device according to claim 1, wherein the at least one metal member is disposed via another insulating layer from the substrate so as to be positioned on a radio wave radiation side of the antenna. The antenna device according to claim 1, wherein the at least one metal member is disposed on the substrate on a side opposite to a radio wave radiation side of the antenna. The antenna device according to claim 3, wherein the at least one metal member is disposed at a position between the antenna and the ground member of the substrate. The at least one metal member includes a member disposed on the antenna via another insulating layer, and a member disposed at a position of the substrate between the antenna and the ground member. The antenna device according to claim 1. The at least one metal member is composed of a plurality of metal members, and at least one of the plurality of metal members is compared with other metal members from the antenna-side interface of the metal member. The antenna device according to claim 1, wherein the distance to the interface on the metal member side is different. The antenna device according to any one of claims 1 to 6,
An oscillating means connected to each of the plurality of antennas of the antenna device and supplying a high-frequency drive signal to each of the antennas to emit radio waves from the antennas;
A high-frequency sensor, comprising: a detecting unit that is connected to each of the plurality of antennas and receives and detects a high-frequency reception signal received by each of the antennas.

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