JP2007104027A - Microstrip antenna and high-frequency sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact microstrip antenna having narrow directivity which is used for switching the direction of radio wave beam. <P>SOLUTION: In the microstrip antenna, a plurality of antenna electrodes 2, 3 and a power feeding line for feeding a high-frequency signal are arranged on the front surface of a substrate 1, and a ground electrode 4 for providing a ground level is provided on the other surface of the substrate 1. In this antenna, switches 9 for opening and closing connection between the antenna electrodes 2, 3 and the ground electrode 4 via through holes 5 (connection members), arranged on predetermined portions 2A, 3A, are connected to the antenna electrodes 2, 3. By operating any one of the switches 9, the direction of the radio wave beam can be switched. An integrated radio wave beam emitted from the antenna electrodes 2, 3 is narrowed by a dielectric lens 34, arranged so as to cover the surfaces of the antenna electrodes 2, 3, and thus the radio beam can be radiated in a narrow range and a radiation distance can be extended. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microstrip antenna that radiates microwaves or higher-frequency radio waves, and more particularly to a technique for controlling the direction of an integrated radio wave beam radiated from a plurality of microstrip antennas. The present invention also relates to a high-frequency sensor using a microstrip antenna.

  Conventionally, an antenna electrode and a ground electrode are disposed on the front and back surfaces of a substrate, respectively, and a microwave high-frequency signal is applied between the antenna electrode and the ground electrode to radiate radio waves vertically from the antenna electrode. A strip antenna is known. As techniques for arraying the microstrip antennas and controlling the directing direction of an integrated radio wave beam radiated from a plurality of microstrip antennas, the following is known. For example, in Patent Document 1, a plurality of antenna electrodes are arranged on a surface of a substrate, and a high-frequency switch is switched to change the length of a high-frequency signal feed line to each antenna electrode. Change the direction of the radio beam. That is, by changing the lengths of the feed lines to the plurality of antenna electrodes, a phase difference is generated between the radio waves radiated from the plurality of antenna electrodes, and the integrated radio beam is directed toward the antenna having a delayed phase. Tilt the pointing direction. Further, for example, the one described in Patent Document 2 is configured by arranging a plurality of antenna electrodes having different directions of integrated radio wave beams and switching antenna electrodes to which a high-frequency signal is applied by a high-frequency switch. Change the direction of direct radio beam.

  An object detection device using radio waves radiated from a microstrip antenna is known. In this object detection device, by changing the direction of the integrated radio wave beam from the microstrip antenna as described above, compared to the case where the direction of the integrated radio beam is fixed, The position and state of the object can be detected more accurately. For example, by changing the directivity direction of the integrated radio wave beam radiated from the microstrip antenna to the XY direction and scanning the two-dimensional range, it is possible to grasp the presence and state of an object over the two-dimensional range. Applications of the object detection device are diverse, such as target detection in an automatic tracking missile and user detection in a toilet device. In any application, it is very useful to be able to change the direction of the integrated radio wave beam radiated from the microstrip antenna. For example, in the case of a user detection device in a toilet device, if the position and state of the user are detected more accurately, a toilet cleaning device, a deodorizing device, and the like can be controlled more appropriately. By the way, the camera may be more suitable for the purpose of accurately grasping the state of the user, but it is difficult to use the camera in the toilet device. Therefore, it is very important for an object detection device using radio waves to control the direction of the integrated radio wave beam so that the user can be more accurately grasped. Incidentally, in Japan, a frequency of 10.525 GHz or 24.15 GHz can be used for the purpose of detecting a human body, and a frequency of 76 GHz can be used for the purpose of preventing a vehicle collision.

JP 7-128435 A JP-A-9-214238

  According to the conventional techniques disclosed in Patent Document 1 and Patent Document 2, it is necessary to switch the feed line that propagates the high-frequency signal by switching in order to change the direction of the integrated radio wave beam. For this purpose, it is necessary to use a high-frequency switch having a low transmission loss and having an impedance to a high-frequency signal of a specific frequency to be used adjusted to a predetermined appropriate value and connected to an appropriate position. However, as the frequency increases, the characteristics of the feed line and the high-frequency switch and variations in the connection state (for example, variations in the dielectric constant of the substrate, the performance of the high-frequency switch, the etching accuracy of the feed line pattern, the mounting position of the switch, etc.) The performance is greatly affected. If the connection is poor, the amount of reflection of the high-frequency signal increases at the connection part of the high-frequency switch, the amount of power supplied to the antenna through the high-frequency switch decreases, or the amount of phase changes so The beam cannot be emitted. In addition, a high-frequency switch with low transmission loss is quite expensive. In particular, a large number of high-frequency switches are required when the direction of the integrated radio wave beam is changed continuously or in multiple stages. However, it is not practical to use many expensive parts for applications such as a user detection device in a toilet device.

  Accordingly, it is an object of the present invention to provide a microstrip antenna that switches the directivity direction of a narrow radio wave beam with a compact directivity.

The microstrip antenna of the present invention includes an insulating substrate, a plurality of antenna electrodes disposed on one surface of the substrate, each having a feeding point for applying a high frequency signal, and disposed on the other surface or inside the substrate. A ground electrode for providing a ground level, and at least one antenna electrode of the plurality of antenna electrodes is disposed in at least one place different from the feeding point for connecting to the ground electrode. A connecting member, a switch connected to an end of the connecting member and opening / closing a connection between at least one antenna electrode of the plurality of antenna electrodes and the ground electrode, and covering a surface of the antenna electrode And a dielectric lens made of a dielectric material. The connection member is disposed at a location that falls within a planar area occupied by the at least one antenna electrode when the at least one antenna electrode is viewed in plan, and the antenna electrode and the ground electrode are connected at that location. .
According to this microstrip antenna, when at least one antenna electrode among a plurality of antenna electrodes is connected to the ground electrode by a switch operation, the phase of the radio wave beam radiated from the antenna electrode connected to the ground electrode, and the other Since the phase of the radio wave beam radiated from the antenna electrode not connected to the ground electrode is shifted, it is possible to switch the directivity direction of the integrated radio wave beam radiated from the plurality of antenna electrodes. Then, the integrated radio wave beam radiated from the antenna electrode can be narrowed by the dielectric lens arranged in front of the antenna electrode, and the radio wave beam can be radiated to a narrow range, thereby extending the radiation distance. In addition, since there is no need to connect a high-frequency switch to an intermediate path of a feed line that propagates high-frequency signals to a plurality of antenna electrodes, transmission loss of high-frequency signals propagated to the antenna electrodes is small and the efficiency is excellent. In addition, as the performance required for the switch, it is only necessary that the isolation (characteristic for blocking a high-frequency wave signal of a specific frequency) is good, and it is not necessary to have a characteristic for allowing a high-frequency signal to pass well. Since it is not necessary to have an appropriate input impedance, an expensive high-frequency switch is unnecessary.

  In a preferred embodiment, the connection member is a conductive through-hole penetrating a portion of the substrate corresponding to one portion of at least one antenna electrode of the plurality of antenna electrodes, and the plurality of antennas One end of one of the electrodes connected to one antenna electrode and the other end connected to the switch that opens and closes the connection between the ground electrode, and is easily connected to each other for manufacturing. There is little variation.

  In a preferred embodiment, the switch is disposed at a connection location between the connection member and the ground electrode. Since the switch arranged in this way is hidden behind the antenna electrode, it does not adversely affect the radio wave radiation characteristics.

  In a preferred embodiment, the dielectric lens is preferably formed of a material having a relatively low relative dielectric constant, such as polyethylene, nylon, polypropylene, or a fluorine resin material. When flame resistance or chemical resistance is desired, for example, nylon or polypropylene is preferable, and when heat resistance and water resistance are also desired, for example, PPS (Polyphenylene Sulfide) resin is preferable. In order to reduce the size and thickness of the dielectric lens 602, a ceramic material such as alumina or zirconia having a relatively high dielectric constant is used for the dielectric lens body, and reflection in the dielectric lens is suppressed. In addition, the surface of the dielectric lens may be covered with the material having a relatively low relative dielectric constant.

  A microstrip antenna according to an embodiment includes a substantially flat first circuit unit having a control circuit for controlling a switch, and a substantially flat plate having a high frequency oscillation circuit for generating a high frequency signal to be applied to an antenna electrode. And a second circuit unit having a shape, and the first and second circuit units are integrally coupled in a stacked manner on the back surface of the substrate. The back surface of the substrate here refers to the substrate surface opposite to the surface on which the antenna electrode is disposed.

  A microstrip antenna according to an embodiment includes a substantially flat first circuit unit having a control circuit for controlling a switch, and a substantially flat plate having a high frequency oscillation circuit for generating a high frequency signal to be applied to an antenna electrode. A second circuit unit in the form of a spacer, and a spacer is interposed between the substrate and the first circuit unit and / or between the first circuit unit and the second circuit unit. The substrate, the first and second circuit units, and the spacer are integrally coupled in a stacked manner. If the low-frequency characteristics are good, it is divided into a sufficient first circuit unit and a second circuit unit that requires good high-frequency characteristics. You can choose freely. For example, the thickness of the substrate of the second circuit unit needs to be reduced as the frequency increases, and the thickness of the substrate of the first circuit unit needs to be stacked (thicker) because the number of parts and wiring increases as the number of events to be controlled increases. However, this situation can be easily dealt with.

  In the microstrip antenna according to one embodiment, the feed line extends from the high-frequency oscillation circuit on the second circuit unit to the antenna electrode on the substrate. The power supply line passes through the inside of the spacer and is surrounded by the spacer.

  In the microstrip antenna according to one embodiment, the first and second circuit units share the same ground electrode sandwiched between the circuit units.

  The present invention also provides a transmitting antenna using the microstrip antenna according to the present invention described above, and the same antenna as the transmitting antenna for receiving a reflected wave or a transmitted wave from a radio wave object output from the transmitting antenna. Alternatively, a high-frequency sensor including a receiving antenna that is different from the transmitting antenna and a processing circuit that receives and processes an electric signal from the receiving antenna is also provided.

  ADVANTAGE OF THE INVENTION According to this invention, the microstrip antenna which switches the directivity direction of a narrow directivity and a compact radio wave beam can be provided.

  Hereinafter, embodiments of a microstrip antenna according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a general microstrip antenna having a plurality of antenna electrodes.

  In FIG. 1, an A antenna electrode 2 and a B antenna electrode 3 having the same size and the same rectangular shape are arranged on the surface of an insulating substrate 1 with a line-symmetric relationship in terms of shape and position. The ground electrode 4 is disposed on almost the entire back surface. A high-frequency voltage Vf of, for example, 10.525 GHz is applied to the feeding points P and P provided at the same side edge of the A antenna electrode 2 and the B antenna electrode 3 through the feeding line 10. The ground electrode 4 is grounded to provide a ground level. The length of the feed line 10 to the A antenna electrode 2 and the B antenna electrode 3 is the same. In some cases, the feeding points P and P are arranged not at the edges of the antenna electrodes 2 and 3 but at a certain distance from the edges of the antenna electrodes 2 and 3 to the inside. With such a configuration, radio wave beams 7 and 8 having the same electric field intensity are radiated from the A antenna electrode 2 and the B antenna electrode 3 in a directivity direction perpendicular to the substrate 1, respectively.

  FIG. 2 is a plan view showing the radio wave scanning principle of the microstrip antenna of the present invention. FIG. 3 is a cross-sectional view taken along the line AA of FIG.

The microstrip antenna shown in FIGS. 2 and 3 includes a substrate 1, an A antenna electrode 2, a B antenna electrode 3, a ground electrode 4, a feed line 10, and a connection member (hereinafter referred to as “through hole”) 5. The A antenna electrode 2 and the B antenna electrode 3 are in a line-symmetrical relationship in terms of shape and position, and the excitation direction is the same. A high frequency signal is propagated to each antenna electrode 2, 3 via the feed line 10. In addition to this, a certain location 2A of one electrode, for example, the A antenna electrode 2, is connected to the ground electrode 4. That is, a conductive through hole 5 passes through a portion of the substrate 1 corresponding to the one location 2A of the A antenna electrode 2, and this through hole 5 is formed at one end of the A antenna electrode 2 at one end. Coupled to the ground electrode 4 at the other end. Thus, the one location 2A of the A antenna electrode 2 is connected to the ground electrode 4 through the through hole 5. A portion of the antenna electrode connected to the ground electrode 4 in this way (or grounded when desired by a switch or other electric circuit described later) is called a “ground point”. The length of one side (the vertical direction in the figure) of the antenna electrodes 2 and 3 shown in FIG. 2 is designed to be the same as or slightly smaller than the half wavelength λg / 2 of the high-frequency signal on the substrate 1. Here, λg is the wavelength of the high-frequency signal propagating through the substrate 1. Further, λ = εr ^1/2 · λg where λ is the wavelength of the radio frequency signal radio wave in vacuum and εr is the dielectric constant of the substrate 1. In the example shown in FIG. 2, the grounding point 2 </ b> A is disposed on the extension line of the feeding point P of the A antenna electrode 2 and in the vicinity of the end face of the A antenna electrode 2. The phase of the radio wave beam emitted from the A antenna electrode 2 advances from the phase of the radio wave beam emitted from the B antenna electrode 3, and as a result, the integrated radio wave beam radiated from the A antenna electrode 2 and the B antenna electrode 3. Is directed toward the B antenna electrode 3 as indicated by an arrow in FIG.

  FIG. 4 is a plan view of the first embodiment of the microstrip antenna of the present invention. 5 is a cross-sectional view taken along the line BB in FIG. In FIG. 4, the dielectric lens 34 is not shown for convenience of explanation.

  The microstrip antenna shown in FIGS. 4 and 5 has a conductive through portion on the substrate 1 corresponding to the grounding points 2A and 2B of the A antenna electrode 2 and the B antenna electrode 3 of the microstrip antenna shown in FIGS. The through hole 5 is penetrated, and the through hole 5 is coupled to the one place of the A antenna electrode 2 and the B antenna electrode 3 at one end, and the antenna electrode 2, 3 and the ground electrode 4 are coupled to the other end. A switch 9 for opening and closing the connection is connected. The grounding points 2A and 2B are disposed on the extension lines of the feeding points P and P of the A antenna electrode 2 and the B antenna electrode 3 and in the vicinity of the end surfaces of the A antenna electrode 2 and the B antenna electrode 3. A dielectric lens 34 made of a dielectric material is installed in front of the A antenna electrode 2 and the B antenna electrode 3 so as to cover the A antenna electrode 2 and the B antenna electrode 3. The installation position of the dielectric lens 34 may be in close contact with the antenna electrode according to the focal length, or a gap may be provided between the antenna electrode and the dielectric lens. In the example shown in FIG. 4, a radio wave emitted from the A antenna electrode 2 by operating the switch 9 connected to the A antenna electrode 2 through the through hole 5 and connecting the A antenna electrode 2 and the ground electrode 4. The phase of the beam advances from the phase of the beam of the radio wave emitted from the B antenna electrode 3, and as a result, the directivity directions of the radio wave beams radiated from the A antenna electrode 2 and the B antenna electrode 3 are indicated by arrows in FIG. It inclines toward the B antenna electrode 3 side. Then, the integrated radio wave beam radiated from the antenna electrode can be narrowed by the dielectric lens 34 disposed in front of the antenna electrode, and the radio wave beam can be radiated to a narrow range, thereby extending the radiation distance. As the performance required for the switch 9, it is sufficient if the isolation (characteristic for blocking the high-frequency wave signal) is good, and it is not necessary to have a characteristic for allowing the high-frequency signal to pass well. Therefore, an actuator such as a solenoid can be used as the switch 9 in addition to a high-frequency switch having a semiconductor structure or a MEMS (hollow) structure. In addition, when the microstrip antenna of the present invention is applied to an object detection device, the focal length of the dielectric lens 34 can be selected according to the distance range to be detected. For example, when the object detection device is installed on the indoor ceiling to detect an object or person in the room, the detection distance range is about 2.5 m to 3 m or less, so the focal length of the dielectric lens 34 is within the detection distance range. What is necessary is just to set to the maximum length 2.5m-3m vicinity.

  FIG. 6 is a cross-sectional view of a second embodiment of the microstrip antenna of the present invention. FIG. 7 shows an exploded view of the microstrip antenna in the same embodiment. FIG. 8 is a plan view of the microstrip antenna incorporated in the embodiment.

  The microstrip antenna shown in FIGS. 6 and 7 includes a dielectric lens 34 disposed on the front surface of the antenna body 31, and an analog circuit unit 32 and a digital circuit unit 33 disposed on the back side of the antenna body 31. However, this microstrip antenna has the following unique structure. That is, as shown in FIGS. 6 and 7, the dielectric lens 34, the antenna body 31, the spacer 35, the digital circuit unit 33, the spacer 35, and the analog circuit unit 33 are stacked in this order, and several of them are stacked. The screw 36 is integrally fixed. The ground electrode 4 covering almost the entire area of the rear surface of the antenna body 31 and the ground electrode 4 covering the almost entire area of the front surface of the analog circuit unit 32 are opposed to each other. The antenna body 31, the spacer 35, the analog circuit unit 32, the spacer 35, and the digital circuit unit 33 each have a substantially flat plate shape, and thus the antenna has a substantially rectangular parallelepiped shape as a whole. A dielectric lens 34 is disposed at the foremost part of the antenna, and an analog circuit unit 32 is disposed at the rearmost part. A portion of the screw 36 that protrudes forward from the antenna body 31 is embedded in the base of the dielectric lens 34 and surrounded by the dielectric, and is not exposed on the front surface of the antenna body 31. Instead of the dielectric lens 34, a substantially flat and thin dielectric cover 43 may be used for antenna protection. The dielectric lens 34 and the dielectric cover 43 can be selected according to the use of the antenna (for example, the detection distance is long).

  As shown in FIG. 8, four antenna electrodes, an A antenna electrode 11, a B antenna electrode 12, a C antenna electrode 13, and a D antenna electrode 14, are arranged on the substrate 1 in a 2 × 2 matrix. The A antenna electrode 11 and the B antenna electrode 12 are in a line-symmetric relationship with respect to shape and position, and the C antenna electrode 13 and the D antenna electrode 14 are also in a line-symmetric relationship with respect to shape and position. The excitation direction of 14 is the same. The electrode patterns of the A antenna electrode 11 and the B antenna electrode 12 and the patterns of the C antenna electrode 13 and the D antenna electrode 14 are basically the same in shape. The length of the feed line 10 to the A antenna electrode 11, the B antenna electrode 12, the C antenna electrode 13, and the D antenna electrode 14 is the same. If the Wilkinson coupler 6 is connected to the feed line 10 portion branched to the A antenna electrode 11 and the B antenna electrode 12 and the feed line 10 portion branched to the C antenna electrode 13 and the D antenna electrode 14, Mutual interference can be prevented. The grounding point 11A is located at approximately one center of the A antenna electrode 11, the grounding point 12A is disposed at approximately one center of the B antenna electrode 12, and the grounding point 13A and D antenna electrode 14 are disposed at approximately one center of the C antenna electrode 13. A grounding point 14A is arranged at a substantially central location, and through-holes (not shown) pass through each of the grounding points 11A to 14A, and a switch (not shown) for opening / closing a connection with the grounding electrode (not shown). It is connected to each antenna electrode 11-14. A relay line for adjusting the impedance of the grounding points 11A to 14A may be provided between each through hole and each switch.

  A high-frequency oscillation circuit 38 is provided near the center of the back surface of the analog circuit unit 32, and a feed line 37 extends linearly from the high-frequency oscillation circuit 38 to the feed line 10 disposed near the center of the surface of the antenna body 31. Extend to. The feed line 37 penetrates through the analog circuit unit 32, the spacer 35, the digital circuit unit 33, the spacer 35, and the antenna body 31 and is connected to the feed line 10 on the antenna body 31. A coaxial cable may be used for the feed line 37 from the viewpoint of reducing transmission loss. In this case, the core wire of the coaxial cable is used as the power supply line 37, and the coaxial metal tube surrounding the core wire of the coaxial cable covers almost the entire area of the ground electrode 4 and the analog circuit unit 32 covering the entire area of the back surface of the antenna body 31. Each is connected to the covering ground electrode 4. A box-shaped shield cover 39 is attached to the back surface of the analog circuit unit 32 by several screws 40. The shield cover 39 covers the outer periphery of the high-frequency oscillation circuit 38 on the back surface of the analog circuit unit 32. The shield cover 39 is provided with a frequency adjusting screw 41. By rotating the frequency adjusting screw 41, the circuit constant of the high-frequency oscillation circuit 38 is changed (for example, the gap distance between the high-frequency oscillation circuit 38 and the shield cover 39 is changed and the capacitance of the resonance circuit is changed). The oscillation frequency of the oscillation circuit 38 is adjusted.

  The spacer 35 is made of a conductor such as metal, or its outer surface is covered with a conductor film. As shown in FIG. 6, one spacer 35 is in contact with the ground electrode 4 covering almost the entire area of the back surface of the antenna body 31 and the ground electrode 4 covering the almost entire area of the front surface of the digital circuit unit 33. Retained. The other spacer 35 is in contact with the ground electrode 4 formed on the outer peripheral portion of the back surface of the digital circuit unit 33 and the ground electrode 4 covering almost the entire front surface of the analog circuit unit 32 and is held at the ground level. . Each of the spacers 35 has a substantially flat plate-like shape as shown in FIG. 9 and surrounds the power supply line 37.

  The digital circuit unit 33 is equipped with a microcomputer for controlling the antenna body 31 and the sensor circuit. In addition, several external ports 42 are arranged on the back surface of the digital circuit unit 33. These external ports 42 include signal input / output ports for external input / output of various signals such as sensor signals, power supply voltages, monitor signals, etc., and writing programs and data to the flash ROM built in the microcomputer described above. There are a data write port for performing, a setting port for performing various settings related to the control operation (for example, the order of turning on / off the switch of the parasitic element, the cycle, etc.) for the microcomputer. These external ports 42 protrude rearward from the back surface of the digital circuit unit 33 and pass through the spacer 35 and the inside of the analog circuit unit 32. Therefore, as illustrated in FIG. 10, the opening at the upper end of the external port 42 is exposed on the back surface of the analog circuit unit 32, thereby enabling access to the digital circuit unit 33. Among the external ports 42, in particular, the data write port may be closed with a synthetic resin or the like in order to make it impossible for the user to rewrite data arbitrarily after the data is written in the manufacturing stage.

  In the antenna shown in FIGS. 6 and 7, all components are stacked and integrally coupled, and the protruding external port on the digital circuit unit 33 is accommodated in the spacer 35 and the analog circuit unit 32. So it is compact. And since the feed line 37 may be a short line corresponding to the thickness of the antenna having this compact laminated structure, the power loss in the feed line 37 can be reduced. Further, the oscillation frequency can be changed using the frequency adjusting screw 41. In addition, since there is a conductive spacer 35 in close contact with each ground electrode 4 between the antenna body 31, the digital circuit unit 33, and the analog circuit unit 32, the ground level of the antenna body 31 and the analog circuit unit 32 can be reduced. Can be ensured to ensure good antenna performance. Further, by laminating the antenna body 31, the digital circuit unit 33, and the analog circuit unit 32 and integrally coupling them, a radio wave radiated from the back surface (ground surface) of the antenna body 31 or a high-frequency oscillation circuit 38 is radiated. Unnecessary harmonics are suppressed from being radiated to the outside, so that radio waves can be efficiently radiated from the front surface of the antenna body 31 in a desired direction. Further, since the screw 36 is embedded in the dielectric lens 34 made of a dielectric and is covered with the dielectric so as not to be exposed on the front surface of the antenna body 31, the screw 36 has conductivity such as metal or gold plating. Even if it has, it can suppress that the electromagnetic wave radiated | emitted from the front surface of the antenna main body 31 interferes with the screw 36, and can radiate | transmit an electromagnetic wave ahead through the dielectric lens 34 efficiently.

  FIG. 11 shows a cross-sectional view of a modification of the microstrip antenna shown in FIGS.

  The antenna shown in FIG. 11 is different from the antenna shown in FIGS. 6 and 7 in that a digital circuit unit 33, a ground electrode 4, and an analog circuit unit 32 are stacked and integrally coupled. Is used. The digital circuit unit 33 and the analog circuit unit 32 share the same ground electrode 4 sandwiched between them. The spacer 35 shown in FIGS. 6 and 7 does not exist. The antenna shown in FIG. 11 is more compact.

  In this embodiment, the screw 36 is inserted and fixed from the analog circuit unit 32 side. However, when adopting a structure that does not use the dielectric lens 34 or the dielectric cover 43 (for example, a structure in which a protective resin film is directly formed on the surface of the antenna electrode), the screw 36 is inserted from the antenna body 31 side. All parts can be fixed by inserting. In addition, a metal rod is inserted in the through hole for passing the screw provided at the four corners of the spacer 35 in place of the screw, and the metal rod and the antenna body 31, the digital circuit unit 33, and the ground electrode of the analog circuit unit 32 are connected. All components can be fixed by connecting them by soldering or the like.

  12A to 12C show variations of dielectric lenses made of a dielectric material applicable to the antenna shown in FIGS. 6 and 7 and FIG. 11 and other microstrip antennas according to the present invention.

  The dielectric lens does not necessarily have to be a spherical lens, and may have various shapes protruding in the normal direction of the antenna surface, for example, a triangular pyramid shown in FIG. 80A or a trapezoidal cone shown in FIG. 80B. Good. Alternatively, even when a flat dielectric plate or film as shown in FIG. 80C is used as a lens, the antenna gain can be improved. In addition, by coating the outer surface of the dielectric lens with a photocatalytic material film, it is possible to prevent moisture and rain and dirt from adhering to the dielectric lens, and to efficiently radiate radio waves over a long period of time. It is.

  The above-described microstrip antenna according to the present invention can be applied to a high-frequency sensor for detecting an object. Such a high-frequency sensor receives a transmitting antenna using a microstrip antenna, a receiving antenna for receiving a reflected wave or transmitted wave from a radio wave object output from the transmitting antenna, and an electric signal from the receiving antenna. And a processing circuit for processing. Here, although the receiving antenna can be provided separately from the transmitting antenna, the transmitting antenna can also be used as the receiving antenna, particularly when a reflected wave is received.

  As mentioned above, although embodiment of this invention was described, this embodiment is only the illustration for description of this invention, and is not the meaning which limits the scope of the present invention only to this embodiment. The present invention can be implemented in various other modes without departing from the gist thereof.

It is a perspective view of a common microstrip antenna provided with a plurality of antenna electrodes. It is a top view which shows the radio wave scanning principle of the microstrip antenna of this invention. It is AA sectional drawing of FIG. It is a top view of 1st Embodiment of the microstrip antenna of this invention. It is BB sectional drawing of FIG. It is a top view which shows the method of inclining a radio wave beam rightward in 2nd Embodiment of the microstrip antenna of this invention. It is an exploded view in the same embodiment. It is a top view of the microstrip antenna concerning the embodiment. It is a top view of the spacer in the embodiment. It is a rear view of the analog circuit unit 606 in the same embodiment. It is sectional drawing of the modification of 2nd Embodiment. 12A to 12C are perspective views of variations of dielectric lenses applicable to the microstrip antenna of the present invention.

Explanation of symbols

1 substrate 2, 11 A antenna electrode 3, 12 B antenna electrode 4 ground electrode 5 connecting member (through hole)
DESCRIPTION OF SYMBOLS 9 Switch 10 Feed line 13 C antenna electrode 14 D antenna electrode 31 Antenna main body 32 Analog circuit unit 33 Digital circuit unit 34 Dielectric lens 35 Spacer 36, 40 Screw 37 Feed line 38 High frequency oscillation circuit 39 Shield cover 41 Frequency adjustment screw 42 External Port 43 dielectric cover

Claims (6)

An insulating substrate;
A plurality of antenna electrodes disposed on one surface of the substrate, each having a feeding point for applying a high-frequency signal;
A ground electrode for providing a ground level, disposed on the other side or inside of the substrate;
A connection member disposed at least at one place different from the feeding point for connecting at least one antenna electrode of the plurality of antenna electrodes to the ground electrode;
A switch connected to an end of the connection member and opening / closing a connection between at least one antenna electrode of the plurality of antenna electrodes and the ground electrode;
A microstrip antenna, comprising: a dielectric lens made of a dielectric material disposed so as to cover a surface of the antenna electrode. A substantially flat first circuit unit having a control circuit for controlling the switch;
A substantially flat second circuit unit having a high-frequency oscillation circuit that generates a high-frequency signal to be applied to the antenna electrode;
2. The microstrip antenna according to claim 1, wherein the first and second circuit units are integrally coupled in a stacked manner on the back surface of the substrate. A substantially flat first circuit unit having a control circuit for controlling the switch;
A substantially flat second circuit unit having a high-frequency oscillation circuit that generates a high-frequency signal to be applied to the antenna electrode;
A spacer that is interposed between the substrate and the first circuit unit and / or between the first circuit unit and the second circuit unit and is held at the same potential as the ground electrode;
The said board | substrate and the said 1st circuit unit and / or the said 1st circuit unit and the said 2nd circuit unit are integrally couple | bonded together in the form laminated | stacked via the said spacer. Microstrip antenna.   The power supply line connected to the said high frequency oscillation circuit on the said 2nd circuit unit and the said antenna electrode on the said board | substrate is provided, The said power supply line passes through the inner side of the said spacer, and is surrounded by the said spacer. Microstrip antenna. The microstrip antenna according to claim 2, wherein the first and second circuit units share the same ground electrode sandwiched between the first and second circuit units. A transmission antenna using a microstrip antenna for outputting a high-frequency radio wave, and the same or the same as the transmission antenna for receiving a reflected wave or a transmitted wave from an object of the radio wave output from the transmission antenna In a high-frequency sensor comprising a receiving antenna that is different from a transmitting antenna, and a processing circuit that receives and processes an electrical signal from the receiving antenna,
The microstrip antenna is
An insulating substrate;
A plurality of antenna electrodes disposed on one surface of the substrate, each having a feeding point for applying a high-frequency signal;
A ground electrode for providing a ground level, disposed on the other side or inside of the substrate;
A connection member disposed at least at one place different from the feeding point for connecting at least one antenna electrode of the plurality of antenna electrodes to the ground electrode;
A switch connected to an end of the connection member and opening / closing a connection between at least one antenna electrode of the plurality of antenna electrodes and the ground electrode;
A high-frequency sensor comprising: a dielectric lens made of a dielectric material disposed so as to cover a surface of the antenna electrode.

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