JP4369314B2 - Antenna directivity control apparatus, position detection apparatus and method - Google Patents

Description

  The present invention relates to an antenna directivity control method and a position detection device that can grasp the position of a moving object that is distant, for example, by controlling the directivity of an antenna using wireless communication.

For example, GPS (Global Positioning System) information using satellites, information obtained from PHS (Personal Handy-phone System) or base stations installed for mobile phones, etc. There is a location information service that identifies the location of terminals owned by.
By using such a location information service, the family can grasp the current location of the child or elderly person with the terminal on the map, so that the family can feel safe and get involved in the incident. It will be possible to respond when a situation such as a drought or drought occurs.

  In addition, when conducting an ecological survey on animals that move freely within a relatively limited range, it is possible to easily supplement the positions of multiple animals by attaching terminals to the bodies of multiple animals. A position detection system that can be used has also been proposed (see, for example, Patent Document 1).

  In such a position detection system, a fixed station includes an antenna device that can change a directivity direction or directivity characteristics in a horizontal plane according to a given control signal, and the fixed station transmits a radio signal in all directions in the horizontal plane. The mobile station is called and the antenna directing direction is controlled so that the received signal from the mobile station becomes maximum when the mobile station returns a signal to the fixed station. This position detection system also calculates the distance to the mobile station from the time relationship between the signal sent from the fixed station to the mobile station and the signal returned from the mobile station and received by the fixed station. It displays the direction and distance of the mobile station with respect to the fixed station.

  Further, in the position detection system described above, an array antenna (Array Antenna) composed of antenna elements in which a number of the same antennas are arranged is used as an antenna for changing the directivity direction. Specifically, a phased array antenna that performs electronic beam scanning and directivity synthesis with variable feed phase, and an adaptive antenna that controls antenna characteristics according to the received signal Etc. are disclosed.

Here, the phased array antenna and the adaptive antenna will be outlined.
For example, when a plurality of dipole antennas are arranged at equal intervals, radiation from each antenna is superimposed like radiation from an aperture to produce a plane wave. Although it is not much different from a plane aperture antenna as it is, if a phase shifter is attached to each antenna and the phase shift delay is electronically controlled, the electromagnetic wave is converged in an arbitrary direction by controlling the wavefront of the plane wave. Can do. Such an antenna is called a phased array antenna.
An adaptive array antenna is conceptually similar to a phased array antenna, but creates a directional null point in any direction to eliminate, for example, multipath fading. Therefore, it is different from the phased array antenna for changing the directivity.

JP-A-8-19035 (pages 4-5, FIG. 3)

  Such phased array antennas and adaptive antennas have a structure in which a phase shifter that changes the phase of a signal transmitted through a transmission path electrically or mechanically is attached to each antenna element. These antennas are expensive. Therefore, the field of use such as military use is limited. As described above, since a high-cost and large-sized antenna is used, it has been difficult to reduce the cost and size of the position detection system.

  The present invention has been made to solve the technical problems as described above, and an object of the present invention is to provide an antenna directivity control method and a position detection device that can be easily realized at low cost and downsizing. It is to provide.

For this purpose, an antenna directivity control apparatus to which the present invention is applied includes a substrate having a surface, a first antenna that penetrates the substrate and receives radio waves, and a direction away from the first antenna. A linear portion extending linearly and an arc portion extending in an arc shape in one direction around the first antenna and connected to an end portion of the linear portion far from the first antenna. electric length to the end of the one-way of the arc portion from an end portion of the linear portion close to a quarter wavelength and substantially the same length der Rutotomoni the first antenna radius of curvature used frequency of the Ri substantially equal length der and a half wavelength of the operating frequency, located radially above the straight line portion around the said first antenna while being disposed along a surface of the substrate at a substantially uniform angle a plurality of second antennas, the surface of the substrate Provided at one end of the side close to the arranged first antenna of each of the plurality of second antennas, it is intended to include a grounding means for grounding by selecting each of the second antenna.
Here, the length of the straight line part and the arc length of the arc part of each of the plurality of second antennas are substantially the same as a quarter wavelength of the used frequency. it can. In addition, it may further include a small protrusion that protrudes from the one end of each of the plurality of second antennas in a direction opposite to a direction in which the arc portion extends. When the small protrusion is provided in this manner, the induced voltage of the second antenna can be increased, and higher front-to-back ratio characteristics and sharper directivity characteristics can be realized.

When regarded from another point of view, the position detecting device to which the present invention is applied, receives a signal generated by the slave unit in the main antenna, in the position detecting device for detecting a position of the slave unit based on the reception state, the surface Connected to a substrate through which the main antenna penetrates, a linear portion extending linearly in a direction away from the main antenna, and an end of the linear portion far from the main antenna, and unidirectional with respect to the main antenna And an arc portion extending in an arc shape, the radius of curvature of the arc portion being substantially the same as a quarter wavelength of the operating frequency, and from the end of the linear portion close to the main antenna, The electrical length to the end in the one direction is substantially the same as the half wavelength of the operating frequency, and is arranged along the surface of the substrate and the straight line centering on the main antenna The parts are radially at approximately the same angle A plurality of control antennas that location, provided on the side of the one end close to the main antenna of each of the plurality of control antenna that is disposed on the surface of the substrate, control of the ground or non-ground for each the plurality of control antennas a control means for changing the direction of directivity of the main antenna and the is intended to include.
Here, the control unit may control to make any one of the plurality of control antennas or two adjacent control antennas ungrounded and ground the other control antennas. In addition, it may further include a small protrusion that protrudes in an arc from one end of each of the plurality of control antennas around the main antenna.

Further, when the present invention is viewed from another viewpoint, the position detection method to which the present invention is applied receives a signal generated by the slave unit by the main antenna of the master unit, and the slave unit with respect to the master unit based on the reception state. In the position detecting method for detecting the position of the main antenna, the main antenna is connected to a straight portion extending linearly in a direction away from the main antenna in the vicinity of the main antenna and an end of the straight portion far from the main antenna. An arc portion extending in a circular arc shape in one direction as a center, the radius of curvature of the arc portion is substantially the same as a quarter wavelength of the operating frequency, and from the end portion of the linear portion close to the main antenna The electrical length to the end in the one direction of the arc portion is substantially the same as the half wavelength of the operating frequency , and is arranged along the surface of the substrate through which the main antenna penetrates. Along with the main antenna The straight line portion is a directional characteristic changing step is performed using a plurality of control antenna located radially at a substantially uniform angle, ground or non at one end closer to the main antenna of each of the plurality of control antennas A directivity changing step for changing the directivity of the main antenna with the plurality of control antennas arranged in the vicinity, and a signal emitted from the slave unit in the directivity of the main antenna changed by the directivity change step. a measuring step of measuring, the calculating step calculates the position of the slave unit based on the measurement result of the measuring step, and a display step of displaying the calculation result of the calculation step to the master unit, is intended to include.
Here, before the directivity changing step, a synchronization step of performing synchronization between the slave unit and the master unit may be performed.

  According to the present invention, it is possible to easily control the directivity characteristics of an antenna at low cost and downsizing.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1A is an explanatory view showing the appearance of the position detection device (parent device) 10 and its child device 60 according to the present embodiment, and FIG. It is explanatory drawing which shows the electromagnetic wave emitted toward. 2A and 2B are schematic configuration diagrams of the inside of the position detection device 10, in which FIG. 2A is a side view and FIG. 2B is a plan view.
As shown in FIG. 1A, the position detection device 10 has a disk shape, has a power switch 10a and a search button 10b, and has a display unit 56 described later. Moreover, the subunit | mobile_unit 60 is also disk shape with a small external shape, and has the power switch 60a and LED60b which lights when the power switch 60a is turned ON.
When the power switch 60a is turned on, the slave unit 60 has a transmitter (transmitter) (not shown) that emits a radio wave having a frequency of, for example, 2.45 GHz (IEEE802.11b or IEEE802.11g) of a wireless LAN (Local Area Network), The position detection device 10 can detect the position of the slave unit 60 based on the radio wave (pulse waveform) shown in FIG. Specifically, the position detection device 10 receives a radio wave transmitted from the slave unit 60, and based on the radio wave, determines in which direction the slave unit 60 is located with respect to the position detection device 10 and how far away. Detected and the contents are displayed on the display unit 56.
As a method of using the position detection device 10 and the child device 60, for example, a child playing in an amusement park has the child device 60. For example, when the child gets lost, the child has the position detection device 10. When the parent presses the search button 10b of the position detection device 10, the position of the child is displayed on the display unit 56 of the position detection device 10, so that the child can be easily found. In this way, the position of the child can be easily detected without providing a large-scale facility in advance.

  As shown in FIG. 2A, the position detection device 10 includes a disk-shaped main board 11, a disk-shaped control antenna board 12 having an outer diameter substantially the same as the outer diameter of the main board 11, and the main board. 11 and a main antenna 13 having one end attached to the center of the control antenna board 12 and the other end attached to the center of the control antenna board 12. The main antenna 13 is for receiving radio waves from a slave (not shown) and is omnidirectional. The main board 11 and the control antenna board 12 are arranged substantially parallel to each other and spaced apart from each other.

  As shown in FIG. 2B, four control antennas 21, 22, 23, and 24 are regularly arranged around the main antenna 13 in a pattern on the surface side of the control antenna substrate 12. Yes. The control antennas 21, 22, 23, and 24 are linear radial portions 21a, 22a, 23a, and 24a that extend radially from the center of the control antenna substrate 12 at intervals of 90 degrees in the circumferential direction. Arc-shaped circumferential portions 21b, 22b, 23b, and 24b extending in one direction along the circumferential direction from the end portions of the radial portions 21a, 22a, 23a, and 24a near the circumferential surface are provided. The radial direction portions 21a, 22a, 23a, 24a and the circumferential direction portions 21b, 22b, 23b, 24b of the control antennas 21, 22, 23, 24 are formed continuously.

Here, the curvature radii of the circumferential portions 21b, 22b, 23b, and 24b in the four control antennas 21, 22, 23, and 24 are substantially the same, and are about λ / 4. For example, since the wavelength λ is 122.95 mm when the use frequency f is 2.45 GHz, the radius of curvature of the control antennas 21, 22, 23, and 24 is 30.74 mm.
Adjacent circumferential portions 21b, 22b, 23b, and 24b are separated from each other by a predetermined distance, and the arc length of the circumferential portions 21b, 22b, 23b, and 24b is about λ / 4 (30.74 mm). is there. That is, the electrical length of the control antennas 21, 22, 23, and 24 is approximately λ / 2 (61.48 mm), and the physical length of the control antennas 21, 22, 23, and 24 is λ / 4 ( 30.74 mm). The four control antennas 21, 22, 23, 24 are arranged so as not to cross each other.

The ends of the four control antennas 21, 22, 23, 24 near the center of the radial direction portions 21 a, 22 a, 23 a, 24 a are located in the vicinity of the main antenna 13. That is, one end of each of the control antennas 21, 22, 23, and 24 is arranged in the vicinity of the place where the main antenna 13 has the highest radiation intensity, for example, about 2 to 3 mm apart, and the radiated electromagnetic field from the main antenna 13 is controlled by the control antenna 21. , 22, 23, 24.
In addition, as a material of the control antennas 21, 22, 23, and 24, a sheet metal antenna, a printed antenna, a wire antenna, and other high-frequency materials that are not limited in shape can be used.

On the control antenna board 12, switching elements 31, 32, 33, 34 as grounding means are provided for each control antenna 21, 22, 23, 24. One end of each of the switching elements 31, 32, 33, and 34 is connected to the ground G, and selectively operates under the control of the control means described later. Therefore, the four control antennas 21, 22, 23, and 24 can be dropped or not dropped to the ground G.
In the present embodiment, one of the control antennas 21, 22, 23, and 24 is dropped to the ground G. However, if both are dropped to the ground G, the grounding effect becomes more reliable.

Next, the theory that the directivity characteristic of the main antenna 13 changes by switching the switching element will be described.
3 is an explanatory diagram for explaining the arrangement of the main antenna 13 and the control antenna 20, FIG. 4 is a graph for explaining the directivity characteristics in the forward direction of FIG. 3, and FIG. FIG. 6 is a graph for explaining the directivity characteristics in the reverse direction, and FIG. Each of the vertical axes of (a) to (f) in FIG. 4 and (a) to (g) of FIG. 5 is a voltage power source, and each horizontal axis is time.
A simulation was performed using the main antenna 13 connected to the transmission source 14 shown in FIG. 3 and the control antenna 20 (21, 22, 23, 24) disposed in the vicinity of the main antenna 13. This simulation was performed with the control antenna 20 in a non-contact state (not connected to the ground G) in order to clarify the effect of the control antenna 20.
Here, the other conditions of the simulation will be described. The electrical length of the control antenna 20 is approximately λ / 2, and the physical length is approximately λ / 4. One end of the control antenna 20 adjacent to the main antenna 13 is designated as point A, and the other end is designated as point B. Further, the point C is located on the opposite side of the main antenna 13 from the point B of the control antenna 20. The separation distance from the main antenna 13 to the point C is approximately λ / 4.

First, directivity characteristics at point B in the forward direction shown in FIG. 3 will be described with reference to FIG.
As shown in FIGS. 4A and 4B, the phase of the electric field and magnetic field of the main antenna 13 are the same. When the magnetic field is differentiated (e = dφ / dt), the induced voltage at point A of the control antenna 20 can be obtained as shown in FIG.
Here, since the electrical length between the points A and B in the control antenna 20 is about λ / 2, the voltage (electric field) at the point B of the control antenna 20 is as shown in FIG. The phase of the induced voltage at point A of the control antenna 20 in FIG.
Further, since the physical length between the point A and the point B in the control antenna 20 is about λ / 4, as shown in FIG. 4E, the electric field of the main antenna 13 at the point B is A phase shift of 90 degrees occurs with respect to the electric field of the main antenna 13.
The phase of the electric field of the main antenna 13 shown in FIG. 4D and the phase of the electric field of the control antenna 20 shown in FIG. As shown in FIG. 4 (f), the electric field is strengthened. That is, the combined electric field at point B ((f) in FIG. 4) has a higher electric field strength than the electric field of main antenna 13 ((d) in FIG. 4).

Next, directivity characteristics at the point C in the reverse direction shown in FIG. 3 will be described. 5 (a) to (d) are the same as FIGS. 4 (a) to (d), and the description thereof is omitted.
Since the physical length between the point A and the point C in the control antenna 20 is about λ / 4, as shown in FIG. 5E, the electric field of the main antenna 13 at the point C is the main antenna at the point A. A phase shift of 90 degrees occurs with respect to 13 electric fields. As a result, (e) in FIG. 5 has the same phase as (e) in FIG.
Further, since the physical length between the points B and C in the control antenna 20 is λ / 2, the electric field of the control antenna 20 at the point C is controlled at the point B as shown in FIG. A phase shift of 180 degrees occurs with respect to the electric field of the antenna 20 (see FIG. 5D).
The phase of the electric field of the main antenna 13 shown in (e) of FIG. 5 and the phase of the electric field of the control antenna 20 shown in (f) of FIG. As shown in FIG. 5 (g), the electric field is weakened by weakening each other. That is, the combined electric field at point C ((g) in FIG. 5) is weaker than the electric field of the main antenna 13 ((e) in FIG. 5).

From the result of such a simulation, as shown in FIG. 6A, it is possible to obtain directivity characteristics in which the electric field is strong in the forward direction and the electric field is weak in the reverse direction. On the other hand, if the control antenna 20 is grounded, the effect of the control antenna 20 is lost, and the directivity characteristic of the main antenna 13 itself, that is, omnidirectionality is changed as shown in FIG.
Therefore, the directivity in one direction can be improved by switching between grounding and non-grounding of the control antenna 20. That is, the directivity can be changed by simply switching between grounding and non-grounding.

Next, control of directivity characteristics of the main antenna 13 by the control antennas 21, 22, 23, and 24 will be described with reference to FIGS.
FIG. 7 is a diagram showing the directivity characteristics controlled by the configuration shown in FIG. 2. FIGS. 7A to 7E show the grounding / non-grounding of the control antennas 21, 22, 23, and 24 in FIG. It shows the change of directivity characteristics by switching.
In the orthogonal coordinate system XY shown in FIG. 2B, when only one of the four control antennas 21, 22, 23, 24 is ungrounded, the ungrounded control antenna is connected to the main antenna 13. On the other hand, it changes to a strong directional characteristic in the direction where it is located. More specifically, when only the control antenna 21 is not grounded, a directivity characteristic that is strong in the positive direction of the X axis and weak in the negative direction can be obtained as shown in FIG. When only the control antenna 22 is not grounded, a directivity characteristic that is strong in the positive direction of the Y axis and weak in the negative direction can be obtained as shown in FIG. When only the control antenna 23 is ungrounded, a directivity characteristic that is strong in the negative direction of the X axis and weak in the positive direction as shown in FIG. 7C can be obtained, and when only the control antenna 24 is ungrounded, As shown in FIG. 7D, a directivity characteristic that is strong in the negative direction of the Y axis and weak in the positive direction can be obtained. That is, when the control antenna installed in the direction in which gain is to be obtained is ungrounded, the gain of the characteristic of the main antenna 13 increases by 6 dB at the maximum and decreases by 6 dB in the opposite direction.
Furthermore, when only two adjacent control antennas among the four control antennas 21, 22, 23, 24 are ungrounded, strong directivity characteristics can be obtained in a direction inclined by 45 degrees with respect to the X axis or the Y axis. You can also. For example, when only the control antenna 22 and the control antenna 23 are not grounded, directivity characteristics as shown in FIG. 7E can be obtained. In other words, when the four control antennas 21, 22, 23, and 24 are used, the directivity characteristics in four directions including the X-axis direction and the Y-axis direction, four directions that intersect each axis at 45 degrees, and eight directions in total. Can be changed.
Such directivity control can be realized by switching the operation of the switching elements 31, 32, 33, and 34 shown in FIG.

Next, switching control of the switching elements 31, 32, 33, and 34 will be described.
FIG. 8 is a functional block diagram of the main part of the position detection device 10, FIG. 9 is a flowchart showing a procedure for position detection, and FIG. 9A is a power switch 10 a of the position detection device 10. FIG. 9B schematically shows an internal processing procedure when the power switch 60a of the slave unit 60 and the power switch 60a of the slave unit 60 are turned on. FIG. 9B is a diagram when the search button 10b of the position detection device 10 is pressed. The internal processing procedure is schematically shown.
As shown in FIG. 8, the position detection device 10 includes a high frequency unit (RF: Radio Frequency) 51, an intermediate frequency amplifier (IF-AM) 52, and a detection unit (IF) connected to the main antenna 13. DET: Detection) 53, data processing unit 54, microcomputer 55, display unit 56, and switching element (SW) 30 (31, 32, 33) connected to control antennas 21, 22, 23, 24 , 34).
When the main antenna 13 receives a radio wave transmitted from the slave unit 60, the radio wave is amplified and tuned by the high frequency unit 51, and an output of an oscillator (not shown) is added to the radio wave. The intermediate frequency amplifier 52 converts the signal into an intermediate frequency and amplifies it, and the detector 53 extracts a predetermined radio wave. The extracted radio wave is sent to the microcomputer 55 via the data processing unit 54, and the content is displayed on the display unit 56. The microcomputer 55 instructs the switching element 30 to switch between grounding and non-grounding of the control antennas 21, 22, 23, and 24, thereby controlling the directivity.

Here, as shown in FIG. 1A, the display unit 56 is provided on the upper surface of the position detection device 10, and corresponds to the positions of the control antennas 21, 22, 23, and 24 along the circumferential direction. It consists of eight LEDs (Light Emitting Diodes) 56a provided at equal intervals and a liquid crystal screen 56b provided at the center thereof. When the position detection device 10 detects the position of the slave unit 60, only one LED 56a in the direction of the slave unit 60 is lit, and the distance from the slave unit 60 is displayed on the liquid crystal screen 56b. Further, the LED 56a can also notify the user by turning on all eight LEDs in a synchronous mode to be described later.
It is also conceivable that only the liquid crystal screen capable of displaying a map is provided as the display unit 56, and the detected position of the slave unit 60 is displayed as a dot on the map on the screen.

The procedure for position detection can be divided into a synchronization mode and a search mode. First, as shown in FIG. 9A, the synchronization mode starts the synchronization operation when the position detection device 10 and the power switches 10a and 60a of the slave unit 60 are turned on (S101), and the synchronization is successful. Whether or not (S102). When the synchronization is successful, the process is terminated. When the synchronization is not successful, the fact is displayed on the display unit 56 (S103), and then the process is terminated.
In the search mode, as shown in FIG. 9B, it is determined whether or not the search button 10b of the position detecting device 10 has been pressed (S201). When the search button 10b is pressed, the position detection of the slave unit 60 is performed. In step S202, it is determined whether the position detection is successful (S202). When the position detection of the slave unit 60 is successful, the position (direction and distance) of the slave unit 60 is displayed on the display unit 56 of the position detection device 10. (S203) and the process ends. When the search button 10b of the position detection device 10 is not pressed and when the position detection of the child device 60 is not successful, the process returns to step S201. In the search mode, it is assumed that the position detection device 10 and the slave unit 60 are turned on. Further, the position detection device 10 can store the ID information of the child device 60 in advance and identify the child device 60 based on the ID information.

Here, in the position detection of the slave unit 60, the directivity characteristics of the main antenna 13 are sequentially changed in eight directions by the switching elements 31, 32, 33, and 34, and the direction in which the radio wave emitted from the slave unit 60 is in the best reception state. , The direction in which the handset 60 is present with respect to the position detection device 10 is known. Further, the distance from the slave unit 60 can be calculated by changing the gain.
Thus, the directivity can be changed with a simple structure, and a high gain and appropriate directivity can be ensured.

Next, a modified example of the control antenna in the position detection apparatus 10 according to the present embodiment will be described.
10-12 is explanatory drawing explaining the modification of a control antenna. In addition, in each modification, except the structure demonstrated below, it is the same as embodiment mentioned above, and illustration of the switching elements 31, 32, 33, 34, and the ground G is abbreviate | omitted ((b of FIG. 2) )reference).

  As a first modification, as shown in FIG. 10, small protrusions 21c, 22c, 23c, and 24c are provided at the ends of the control antennas 21, 22, 23, and 24 on the main antenna 13 side. The small projecting portions 21c, 22c, 23c, and 24c project in the direction opposite to the circumferential portions 21b, 22b, 23b, and 24b of the control antennas 21, 22, 23, and 24. If comprised in this way, an induced voltage can be made high and a gain can be enlarged.

In the second modified example, as shown in FIG. 11, in the control antennas 21, 22, 23, and 24, instead of the circumferential portions 21b, 22b, 23b, and 24b (see FIG. 2B), they are erected. It has parts 21d, 22d, 23d, and 24d. The circumferential portions 21b, 22b, 23b, and 24b are provided on the surface of the control antenna 12, but the standing portions 21d, 22d, 23d, and 24d are erected from the control antenna 12 and in the same direction as the main antenna 13. It extends to.
With this configuration, it is possible to arrange the control antennas with a small interval in terms of layout, and it is possible to provide a large number of control antennas. For this reason, position detection with higher accuracy is possible.

In the third modification, as shown in FIG. 12, control antennas 41, 42, 43, 44 extending in the radial direction are provided on the surface of the control antenna substrate 12. The control antennas 41, 42, 43, 44 are linear at both ends, and are provided with coil portions 41a, 42a, 43a, 44a in the middle. Each control antenna 41, 42, 43, 44 has a physical length of approximately λ / 4 and an electrical length of approximately λ / 2, similar to the control antennas 21, 22, 23, 24 described above. .
With this configuration, it is possible to detect the position with higher accuracy while making the position control device 10 compact.

It is explanatory drawing which shows the position detection apparatus which concerns on this Embodiment, and its subunit | mobile_unit. It is a schematic block diagram inside the position detection apparatus shown in FIG. It is explanatory drawing explaining the arrangement configuration of a main antenna and a control antenna. It is a graph for demonstrating the directivity characteristic in the forward direction of FIG. It is a graph for demonstrating the directional characteristic in the reverse direction of FIG. It is explanatory drawing explaining the directional characteristic of the main antenna shown in FIG. It is explanatory drawing explaining the directional characteristic of the main antenna shown in FIG. It is a functional block diagram of the principal part of the position detection apparatus shown in FIG. It is a flowchart for the position detection apparatus shown in FIG. 1 to detect the position of a subunit | mobile_unit. It is explanatory drawing explaining the 1st modification of a control antenna. It is explanatory drawing explaining the 2nd modification of a control antenna. It is explanatory drawing explaining the 3rd modification of a control antenna.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Position detection apparatus, 11 ... Main board, 12 ... Control antenna board, 13 ... Main antenna, 14 ... Transmission source, 20, 21, 22, 23, 24 ... Control antenna, 21a, 22a, 23a, 24a ... Radial direction Part, 21b, 22b, 23b, 24b ... circumferential direction part, 30, 31, 32, 33, 34 ... switching element, 60 ... slave unit, G ... ground

Claims (8)

A substrate having a surface ;
A first antenna that penetrates the substrate and receives radio waves;
A linear portion extending linearly in a direction away from the first antenna and an arc portion extending in an arc shape in one direction around the first antenna by connecting to an end of the linear portion far from the first antenna The radius of curvature of the arc portion is substantially the same as a quarter wavelength of the operating frequency, and the end of the arc portion in one direction from the end of the straight portion close to the first antenna The electrical length to the portion is substantially the same as the half wavelength of the operating frequency, and the linear portion is arranged along the surface of the substrate and the straight portion is substantially centered on the first antenna. A plurality of second antennas radially located at equal angles;
A grounding means provided at one end of the plurality of second antennas disposed on the surface of the substrate on the side close to the first antenna, and selectively grounding each of the second antennas;
An antenna directivity control device including: The length of the straight portion of each of the plurality of second antenna is substantially the same length and a quarter-wave of the used frequency,
Arc length of the arc portion of each of the plurality of second antenna, the control device of the antenna directivity of claim 1, which is a quarter wavelength and substantially the same length of used frequency . Antenna directivity characteristics of claim 1 or 2 from the one end of each of the plurality of second antenna, the direction in which the arcuate portion extends, characterized in that it further comprises a small protrusion protruding in the opposite direction Control device. In the position detection device that receives the signal emitted from the slave unit by the main antenna and detects the location of the slave unit based on the reception state,
A substrate having a surface through which the main antenna penetrates;
A linear portion extending linearly in a direction away from the main antenna, and an arc portion extending in an arc shape in one direction around the main antenna, connected to an end of the linear portion far from the main antenna, The radius of curvature of the section is substantially the same as a quarter wavelength of the operating frequency, and the electrical length from the end of the straight section close to the main antenna to the end of the arc section in the one direction Is a length substantially the same as a half wavelength of the used frequency, and is arranged along the surface of the substrate , and a plurality of controls in which the linear portion is radially located at substantially the same angle with respect to the main antenna. An antenna,
Each of the plurality of control antennas arranged on the surface of the substrate is provided at one end on the side close to the main antenna, and each of the plurality of control antennas is controlled to be grounded or non-grounded to direct the main antenna. Control means for changing the direction of the characteristics;
A position detecting device including:   5. The position according to claim 4, wherein the control unit performs control so that any one of the plurality of control antennas or two adjacent control antennas are ungrounded and the other control antenna is grounded. 6. Detection device.   6. The position detection device according to claim 4, further comprising a small protrusion that protrudes in an arc shape in one direction from the one end of each of the plurality of control antennas around the main antenna. In a position detection method for receiving a signal emitted from a slave unit by the main antenna of the master unit and detecting the position of the slave unit relative to the master unit based on the reception state,
An arc extending linearly in the direction away from the main antenna in the vicinity of the main antenna and an arc extending in one direction around the main antenna by connecting to the end of the linear portion far from the main antenna And the radius of curvature of the arc portion is substantially the same as a quarter wavelength of the operating frequency and the end portion of the arc portion in one direction from the end portion of the straight line portion close to the main antenna. an electrical length 1/2 wavelength and substantially the same length of used frequencies up, the linear portion centered on the main antenna together with the main antenna is arranged along the surface of the substrate that penetrates Is a directivity characteristic changing step performed using a plurality of control antennas radially located at substantially equal angles, and is grounded or ungrounded at one end of each of the plurality of control antennas close to the main antenna, Multiple A directional characteristic changing step of changing the directional characteristic of the main antenna control antenna disposed near,
A measurement step of measuring a signal emitted by the slave unit in the directivity characteristic of the main antenna changed by the directivity characteristic changing step;
A calculation step of calculating the position of the slave unit based on the measurement result of the measurement step;
A display step of displaying the calculation result of the calculation step on the master unit ;
A position detection method including:   8. The position detection method according to claim 7, wherein a synchronization step of synchronizing between the slave unit and the master unit is performed before the directivity characteristic changing step.

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