JP5033213B2 - Waveguide and radio wave control method - Google Patents

Description

  The present invention relates to a waveguide that can control radio waves radiated from a radio wave emission port to the outside of the waveguide.

  In recent years, radio frequency identification (RFID) tags have been actively used. There are two types of RFID tags, an active type with a built-in battery and a passive type without a built-in battery. The active type uses a built-in battery for transmission and reception. The communication distance is long, but the built-in battery makes it difficult to reduce the size and the price is high. On the other hand, the passive type receives radio waves from an external RFID reader by non-contact power transmission and performs transmission / reception using the energy. Although the communication distance is limited, the passive type can be reduced in size and price (non-patent document). 1). As the non-contact power transmission, an electromagnetic induction method is generally used although it depends on the distance. For example, it is conceivable to transmit a radio wave to the RFID side through a radio wave emission port opened in the waveguide using a waveguide provided with a radio wave emitting antenna.

  When the above-described waveguide is used, it is necessary to give a strong radio wave to the passive RFID. Therefore, the radio wave may be emitted to a place other than the RFID, and the propagation efficiency of the radio wave is deteriorated. It was. Since radio wave emitting antennas are generally expensive, there is a problem that the cost increases when many radio wave emitting antennas are provided. Accordingly, an object of the present invention has been made to solve the above-described problem, and when a radio wave is applied to an object such as a passive RFID using a waveguide, the propagation of the radio wave can be controlled efficiently. Another object is to provide a waveguide or the like that does not increase costs.

The waveguide according to the present invention is a closed waveguide having a radio wave source disposed on one end face, and is a predetermined waveguide that does not block the waveguide formed on the inner surface and in the cross-sectional direction of the waveguide. A radio wave control unit having a shape and capable of adjusting a position in an axial direction of the waveguide , wherein the radio wave control unit has one end surface different from the one end surface of the waveguide in which the radio wave source is disposed, and the radio wave control A standing wave by a radio wave radiated from the radio wave source into the waveguide, and a radio wave radiation opening opened on a side surface of the waveguide, the radio wave source being arranged At least one provided between one end face different from the one end face of the waveguide provided and the radio wave control unit, and a radio wave radiated from the radio wave source into the waveguide; Based on the radio wave control unit placed at the adjusted position, the maximum position of radio wave displacement with the radio wave control unit as an end is the position of the radio wave emission port. By generating a wave to fit, and controlling the radio wave radiated from the radio wave emitting opening to conductor wave extravascular.

  Here, in the waveguide according to the present invention, the position of the radio wave emission port can be adjusted in the axial direction of the waveguide.

  Here, in the waveguide according to the present invention, a plurality of the radio wave emission ports can be provided.

  The radio wave control method of the present invention is characterized in that a predetermined radio wave is transmitted to a target with an RFID tag using the waveguide according to any of the present inventions.

  The waveguide of the present invention is a closed tube in which a radio wave source such as a radio wave emitting antenna is disposed on one end face toward the inner surface of the waveguide. An open radio wave emission port is provided on the side surface of the waveguide. A fillet is formed on the inner surface and in the cross-sectional direction of the waveguide. The fillet has a predetermined shape that does not block the waveguide, and the position can be adjusted in the axial direction of the waveguide.

  The radio wave emitted from the power supply unit is repeatedly reflected because the inner surface of the waveguide and the fillet are made of a conductive material. As a result, as shown in the following simulation results, it was confirmed that a standing wave having a fillet as a fixed end was synthesized. That is, in reality, the end of the fillet and the waveguide (wall) behave like a fixed end, so that the wave has a complicated phenomenon. Therefore, although an ideal standing wave does not occur in the closed tube, even in such a case, it was confirmed as a result of the simulation that a portion where the strength of the radio wave is constantly strong and a portion where the strength is weak are unevenly distributed.

  Therefore, according to the waveguide of the present invention, by adjusting the position of the fillet in the axial direction, changing the phase of the radio wave, and adjusting the position of the antinode of the radio wave to the position of the radio wave emission port, The radio wave can be controlled so as to radiate a strong radio wave from the radio wave emission port without changing the position of the radio wave emission port. That is, based on the radio wave radiated from the radio wave source into the waveguide and the fillet placed at the adjusted position, the wave where the maximum position (antinode) of radio wave displacement matches the position of the radio wave radiation outlet with the fillet at the end. Thus, it is possible to control the radio wave radiated from the radio wave emission port to the outside of the waveguide. As a result, there is an effect that it is possible to provide a waveguide that can efficiently control the propagation of radio waves and does not increase the cost.

It is a figure which shows the photograph of the experiment apparatus 1 which the inventor used for experiment etc. FIG. It is a figure which shows the internal structure of the waveguide 10a. It is a figure which shows the internal structure of the waveguide 20 of this invention. It is a figure for demonstrating the acquired knowledge. An incident wave (y ₁ : Formula 1) and a reflected wave (t 1) when the period T = 1, the wavelength λ = 1, the amplitude A = 1, the incident point x = 0, and the reflection point x = L = λ. y _2: equation 2) is a diagram showing the numerical simulation results of the composite wave _(y 1 + y _2). Numerical values of simulation results of incident wave (y ₁ : formula 1), reflected wave (y ₂ : formula 2), and synthesized wave (y ₁ + y ₂ ) at t = 1/6 = 0.166667 under the same conditions as FIG. It is a figure shown by. Numerical values of simulation results of incident wave (y ₁ : formula 1), reflected wave (y ₂ : formula 2), and synthesized wave (y ₁ + y ₂ ) at t = 1/4 = 0.25 under the same conditions as FIG. It is a figure shown by. Numerical values of simulation results of incident wave (y ₁ : formula 1), reflected wave (y ₂ : formula 2), and synthesized wave (y ₁ + y ₂ ) at t = 1/2 = 0.5 under the same conditions as in FIG. It is a figure shown by. Numerical values of simulation results of incident wave (y ₁ : expression 1), reflected wave (y ₂ : expression 2), and synthesized wave (y ₁ + y ₂ ) at t = 3/5 = 0.6 under the same conditions as FIG. It is a figure shown by. Numerical values of simulation results of incident wave (y ₁ : formula 1), reflected wave (y ₂ : formula 2), and synthesized wave (y ₁ + y ₂ ) at t = 7/8 = 0.875 under the same conditions as in FIG. It is a figure shown by. It is a figure which shows the result which put together the simulation of the synthetic wave of FIGS. FIG. 11 is a graph depicting the simulation results of the synthesized wave summarized in FIG. 10. It is a figure which shows the result which put together the simulation of the synthetic wave in the case of dividing the time of 1 period T into 8 equally on the same conditions as FIG. FIG. 14 is a graph depicting the simulation results of the synthesized wave summarized in FIG. 13. It is a figure which shows the result of having put together the simulation of the synthetic wave in the case of the same conditions as FIG. 5 (however, when closed tube length L = √2λ). FIG. 16 is a graph depicting the simulation results of the synthesized wave summarized in FIG. 15. FIG. It is a figure which shows the result which put together the simulation of the synthetic wave in the case of dividing the time of 1 period T into 8 equally on the same conditions as FIG. FIG. 18 is a graph depicting the simulation results of the synthesized wave summarized in FIG. 17. Figure 13 is a diagram showing a result of summarizing the simulation of the composite wave in the case of the condition _{(y 1 + y 2 + y} 3). FIG. 20 is a graph depicting the simulation results of the synthesized wave summarized in FIG. 19. Under the same conditions as FIG. 19 is a diagram showing a result of summarizing the simulation of the composite wave in the case where 24 equal time one period T as a closed tube length _{L = √2λ (y 1 + y} 2 + y 3). Under the same conditions as FIG. 19 is a diagram showing a result of summarizing the simulation of the composite wave in the case where 24 equal time one period T as a closed tube length _{L = √2λ (y 1 + y} 2 + y 3). It is the graph which drew the simulation result of the synthetic wave put together in FIG. It is a figure which shows the waveguide in Example 1 of this invention. It is a figure which shows the waveguide in Example 1 of this invention. It is a figure which shows the waveguide in Example 2 of this invention. It is a figure which shows the waveguide in Example 2 of this invention. It is a figure which shows another waveguide in Example 2 of this invention. It is a figure which shows the waveguide in Example 3 of this invention. It is a figure which shows the example of the waveguide actually manufactured in Example 4 of this invention. It is a figure which shows the real photograph of the waveguide 20 shown by FIG.

  The inventor repeated an experiment of applying a radio wave to an object, for example, a passive RFID, using a waveguide, and as a result, reached the waveguide of the present invention based on the obtained knowledge. In the following, first, an experiment for reaching the waveguide of the present invention will be described, and then the knowledge obtained will be described. Subsequently, after showing various simulations for explaining the knowledge, each embodiment of the present invention will be described in detail with reference to the drawings.

Experiment.
FIG. 1 is a view showing a photograph of an experimental apparatus 1 used by the inventors for experiments, etc. FIG. 1 (A) is a front view of the experimental apparatus 1, and FIG. 1 (B) is a perspective view of the experimental apparatus 1. . 1A and 1B, reference numeral 2 denotes a case in which a plurality of articles with passive RFID tags are attached, 3 denotes a shelf on which case 2 is placed, 10a denotes a waveguide (left gate), Reference numerals 12a and 12b denote radio wave emission openings opened in the waveguide 10a, 10b denotes a waveguide (right gate), and 12c and 12d denote radio wave emission openings opened in the waveguide 10b. Each of the waveguides 10a and 10b is provided with one propagation emitting antenna (not shown). The distance between the waveguide 10a and the center of the shelf 3 was 88.5 cm, and the distance between the waveguides 10a and 10b was 177 cm. From the waveguides 10a and 10b, radio waves are radiated to the case 2 placed on the shelf 3 through the radio wave emission ports 12a and 12b, 12c and 12d, respectively. The inventor repeated an experiment for measuring how much radio waves can be received by the case 2 in which a plurality of articles with passive RFID tags are attached. The configuration obtained by removing the waveguides 10a and 10b from the experimental apparatus 1 is also used for the waveguide experiment of the present invention.

  FIG. 2 shows the internal structure of the waveguide 10a (front view of the waveguide 10a). In FIG. 2, the portions denoted by the same reference numerals as those in FIG. In FIG. 2, reference numeral 16a denotes a radio wave emitting antenna, and E denotes a radio wave emitted from the radio wave emitting antenna 16a into the waveguide 10a.

  The waveguide 10a has been described above with reference to FIG. Since the internal structure of the waveguide 10b is the same as the internal structure of the waveguide 10a, description thereof is omitted.

Obtained knowledge.
The inventor discovered the following knowledge through various experiments. FIG. 3 shows an internal structure of the waveguide 20 according to the present invention (a cross-sectional view in the side surface X direction of the waveguide 20 (see FIG. 1A)). In FIG. 3, reference numeral 26 denotes a radio wave emitting antenna, E denotes a radio wave emitted from the radio wave emitting antenna 26 into the inside of the waveguide 20, 22 and 22 ′ denote radio wave emitting openings opened on the side surface of the waveguide 20, 21. Is a radio wave control plate (hereinafter referred to as “fillet”) provided in the vicinity of the radio wave emission port 22. When the inventor emits the radio wave E from the radio wave emitting antenna 26 with the structure shown in FIG. 3, the intensity of the radio wave radiated from the radio wave emission port 22 or the like depending on the position of the fillet 21 in the axial direction X of the waveguide 20. The knowledge that can be controlled was able to be acquired.

  FIG. 4 shows a diagram for explaining the obtained knowledge. In FIG. 4, the portions denoted by the same reference numerals as those in FIG. As shown in FIG. 4, it is considered that a standing wave (standing wave) SW having the fillet 21 as an end (fixed end) is generated between the surface of the radio wave emitting antenna 26 and the fillet 21. As shown in FIG. 4, assuming that the standing wave SW has three antinodes (an1, an2 and an3), when the position of the antinode an1 matches the position of the radio wave emission port 22, the radio wave emission port 22 The radio wave Ean1 having the maximum intensity can be emitted in the direction D1. In the direction D2, it is possible to radiate a radio wave having an intensity corresponding to an angle between the D1 direction and the D2 direction based on the portion of the belly an1 from the radio wave emission port 22. As described above, since the inventor can change the phase of the standing wave SW depending on the position of the fillet 21 in the axial direction (X direction), the radio wave radiated from the radio wave emission port 22 according to the position of the antinode an1 or the like due to the phase. The knowledge that it can control was able to be acquired. The waveguide of the present invention is constructed based on the above knowledge.

simulation.
The inventor performed a simulation of a waveform when a radio wave was emitted from one end of a closed tube (waveguide) and reflected at the other end. The purpose of the simulation is to confirm that portions corresponding to antinodes and nodes in the standing wave are formed, including the case where two or more reflections occur even if an ideal standing wave does not occur in the closed tube. If this is confirmed, the intensity of the radio wave emitted from the radio wave emission port in the place corresponding to the belly will be strong, and the intensity of the radio wave emitted from the radio wave emission port in the place corresponding to the node will be weak. Become. In other words, the radio wave intensity is unevenly distributed. As described above, it is considered that a standing wave SW having the fillet 21 as an end (fixed end) is generated between the surface of the radio wave emitting antenna 26 and the fillet 21. Therefore, by adjusting the position of the fillet 21 in the axial direction (X direction) to change the phase of the standing wave SW, and adjusting the position of the antinode an1 and the like to the position of the radio wave emission port 22, the tube length of the closed tube and the radio wave emission port 22 The radio wave can be controlled so as to radiate a strong radio wave from the radio wave emission port 22 without changing the position. As a result, a waveguide with good propagation efficiency can be obtained.

  Hereinafter, the simulation performed by the inventor will be described in detail. The simulation was performed with a simple example. The equation of the wave of one-dimensional simple vibration is given by Equation 1, where the initial phase at the origin is zero.

Here, x is position, t is time, A is amplitude, T is period, and λ is wavelength. In this case, if a radio wave source (radio wave emitting antenna) is disposed at one end of a simple closed tube and the location is x = 0, the equation 1 is the displacement y ₁ (x, t). However, radio waves reflected at the opposite end of the closed tube are not considered.

  Next, the equation of the wave of the radio wave reflected at the end opposite to one end of the closed tube in which the radio wave source is disposed (x = L, L is the closed tube length) is expressed by the fact that x = L is a fixed end. Is given by 2.

Therefore, the equation of the wave of the radio wave considering only the amount of one round trip in the closed tube after the radio wave is emitted from the radio wave source is given by y ₁ + y ₂ . 5A and 5B show the incident wave at t = 0 when the period T = 1, the wavelength λ = 1, the amplitude A = 1, the incident point x = 0, and the reflection point x = L = λ. Numerical simulation results of (y ₁ : Formula 1), reflected wave (y ₂ : Formula 2), and synthesized wave (y ₁ + y ₂ ) are shown. For the convenience of drawing, FIG. 5A shows the simulation results up to x = 0.000-0.500 (row direction), and FIG. 5B shows x = 0.550-1.200 (row direction). The simulation results up to are shown. For example, the incident wave y ₁ = −0.588, the reflected wave y ₂ = 0.588, and the combined wave y ₁ + y ₂ = −1.176 at x = 0.100. Note that L = λ is an example of f = c / L, where f is the frequency and c is the velocity of the radio wave.

6A and 6B show the incident wave (y ₁ : expression 1), the reflected wave (y ₂ : expression 2), and the combined wave at t = 1/6 = 0.166667 under the same conditions as FIG. Numerical simulation results of (y ₁ + y ₂ ) are shown. For convenience of drawing, FIG. 6A shows the simulation results up to x = 0.000 to 0.500 (row direction), and FIG. 6B shows x = 0.550 to 1.200 (row direction). The simulation results up to are shown.

7A and 7B show incident waves (y ₁ : Formula 1), reflected waves (y ₂ : Formula 2), and composite waves at t = 1/4 = 0.25 under the same conditions as FIG. Numerical simulation results of (y ₁ + y ₂ ) are shown. For convenience of drawing, FIG. 7A shows the simulation results up to x = 0.000 to 0.500 (row direction), and FIG. 7B shows x = 0.550 to 1.200 (row direction). The simulation results up to are shown.

8A and 8B show incident waves (y ₁ : Formula 1), reflected waves (y ₂ : Formula 2), and composite waves at t = 1/2 = 0.5 under the same conditions as FIG. Numerical simulation results of (y ₁ + y ₂ ) are shown. For the sake of drawing, FIG. 8A shows the simulation results up to x = 0.000 to 0.500 (row direction), and FIG. 8B shows x = 0.550 to 1.200 (row direction). The simulation results up to are shown.

9A and 9B show incident waves (y ₁ : Formula 1), reflected waves (y ₂ : Formula 2), and composite waves at t = 3/5 = 0.6 under the same conditions as FIG. Numerical simulation results of (y ₁ + y ₂ ) are shown. For convenience of drawing, FIG. 9A shows the simulation results up to x = 0.000 to 0.500 (row direction), and FIG. 9B shows x = 0.550 to 1.200 (row direction). The simulation results up to are shown.

10A and 10B show the incident wave (y ₁ : expression 1), the reflected wave (y ₂ : expression 2), and the combined wave at t = 7/8 = 0.875 under the same conditions as FIG. Numerical simulation results of (y ₁ + y ₂ ) are shown. For convenience of drawing, FIG. 10A shows the simulation results up to x = 0.000-0.500 (row direction), and FIG. 10B shows x = 0.550-1.200 (row direction). The simulation results up to are shown.

  FIG. 11 shows the results of summarizing the synthetic wave simulations of FIGS. For convenience of drawing, FIG. 11A shows a simulation result up to x = 0.000 to 0.500 (row direction), and FIG. 11B shows x = 0.550 to 1.200 (row direction). The simulation results up to are shown. In FIGS. 11A and 11B, the column direction is time t = 0 to 7/8.

FIG. 12 is a graph depicting the simulation results of the synthesized wave summarized in FIG. In FIG. 12, the horizontal axis is x, and the vertical axis is y ₁ + y ₂ . In FIG. 12, in the original drawing, the time t = 0 is a red square, t = 1/6 is a yellow triangle, t = 1/4 is a blue wedge, t = 1/2 is a purple square, t = 3/5 is an orange circle, t = 7/8 is shown in each graph of the blue vertical line (hereinafter, in other graphs, each graph is color-coded in the original drawing, but explanation of the color-coding is omitted). As shown in FIG. 12, it was possible to confirm the generation of a standing wave having nodes at both ends (x = 0, L) and midpoint (x = 0.500) of the closed tube in the closed tube. That is, the intensity of the radio wave at the place corresponding to the node (x = 0.000 and near 0.500) is weak, while the intensity of the radio wave at the place corresponding to the belly (near x = 0.250 and 0.750). Will be strong. Therefore, if the position of the fillet 21 is adjusted so that the position corresponding to the belly (near x = 0.250 and 0.750) and the position of the radio wave emission port 22 are matched, strong radio waves are emitted from the radio wave emission port 22. Radio waves can be controlled to radiate.

  FIG. 13 shows the result of summarizing the simulation of the synthesized wave when the time of one period T is equally divided into eight under the same conditions as FIG. For convenience of drawing, FIG. 13A shows the simulation results up to x = 0.000-0.500 (row direction), and FIG. 13B shows x = 0.550-1.200 (row direction). The simulation results up to are shown. In FIGS. 13A and 13B, the column direction is time t = 0/8 to 8/8.

FIG. 14 is a graph depicting the simulation results of the combined wave summarized in FIG. In FIG. 14, the horizontal axis is x and the vertical axis is y ₁ + y ₂ . As shown in FIG. 14, it was possible to confirm the generation of a standing wave having nodes at both ends (x = 0, L) and the middle point (x = 0.500) of the closed tube. That is, the intensity of the radio wave at the place corresponding to the node (x = 0.000 and near 0.500) is weak, while the intensity of the radio wave at the place corresponding to the belly (near x = 0.250 and 0.750). Will be strong. Therefore, if the position of the fillet 21 is adjusted so that the position corresponding to the belly (near x = 0.250 and 0.750) and the position of the radio wave emission port 22 are matched, strong radio waves are emitted from the radio wave emission port 22. Radio waves can be controlled to radiate.

  In the above simulation, it can be considered that there was a special characteristic of L = λ. Therefore, as another example, simulation was performed with L = √2λ. L = λ is an example of f = √2 (c / L), where f is the frequency and c is the velocity of the radio wave. That is, this is an example in which the relationship is not limited to a general relationship of f = nc / 2L (n: an integer of 1 or more). FIG. 15 shows the result of summarizing the simulation of the synthesized wave under the same conditions as in FIG. 5 (however, the closed tube length L = √2λ). For convenience of drawing, FIG. 15A shows the simulation results up to x = 0.000 to 0.500 (row direction), and FIG. 15B shows x = 0.550 to 1.200 (row direction). The simulation results up to are shown. In FIGS. 15A and 15B, the column direction is time t = 0 to 7/8 as in the case of FIG.

FIG. 16 is a graph depicting the simulation results of the synthesized wave summarized in FIG. In FIG. 16, the horizontal axis is x, and the vertical axis is y ₁ + y ₂ . As shown in FIG. 16, it was possible to confirm the generation of a standing wave with nodes near x = 0.400 and 0.900 in the closed tube. However, when x = 0 and 1.000, it is not a clause. Therefore, the intensity of the radio wave at the location corresponding to the node (x = 0.400 and near 0.900) is weak, while the strength of the radio wave at the location corresponding to the antinode (x = 0.150 and near 0.650). Will be strong. Accordingly, if the position of the fillet 21 is adjusted so that the position corresponding to the belly (near x = 0.150 and 0.650) and the position of the radio wave emission port 22 are matched, strong radio waves can be emitted from the radio wave emission port 22. Radio waves can be controlled to radiate.

  FIG. 17 shows the result of summarizing the simulation of the synthesized wave when the time of one period T is equally divided into eight under the same conditions as in FIG. For convenience of drawing, FIG. 17A shows the simulation results up to x = 0.000 to 0.600 (row direction), and FIG. 17B shows x = 0.650 to 1.400 (row direction). The simulation results up to are shown. In FIGS. 17A and 17B, the column direction is time t = 0/8 to 8/8.

FIG. 18 is a graph depicting the simulation results of the composite wave summarized in FIG. In FIG. 18, the horizontal axis is x, and the vertical axis is y ₁ + y ₂ . As shown in FIG. 18, it was possible to confirm the generation of standing waves with nodes near x = 0.400 and 0.900 in the closed tube. However, when x = 0 and 1.000, it is not a clause. Therefore, the intensity of the radio wave at the location corresponding to the node (x = 0.400 and near 0.900) is weak, while the strength of the radio wave at the location corresponding to the antinode (x = 0.150 and near 0.650). Will be strong. Therefore, if the position of the fillet 21 is adjusted so that the position corresponding to the belly (near x = 0.150 and 0.650) and the position of the radio wave emission port 22 are matched, the radio wave having a strong intensity from the radio wave emission port 22 The radio wave can be controlled so as to be emitted.

The simulation result of the combined wave (y ₁ + y ₂ ) has been shown above. Here, considering the case where the reflected wave y ₂ is reflected once again at the point of x = 0, the equation of the wave is given by Equation 3.

Therefore, the equation of the wave motion of the radio wave considering only 1.5 reciprocations in the closed tube after the radio wave is emitted from the radio wave source is given by y ₁ + y ₂ + y ₃ . FIG. 19 shows the result of summarizing the simulation of the composite wave (y ₁ + y ₂ + y ₃ ) under the same conditions as in FIG. For convenience of drawing, FIG. 19A shows the simulation results up to x = 0.000 to 0.500 (row direction), and FIG. 19B shows x = 0.550-1.200 (row direction). The simulation results up to are shown. In FIGS. 19A and 19B, the column direction is time t = 0/8 to 8/8.

FIG. 20 is a graph depicting the simulation results of the synthesized wave summarized in FIG. In FIG. 20, the horizontal axis is x, and the vertical axis is y ₁ + y ₂ + y ₃ . As shown in FIG. 20, there is no node that exactly satisfies y ₁ + y ₂ + y ₃ = 0 in the closed tube. However, a portion where the strength of the radio wave is constantly strong (x = 0.250 and near 0.750) and a portion where the strength of the radio wave is constantly weak (x = 0.000, near 0.500 and 1.000) It can be seen that. Therefore, the discussion considering only the amount of one reciprocation in the closed tube after the radio waves from FIGS. 5 to 18 are emitted from the radio wave source can be applied to the case of 1.5 reciprocations.

Since the radio wave y1 emitted from the radio wave source and the reflected waves y2 and y3 have different phases, even if one end on the radio wave source side is a fixed end, y ₁ + y ₂ + y _3, which is the total displacement, is 0 It is normal not to be. More specifically, at the origin x = 0, the total displacement y ₂ + y ₃ of the reflected wave y2 and the re-reflected wave y3 is zero. However, since the radio wave y1 from the radio wave source is further added, y ₁ + y ₂ + y ₃ ≠ 0. From the above, the intensity of the radio wave at the portion corresponding to the node (near x = 0.050, 0.500 and 0.950) is weak, while the portion corresponding to the antinode (x = 0.250 and 0. 0). In the vicinity of 750), the intensity of the radio wave is strong. For this reason, if the position of the fillet 21 is adjusted so that the position substantially corresponding to the belly (near x = 0.250 and 0.750) and the position of the radio wave emission port 22 are matched, the strength from the radio wave emission port 22 is strong. The radio wave can be controlled to radiate the radio wave.

FIGS. 21A and 21B are simulations of the combined wave (y ₁ + y ₂ + y ₃ ) when the closed tube length L = √2λ and the time of one period T is equally divided into 24 under the same conditions as FIG. The summarized results are shown. For convenience of drawing, FIG. 21A shows the simulation results up to x = 0.000 to 0.500 (row direction), and FIG. 21B shows x = 0.550 to 1.400 (row direction). The simulation results up to are shown. In FIGS. 21A and 21B, the column direction is time t = 0/24 to 24/24.

FIG. 22 is a graph depicting the simulation results of the synthesized wave summarized in FIGS. 21 (A) and (B). In FIG. 22, the horizontal axis is x, and the vertical axis is y ₁ + y ₂ + y ₃ . As shown in FIG. 22, there is no node that exactly satisfies y ₁ + y ₂ + y ₃ = 0 in the closed tube. However, a portion where the strength of the radio wave is constantly strong (x = 0.200 and near 0.700) and a portion where the strength of the radio wave is constantly weak (x = 0.000, near 0.450 and 0.950) It can be seen that. Accordingly, as in the case of FIG. 20, the discussion taking into account only one reciprocation within the closed tube after the radio waves of FIGS. Applicable. That is, the intensity of the radio wave at a location substantially corresponding to the node (near x = 0.000, 0.450, and 0.950) is weak, whereas a location substantially corresponding to the belly (x = 0.200 and 0.700). In the vicinity), the intensity of the radio wave is strong. For this reason, if the position of the fillet 21 is adjusted so that the position substantially corresponding to the belly (x = 0.200 and 0.700 vicinity) and the position of the radio wave emission port 22 are matched, the strength from the radio wave emission port 22 is strong. The radio wave can be controlled to radiate the radio wave.

  It may be necessary to consider the interference of the combined wave for two or more round trips with both ends of the closed tube (waveguide) as fixed ends. However, as a result of the above simulation, it was found that the portion where the intensity of the radio wave is constantly strong and the portion where it is weak are unevenly distributed although it is not a standing wave. Therefore, even when there is interference of two or more reciprocal composite waves, the radio wave emission port considering only one reciprocation in the closed tube after the radio wave shown in FIGS. 5 to 18 is emitted from the radio wave source. The discussion on 12a etc. can be applied.

  Actual radio waves are not simple vibrations as assumed in the above simulation. In addition, radio waves are also reflected on the wall of the closed tube. That is, in reality, the fillet 21 and the terminal end (wall) of the waveguide 20 behave like fixed ends, so that the wave has a complicated phenomenon. Therefore, an ideal standing wave does not occur in the closed tube, but even in such a case, it is considered that the portion where the strength of the radio wave is constantly strong and the portion where the strength is weak are unevenly distributed as described above. For this reason, it is possible to apply a discussion that takes into account only one reciprocation of the inside of the closed tube after the radio waves shown in FIGS. That is, a suitable waveguide 20 can be configured by adjusting the positional relationship between the fillet 21 and the radio wave emission port 22.

  When a radio wave is applied to an object, for example, a passive RFID, using a waveguide, the fillet 21 or the like according to the frequency (and thus the wavelength) of the radio wave required by the passive RFID and the position of the radio wave emission port 22 By adjusting the position of, the waveguide 20 suitable for the application can be obtained. If the UHF band RFID (952 to 954 MHz) is selected, the wavelength of the radio wave is substantially unchanged at 31.42 to 31.49 cm. For this reason, you may think that the position (x direction) of a radio wave emission opening and a fillet is fixed.

  Based on the above simulation results, each embodiment of the present invention will be described in detail with reference to the drawings.

  FIGS. 23A and 23B show the waveguide according to the first embodiment of the present invention. 23A and 23B, the same reference numerals as those in FIG. 3 indicate the same elements, and thus description thereof is omitted. As shown in FIG. 23A, the waveguide 20 is a closed tube in which a radio wave source 26 such as a radio wave emitting antenna is disposed on one end surface (left side in the figure) toward the inner surface of the waveguide 20. . The waveguide 20 is formed of a conductive material as a whole, or is formed of a material such as wood that is not a conductive material, and the entire inner surface of the waveguide 20 is covered with a covering portion 27 of a conductive material. It may be a structure. In any case, it is preferable to use a material having a function of reflecting radio waves in the UHF band (952 to 954 MHz) as the conductive material. As shown in FIGS. 23A and 23B, an open radio wave emission port 22 is provided on the side surface of the waveguide 20. A fillet (radio wave control unit) 21 is formed on the inner surface and the cross-sectional direction (y direction) of the waveguide 20, and the fillet 21 has a predetermined shape that does not block the waveguide 20, and the waveguide 20. The position can be adjusted in the axial direction (x direction). The position of the fillet 21 may be adjusted, for example, by moving it in the x direction in a sliding manner. The material of the fillet 21 is also the conductive material. The predetermined shape of the fillet 21 is preferably a rectangle, but is not limited to this, and is not limited to this, for example, a shape having a vacant center compared to a rectangle such as a U shape, In this way, the shape may be such that the peripheral portion is vacant as compared to a rectangle. As shown in FIG. 23A, the radio wave E emitted from the power supply unit 26 is repeatedly reflected because the inner surface of the waveguide 20 and the material of the fillet 21 are conductive materials. As a result, as shown in the simulation results described above, a standing wave having the fillet 21 as a fixed end is synthesized. However, since the position of the antinode of the radio wave E shown in FIG. 23A does not coincide with the position of the radio wave emission port 22, the radio wave with the maximum intensity is not radiated from the radio wave emission port 22.

  Therefore, as shown in FIG. 23B, the position of the fillet 21 in the axial direction (x direction) is adjusted from x1 to x2 to change the phase of the radio wave E, and the position of the antinode of the radio wave E is changed to the radio wave emission port. The radio wave is controlled so as to radiate a strong radio wave from the radio wave emission port 22 without changing the tube length (L) and the position of the radio wave emission port 22 by adjusting to the position of the wave 22. Can do. By making it possible to adjust the position of the fillet 21 in the axial direction (x direction), it is possible to deal with a wide radio wave band.

  In FIG. 23B, the standing wave E is shown only on the left side of the fillet 21 in the figure. However, since the fillet 21 has a predetermined shape that does not block the waveguide 20 as described above, a standing wave having the fillet 21 as a fixed end is also generated on the right side of the fillet 21 in the figure. In this case, if another radio wave emission port 22 exists on the right side of the fillet 21 in the figure, radio waves can also be emitted from the right radio wave emission port 22. When the position of the antinode on the right side of the radio wave matches the position of the right side of the radio wave emission port 22, the radio wave having the maximum intensity can be emitted from the radio wave emission port 22 on the right side. That is, by setting the shape of the fillet 21 to a predetermined shape that does not block the waveguide 20, radio waves can be radiated from a plurality of radio wave radiation ports on the left and right of the fillet 21.

  As described above, according to the first embodiment of the present invention, the waveguide 20 is a closed tube in which a radio wave source 26 such as a radio wave emitting antenna is disposed on one end face toward the inner surface of the waveguide 20. An open radio wave emission port 22 is provided on the side surface of the waveguide 20. A fillet (radio wave control unit) 21 is formed on the inner surface and the cross-sectional direction (y direction) of the waveguide 20, and the fillet 21 has a predetermined shape that does not block the waveguide 20, and the waveguide 20. The position can be adjusted in the axial direction (x direction). The radio wave E emitted from the power supply unit 26 is repeatedly reflected because the inner surface of the waveguide 20 and the material of the fillet 21 are conductive materials. As a result, as shown in the simulation results described above, a standing wave having the fillet 21 as a fixed end is synthesized. By adjusting the position of the fillet 21 in the axial direction (x direction) to change the phase of the radio wave E, and adjusting the position of the antinode of the radio wave E to the position of the radio wave emission port 22, the tube length (L) is obtained. The radio wave can be controlled so as to radiate a strong radio wave from the radio wave emission port 22 without changing the position of the radio wave emission port 22. That is, based on the radio wave E radiated from the radio wave source 26 into the waveguide 20 and the fillet 21 placed at the adjusted position, the maximum position (antinode) of the displacement of the radio wave E with the fillet 21 as an end is the radio wave. By generating a wave that matches the position of the radiation port 22, the radio wave radiated from the radio wave radiation port 22 to the outside of the waveguide 20 can be controlled. As a result, it is possible to provide the waveguide 20 that can efficiently control the propagation of the radio wave E and does not increase the cost.

  FIGS. 24A and 24B show a waveguide according to the second embodiment of the present invention. 24A and 24B, the same reference numerals as those in FIGS. 23A and 23B indicate the same elements, and thus description thereof is omitted. As shown in FIG. 24A, the radio wave E emitted from the power supply unit 26 is repeatedly reflected because the inner surface of the waveguide 20 and the material of the fillet 21 are conductive materials. As a result, as shown in the simulation results described above, a standing wave having the fillet 21 as a fixed end is synthesized. However, since the position of the antinode of the radio wave E shown in FIG. 24A does not coincide with the position of the radio wave emission port 22, the radio wave with the maximum intensity is not radiated from the radio wave emission port 22.

  Therefore, the position of the radio wave emission port 22 can be adjusted in the axial direction (x direction) of the waveguide 20, and the position of the radio wave emission port 22 is adjusted from x3 to x4 as shown in FIG. As a result, the position of the antinode of the radio wave E is matched with the position of the radio wave emission port 22. As described above, the radio wave can be controlled to radiate a strong radio wave from the radio wave emission port 22 without changing the tube length (L) and the position of the fillet 21 of the waveguide. By making it possible to adjust the position of the radio wave emission port 22 in the axial direction (x direction), it is possible to radiate radio waves to a location according to the purpose of RFID detection, for example. The position of the radio wave emission port 22 may be adjusted, for example, by moving in the x direction in a sliding manner.

  FIG. 25 shows another waveguide according to the second embodiment of the present invention. 25, the same reference numerals as those in FIGS. 24A and 24B indicate the same elements, and thus the description thereof is omitted. As shown in FIG. 25, the waveguide 20 has a fillet 21 whose position can be adjusted in the axial direction (x direction) of the waveguide 20 described in the first embodiment, and the axial direction of the waveguide 20 described above ( It may be provided with a radio wave emission port 22 whose position can be adjusted in the (x direction).

  As described above, according to the second embodiment of the present invention, the position of the radio wave emission port 22 can be adjusted in the axial direction (x direction) of the waveguide 20. As a result, since the position of the antinode of the radio wave E can be matched with the position of the radio wave emission port 22, the intensity from the radio wave emission port 22 can be changed without changing the tube length (L) and the position of the fillet 21. The radio wave can be controlled so as to emit a strong radio wave. Therefore, it is possible to provide the waveguide 20 that can efficiently control the propagation of the radio wave E and does not increase the cost.

  FIG. 26 shows a waveguide according to the third embodiment of the present invention. 26, the same reference numerals as those in FIGS. 23A and 23B denote the same elements, and thus the description thereof is omitted. As shown in FIG. 26, the waveguide 20 has a fillet 21 whose position can be adjusted in the axial direction (x direction) of the waveguide 20 described in the first embodiment, and the waveguide 20 described in the second embodiment. A plurality of radio wave emission ports 22a and 22b whose positions can be adjusted in the axial direction (x direction) may be provided.

  In the first embodiment, an example in which radio waves are radiated from the left and right radio wave emission ports of the fillet 21 has been described using FIG. As shown in FIG. 26, the plurality of radio wave emission ports 22a and 22b may exist on the left side (one side) of the fillet 21 in the drawing. In this case, as described in the first embodiment, the position of the fillet 21 in the axial direction (x direction) is adjusted to change the phase of the radio wave E, and the position of the antinode of the radio wave E is changed to that of the radio wave emission ports 22a and / or 22b. By adjusting the position (the position of 22a and 22b, or the position of either 22a or 22b) without changing the tube length of the waveguide (L) and the positions of the radio wave emission ports 22a and 22b, The radio wave can be controlled so as to radiate a strong radio wave from the radio wave emission port 22a and / or 22b. Alternatively, as described in the second embodiment, the position of the antinode of the radio wave E is adjusted to the position of the radio wave emission port 22a and / or 22b by adjusting the position of the radio wave emission port 22a and / or 22b. As described above, the radio wave can be controlled so as to radiate a strong radio wave from the radio wave emission ports 22a and / or 22b without changing the tube length (L) and the position of the fillet 21 of the waveguide. Assuming that at least one radio wave emission port 22a is present on one side of the fillet 21, n or more (n ≧ 0) can be provided on the left and right sides of the fillet 21.

  As described above, according to the third embodiment of the present invention, the waveguide 20 can be adjusted in the axial direction (x direction) of the waveguide 20 described in the first embodiment, and the second embodiment. A plurality of radio wave emission ports 22a and 22b whose positions can be adjusted in the axial direction (x direction) of the waveguide 20 described in the above may be provided. In this case, similarly to the effects described in the first and second embodiments, it is possible to provide the waveguide 20 that can efficiently control the propagation of the radio wave E and does not increase the cost.

  FIG. 27 shows an example of a waveguide actually manufactured according to the fourth embodiment of the present invention. 27, the same reference numerals as those in FIG. 25 indicate the same elements, and thus description thereof is omitted. As shown in FIG. 27, the cross section of the waveguide 20 is 30 cm in the x-axis direction and 22 cm in the y-axis direction, the length of the fillet 21 in the y-axis direction is 6 cm, the tip of the fillet 21 and the waveguide 20. The distance from the wall was 16 cm.

  FIG. 28 shows an actual photograph of another waveguide 20 actually manufactured in Example 4 of the present invention. 28, the same reference numerals as those in FIG. 23 indicate the same elements, and thus description thereof is omitted. FIG. 28 is a perspective view of the radio wave emission port 22 and the fillet 21 taken. A case in which a plurality of articles (objects to which RFID tags are attached) with RFID tags attached are placed by using this waveguide 20 as the waveguides (left and right gates) of the experimental apparatus 1 described in FIG. 2 transmits a predetermined radio wave (for example, UHF band (952 to 954 MHz)). As described above, by adjusting the position of the fillet 21, the radio wave emission port 22, and the radio wave emission port 22 ′ (see FIG. 3) in the x-axis direction in combination as appropriate, strong radio waves are emitted from the radio wave emission port 22. You can control the radio waves.

  As an application example of the present invention, the present invention can be applied to a case where radio waves are given to a passive RFID using a waveguide.

  DESCRIPTION OF SYMBOLS 1 Experimental apparatus, 2 Case, 3 Shelf, 10a, 10b, 20 Waveguide, 11a, 11b, 21 Fillet, 12a, 12b, 12c, 12d, 22, 22 ', 22a, 22b Radio wave emission port, 16a, 26 Radio wave Source (radio wave emitting antenna), 27 covering section.

Edited by Nobuo Nakajima, “Wireless Technology and its Applications 4 New Generation Wireless Technology”, published on March 25, 2004, Maruzen Co., Ltd.

Claims (4)

A closed waveguide with a radio wave source on one end surface ,
A radio wave control unit having a predetermined shape that does not block the waveguide formed in the cross-sectional direction on the inner surface of the waveguide, and capable of adjusting the position in the axial direction of the waveguide, A standing wave by the radio wave radiated from the radio wave source into the waveguide can be generated between the radio wave control unit and the one end face different from the one end face of the waveguide in which the source is disposed. ,
A radio wave emission port opened on a side surface of the waveguide, at least one between the one end surface different from the one end surface of the waveguide where the radio wave source is disposed and the radio wave control unit. Provided with,
Based on the radio wave radiated into the waveguide from the radio wave source and the radio wave control unit placed at the adjusted position, the maximum position of radio wave displacement with the radio wave control unit as an end is the position of the radio wave emission port. A waveguide characterized by controlling a radio wave radiated from the radio wave radiation port to the outside of the waveguide by generating a wave that matches a position.   2. The waveguide according to claim 1, wherein the position of the radio wave emission port is adjustable in the axial direction of the waveguide.   3. The waveguide according to claim 1, wherein a plurality of the radio wave emission ports are provided. A radio wave control method, comprising: transmitting a predetermined radio wave to a target with an RFID tag using the waveguide according to claim 1.