JP2011087296A - Rfid reader antenna and rfid shelf having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an RFID reader antenna capable of concurrently recognizing individual article units for a plurality of articles within a short distance. <P>SOLUTION: An RFID reader antenna includes: a printed circuit board (PCB) formed from a dielectric substance; a plurality of slot groups, each having a plurality of slots and being disposed on a first face of the PCB; a ground face disposed on areas, excluding the plurality of slot groups, of the first face of the PCB; and a feeder formed from a microstrip line with an open end on a second face of the PCB to feed the plurality of slot groups. Because the slots periodically formed on the ground face are fed in series by using the single microstrip line, the RFID reader antenna can reliably recognize a larger area with a simple structure. In particular, the RFID reader antenna can be useful for the bookstands for book management or smart shelves for displaying articles or goods including clothing goods in superstores or hypermarkets in the RFID application for individual article unit recognition. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an RFID reader antenna and an RFID shelf including the RFID reader antenna. More specifically, the present invention relates to an RFID reader antenna capable of simultaneously recognizing individual article units for a plurality of items at a short distance and an RFID shelf including the RFID reader antenna.

  The field of application of RFID has been expanded from pallet, case or box unit recognition to individual item unit recognition (ILT).

  High frequency (HF) RFID technology is generally preferred for individual article unit recognition, but tag size and value, recognition distance and data processing speed, and existing ultra high frequency (UHF) Frequently) issues such as compatibility with RFID standards in the band have been raised.

  Unlike RFID technology in the high frequency (HF) band using the magnetic coupling (Magnetic Coupling) method, RFID technology in the ultra-high frequency (UHF) band using the back scattering (Electromagnetic Wave) method has a recognition distance. It has been widely used for distribution / distribution in pallet units and material management in box units using the advantage of being relatively long, 3 m to 5 m.

  However, the ultra-high frequency (UHF) band RFID technology has a performance in which the recognition rate rapidly drops due to scattering and interference of electromagnetic waves in an application field of individual article unit recognition (ILT) where a large number of articles are densely packed. In order to overcome the shortcomings of ultra-high frequency (UHF) band RFID technology as described above in individual article unit recognition, recently, near field (Near Field), or near field and far field (Far) in the ultra high frequency (UHF) band. RFID technology using Field) is being actively promoted.

  Ultra-high frequency (UHF) band RFID technology developers use ultra-high frequency (UHF) band far field for pallet and box unit recognition and ultra-high frequency (UHF) band near field for large-scale individual article unit recognition Is used, it is claimed that not only pallets and boxes but also individual article unit recognition is possible in one frequency band.

  Unlike RFID in the high frequency (HF) band, which uses the magnetic coupling method, if a near field in the ultra high frequency (UHF) band is used, the magnetic coupling method and the electric coupling method (Electrical Coupling) depending on the article and service environment to which the tag is attached. Can be selected appropriately.

  However, the near-field RFID reader antenna in the ultra-high frequency (UHF) band has to be designed with a different concept from the existing far-field antenna. In other words, it must be designed in consideration of the environment for individual article unit recognition, tag attachment position, required near field distribution, and the like.

  In addition, since near-field communication is performed by a coupling method between a reader antenna and a tag antenna, the structure of the tag antenna should also be considered in the design of the reader antenna. Furthermore, when recognizing a plurality of dense individual unit articles, the design concept of the reader antenna must change depending on the distance between the reader antenna and the recognized article and the direction of the article.

  That is, when a plurality of closely packed items are separated from the reader antenna at a short distance, the reader antenna must be designed as an antenna that appropriately mixes near field and far field, and a plurality of tag directions are If it is not constant, the reader antenna needs to be designed as an antenna having the characteristics of circular polarization.

Korean Published Patent No. 2006-702003

  An object of the present invention is to provide an RFID reader antenna capable of simultaneously recognizing individual article units for a plurality of articles at a short distance and an RFID shelf including the RFID reader antenna.

  An RFID reader antenna for achieving the above-described object of the present invention includes a printed circuit board formed of a dielectric and a plurality of slots, and a plurality of slot groups disposed on the first surface of the printed circuit board. A ground plane disposed in a region other than the plurality of slot groups in the first surface of the printed circuit board; and a second surface of the printed circuit board for supplying power to the plurality of slot groups. And a power supply line formed of a microstrip line having an open end.

  Here, the plurality of slot groups may be arranged at a position where a current distribution value by the feeder line is larger than a predetermined current distribution value.

  Here, the plurality of slot groups may be arranged such that a phase difference between transmission signals by the slot group is smaller than a predetermined phase difference.

  Here, the plurality of slot groups may be configured such that the intensity of the transmission signal from the slot group is larger than a predetermined intensity.

  Here, the intensity of the transmission signal by the slot group can be controlled according to the length of the slot intersecting with the feeder line.

  Here, the length of the slot intersecting with the feeder line may be configured to be longer as it is closer to the open end of the feeder line.

  Here, the transmission signal by the slot group can be arranged so as to exhibit the characteristics of circular polarization.

  Here, the characteristic of the circular polarization of the transmission signal by the slot group can be formed by the distance between the slots constituting the slot group.

  Here, the slots constituting the slot group may be arranged so that the directions of transmission signals by the slots are formed in directions intersecting each other.

  Here, the slots constituting the slot group can be arranged such that phases of transmission signals by the slots are formed different from each other.

  Here, in the slots constituting the slot group, the phase of the transmission signal by the slots can be controlled according to the distance between the slots.

  Here, the feeder line may be arranged so that a standing wave is formed.

  Here, the power supply line may be formed so as to be serially fed to each of the slot groups.

  Here, the feeder line may be configured in a meander shape for compensating the length.

Here, the RFID reader antenna may use a wavelength in a very high frequency band.

  Here, the RFID reader antenna may provide a near field and a far field at the same time.

  An RFID shelf including an RFID reader antenna for achieving another object of the present invention described above includes a printed circuit board formed of a dielectric and a plurality of slots, and is disposed on the first surface of the printed circuit board. A plurality of slot groups, a ground plane disposed in a region of the first surface of the printed circuit board other than the plurality of slot groups, and the printed circuit board for supplying power to the plurality of slot groups. And a power supply line formed of a microstrip line having an open end on the second surface of the circuit board.

  Here, the transmission signal by the slot group can be arranged so as to exhibit the characteristics of circular polarization.

  Here, the characteristic of the circular polarization of the transmission signal by the slot group can be formed by the distance between the slots constituting the slot group.

  Here, the slots constituting the slot group may be arranged so that the directions of transmission signals by the slots are formed in directions intersecting each other.

  According to the RFID reader antenna and the RFID shelf including the RFID reader antenna as described above, a single-layer single antenna is used in an individual article unit recognition RFID application, and a near field having a wide recognition area in the vicinity (Near Field Zone). It is possible to provide an antenna that mixes the characteristics of the far field and the far field.

  That is, it is possible to provide an RFID antenna capable of stably recognizing a wide area with a simple structure by feeding a series of slots periodically formed on a ground plane using a single microstrip line. it can.

  In particular, in RFID applications for individual article unit recognition, it can be very usefully used for bookshelves for book management and smart shelves for large mart article display including clothing articles.

1 is a conceptual diagram illustrating an RFID reader antenna according to an embodiment of the present invention. 1 is a configuration diagram illustrating an RFID reader antenna according to an embodiment of the present invention. FIG. 5 is a conceptual diagram for explaining a current distribution by a feeder line in an RFID reader antenna according to an embodiment of the present invention. 1 is a cross-sectional view illustrating an RFID reader antenna according to an embodiment of the present invention. FIG. 3 is a perspective view for explaining a configuration of a slot in an RFID reader antenna according to an embodiment of the present invention. FIG. 6 is an exemplary diagram for explaining a circularly polarized wave characteristic depending on a slot configuration in an RFID reader antenna according to an embodiment of the present invention. FIG. 5 is a perspective view for explaining a configuration of a slot in an RFID reader antenna according to another embodiment of the present invention. FIG. 6 is an exemplary diagram for explaining the characteristics of circularly polarized waves according to a slot configuration in an RFID reader antenna according to another embodiment of the present invention.

  While the invention is amenable to various modifications and alternative forms, specific embodiments will be described in detail hereinafter with reference to the drawings.

  However, this should not be construed as limiting the present invention to the specific embodiments but should include all modifications, equivalents or alternatives that fall within the spirit and scope of the present invention.

  Terms such as “first” and “second” are used to describe various components, but the components are not limited by the terms. The above terms are only used to distinguish one component from another. For example, the first component can be named as the second component without departing from the scope of the present invention, and the second component can be named as the first component as well. The term “and / or” includes any of a combination of a plurality of related description items or a plurality of related description items.

  When a component is “coupled” or “connected” to another component, it may be directly coupled to or connected to another component, while other components It must be understood that the element can exist. On the other hand, when a component is “directly connected” or “directly connected” to another component, it must be understood that no other component exists between them.

  The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. A singular expression includes a plurality of expressions unless the context clearly differs. In this application, terms such as “comprising” or “having” are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described in the specification. And should not be understood as pre-excluding the existence or additionality of one or more other features or numbers, steps, actions, components, parts or combinations thereof. Don't be.

  Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Have. The same terms defined in commonly used dictionaries should be construed to have a meaning consistent with the contextual meaning of the related art and, unless explicitly defined in this application, are ideal and overly formal Not interpreted in meaning.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate overall understanding, the same components in the drawings are denoted by the same reference numerals, and redundant description of the same components is omitted.

  FIG. 1 is a conceptual diagram for explaining an RFID reader antenna according to an embodiment of the present invention.

  Referring to FIG. 1, a near field region and a far field region of a general antenna are shown.

  The near-field region is a region where electric field energy or magnetic field energy is concentrated, and communication is performed between the RFID reader and the tag by an electric field coupling or magnetic field coupling method. In the far field region, the electric field and the magnetic field are strongly coupled. In the region where the electromagnetic wave is present, communication is performed between the RFID reader and the tag by an electromagnetic wave method.

  Therefore, the design concept of the RFID tag and the reader antenna must be changed depending on in which region the RFID application is mainly performed. In addition, as the RFID application, an application in a far field, an application in a near field, or an application of appropriately mixing a far field and a near field is possible.

  In FIG. 1, r is a distance that roughly indicates the boundary between the near-field region and the far-field region centering on the antenna. When a general antenna is used as a reference, r = 2D2 / λ. When an electrically small antenna is used as a reference, r = λ / 2π. Here, D is the maximum size of the antenna, and λ is the wavelength of the center frequency.

  FIG. 2 is a block diagram illustrating an RFID reader antenna according to an embodiment of the present invention.

  Referring to FIG. 2, an RFID reader antenna 200 according to an embodiment of the present invention includes a printed circuit board 210 formed of a dielectric and a plurality of slots, and is disposed on a first surface of the printed circuit board. A plurality of slot groups 220, a ground plane 230 disposed in a region other than the plurality of slot groups on the first surface of the printed circuit board, and the printed circuit board for supplying power to the plurality of slot groups. And a power supply line 240 formed of a microstrip line having an open end on the second surface of the circuit board.

  First, the printed circuit board (PCB) 210 is a thin board on which a chip or other electronic component is installed. Generally, a printed circuit board is made of reinforced fiber glass or plastic, and components are connected to each other through a circuit made of copper. Here, the printed circuit board 210 may be formed of a dielectric.

  Next, the plurality of slot groups 220 may be configured by a plurality of slots and disposed on the first surface of the printed circuit board 210. That is, the plurality of slots may form one slot group, and the plurality of slot groups may be formed on the first surface of the printed circuit board 210.

  FIG. 3 is a conceptual diagram for explaining a current distribution by a feeder line in an RFID reader antenna according to an embodiment of the present invention.

  Referring to FIG. 1 and FIG. 3 in parallel, the plurality of slot groups 220 may be arranged at positions where the current distribution value by the feeder line 240 is larger than a predetermined current distribution value. it can. For example, the predetermined current distribution value may be 5% lower than the maximum current distribution value, or 10% lower.

  The plurality of slot groups 220 may be arranged such that a phase difference between transmission signals by the slot groups is smaller than a predetermined phase difference. For example, the predetermined phase difference can be set to 5 degrees or 10 degrees with reference to the transmission signal by the first slot group.

  Referring to FIG. 1 and FIG. 3 in parallel, since the feed line 240 has an open end (Open End) 241, when power is fed using the feed line 240, a traveling wave and a reflected wave are combined, A standing wave 330 is formed on the feeder line 240. In FIG. 3, a standing wave distribution 330 indicates a current distribution.

  There is almost no current distribution in the open end 241. However, the current distribution is maximum at the point 311 moved by a distance of λ / 4 from the open end 241. Every time the point 311 moves from the point 311 where the current distribution is maximum by a distance of λ / 2, points 312 and 313 where the current distribution is maximum exist periodically.

  However, there is a difference of 180 degrees from the current phase 321 at the point 311 where the current distribution is maximum and the current phase 322 at the other maximum point 312 moved by a distance of λ / 2. The current phase 323 at another maximum point 313 moved by a distance of λ / 2 from the point 312 is further different from the current phase 322 at the maximum point 312 by 180 degrees.

  That is, the current distribution is maximum at the point 313 moved by a multiple of the distance λ from the maximum point 311 of the current distribution closest to the terminal point 241 of the feeder line 240, but at the same time, the same points are also periodically set in the phases 321 and 323. It can be seen that it can be formed.

  Therefore, it corresponds to a point where the current distribution is maximum, and resonates at the frequency at a position corresponding to a point moved by a multiple of the distance λ from the maximum point 311 of the current distribution closest to the terminal point of the feeder line. When a slot having an appropriate shape is formed and arranged, the transmission signal can be efficiently emitted by the slot.

  That is, in order to feed a plurality of slots with a current having a uniform size and phase, in the present invention, a point separated by λ / 4 from the end of the feed line 240 and a point separated from the λ / 4 point by a λ interval. When the feeder line 240 is designed so that a slot group is periodically formed and a current distribution having a uniform phase and size is excited in the slot group, the slot group periodically formed with one feeder line 240 is used. It is possible to generate a substantially uniform near field in a wide range.

  Furthermore, the transmission signals from the plurality of slot groups 220 may be arranged so as to exhibit circular polarization characteristics, and the circular polarization characteristics of the transmission signals from the slot groups 220 are determined from the slot groups. Can be formed by the distance between the slots constituting the.

  The slots constituting the slot group 220 may be arranged such that directions of transmission signals by the slots are formed in directions intersecting each other, and the slots constituting the slot group 220 are The transmission signals of the slots may be arranged so that the phases thereof are different from each other. In the slots constituting the slot group 220, the phase of the transmission signal by the slots can be controlled according to the distance between the slots.

  FIG. 4 is a cross-sectional view illustrating an RFID reader antenna according to an embodiment of the present invention.

  Referring to FIGS. 1 and 4 in parallel, a ground plane 230 is formed on the first surface (upper surface) of the printed circuit board 210, and a power supply line 240 for power supply is formed on the second surface (lower surface). Is formed. Slots 221, 222, and 223 that resonate at a specific frequency for electromagnetic radiation are periodically formed on the ground surface 230.

  A standing wave-like current distribution is formed in the feeder line 240 whose end is opened (241). There is a point where the current distribution is maximum at a point away from the terminal point 241 of the feeder line 241 by a distance of λ / 4, and one slot group 221 that resonates at a specific frequency is connected to the above point. Form on the ground 230.

  One slot group 221 formed on the ground plane 230 can have various patterns according to the application of the present invention. That is, the slot group may be composed of a pair of slots or may be composed of three or more slots. Furthermore, it may be formed in various patterns for each slot. In the following description, it is assumed that there are two slots constituting the slot group.

  Further, since the antenna radiates an electric field having a circular polarization characteristic, the slots of the slot group 221 are formed so as to intersect with each other, and the phase difference of the current excited in the slots is 90 degrees. Can be. Here, the phase difference between the currents excited in the two slots can be controlled according to the distance S.

  That is, using the distance between two orthogonal slots, the excited current can have a phase difference of 90 degrees in the two orthogonal slots. In addition, even when there are three or more slots, it is possible to set so as to emit an electric field having a circular polarization characteristic by using the above method.

  Referring to FIGS. 1 and 4 in parallel, when the distance of λ is moved from the point where the slot group 221 exists, the current distribution and the phase have the same size as the position where the slot group 221 exists. As the slot group 222 is formed at the point, the slot group 221, 222, 223 has the same current distribution and phase as the slot group 221. It can be powered.

  That is, a current distribution having the same phase and size is excited in a plurality of slot groups 221, 222, and 223 that are periodically formed at λ intervals using a feeder 240 having a standing wave current distribution. be able to.

  Next, the grounding surface 230 may be disposed in a region other than the plurality of slot groups on the first surface of the printed circuit board 210. That is, since the plurality of slot groups 220 existing on the first surface of the printed circuit board 210 are regions used for electromagnetic wave radiation, all regions other than the plurality of slot groups are formed on the ground plane. It becomes like this.

  Next, the power supply line 240 may be arranged so that a standing wave is formed, and the power supply line 240 is formed to supply power in series to the respective slot groups. Can be things. In addition, the feeder line 240 may be configured in a meander shape for compensating the length.

  FIG. 5 is a perspective view for explaining the structure of the slot in the RFID reader antenna according to the embodiment of the present invention.

  Referring to FIG. 5, an RFID reader antenna according to an embodiment of the present invention includes a slot group 220 periodically formed on a ground surface 230 of a single-layer printed circuit board 210 and a feeder line 240 formed on the opposite surface. It is a structure which uses and feeds in series.

  That is, an RFID reader antenna according to an embodiment of the present invention includes a printed circuit board 210 formed of a single dielectric layer, a feeder line 240 for feeding power to the lower end of the printed circuit board 210, and the printed circuit. And a ground plane 230 formed at the upper end of the substrate 210. The ground plane 230 may include a plurality of slot groups 221, 222, and 223 for radiation.

  Further, when the plurality of slot groups 221, 222, and 223 are serially fed using the feed line 240 formed of a microstrip line as described above, the amount of current decreases in order from the feed point 242 to the terminal 241. Thus, the amount of current excited in the last slot group may be very small.

  That is, the current fed to the feeding point 242 is excited in the first slot group 223, then excited in the second slot group 222, and the remaining current is excited in the last slot group 221. The current excited in the above process gradually decreases while passing through the slot groups 223, 222, and 221.

  In the present invention, in order to solve this, distances d3, d2, and d1 at which the feeder line 240 and the slot intersect are used. That is, since the amount of current excited in the slot can be changed depending on the distance at which the microstrip line and the slot intersect, when the intersecting distances d3, d2, and d1 are sequentially increased (d3 <d2 <d1). The amount of current excited in the three slot groups can be made uniform.

  In addition, the power supply line 240 between the slot groups may have a meander shape 243 in order to supply currents of the same phase to the slot groups 223, 222, and 221. The phase of the current excited in each slot group can be controlled using the length of the feeder line 240 having the meander shape 243. Here, the distance between the terminal end 241 of the feed line 240 and the first slot group 221 is λ / 4.

  Another object of the present invention is to enable the RFID reader antenna to stably recognize the tag regardless of the direction of the RFID tag. Therefore, the reader antenna must have a circular polarization characteristic.

  Due to the circular polarization characteristics of the reader antenna, the slots constituting the slot group must be formed so as to physically intersect each other, and when the slot group is constituted by two slots, The phase difference between the currents excited between the two slots formed by the slot pair must be 90 degrees. The phase difference between the currents excited in the two slots can be controlled according to S. That is, the distance between two orthogonal slots can be used so that the current excited in the two orthogonal slots has a phase difference of 90 degrees.

  As a result, the plurality of slot groups can be arranged such that a phase difference between transmission signals by the slot groups is smaller than a predetermined phase difference, and the plurality of slot groups Can be configured such that the intensity of the transmission signal by the slot group is greater than a predetermined intensity.

  For example, the predetermined phase difference may be set to 5 degrees or 10 degrees with reference to the transmission signal by the first slot group, and the predetermined intensity is an intensity 5% smaller than the maximum intensity. Etc. may be determined.

  Further, the intensity of the transmission signal by the slot group can be controlled according to the length of the slot intersecting with the feed line, and the length of the slot intersecting with the feed line is determined by the feed line. The closer to the open end, the longer it can be constructed.

  FIG. 6 is an exemplary diagram for explaining the characteristics of circularly polarized waves depending on the slot configuration in the RFID reader antenna according to the embodiment of the present invention.

  Referring to FIG. 6, it is possible to confirm a change in the direction of the electric field excited in each slot according to a change in time. When it is assumed that the number of slots constituting the slot group is two, the phase difference between the currents excited in the two slots is set to 90 degrees by appropriately using the distance S between the pair of slots 221 constituting the slot group. , The direction of the electric field 600 radiating from the slot pair can be formed as shown in FIG.

  That is, the direction of the electric field 600 that is radiated is rotated once as the time of one period T elapses. That is, assuming that the direction of the electric field 600 is “−X” direction at t = 0, the direction of the electric field 600 is “Y” direction at t = T / 4, and the direction of the electric field 600 is “X” at t = 2T / 4. Direction, and at t = 3T / 4, the direction of the electric field 600 has a “−Y” direction.

  FIG. 7 is a perspective view illustrating a slot configuration in an RFID reader antenna according to another embodiment of the present invention.

  Referring to FIG. 7, the antenna of FIG. 7 is formed of a single-layer printed circuit board and has a structure in which power is fed in series by a feeder line. The RFID reader antenna according to another embodiment of the present invention includes a printed circuit board 210 formed of a single dielectric, a power supply line 240 for supplying power to the lower end of the printed circuit board 210, and the printed circuit. And a grounding surface 230 at the upper end of the substrate 210. The ground plane 230 may have a plurality of slot groups 224, 225, and 226 for radiation.

  In addition, when a plurality of slot groups 224, 225, and 226 are fed in series using the feeder line 240 as described above, the amount of current decreases in order from the feeding point 242 to the terminal 241. The amount of current excited in the slot pair can be very small. That is, the current fed to the feeding point 242 is excited in the first slot group 226 and then excited in the second slot group 225, and the remaining current is excited in the last slot group 224. The current excited in the above process decreases in order while passing through the slot groups 226, 225, and 224.

  In the present invention, in order to solve this, distances d3, d2, and d1 at which the feeder line 240 and the slot intersect are used. That is, since the amount of current excited in the slot can be changed depending on the distance at which the microstrip line and the slot intersect, when the intersecting distances d3, d2, and d1 are sequentially increased (d3 <d2 <d1). The amount of current excited in the three slot groups can be made uniform.

  Further, in order to supply currents of the same phase to the slot groups 226, 225, and 224, the feed line 240 between the slot groups may have a meander shape 243.

  In addition, since the antenna of FIG. 7 also exhibits circular polarization characteristics, the slots must be formed so as to physically intersect each other, and the level of current excited between the two slots formed in pairs. The phase difference must be 90 degrees. The phase difference between the currents excited in the two slots can be controlled according to S. That is, the distance between two orthogonal slots must be used so that the current excited in the two orthogonal slots has a 90 degree phase difference.

  Further, when there are three or more slots constituting the slot group, similarly, the phase difference of the current in each slot has different phase difference values such as 60 degrees in order to show the characteristics of circular polarization. It is possible to control as follows.

  FIG. 8 is an exemplary diagram for explaining the characteristics of circularly polarized waves depending on the slot configuration in an RFID reader antenna according to another embodiment of the present invention.

  Referring to FIG. 8, in an RFID reader antenna according to another embodiment of the present invention, a change in the direction of an electric field excited in each slot according to a change in time can be confirmed. When the phase difference between the currents excited in the two slots is maintained at 90 degrees by appropriately using the distance S between the pair of slots 224-1 and 224-2 constituting the slot group 224, the slot radiates. The direction of the electric field 800 is shown as in FIG. That is, the direction of the electric field 800 that is radiated is rotated once as the time of one period T elapses.

  On the other hand, the RFID reader antenna may use a wavelength in a very high frequency band, and the RFID reader antenna may provide a near field and a far field at the same time.

  Further, the RFID shelf including the RFID reader antenna includes a printed circuit board formed of a dielectric material, a plurality of slots, a plurality of slot groups arranged on the first surface of the printed circuit board, and the printed circuit board. Of the first surface, a ground plane disposed in a region other than the plurality of slot groups, and a micro-terminal having an end opened on the second surface of the printed circuit board for supplying power to the plurality of slot groups. And a feeder line formed by a strip line.

  In the RFID shelf including the RFID reader antenna, the transmission signal by the slot group can be arranged so as to show the characteristics of circular polarization, and the circular polarization characteristic of the transmission signal by the slot group is It can be formed by the distance between the slots constituting the slot group. In addition, the slots constituting the slot group in the RFID shelf including the RFID reader antenna can be arranged such that directions of transmission signals by the slots are formed in directions intersecting each other.

  Although the present invention has been described with reference to the embodiments, those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention described in the claims. Must understand.

200 RFID reader antenna 210 Printed circuit board 220 Multiple slot groups 221, 222, 223 Slot group 221-1 First slot 221-2 Second slot 230 Ground plane 240 Feed line 241 Open termination 242 Feed point 243 Meander shape

Claims (20)

A printed circuit board formed of a dielectric;
A plurality of slots configured by a plurality of slots and disposed on the first surface of the printed circuit board;
Of the first surface of the printed circuit board, a ground plane disposed in a region other than the plurality of slot groups,
An RFID reader antenna comprising: a power supply line formed of a microstrip line having an end terminated on the second surface of the printed circuit board for supplying power to the plurality of slot groups.   2. The RFID reader antenna according to claim 1, wherein the plurality of slot groups are arranged at positions where a current distribution value by the feeder line is larger than a predetermined current distribution value.   2. The RFID reader antenna according to claim 1, wherein the plurality of slot groups are arranged such that a phase difference between transmission signals by the slot group is smaller than a predetermined phase difference.   2. The RFID reader antenna according to claim 1, wherein the plurality of slot groups are configured such that an intensity of a transmission signal from the slot group is larger than a predetermined intensity.   The RFID reader antenna according to claim 4, wherein the intensity of the transmission signal by the slot group is controlled in accordance with the length of the slot intersecting with the feeder line.   6. The RFID reader antenna according to claim 5, wherein the length of the slot intersecting with the feed line is configured to be longer as it is closer to the open end of the feed line.   2. The RFID reader antenna according to claim 1, wherein the transmission signals by the slot groups are arranged so as to exhibit circular polarization characteristics.   The RFID reader antenna according to claim 7, wherein the characteristic of circular polarization of a transmission signal by the slot group is formed by a distance between slots constituting the slot group.   2. The RFID reader antenna according to claim 1, wherein the slots constituting the slot group are arranged such that directions of transmission signals by the slots are formed in directions intersecting each other.   2. The RFID reader antenna according to claim 1, wherein the slots constituting the slot group are arranged so that phases of transmission signals by the slots are formed different from each other.   2. The RFID reader antenna according to claim 1, wherein a phase of a transmission signal by the slot in the slots constituting the slot group is controlled according to a distance between the slots.   The RFID reader antenna according to claim 1, wherein the feeder line is disposed so as to form a standing wave.   2. The RFID reader antenna according to claim 1, wherein the feed line is formed so as to feed power in series to the respective slot groups.   The RFID reader antenna according to claim 1, wherein the feeder line is configured in a meander shape for compensating the length.   The RFID reader antenna according to claim 1, wherein the RFID reader antenna uses a wavelength in a very high frequency band.   The RFID reader antenna according to claim 1, wherein the RFID reader antenna provides a near field and a far field at the same time. A printed circuit board formed of a dielectric;
A plurality of slots configured by a plurality of slots and disposed on the first surface of the printed circuit board;
Of the first surface of the printed circuit board, a ground plane disposed in a region other than the plurality of slot groups,
An RFID including an RFID reader antenna configured to include a power supply line formed of a microstrip line having an end terminated on the second surface of the printed circuit board for supplying power to the plurality of slot groups shelf.   18. The RFID shelf including the RFID reader antenna according to claim 17, wherein the transmission signals by the slot group are arranged so as to exhibit circular polarization characteristics.   19. The RFID shelf including an RFID reader antenna according to claim 18, wherein the characteristic of circular polarization of a transmission signal by the slot group is formed by a distance between slots constituting the slot group.   18. The RFID shelf including the RFID reader antenna according to claim 17, wherein the slots constituting the slot group are arranged so that directions of transmission signals by the slots are formed in directions intersecting each other.

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