The present invention relates to a wireless communication apparatus, an electronic equipment, and a radiographing system.
Some wireless communication apparatuses that perform wireless communication using wireless LAN and Bluetooth (Registered Trademark) adopt a communication system utilizing a plurality of antennas, such as a Multiple Input Multiple Output (MIMO) system. In such a communication system that performs communication simultaneously through a plurality of antennas, communication speed is increased compared to a system where only one antenna is used, but there is a drawback in that communication performance is deteriorated if the radio waves output from the respective antennas interfere with each other. Therefore, WO2010/073429 A1 proposes an antenna unit in which each of a plurality of power fed antenna elements are each provided with two parasitic antennas having a switch. The antenna unit disclosed in WO2010/073429 A1 allows the parasitic antenna to operate as a reflector by switching electrical lengths of the parasitic antenna elements using a switching circuit, in addition to a metal block serving as a reflector, so as to enable switching of directivity of radio waves to thereby reduce radio frequency interference.
There are demands to apply a communication system using a plurality of antennas as described above to an apparatus such as a portable, compact, thin-plate shaped, i.e., tablet-shaped, X-ray imaging apparatus that is capable of visualizing an inside of a living body by X-ray irradiation. However, when a technique as disclosed in WO2010/073429 A1 is applied to such a thin plate-shaped apparatus, since the apparatus has a small thickness, the electrical length may not be maintained unless the parasitic antennas and the metal blocks are bent. When the parasitic antennas and the metal blocks are bent, reflection of radio waves may be deviated, such that partial interference of radio waves becomes inevitable, and the communication performance may be deteriorated.
According to a first aspect of the present invention, a wireless communication apparatus includes a first antenna, a second antenna, a control unit configured to output a signal to the first antenna and the second antenna, a first wiring configured to connect the control unit and the first antenna, a second wiring configured to connect the control unit and the second antenna, a casing formed of a conductor, the casing being configured to accommodate the first antenna, the second antenna, the control unit, the first wiring, and the second wiring, and including a first opening disposed in opposition to the first antenna and a second opening disposed in opposition to the second antenna, and a partition portion formed of a conductor and configured to partition the first antenna and the first opening from the second antenna and the second opening.
According to a first aspect of the present invention, a wireless communication apparatus includes a first antenna, a second antenna, a control unit configured to output a signal to the first antenna and the second antenna, a first wiring configured to connect the control unit and the first antenna, a second wiring configured to connect the control unit and the second antenna, a casing including a pair of a first plate-shaped surface and a second plate-shaped surface that are each formed of a conductor and that are disposed in opposition to each other, a first side surface, a second side surface, a third side surface, and a fourth side surface configured to connect edges of the first plate-shaped surface and the second plate-shaped surface, the casing configured to accommodate the first antenna, the second antenna, the control unit, the first wiring, and the second wiring, and the casing including a first opening disposed in opposition to the first antenna, a second opening disposed in opposition to the second antenna, and a fifth opening provided between the first opening and the second opening, a first partition portion formed of a conductor and disposed so as to partition the first antenna and the first opening from the fifth opening, a second partition portion formed of a conductor and disposed so as to partition the second antenna and the second opening from the fifth opening, and a third surrounding portion formed of a conductor and disposed so as to surround the fifth opening in a surface direction of the first plate-shaped surface.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
A first embodiment for carrying out the present technique will be described with reference to the drawings.
At first, a radiographing system to which the present embodiment may be applied is described.
The radiation generating apparatus 550 is installed movably on a ceiling 503. The radiographing system 900 is a ceiling traveling system, and the radiation generating apparatus 550 may be moved three-dimensionally in up-down and right-left directions with respect to the ceiling 503.
A stand 501 is fixed to and installed on a floor surface 504. The stand 501 is a support base for upright radiographing. A bed 502 is fixed to and installed on the floor surface 504. The bed 502 is a support base for lying position radiographing. The stand 501 and the bed 502 are each provided with the wireless communication apparatus 1, which are mounted in a detachable manner. The wireless communication apparatus 1 may be replaced and installed. In other words, the wireless communication apparatus 1 accommodated in a storage portion of the bed 502 may be reinstalled in the stand 501.
The radiographing system 900 includes an input device not shown such as a mouse or a keyboard connected to the control apparatus 700 through which an operator may enter instructions, and a display portion 703 that displays a radiation image being taken and various information. The display portion 703 may also serve as the input device such as a touch panel. Further, a terminal apparatus, such as a tablet or a smartphone, that enables instructions from an operator to be entered to the control apparatus 700 and to display the radiation image being taken and various information may be used as the input device and display portion 703. The control apparatus 700 and the display portion 703 are installed in an exterior of a radiographing chamber 600, i.e., operation chamber.
The control apparatus 700 may communicate with a plurality of wireless communication apparatuses 1 and control the radiographing thereof. Further, the control apparatus 700 communicates with the radiation generating apparatus 550 and controls the irradiation of radiation of the radiation generating apparatus 550. In the present embodiment, an example is illustrated where there are three wireless communication apparatuses 1, but the number of wireless communication apparatuses 1 is not limited to three, and it may be one, two, or four or more.
The wireless communication apparatus 1 is transited to an imaging enabled state, i.e., READY state, based on the control performed by the control apparatus 700, and is enabled to perform radiographing by synchronizing with the control apparatus 700. The wireless communication apparatus 1 may perform radiographing of radiation irradiated from the radiation generating apparatus 550 to generate a radiation image data.
The control apparatus 700 may acquire the radiation image data generated by each of the wireless communication apparatuses 1 and transmitted through wireless communication. The radiation image data generated in each wireless communication apparatus 1 is formed into a radiation image at the control apparatus 700 and displayed on the display portion 703 or displayed on a display unit of a terminal device.
The control apparatus 700 has a function to perform various image processing, such as a noise removal processing or a gradation processing, to the radiation image being formed. Further, the control apparatus 700 includes, as a functional configuration, an imaging control unit 701 that sets imaging conditions of the radiation generating apparatus 550, and controls irradiation of radiation from the radiation generating apparatus 550 based on the imaging conditions being set. Further, the control apparatus 700 includes, as functional configuration, a communication control unit 702 that controls wired or wireless communication with the wireless communication apparatus 1 and controls setting of communication conditions of the wireless communication apparatus 1.
As illustrated in
The control apparatus 700 is connected to a Radiology Information System (RIS) 710 that communicates an examination order through a network to the control apparatus 700, a Picture Archiving and Communication Systems (PACS) 711 that manages radiation image, and a Hospital Information System (HIS) 712 that manages the progress of examination.
For example, in a radiation department of a hospital, when an examination order is received by the RIS 710, imaging information related to radiographing, such as imaging conditions and imaging technique, is communicated to the control apparatus 700. The control apparatus 700 executes radiographing according to the received examination order. Then, the control apparatus 700 assigns supplementary information including an examination order to the radiation image being taken, and outputs the same.
The PACS 711 is a server whose main purpose is to manage images. The PACS 711 includes a storage device that stores radiation image and supplementary information. Image inspection operations, detailed postprocessing, and diagnosis operations of the radiation image are executed using a high definition monitor connected to the PACS 711. As described, the radiation image output from the control apparatus 700 is communicated to the PACS 711.
The HIS 712 is a hospital management system, and includes a server for managing an accounting information. When carrying out radiographing, the operator enters an examination instruction from a terminal of the HIS 712. Then, the HIS 712 contacts the radiation department of the hospital, which is a request destination. The request information is called an examination order. The examination order includes a name of a department which is the request client, examination items, and personal data of a subject. Execution information of examination in the radiographing system 900 is notified to the HIS 712. The execution information notified to the HIS 712 is used for an accounting process after examination, in addition to managing the progress of examination.
The control apparatus 700, the RIS 710, the PACS 711, and the HIS 712 are connected through a network composed, for example, of a Local Area Network (LAN) or a Wide Area Network (WAN).
Next, an outline of configuration of the wireless communication apparatus 1 will be described.
The scintillator 403 converts irradiated radiation into light corresponding to the intensity thereof, and the photoelectric conversion element is an element that convers the light from the scintillator 403 into electric signals. The scintillator protective film 404 is composed of a material having low moisture permeability, and protects the scintillator 403. Electric signals read from the X-ray sensor 401 through a flexible circuit substrate 115 is processed by a control unit (not shown) mounted on a printed circuit board 110A or a printed circuit board 110B serving as control boards. Hereafter, the printed circuit board 110A and the printed circuit board 110B are collectively referred to as a printed circuit board 110.
In the printed circuit board 110, the electric signals being read is converted by an A/D conversion circuit into digital data, i.e., radiation image data, that indicates attenuation of radiation by a subject. The radiation image data and various settings are stored in a storage unit composed of a volatile memory or a nonvolatile memory. Further, the wireless communication apparatus 1 is equipped with a rechargeable battery 250 for supplying necessary power. The X-ray sensor 401 may be a direct conversion type sensor composed of a conversion element unit in which conversion elements such as a-Se and electric elements such as TFT are arranged two-dimensionally, but it is not limited thereto. Details of components formed on the casing 101 of the wireless communication apparatus 1, such as a first opening 104A, a second opening 105A, a third opening 104B, and a fourth opening 105B, are described below. Further, a connector not shown for feeding power from an exterior through wired connection or for communicating with the exterior may be provided on a part of the casing 101.
Next, details of the wireless communication apparatus 1 will be described with reference to the drawings. In the following description, a suffix is added to the reference sign “1” of the wireless communication apparatus 1, including the modified example of the wireless communication apparatus 1, to thereby distinguish the examples, wherein similar components are denoted with the same reference numbers in the description.
A wireless communication apparatus 1A illustrated in
As illustrated in
The casing 101 has a hollow thin plate shape as a whole, and constitute a hexahedron that forms a thin plate-shaped interior space S by six surfaces, which are a pair of plate-shaped surfaces that are disposed in opposition to and in parallel with each other, and four side surfaces that connect the edges of the two plate-shaped surfaces. That is, one pair of plate-shaped surfaces is composed of an upper surface 101a serving as a first plate-shaped surface and a lower surface 101b serving as a second plate-shaped surface. Further, four side surfaces that connect the edges of the upper surface 101a and the lower surface 101b are composed of a front surface 101c serving as a first side surface, a rear surface 101d serving as a second side surface, a side surface 101e serving as a third side surface, and a side surface 101f serving as a fourth side surface.
The above-mentioned upper surface 101a, the lower surface 101b, the front surface 101c, the rear surface 101d, the side surface 101e, and the side surface 101f may form the interior space S as a sealed space, for example, by integrally forming the surfaces other than the upper surface 101a, mounting components to the interior thereof, and then attaching the upper surface 101a. The material for forming the upper surface 101a, the lower surface 101b, the front surface 101c, the rear surface 101d, the side surface 101e, and the side surface 101f, that is, the six surfaces, is formed of a conductor. Magnesium alloy, stainless steel and other steel materials, aluminum alloy, zinc alloy, copper, iron, and other metals, may be used as the conductor. Further, conductive resin, a resin member having a mesh-shaped electroconductive member embedded in an interior of the resin member, and a resin member having a conductivity formed of carbon fiber reinforced plastic may be used as the conductor. However, the wireless communication apparatus 1 is formed as a portable member, and it is required to have sufficient strength against impacts such as dropping. Therefore, the casing 101 should have all six surfaces formed of a material having high intensity, such as metal, and in other words, the casing 101 is formed of a conductive material, since it is difficult to achieve a desirable intensity using nonconductive materials.
In
The first opening 104A is formed on the front surface 101c of the casing 101 at a position being opposed in the Y direction to an antenna element 102A of the first antenna 102 described in detail later. Further, the second opening 105A is formed on the front surface 101c of the casing 101 at a position being opposed in the Y direction to an antenna element 103A of the second antenna 103 described in detail later. The first opening 104A and the second opening 105A are disposed in parallel in the Y direction, which is the right-left direction orthogonal to the thickness direction of the casing 101, similar to the antenna element 102A and the antenna element 103A. Further, a nonconductive resin member not shown is fit in the first opening 104A and the second opening 105A, which enables to seal the interior space S while allowing radio waves to pass, or irradiate, therethrough.
Similarly, the third opening 104B is formed on the upper surface 101a of the casing 101 at a position being opposed in the Z direction to the antenna element 102A described in detail later. Further, the fourth opening 105B is formed on the upper surface 101a of the casing 101 at a position being opposed in the Z direction to the antenna element 103A described in detail later. The third opening 104B and the fourth opening 105B are disposed in parallel in the Y direction, which is the right-left direction, similar to the antenna element 102A and the antenna element 103A. Further similarly, a nonconductive resin member not shown is fit to the third opening 104B and the fourth opening 105B, which enables to seal the interior space S while allowing radio waves to pass, or irradiate, therethrough. In
The printed circuit board 110 serving as a control unit, the first cable 108, the second cable 109, the first antenna 102, the second antenna 103, the first surrounding portion 106, and the second surrounding portion 107 are accommodated in the interior space S of the casing 101. Among these components, the printed circuit board 110 has installed thereon a CPU not shown for performing various control operations and the wireless IC 111 that generates and outputs radio waves. One end of the first cable 108 and one end of the second cable 109 are connected via connectors not shown to the wireless IC 111, on the other end of the first cable 108 is connected the first antenna 102, and on the other end of the second cable 109 is connected the second antenna 103. Further, the first cable 108 and the second cable 109 are formed of a so-called coaxial cable with a diameter of approximately 1 to 2 mm. Further, the wireless IC 111 performs Multiple Input Multiple Output (MIMO) communication using the first antenna 102 and the second antenna 103. It is noted that each of the above mentioned cables is an example of wiring and a printed wiring patterned on a printed wiring board may be used as an alternative to a cable, for example. Also, each of the antennas may be a printed antenna patterned on a printed wiring board, and at least two of the antenna, the cable and the control unit maybe formed on a single printed wiring board.
The first antenna 102 and the second antenna 103 are each a monopole antenna, in which is adopted an inverted L-shaped antenna or an inverted F-shaped antenna. Among these antennas, the first antenna 102 includes a first antenna element 102A and a first ground 102B which are branched from and connected to a feeding point, i.e., wave source port, to which the other end of the first cable 108 is connected. The first antenna element 102A is supported by an antenna support member not shown, such as a dielectric 102C of
Similarly, the second antenna 103 includes a second antenna element 103A and a second ground 103B which are branched from and connected to a feeding point to which the other end of the second cable 109 is connected. The second antenna element 103A is supported by an antenna support member not shown, such as a dielectric 103C of
Configuration Example with Support Plate
A wireless communication apparatus 1X equipped with the support plate 201 serving as a support member for supporting the printed circuit board 110 and the X-ray sensor 401 within the casing 101 will be described with reference to
As illustrated in
As described, in a case where the support plate 201 is provided on the wireless communication apparatus 1X, the first ground 102B of the first antenna 102 and the second ground 103B of the second antenna 103 mentioned above are fixed to and supported on the support plate 201. Further, the first antenna element 102A of the first antenna 102 and the second antenna element 103A of the second antenna 103 are supported by an antenna support member, such as a dielectric 102C and a dielectric 103C of
Simulation of a Case where Six Surfaces of a Casing are a Conductor
A difference of radio frequency interferences between the first antenna 102 and the second antenna 103 that occurs in a case where all six surfaces of the casing 101 are a conductor and a case where only the lower surface 101b is a conductor will be described with reference to the drawings.
A wireless communication apparatus 1sa illustrated in
A result having performed a simulation of simultaneously outputting radio waves of 2.4 [GHz] from the first antenna 102 and the second antenna 103 in the wireless communication apparatus 1sa of the simulation model configured as above is illustrated in
Next, a configuration of the first surrounding portion 106 and the second surrounding portion 107 in the wireless communication apparatus 1A will be described. As illustrated in
The first surrounding portion 106 partitions the first antenna 102, the first opening 104A, and the third opening 104B from the second antenna 103 and the printed circuit board 110. In other words, the first surrounding portion 106 realizes separation of radio waves such that the radio waves output from the first antenna 102 are not diffused and reflected in the interior space S including the second antenna 103 excluding the first surrounding portion 106. The first surrounding portion 106 is composed of a first plate portion 106A, a second plate portion 106B, and a third plate portion 106C which are erected to extend from the lower surface 101b in a thickness direction orthogonal to the lower surface 101b. That is, by having the front surface 101c, the first plate portion 106A, the second plate portion 106B, and the third plate portion 106C arranged in a quadrangular shape when viewed in the thickness direction, the first surrounding portion 106 surrounds the first antenna 102 in a surface direction parallel to the upper surface 101a.
Specifically, the first plate portion 106A has one end thereof connected to the front surface 101c, and is arranged to extend in the Y direction that is a direction intersecting the front surface 101c. Further, the second plate portion 106B has one end thereof connected to the front surface 101c, and is arranged to extend in the direction intersecting the front surface 101c and disposed in parallel with the first plate portion 106A. The third plate portion 106C is disposed parallelly and in opposition to the front surface 101c, and it is connected to the first plate portion 106A and arranged to form a first passage portion 106D at a distance D1 from the second plate portion 106B. The third plate portion 106C may also be connected to the second plate portion 106B and arranged to form the first passage portion 106D between the first plate portion 106A. Moreover, the third plate portion 106C may have both ends connected to the first plate portion 106A and the second plate portion 106B, and have the first passage portion 106D formed in a slit-like shape in the middle.
Similarly, the second surrounding portion 107 serving as a partition portion partitions the second antenna 103, the second opening 105A, and the fourth opening 105B from the first antenna 102 and the printed circuit board 110. In other words, the second surrounding portion 107 realizes separation of radio waves such that the radio waves output from the second antenna 103 are not diffused and reflected in the interior space S including the first antenna 102 excluding the second surrounding portion 107. The second surrounding portion 107 is composed of a first plate portion 107A, a second plate portion 107B, and a third plate portion 107C which are erected to extend from the lower surface 101b in a thickness direction orthogonal to the lower surface 101b. That is, by having the front surface 101c, the first plate portion 107A, the second plate portion 107B, and the third plate portion 107C arranged in a quadrangular shape when viewed in the thickness direction, the second surrounding portion 107 surrounds the second antenna 103 in a surface direction parallel to the upper surface 101a.
Specifically, the first plate portion 107A has one end thereof connected to the front surface 101c, and is disposed to extend in the Y direction that is a direction intersecting the front surface 101c. Further, the second plate portion 107B has one end thereof connected to the front surface 101c, and is disposed to extend in the direction intersecting the front surface 101c and disposed parallelly and in opposition to the first plate portion 107A. The third plate portion 107C is disposed parallelly and in opposition to the front surface 101c, and it is connected to the first plate portion 107A and arranged to form a second passage portion 107D at a distance D2 from the second plate portion 107B. The third plate portion 107C may also be connected to the second plate portion 107B and arranged to form the second passage portion 107D between the first plate portion 107A. Moreover, the third plate portion 107C may have both ends connected to the first plate portion 107A and the second plate portion 107B, and have the second passage portion 107D formed in a slit-like shape in the middle.
The above-mentioned first passage portion 106D is formed to allow the first cable 108 to pass through, and the above-mentioned second passage portion 107D is formed to allow the second cable 109 to pass through. For example, when assembling the wireless communication apparatus 1A, the operator manually inserts the first cable 108 from above to the first passage portion 106D, and manually inserts the second cable 109 from above to the second passage portion 107D. Thereafter, the upper surface 101a is closed to complete the wireless communication apparatus 1A. For example, when through holes for passing through the first cable 108 and the second cable 109 are formed to the third plate portions 106C and 107C, the operator must perform an operation to pass the cables through the through hole. However, according to the present embodiments, the operator simply places the first cable 108 and the second cable 109 from above into the first passage portion 106D and the second passage portion 107D.
As described, it is necessary to form the first passage portion 106D that allows the first cable 108 to pass through and the second passage portion 107D that allows the second cable 109 to pass through to the first surrounding portion 106 and the second surrounding portion 107. However, if the first surrounding portion 106 and the second surrounding portion 107 allow radio waves to pass through the first passage portion 106D and the second passage portion 107D, the radio waves are reflected within the interior space S of the casing 101 and cause radio frequency interferences. Therefore, the maximum widths of the first passage portion 106D and the second passage portion 107D are set as described below.
An electric field intensity formed when radio waves are transmitted is illustrated with reference to the drawings, taking the first passage portion 106D as an example.
Further, as illustrated in
That is, by setting the distance D1 of the width of the first passage portion 106D and the distance D2 of the width of the second passage portion 107D to be smaller than λ/2 the wavelength of the frequency being used, the effect of suppressing the radio frequency interference may be achieved, and by setting the distances to λ/4 or smaller, the maximum effect may be achieved. However, as the distance D1 of the width of the first passage portion 106D and the distance D2 of the width of the second passage portion 107D increases, the assembling property of laying the first cable 108 and the second cable 109 becomes easier. Therefore, the distance D1 of the width of the first passage portion 106D and the distance D2 of the width of the second passage portion 107D should preferably be as great as possible within the range smaller than wavelength λ/2.
Simulation of a Case where the First Passage Portion and the Second Passage Portion are Opposed and the Width of the First Passage Portion and the Second Passage Portion is Varied
Next, a simulation of a wireless communication apparatus in which the first passage portion 106D of the first surrounding portion 106 and the second passage portion 107D of the second surrounding portion 107 are disposed in opposition will be described with reference to the drawings.
A wireless communication apparatus 1Asb illustrated in
Using the wireless communication apparatus 1Asb of the simulation model configured as above, a simulation is performed of a case where radio waves with a frequency of 2.4 [GHz] are output simultaneously from the first antenna 102 and the second antenna 103. Then, the results of numeric values of correlation coefficients of a case where a dimension d2 of the first passage portion 106D and the second passage portion 107D is varied from 22.5 [mm] in this simulation are shown in
The wavelength of radio waves with a frequency of 2.4 [GHz] is approximately 124.9 [mm]. As illustrated in
Simulation of a Case where the First Passage Portion and the Second Passage Portion are Opposed and a Case where they are not Opposed
Next, difference of radio frequency interferences between a case where the first passage portion 106D and the second passage portion 107D are opposed and a case where they are not opposed will be described with reference to the drawings.
A wireless communication apparatus 1Asc illustrated in
The correlation coefficient of the degree of interference of radio waves illustrated in
As illustrated in
In the wireless communication apparatus 1A illustrated in
Simulation of a Case where the Separated Distances of the First Opening and the Second Opening are Varied
Next, a difference in radio frequency interference of a case where the separated distance between the first opening 104A and the second opening 105A is varied will be described with reference to the drawings.
As illustrated in
As illustrated in
According to this simulation, the first opening and the second opening are arranged on the same surface of the casing 101, but for example, a sufficient distance may be ensured by arranging the second opening on a different surface.
Configuration of Interior of Casing for Suppressing Interference at Exterior of Casing when Stored in Bucky
As illustrated
In order to suppress the radio frequency interference at the exterior of the casing when the bucky is stored, as illustrated in
The effect of providing the third surrounding portion 2001 will be described with reference to
In Expression 1, x1, y1, and z1 are dimensions of the interior of the third surrounding portion, and m, n, and p indicate number of waves, which are maximum numerical values of waves of the electric field or magnetic field formed as stationary waves within the interior of the space. Further, εr represents a relative dielectric constant within the space, ε0 represents a dielectric constant of vacuum, and μ0 represents a magnetic permeability of vacuum.
Simulation of a Case where a Plurality of Third Surrounding Portions are Disposed
Next, a simulation of a case where a plurality of third surrounding portions are disposed will be described.
In this simulation, the dimensions of the third surrounding portions 2205 to 2209 are varied so as to suppress interference of frequency of a 5 GHz band of a Wi-fi (5.18 to 5.32 GHz, and 5.5 to 5.845 GHz). The resonance frequency and dimensions of each of the third surrounding portions 2205 to 2209 calculated using Expression (1) will be shown in Table 4.
Simulation of Radiation Efficiency in a Case where the Volume of the Surrounding Structure is Varied
Next, an example is described of a case where the radiation efficiency is varied when the dimensions of the first surrounding portion 106 and the second surrounding portion 107 are varied.
During non-resonance, the radio waves emitted from the antennas travel and are reflected repeatedly on the wall surface of the surrounding portion, but during resonance, stationary waves are generated in the interior of the first and second surrounding portions 106 and 107, and the amplitude of radio waves are doubled. As a result, the radiation efficiency is enhanced. In this example, radiation efficiencies are compared among a dimension A where no cavity resonance occurs in the 5 GHz band, which is a communication band of Wi-fi, and dimensions B, C, and D where cavity resonance occur. The results having computed the respective dimensions using Expression 1 are shown in Table 5.
Dimensions B, C, and D are set to dimensions that cause resonance at 5.44 GHz as a substantial center of frequencies within the range of the 5 GHz band from 5.18 GHz to 5.845 GHz. By causing resonance approximately at the center of frequencies, the radiation efficiency of the entire 5 GHz band may be enhanced compared to a case where resonance is realized by an upper limit frequency or a lower limit frequency of the band. Meanwhile, as for dimension A, the dimension is set such that resonance is realized at 4.84 GHz which is outside the 5 GHz band.
The dimension D has a higher radiation efficiency compared to dimensions B and C. This is related to the magnitude of a quality factor, i.e., Q-value, which is a coefficient showing the smallness of power loss by resonance in a resonance circuit, as indicated in the expression (11.1) on page 133 of “Introduction to Microwaves” (Toshi Tateno, Denpa Shinkou Kai, 1983). Q-value is represented by a ratio of power accumulated in the circuit and power that is lost.
If the Q-value is high, the power loss within the surrounding portion is small, such that the radiation efficiency becomes high, and if the Q-value is low, the power loss within the surrounding portion is high, such that the radiation efficiency becomes small. From expression (11.2), if the frequency is fixed and the skin depth is not varied, the Q-value becomes high as the ratio of the capacity of the cavity and the surface area of the inner wall becomes high, such that the radiation efficiency may be increased by setting the dimension t3 to a large dimension D.
The present simulation is illustrated with respect to a 5 GHz-band for a Wi-fi, but the radiation efficiency may also be enhanced in the range of a 2.4 GHz band (2.412 GHz to 2.484 GHz) for a Wi-fi by setting the dimension to realize cavity resonance in the communication frequency band.
In a Case where the First Surrounding Portion and the Second Surrounding Portion are Fixed to and Supported on a Support Plate
Next, a wireless communication apparatus 1Aa serving as a modified example in which a part of the wireless communication apparatus 1A illustrated in
As illustrated in
In detail, the first surrounding portion 106 is equipped with a fourth plate portion 106E serving as a bottom plate, wherein the first plate portion 106A, the second plate portion 106B, and the third plate portion 106C are integrally fixed to the fourth plate portion 106E. Further, the fourth plate portion 106E is fixed to the support plate 201 in a manner embedded therein, and thereby, the first surrounding portion 106 is fixed on and supported by the support plate 201. Further, the first ground 102B of the first antenna 102 is supported on the fourth plate portion 106E.
Similarly, the second surrounding portion 107 is equipped with a fourth plate portion 107E serving as a bottom plate, wherein the first plate portion 107A, the second plate portion 107B, and the third plate portion 107C are integrally fixed to the fourth plate portion 107E. Further, the fourth plate portion 107E is fixed to the support plate 201 in a manner embedded therein, and thereby, the second surrounding portion 107 is fixed to and supported on the support plate 201. Further, the second ground 103B of the second antenna 103 is supported on the fourth plate portion 107E.
As described, by forming the first surrounding portion 106 and the second surrounding portion 107 in a box-like shape and assembling the same onto the support plate 201, the assembling performance may be enhanced. The other configurations are similar to the wireless communication apparatus 1A illustrated in
In a Case where the First Surrounding Portion and the Second Surrounding Portion are Formed Integrally with the Support Plate
Next, a wireless communication apparatus 1Ab serving as a modified example in which a part of the wireless communication apparatus 1A illustrated in
As illustrated in
In detail, the first plate portion 106A, the second plate portion 106B, and the third plate portion 106C of the first surrounding portion 106 are formed integrally with the support plate 201. Similarly, the first plate portion 107A, the second plate portion 107B, and the third plate portion 107C of the second surrounding portion 107 are formed integrally with the support plate 201.
As described, by forming the first surrounding portion 106 and the second surrounding portion 107 integrally with the support plate 201, the assembling property may be enhanced. The other configurations are similar to the wireless communication apparatus 1A illustrated in
As described, the wireless communication apparatus 1A according to the first embodiment has the first antenna 102, the first opening 104A, and the third opening 104B surrounded by the first surrounding portion 106, and has the second antenna 103, the second opening 105A, and the fourth opening 105B surrounded by the second surrounding portion 107. Thereby, even though the apparatus is not equipped with the parasitic antenna element or the metal block as disclosed in WO2010/073429 A1, the radio frequency interference between the first antenna 102 and the second antenna 103 may be reduced. Furthermore, even if all six surfaces of the casing 101 are conductors, the radio frequency interference between the first antenna 102 and the second antenna 103 may be reduced.
Since the apparatus includes the first passage portion 106D and the second passage portion 107D, the wireless IC 111 and the first antenna 102 of the printed circuit board 110 may be connected by the first cable 108, and the wireless IC 111 and the second antenna 103 may be connected by the second cable 109. Then, even if the first passage portion 106D and the second passage portion 107D are formed on the first surrounding portion 106 and the second surrounding portion 107, the radio frequency interference may be reduced if the width of the first passage portion 106D and the second passage portion 107D is less than ½ the wavelength λ, or preferably ¼ or less.
Further, since the first passage portion 106D and the second passage portion 107D are arranged so as not to be disposed in opposition to each other, the radio frequency interference may be reduced, and the widths of the first passage portion 106D and the second passage portion 107D may be increased correspondingly. If the widths of the first passage portion 106D and the second passage portion 107D are great, the assembling property may be enhanced. The width of the first passage portion 106D and the second passage portion 107D is preferably 15 [mm] or greater, considering the operation performed by the operator to pass the first cable 108 and the second cable 109 therethrough.
The radio frequency interference may be reduced by separating the first opening 104A and the second opening 105A by a separated distance i of ¼ the wavelength λ or greater. In the simulation, the separated distance i between the first opening 104A and the second opening 105A is varied, but the separated distance between the third opening 104B and the fourth opening 105B is considered to be similar. That is, the radio frequency interference may be reduced by separating the third opening 104B and the fourth opening 105B by a separated distance which is ¼ the wavelength λ or greater.
Further, if the apparatus is equipped with the support plate 201, the assembling property may be enhanced by having the first surrounding portion 106 and the second surrounding portion 107 fixed to and supported on the support plate 201, or by forming the same integrally with the support plate 201.
Next, a second embodiment in which a part of the first embodiment is varied will be described with reference to the drawings.
As illustrated in
A distance D3 of the width of the passage portion 301B is formed to be smaller than ½ the wavelength λ of radio waves output from the first antenna 102 and the second antenna 103, preferably ¼ the wavelength λ or smaller. Thereby, the radio frequency interference between the first antenna 102 and the second antenna 103 may be reduced.
Simulation of a Case where a Width of a Passage Portion Formed by a Partition Plate is Varied
Next, a simulation of a case where a width of the passage portion 301B formed between the partition plate 301A and the rear surface 101d of the casing 101 will be described with reference to the drawings.
A wireless communication apparatus 1Bsa illustrated in
Regarding the wireless communication apparatus 1Bsa of the simulation model configured as above, a simulation is performed of a case where the first antenna 102 and the second antenna 103 output radio waves with a frequency of 2.4 [GHz] simultaneously. The result of numerical values of a correlation coefficient of a case where the dimension i2 of the passage portion 301B is varied from 22.5 [mm] in this simulation is illustrated in
As illustrated in
Simulation of a Case where a Dielectric is Interposed Between the Casing and the Partition Plate
Next, a simulation of a case where a the dielectric 301C is interposed between the upper surface 101a of the casing 101 and the partition plate 301A will be described with reference to the drawings.
A wireless communication apparatus 1Bsb illustrated in
In the wireless communication apparatus 1Bsb of the simulation model configured as above, a simulation is performed of a case where radio waves having a frequency of 2.4 [GHz] are simultaneously output from the first antenna 102 and the second antenna 103. The result of numerical values of correlation coefficient of a case where the dimension j2 of the height of the dielectric 301C is varied according to this simulation is illustrated in
As illustrated in
Simulation of a Case where a Gap is Formed Between the Casing and the Partition Plate
Next, a simulation of a case where there is a gap between the upper surface 101a of the casing 101 and the partition plate 301A is described with reference to the drawings.
This simulation is performed of a case where the dielectric 301C of the wireless communication apparatus 1Bsb illustrated in
As illustrated in
As described, the wireless communication apparatus 1B according to the second embodiment has the first antenna 102, the first opening 104A, and the third opening 104B partitioned from the second antenna 103, the second opening 105A, and the fourth opening 105B by the partition plate portion 301. Thereby, even though the apparatus is not equipped with the parasitic antenna element or the metal block as disclosed in WO2010/073429 A1, the radio frequency interference between the first antenna 102 and the second antenna 103 may be reduced. Furthermore, even if all six surfaces of the casing 101 are conductors, the radio frequency interference between the first antenna 102 and the second antenna 103 may be reduced.
Further, the apparatus includes the passage portion 301B, such that the wireless IC 111 of the printed circuit board 110 and the first antenna 102 may be connected by the first cable 108. Further, even if the passage portion 301B is formed on the partition plate portion 301, the radio frequency interference may be reduced if the width of the passage portion 301B is less than ½ the wavelength λ, preferably ¼ or smaller.
According to the first and second embodiments described above, a communication according to a MIMO system using the first antenna 102 and the second antenna 103 was described as an example. However, the present technique is not limited thereto, and communication according to a Single Input Multiple Output (SIMO) system or a Multiple Input Single Output (MISO) system may also be performed. In other words, any communication system may be adopted, as long as a plurality of antennas are used for communication.
Further according to the first and second embodiments, the first antenna 102 and the second antenna 103 are monopole antennas. However, the present technique is not limited thereto, and other antennas, such as a dipole antenna, may be used.
Further according to the first and second embodiments, there are two antennas provided, which are the first antenna 102 and the second antenna 103. However, the present technique is not limited to this example, and three or more antennas may be provided. In that case, it is necessary that each of the antennas are partitioned by the partition portion.
Further according to the first and second embodiments, the first antenna 102 and the second antenna 103 are partitioned by a partition portion formed of a conductor, such as the first surrounding portion 106, the second surrounding portion 107, and the partition plate portion 301. If the respective antennas are partitioned as described above, it is necessary to separate the respective antennas and the partition portion by a predetermined distance so as not to allow electrical connection thereof.
Further according to the first embodiment, the first antenna 102 is surrounded by the first surrounding portion 106 and the second antenna 103 is surrounded by the second surrounding portion 107. However, if even only one of the two antennas is surrounded by the surrounding portion, the radio frequency interfaces of both antennas may be reduced, such that it may be possible to dispose only one of the surrounding portions.
Further according to the first and second embodiments, the first antenna 102 and the second antenna 103 are disposed in parallel in the X direction. However, the directions and arrangements of the antennas may be any position and any angle, or posture.
Further according to the first and second embodiments, the widths of the first passage portion 106D, the second passage portion 107D, and the passage portion 301B are set to less than ½ the wavelength λ, preferably ¼ or smaller. That is, the lowest limit of these widths should be set to a width allowing the first cable 108 and the second cable 109 to pass therethrough. However, considering the workability for passing through and installing the first cable 108 and the second cable 109, the widths thereof should preferably be 15 mm or greater. Further, the shapes of the first passage portion 106D, the second passage portion 107D, and the passage portion 301B may be formed as slits. However, any shape may be adopted, as long as the first cable 108 and the second cable 109 may be passed through. In that case, an arbitrary maximum width of the first passage portion 106D, the second passage portion 107D, and the passage portion 301B should be less than ½ the wavelength λ, preferably ¼ or smaller.
Further according to the first and second embodiments, the casing 101 is a hexahedron. However, the present technique is not limited thereto, and the casing may adopt any shape, as long as the casing has at least six surfaces formed of a conductor and the first antenna 102 and the second antenna 103 are surrounded from all directions. Further, even if the corner portions of the casing are not pointed and are rounded, if the casing has six surfaces, it may be considered as a hexahedron.
According to the second embodiment, the dielectric 301C is disposed between the partition plate 301A and the upper surface 101a, or a gap is formed therebetween. The dielectric or the gap may similarly be applied between the first surrounding portion 106 or the second surrounding portion 107 and the upper surface 101a of the first embodiment.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2023-011252, filed Jan. 27, 2023 and the benefit of Japanese Patent Application No. 2023-207886, filed Dec. 8, 2023, which are hereby incorporated by reference herein in their entirety.
Number | Date | Country | Kind |
---|---|---|---|
2023-011252 | Jan 2023 | JP | national |
2023-207886 | Dec 2023 | JP | national |