Patent Application
20180191063
The disclosure herein generally relates to an antenna structure and an electronic device.
Conventionally, portable information devices, in which antenna substrates provided with chip antennas and ground patterns are arranged on rear surfaces of liquid crystal panels so that the chip antennas are located in upper portions of the liquid crystal panels, have been known (e.g. See Japanese Unexamined Patent Application Publication No. 2002-73210). Japanese Unexamined Patent Application Publication No. 2002-73210 discloses that according to the arrangement of the chip antennas, radiation characteristics on the display surface side and on the rear surface side of the liquid crystal panel can be made unbiased and that a thickness of a display unit including the liquid crystal panel can be decreased.
However, because the aforementioned related art requires an antenna substrate on which a ground is arranged, a size of an antenna structure is difficult to be reduced and a of an electronic device including the antenna structure is difficult to be reduced.
Then, an aspect of the present invention aims at reducing a size of an antenna structure.
According to an aspect of the present invention, an antenna structure including
a radiating element;
a power feeding element for feeding power to the radiating element in a noncontact manner;
a backlight chassis, on which a light source for generating light is attached, a liquid crystal panel being irradiated with the light; and
a transmission line that uses the backlight chassis as a ground,
the power feeding element being connected to a terminal end of the transmission line, is provided.
According to an aspect of the present invention, because the backlight chassis is used as a ground and an antenna substrate on which a ground is arranged becomes unnecessary, a size of the antenna structure can be reduced.
In the following, with reference to drawings, embodiments for implementing the present invention will be described.
The electronic device 2 is provided with a display panel 19 that can display an image, and a frame 3 to which the display panel 19 is fixed. The frame 3 supports the display panel 19 in a state of covering an outer periphery portion of the display panel 19. Moreover, the electronic device 2 is provided with an antenna structure 1 for realizing a wireless communication function with an outside of the electronic device 2. The antenna structure 1 accommodates, for example, a wireless communication standard, such as Bluetooth (registered trademark), or a wireless LAN (Local Area Network) standard such as IEEE 802.11ac.
The antenna structure 1 is provided with a radiating element 22 or a plurality of radiating elements 22.
The display panel 19 is provided with, for example a liquid crystal panel 4, a front surface panel 5 and a backlight unit 9.
The liquid crystal panel 4 is, for example, a display panel including a pair of glass substrates, and a liquid crystal arranged between the pair of glass substrates.
The front surface panel 5 is a cover panel for covering a display surface of the liquid crystal panel 4. The front surface panel 5 may be a protection panel for protecting the liquid crystal panel 4, or may be a touch panel.
The backlight unit 9 is a panel unit, which is arranged on the rear surface side of the liquid crystal panel 4, and irradiates the liquid crystal panel 4 with light. The backlight unit 9 is, for example an edge type backlight unit provided with a backlight chassis 8, a light source 7 and a light guide plate 6. Moreover. although not shown in figures, the backlight unit 9 includes a diffuser plate or a polarization plate.
The backlight chassis 8 stores the light source 7 and the light guide plate 6 on the liquid crystal panel 4 side. The backlight chassis 8 a member formed from a conductive metal (iron, aluminum or the like) and formed in a shape of box that opens on the liquid crystal panel 4 side. The back light chassis 8 includes a bottom surface part 8a and a side surface part 8b. The backlight chassis 8 has an opening on the liquid crystal panel 4 side.
The light source 7 is an object that generates light with which the liquid crystal panel 4 is irradiated, and attached to the side surface part 8b of the backlight chassis 8. The light source 7 is configured, for example, including a plurality of light emitting elements. The light emitting element specifically includes, for example, an LED (Light Emitting Diode).
The light guide plate 6 is a panel that guides a light from the light source 7 to the liquid crystal panel 4. A light from the light source 7 is incident to the light guide plate the light guide plate 6 outputs the incident light toward the liquid crystal panel 4. The light guide plate 6 is, for example, a member formed from a resin in a shape of a plate.
Note that the backlight unit 9 is not required to be an edge type backlight unit, but may be a directly under type backlight unit. In the case of the directly under type backlight unit, the light guide plate 6 becomes unnecessary, and the light source 7 is attached to the bottom surface part 8a of the backlight chassis 8.
On the rear surface side of the bottom surface part 8a of the backlight chassis 8, a circuit module 10 is arranged. The circuit module 10 includes a reception circuit connected via a transmission line 11 to a power feeding element 21 for feeding power to the radiating element 22 in a noncontact manner. The circuit module 10 may include a driving circuit for driving the light source 7 and the liquid crystal panel 4.
The transmission line 11 uses the conductive backlight chassis 8 as a ground. The transmission line specifically includes, for example, a coaxial cable, a microstrip line, a strip line, a coplanar waveguide with ground plane (a coplanar waveguide having a ground plane arranged on a surface opposite to a conductor surface on which a signal line is formed), a coplanar strip line, or the like.
The power feeding element 21, is a linear conductor, which is connected to a terminal end 12 of the transmission line 11, and is connected to the radiating element 22 in a noncontact manner to feed power at high frequencies to the radiating element 22. The shape of the power feeding element 21 is not limited to a linear shape as illustrated in
The radiating element 22 is a linear conductor, which is connected to the power feeding element 21 in a noncontact manner to be fed power at high frequencies from the power feeding element 21, to function as a radiating conductor. The shape of the radiating element 22 is not limited to a linear shape, and may be any other shape such as an L shape, a meander shape, or a loop shape.
The radiating element 22 and the power feeding element 21 may overlap or may not overlap in a planar view from a given direction such as an X-axis direction, a Y-axis direction or a Z-axis direction, as long as the power feeding element 21 and the radiating element 22 are separated from each other by a distance which is enough for feeding power to the radiating element 22 in a noncontact manner.
The power feeding element 21 is arranged on an upper part of the bottom surface part 8a of the backlight chassis 8. The power feeding element 21 may be arranged on a surface of the bottom surface part 8a closer to the liquid crystal panel 4, or may be arranged on a surface of the bottom surface part 8a farther from the liquid crystal panel 4.
The radiating element 22 is arranged on the display surface of the liquid crystal panel 4 in the case of
In this way, because the power feeding element 21 is connected to the terminal end 12 of the transmission line 11 that uses the backlight chassis 3 as a ground, it becomes unnecessary to newly arrange an antenna substrate provided with a ground plane. Thus, because the antenna substrate provided with a ground plane becomes unnecessary, a size of the antenna structure 1 can be easily reduced. Moreover, because the size of the antenna structure 1 can be reduced, a size of the electronic device 2 provided with the antenna structure 1 (particularly, reduction in a size of the frame 3) can be easily reduced.
A tip 17 of the core wire 14 is an open end. The outer conductor 15 of the coaxial cable 13 is conductably connected to the bottom surface part 8a of the backlight chassis 8 via a connection conductor 16. A cutout portion 8c is arranged in the side surface part 8b of the backlight chassis 8 so that the coaxial cable 13 can be easily wired from the rear surface of the backlight chassis 8 to the front surface of the backlight chassis 8. The coaxial cable 13 passes through the cutout portion cut out of the side surface part 8b, and arranged from the rear surface to the front surface of the bottom surface part 8a. The outer conductor 15 and the core wire 14 of the coaxial cable 13 are arranged in the cutout portion 8c.
The power feeding element 21 is a first resonator, for example, connected to the terminal end 12 of the transmission line 11 that uses the backlight chassis 8 as a ground.
The radiating element 23 is arranged in a region on the liquid crystal panel 4 where the signal wiring 4a is not arranged. For example, the radiating element 22 is arranged in a region 4c having a shape of a band or frame that is along an edge of the liquid crystal panel 4.
The radiating element 22 is a second resonator, for example, arranged separated from the power feeding element 21, and functions as a radiating conductor by the power feeding element 21 that resonates. The radiating element 22 is fed power by, for example, an electromagnetic field, coupling to the power feeding element 21, and functions as a radiating conductor.
The radiating element 22 has a conductor part 23 that extends in the X-axis direction along the outer periphery part 8d. The conductor part 23 is arranged separated from the outer periphery part 8d.
According to the conductor part 23 along the outer periphery part 8d included in the radiating element 22, for example, a directivity of the antenna structure 1 can be easily controlled.
The power feeding element 21 and the radiating element 22 are arranged being separated item each other by, for example, a distance with which electromagnetic fields can be coupled to each other. The radiating element 22 includes a power feeding part 36 for receiving power from the power feeding element 21. The radiating element 22 is fed power at the power feeding part 36 via the power feeding element 21 according to the electromagnetic field coupling in a noncontact manner. The radiating element 22, which is fed power in this way, functions as a radiating conductor of the antenna structure 1.
In the case where the radiating element 22 is a linear conductor connecting two points, as illustrated in
Moreover, although not illustrated, the radiating element 22 may be a loop shaped conductor such as a linear conductor forming a quadrangle. When the radiating element 22 is a loop shaped conductor, the same resonating current as a loop antenna (electric current distributed in a shape of a stationary wave) is formed on the radiating element 22. That is, the radiating element 22 functions as a loop antenna resonating with a wavelength of the predetermined frequency (in the following, referred to as a loop mode).
Moreover, although not illustrated, the radiating element 22 may be a linear conductor connected to a ground level of the terminal end 12. The ground level of the terminal end 12 is, for example, the backlight chassis 8, or a conductor conductably connected to the backlight chassis 8. For example, an end portion 22b of the radiating element 22 is connected to the outer periphery part 8d of the backlight chassis 8. When the radiating element 22 is a linear conductor in which one end of the radiating element 22 is connected to the ground level of the terminal end 12 and another end is an open end, the same resonating current as a λ/4 monopole antenna (electric current distributed in a shape of a stationary wave) is formed on the radiating element 22. That is, the radiating element 22 functions as a monopole antenna resonating with a quarter of wavelength of the predetermined frequency (in the following, referred to as a monopole mode).
Moreover, in the case illustrated in
An impedance at a site on the radiating element 22 increases, in the case of the dipole mode, as the site is separated from the central portion 90 and approaches the end portion 22a of the end portion 22b. In the case of a coupling at high impedance in the electromagnetic field coupling, even if impedance between the power feeding element 21 and the radiating element 22 somewhat varies, an influence to the impedance matching is small, as long as the impedance at the coupling is greater than or equal to a predetermined value. Thus, in order to perform matching easily, the power feeding part 36 of the radiating element 22 is preferably located at a portion of the high impedance of the radiating element 22.
In the case of the dipole mode, for example, in order to perform an impedance matching of the antenna structure 1 easily, the power feeding part 36 may be located at a site separated from the portion of the lowest impedance at the resonance frequency of the fundamental mode of the radiating element 22 (in this case, the central portion 90) by a distance which is greater than or equal to one-eighth of an entire length of the radiating element 22 (preferably greater than or equal to one-sixth of the entire length, and more preferably greater than or equal to one-fourth of the entire length). In the case illustrated in
In the case of the loop mode, for example, in order to perform an impedance matching of the antenna structure 1 easily, the power feeding part 36 may be located at a site within a region separated from the portion of the lowest impedance at the resonance frequency of the fundamental mode of the radiating element 22 by a distance which is less than or equal to one-sixteenth of a perimeter on an inner periphery side of the loop of the radiating element 22 (preferably less than or equal to one-twelfth of the perimeter, and more preferably less than or equal to one-eighth of the perimeter).
In the case of the monopole mode in which the end portion 22b is connected to the ground level of the terminal end 12, when the power feeding part 36, which is a site where the power feeding element 21 feeds power to the radiating element 22, is located at a site close to the end portion 22a side with respect to a portion of the lowest impedance at the resonance frequency of the fundamental mode of the radiating element 22 (in this case the end portion 22b), it is possible to easily perform an impedance matching of the antenna structure 1. Particularly, the power feeding part 36 is preferably located on the end portion 21a side of the central portion 90.
An impedance at a site on the radiating element 22 increases, in the case of the monopole mode in which the end portion 22b is connected to the ground level of the terminal end 12, as the site approaches the end portion 22a from the end portion 22b of the radiating element 22. In the case of a coupling at high impedance in the electromagnetic field coupling, even if impedance between the power feeding element 21 and the radiating element 22 somewhat varies, an influence to the impedance matching is small, as long as the impedance at the coupling is greater than or equal to a predetermined value. Thus, in order to perform matching easily, the power feeding part 36 of the radiating element 22 is preferably located at a portion of the high impedance of the radiating element 22.
In the case of the monopole mode in which the end portion 22b is connected to the ground level of the terminal end 12, for example, in order to perform the impedance matching of the antenna structure 1 easily, the power feeding part 36 may be located at a site separated from the portion of the lowest impedance at the resonance frequency of the fundamental mode of the radiating element 22 (in this case, the end portion 22b) by a distance which is greater than or equal to one-fourth of an entire length of the radiating element 22 (preferably greater than or equal to one-third of the entire length, and more preferably greater than or equal to a half of the entire length), and further preferably located on the end portion 22a side of the central portion 90.
Moreover, in the case where a wavelength radio wave in vacuum at the resonance frequency of the fundamental mode of the radiating element 22 is denoted by λ01, the shortest distance D11 between the power feeding part 36 and the backlight chassis 8 is greater than or equal to 0.0034λ01 and less than or equal to 0.21λ01. The shortest distance D11 is more preferably greater than or equal to 0.0043λ01 and less than or equal to 0.199λ01, and further preferably greater than or equal to 0.0069λ01 and less than or equal to 0.164λ01. When the shortest distance D11 is set within the aforementioned regions, the antenna structure 1 has advantages that an actual gain of the radiating element 22 is enhanced. Moreover, because the shortest distance D11 is less than (λ01/4), the antenna structure 1 does not generate circular polarization, but generates linear polarization.
Note that the shortest distance D11 refers to a distance connecting by a line between the closest portions of the power feeding part 36 and of the outer periphery part 8d, and the shortest distance D12 refers to a distance connecting by a line between the closest portions of the power feeding part 37 and the outer periphery part 8d. The outer periphery part 8d, in this case, is an outer periphery part of the backlight chassis 8 that is a ground level of the terminal end 12 connected to the power feeding element 21 for feeding power to the power feeding part 36. Moreover, the radiating element 22 and the backlight chassis 8 may be in the same plane, or may be in different planes. Moreover, the radiating element 22 may be arranged on a plane parallel to the plane on which the backlight chassis 8 is arranged, or may be arranged on a plane that intersects the plane of the backlight chassis 8 at an optional angle.
Moreover, in the case where a wavelength of a radio wave in vacuum at the resonance frequency of the fundamental of the radiating element 22 is denoted by λ01, the shortest distance D21 between the power feeding element 21 and the radiating element 22 is preferably less than or equal to 0.2×λ01 (more preferably less than or equal to 0.1×λ01, and further preferably less than or equal to 0.05×λ01). When the power feeding element 21 and the radiating element 22 are arranged separated by the aforementioned distance D21, the antenna structure 1 has an advantage in that an actual gain of the radiating element 22 is enhanced.
Note that the shortest distance D21 refers to a distance connecting by a line between the closest portions of the power feeding element 21 and of the radiating element 22. Moreover, the power feeding element 21 and the radiating element 22 may intersect each other or may not intersect viewed in a given direction as long as electromagnetic fields of the power feeding element 21 and the radiating element 22 are coupled to each other. The intersection angle may be an angle selected as suited. Moreover, the radiating element 22 and the power feeding element 21 may be in the same plane, or may be in different planes. Moreover, the radiating element 22 may be arranged on a plane parallel to the plane on which the power feeding element 21 is arranged, of map be arranged on a plane that intersects the plane of the power feeding element 21 at an angle selected as suited.
Moreover, a distance, in which the power feeding element 21 and the radiating element 22 run parallel to each other with the shortest distance D21, is preferably less than or equal to three-eighths of a physical length of the radiating element 22, in the case of the dipole mode. The distance is more preferably less than or equal to one-fourth of the physical length, and further preferably less than or equal to one-eighth of the physical length. In the case of the loop mode, the distance is preferably less than or equal to three-sixteenths of a perimeter on an inner periphery side of the loop of the radiating element 22. The distance is more preferably less than or equal to one-eighth of the perimeter, and further preferably less than or equal to one-sixteenth of the perimeter. In the case of the monopole mode, the distance is preferably less than or equal to three-fourths of a physical length of the radiating element 22. The distance is more preferably less than or equal to a half of the physical length, and further preferably less than or equal to one-fourth of the physical length.
Positions of the power feeding element 21 and the radiating element 22, which are the closest to each other with the shortest distance D21, are sites where the coupling between the power feeding element 21 and the radiating element 22 are strong. When the distance in which the power feeding element 21 and the radiating element 22 run parallel to each other is long, the power feeding element 21 is coupled to both a high impedance portion and a low impedance portion of the radiating element 22, and an impedance matching may not be made. Then, the power feeding element is strongly coupled only to the site at which variation of impedance is small. Thus a short distance in which the power feeding element 21 and the radiating element 22 run parallel to each other has an advantage in the impedance matching.
Moreover, an electric length that gives the fundamental mode of resonance of the power feeding element 21 is denoted by Le21, an electric length that gives the fundamental mode of resonance of the radiating element 22 in denoted by Le22, and a wavelength on the power feeding element 21 or the radiating element 22 at the resonance frequency f11 of the fundamental mode of the radiating element 22 is denoted by λ1. In the case where the fundamental mode of resonance of the radiating element 22 is the dipole mode, Le21 is preferably leas than or equal to (3/8)·λ1 and Le22 is preferably greater than or equal to (3/8)·λ1 and less than or equal to (5/8)·λ1. In the case of the fundamental mode of resonance of the radiating element 22 being the loop mode, Le21 is preferably less than or equal to (3/8)·λ1 and Le22 is preferably greater than or equal to (7/8)·λ1 and leas than or equal to (9/8)·λ1. In the case of the fundamental mode of resonance of the radiating element 22 being the monopole mode, Le21 is preferably less than or equal, to (3/8)·λ1 and Le22 is preferably greater than or equal to (1/8)·λ1 and less than or equal to (3/8)·λ1.
Moreover, the backlight chassis 8 is formed so that the outer periphery part 8d is located along the radiating element. Then, the power feeding element 21 can form a resonance electric current (electric current distributed in a form of standing wave) on the power feeding element 21 and the backlight chassis 8 according to an interaction with the outer periphery part 8d, and performs an electromagnetic field coupling with the radiating element 22. Thus, a lower limit of the electric length Le21 of the power feeding element 21 does not particularly exist. The electric length Le21 may have a length sufficient to perform physically the electromagnetic field coupling with the radiating element 22.
Moreover, in the case of giving a degree of freedom to the shape of the power feeding element 21, the electric length Le21 is more preferably greater than or equal to (1/8)·λ1 and less than or equal to (3/8)·λ1, or greater than or equal to (1/8)·λ2 less than or equal to (3/8)·λ2, and particularly preferably greater than or equal to (3/16)·λ1 and less than or equal to (5/16)·λ1, or greater than or equal to (3/16)·λ2 and less than or equal to (5/16)·λ2. When the electric length Le21 falls within the aforementioned range, the power feeding element 21 resonates successfully at the designed frequency of the radiating element 22 (resonance frequency f11), and a successful electromagnetic field coupling between the power feeding element 21 and the radiating element 22 can be obtained without depending on the backlight chassis 8, and it is preferable.
Moreover, in order to reduce the size of the antenna structure 1, the electric length Le21 of the power feeding element 21 is more preferably less than (1/4)·λ1 or less than (1/4)·λ2, and particularly preferably less than or equal to (1/8)·λ1 or less than or equal to (1/8)·λ2.
Note that a state in which an electromagnetic field coupling realized means a state in which a matching is made. Moreover, in this case, the electric length of the power feeding element it not required to be designed it conformity to the resonance frequency f11 of the radiating element 22, and the power feeding element 21 can be designed freely as a radiating conductor. Thus, multi-frequency of the antenna structure 1 can be easily realized.
Note that in the case where the power feeding element 21 does not include a matching circuit or the like, a physical length L21 of the power feeding element 21 (in
The physical length L21 of the power feeding element 21 is a physical length that gives an electric length Le21, and is equal to Le21 in an ideal case that does not include other element. In the case where the power feeding element 21 includes a matching circuit or the like, the physical length L21 is preferably greater than zero and less than or equal to Le21. The physical length L21 can be made shorter (a size can be reduced) by using a matching circuit such as an inductor. The physical length L21 is shorter than the entire length of the radiating element 22.
Moreover, in the case where the fundamental mode of resonance of the radiating element 22 is the dipole mode (the radiating element 22 is a linear conductor where both ends are open ends), the electric length Le22 is preferably greater than or equal to (3/8)·λ1 and less than or equal to (5/8)·λ1, more preferably greater than or equal to (7/16)·λ1 and less than or equal to (9/16)·λ1, and particularly preferably greater than or equal to (15/32)·λ1 and less than or equal to (17/32)·λ1. Moreover, taking into account a higher order mode, the electric length Le22 is preferably greater than or equal to (3/8)·λ1·m and less than or equal to (5/8)·λ1·m, more preferably greater than or equal to (7/16)·λ1·m and less than of equal to (9/16)·λ1·m, and particularly preferably greater than or equal to (15/32)·λ1·m and less than or equal to (17/32)·λ1·m.
In the aforementioned ranges, m represents a mode number of the higher order mode, and is a natural number. The number m is preferably an integer of 1 to 5, and particularly preferably an integer of 1 to 3. The case with m of one is a case of the fundamental mode. When the electric length Le22 falls within the aforementioned range, the radiating element 22 fully functions as a radiating conductor, and an efficiency of the antenna structure 1 is excellent and is preferable.
Moreover, similarly, in the case where the fundamental mode of resonance of the radiating element 22 is the loop mode (the radiating element 22 is a loop conductor) the electric length Le22 is preferably greater than or equal to (7/8)·λ1 and less than of equal to (9/8)·λ1, more preferably greater than or equal to (15/16)·λ1 and less than or equal to (17/16)·λ1, and particularly preferably greater than or equal to (31/32)·λ1 and less than of equal to (33/32)·λ1. Moreover, for a higher order mode, the electric length Le22 is preferably greater than or equal to (7/8)·λ1·m and less than or equal to (9/8)·λ1·m more preferably greater than or equal to (15/16)·λ1·m and leas than or equal to (17/16)·λ1·m, and particularly preferably greater than of equal to (31/32)·λ1·m and less than or equal to (33/32)·λ1·m. When the electric length Le22 falls within the aforementioned range, the radiating element 22 fully functions as a radiating conductor, and an efficiency of the antenna structure 1 is excellent and it is preferable.
Moreover, similarly, in the case where the fundamental mode of resonance of the radiating element 22 is the monopole mode (the radiating element 22 is connected to the ground level of the terminal end 12 and has an open end), the electric length Le22 is preferably greater than or equal to (1/8)·λ1and less than or equal to (3/8)·λ1, more preferably greater than or equal to (3/16)·λ1 and less than of equal to (5/16)·λ1, and particularly preferably greater than or equal to (7/32)·λ1 and less than or equal to (9/32)·λ1. When the electric length Le22 falls within the aforementioned range, the radiating element 22 fully functions radiating conductor, and an efficiency of the antenna structure 1 is excellent and it is preferable.
Note that the physical length L22 of the radiating element 22 is determined by a wavelength λg2=λ02·k2, where λ01 is a wavelength of a radio wave in vacuum at a resonance frequency of the fundamental mode of the radiating element 22 and k2 is a shortening rate of a wavelength shortening effect by an environment in which the radiating element 22 is implemented. Here, k2 is a value calculated from a specific permittivity, a specific permeability and a thickness of a medium (environment) of a dielectric base material in which the radiating element 22 is arranged, such as an effective specific permittivity (εr2) and an effective specific permeability (μr2) of an environment of the radiating element 22, a resonance frequency, or the like. That is, in the case where the fundamental mode of resonance of the radiating element 22 is the dipole mode, the physical length L22 is ideally (1/2)·λg2. The length L22 of the radiating element 22 is preferably greater than or equal to (1/4)·λg2 and less than or equal to (3/4)·λg2, and further preferably greater than or equal to (3/8)·λg2 than or equal to (5/8)·λg2. In the case where the fundamental mode of resonance of the radiating element 22 is the loop mode, the length L22 is greater than or equal to (7/8)·λg2 and less than or equal to (9/8)·λg2. In the case where the fundamental mode of resonance of the radiating element 22 is the monopole mode, the length L22 is greater than or equal to (1/8)·λg2 and less than or equal to (3/8)·λg2.
The physical length of the radiating element 22 is a physical length that gives an electric length Le22, and is equal to Le22 in an ideal case that does not include another element. The length L22 is, even if L22 is made shorter by using a matching circuit such as an inductor, preferably greater than zero and less than or equal to Le22, and particularly preferably greater than or equal to 0.4 times Le22 and less than or equal to Le22. When the length L22 of the radiating element 22 is adjusted to the aforementioned length, the radiating element 22 has an advantage in enhancing an operation gain of the radiating element 22.
Moreover, in the case where an interaction between the power feeding element 21 and the outer periphery part 8d of the backlight chassis 8 can be used, as illustrated in
In the case where the power feeding element 21 does not include a matching circuit or the like, the physical length L21 of the power feeding element 21, when the radiating function of the power feeding element 21 is used, is determined by a wavelength λg3=λ3·k1, where λ3 is a wavelength of a radio wave in vacuum at a resonance frequency f2 of the power feeding element 21 and k1 is a shortening rate of a wavelength shortening effect by an environment in which the power feeding element 21 is implemented. Here, k1 is a value calculated from a specific permittivity, a specific permeability and a thickness of a medium (environment) of a dielectric base material in which the power feeding element 21 is arranged, such as an effective specific permittivity (εr1) and an effective specific permeability (μr1) of an environment of the power feeding element 21, a resonance frequency, or the like. That is, the length L21 is greater than or equal to (1/8)·λg3 and less than or equal to (3/8)·λg3, and preferably greater than or equal to (3/16)·λg3 and less than or equal to (5/16)·λg3.
A resonance frequency of the fundamental mode of the power feeding element is f21, a resonance frequency of the second order mode of the radiating element is f32, a wavelength in vacuum at the resonance frequency of the fundamental mode of the radiating element is λ0, a value obtained by normalizing the shortest distance between the power feeding element and the radiating element by λ0 is x. According to the antenna structure of the embodiment, when the frequency ratio p (=f21/f32) is greater than or equal to 0.7 and less than or equal to (0.1801˜x−0.468), an excellent matching can be made at the resonance frequency of the fundamental mode of the radiating element and at the resonance frequency of the second order mode.
For example, in the case of the antenna structure 1, when the resonance frequency of the fundamental mode of the power feeding element 21 is f21, and resonance frequency of the second order mode of the radiating element 22 is f112, when the frequency ratio p (=f21/f112) is greater than or equal to 0.7 and less than or equal to (0.1801·x−0.468), an excellent matching can be made at the resonance frequency of the fundamental mode of the radiating element and at the resonance frequency of the second order mode.
Next, results of analysis for the S11 characteristic of the antenna structure 1 will be described.
Respective dimensions shown in
With the illustrations in
As described above, the antenna structure and the electronic device have been described by the embodiments. The present invention is not limited to the embodiments. Various variations and enhancements, such as combination/replacement with/by a part or a whole of the other embodiment may be made without departing from the scope of the present invention.
For example, the power feeding element 21 may feed power to the radiating element 22 in a noncontact manner according to a capacitance coupling or an electromagnetic coupling with the radiating element 22.
For example, a plurality of antenna structures may be installed in an electronic device.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-172383 | Sep 2015 | JP | national |
The present application is a continuation application filed under 35 U.S.C. 111(a) claiming benefit under 35 U.S.C. 120 and 365(c) of PCT International Application No. PCT/JP2016/074470 filed on Aug. 23, 2016 and designating the U.S., which claims priority of Japanese Patent Application No. 2015-172383 filed on Sep. 1, 2015. The entire contents of the foregoing applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2016/074470 | Aug 2016 | US |
| Child | 15905307 | US |
