JP6366330B2 - Multiband antenna - Google Patents

Description

  The present invention relates to a multi-band antenna that supports transmission / reception of a multi-frequency broadband in a low frequency band, an intermediate frequency band, and a high frequency band.

  Recently, portable terminals such as smartphones and tablet terminals are required to support LTE (Long Term Evolution) as a standard for high-speed data communication. Note that G represents the generation.

  The LTE is a fourth-generation mobile communication (4G) wireless communication technology that prevents an increase in mutual interference due to the occurrence of multipath due to a wider band.

  The fourth generation mobile communication is intended to promote mobile phones all over the world such as Japan, the US, Europe, Southeast Asia, and China using the same LTE method, but it also uses the previous generation of communication, and the fourth generation. The antenna used for mobile communication not only covers, for example, 698 to 960 MHz in the low frequency band and 3 frequency bands (1428 MHz to 1595 MHz, 1710 MHz to 2170 MHz, 2500 MHz to 2700 MHz) in the intermediate frequency band, and 4G Therefore, it is required to newly cover the high frequency band from 3.4 GHz to 3.6 GHz.

  The present inventors have developed an antenna that forms the basis of a multiband antenna that can meet the above requirements (Patent Document 1). The multiband antenna includes a shaft portion common to a low frequency band and a high frequency band, a single feeding portion connected to the shaft portion and a ground plate, and a branch from the shaft portion in units of frequency bands. A low frequency band feeding element and a high frequency band feeding element, which are asymmetric antenna elements, and a low frequency band parasitic element and a high frequency element combined with the low frequency band feeding element and the high frequency band feeding element, respectively. A parasitic element in a frequency band, the parasitic element in the low frequency band and the parasitic element in the high frequency band, the feeder element in the low frequency band, the feeder element in the high frequency band, and the ground plate It is the thing of the structure incorporated in the space between.

Patent No. 5324608

  However, as is clear from FIGS. 8, 12, 13, and 14 of the patent publication, the multiband antenna disclosed in Patent Document 1 has a frequency band of 698 to 960 MHz in the low frequency band and three frequency bands in the intermediate frequency band ( 1428 MHz to 1595 MHz, 1710 MHz to 2170 MHz, 2500 MHz to 2700 MHz), but it is not possible to cover the high frequency band for 4G from 3.4 GHz to 3.6 GHz.

  Therefore, it is an urgent issue to develop a multi-band antenna that supports a multi-frequency wide band of a low frequency band, an intermediate frequency band, and a high frequency band.

  In addition, the antenna of the fourth generation mobile communication (4G) is required not only to meet the demand for supporting the multi-frequency broadband, but also to reduce the size of the antenna. That is, various antennas such as LTE, wireless LAN, Bluetooth (registered trademark), and GPS reception are mounted on tablet terminals that are compatible with 4G mobile communication (4G) among mobile terminals. If the antennas are brought close together, it will not be possible to build a good reception environment by causing radio wave interference.Therefore, miniaturization of antennas is required in order to avoid radio wave interference by separating the distance between antennas. Yes.

  An object of the present invention is to provide a multiband antenna that is compatible with multi-frequency broadband transmission / reception and that is further reduced in size and thickness.

  4th generation mobile communication (4G) is a single antenna, 698 to 960 MHz in the low frequency band, 3 frequency bands in the intermediate frequency band (1428 MHz to 1595 MHz, 1710 MHz to 2170 MHz, 2500 MHz to 2700 MHz), high frequency band Since it is required to cover up to 3.4 GHz to 3.6 GHz, it is conceivable to mount a three-element antenna element having an electrical length corresponding to each frequency band on the substrate.

  However, since the lower limit frequency of the multi-frequency broadband is 698 MHz and the upper limit frequency is 3.6 GHz, the electrical length for the lower limit frequency and the upper limit frequency is wide, so each frequency band has its own antenna. There is a limit to the size of the miniaturization in order to realize the miniaturization corresponding to the element.

  Therefore, the inventors changed the way of thinking and changed the density of the surface current flowing through the feeding element, the parasitic element, and the shaft portion for each frequency band depending on the combination of the element and the shaft portion, thereby reducing the low frequency. It corresponds to the band, intermediate frequency band and high frequency band, and further miniaturization is realized. Focusing on the line width of the shaft portion, the feeding element, and the parasitic element, the surface current density is varied for each frequency.

  Specifically, the multi-band antenna according to the present invention is a multi-band antenna that supports transmission / reception of a multi-frequency broadband, and includes a shaft portion common to a low frequency band, an intermediate frequency band, and a high frequency band, and the shaft portion. And a single feeding part connected to the ground plate, an asymmetrical upper feeding element branched from the shaft part, and an asymmetrical lower parasitic element separated from the shaft part, the upper stage Each of the feeding elements is provided with an asymmetrical perturbation element.

  As described above, according to the present invention, since the asymmetrical perturbation element is provided in the upper feed element that is branched from the common shaft portion and is asymmetric, the surface current flowing through the feed element, the parasitic element, and the shaft portion is reduced. The density can be made different for each frequency band, and it is possible to deal with the low frequency band, the intermediate frequency band, and the high frequency band as apparent from the actual measurement values shown in FIGS. Is.

  Furthermore, the density of the surface current flowing through the feeding element, the parasitic element, and the shaft portion is varied for each frequency band by the combination of the element and the shaft portion, so that a multi-frequency broadband from a low frequency band to a high frequency band can be obtained. In order to cope with this, the electrical lengths of these feeding elements and parasitic elements can be shortened, and further miniaturization can be realized.

(A) is a front view which shows the multiband antenna which concerns on embodiment of this invention, (b) is the back view. It is a characteristic view which shows the measured value of VSWR in the multiband antenna which concerns on embodiment of this invention shown in FIG. (A) is a surface view showing an example in which a plate-shaped perturbation element is attached to one feeding element, and (b) is a characteristic diagram showing actual measurement values of VSWR in the antenna of FIG. 3 (a). (A) is a surface view showing an example in which a prismatic perturbation element is attached to one feeding element, and (b) is a characteristic diagram showing an actual measurement value of VSWR in the antenna of FIG. 3 (a). (A) is a surface view showing an example in which a plate-like perturbation element is attached to two feeding elements, and (b) is a characteristic diagram showing an actual measurement value of VSWR in the antenna of FIG. 3 (a). The left side of (a) is a characteristic diagram showing the density of the surface current flowing on the surface side of the feeding element and the parasitic element and the shaft portion at 698 MHz, and the right side flows on the back surface side of the feeding element and the parasitic element and the shaft portion at 698 MHz. A characteristic diagram showing the density of the surface current, the left side of (b) is a characteristic diagram showing the density of the surface current flowing on the surface side of the feeding element and the parasitic element and the shaft portion at 1000 MHz, and the right side is the feeding element and the parasitic element at 1000 MHz. The characteristic diagram which shows the density of the surface current which flows to the back side of the element and the shaft part, the left side of (c) is the characteristic diagram which shows the density of the surface current which flows on the surface side of the feeding element and parasitic element and the shaft part at 1400 MHz, The right side is a characteristic diagram showing the density of the surface current flowing on the back side of the feeding element and the parasitic element and the shaft at 1400 MHz. The left side of (a) is a characteristic diagram showing the density of the surface current flowing to the surface side of the feeding element and the parasitic element and the shaft portion at 1595 MHz, and the right side flows to the back surface side of the feeding element and the parasitic element and the shaft portion at 1595 MHz. The characteristic diagram showing the density of the surface current, the left side of (b) is a characteristic diagram showing the density of the surface current flowing on the surface side of the feeding element and the parasitic element and the shaft portion at 1700 MHz, and the right side is the feeding element and the parasitic element at 1700 MHz. The characteristic diagram which shows the density of the surface current which flows into the element and the back side of the shaft part, the left side of (c) is the characteristic diagram which shows the density of the surface current which flows on the surface side of the feeding element and parasitic element and the shaft part at 2200 MHz, The right side is a characteristic diagram showing the density of the surface current flowing on the back surface side of the feeding element and the parasitic element and the shaft portion at 2200 MHz. The left side of (a) is a characteristic diagram showing the density of the surface current flowing on the surface side of the feeding element and the parasitic element and the shaft part at 2500 MHz, and the right side flows on the back side of the feeding element and the parasitic element and the shaft part at 2500 MHz. The characteristic diagram showing the density of the surface current, the left side of (b) is a characteristic diagram showing the density of the surface current flowing on the surface side of the feeding element and the parasitic element and the shaft portion at 2700 MHz, the right side is the feeding element and the parasitic element at 2700 MHz It is a characteristic view which shows the density of the surface current which flows into an element and the back surface side of a shaft part. The left side of (a) is a characteristic diagram showing the density of the surface current flowing on the surface side of the feeding element and the parasitic element and the shaft part at 3400 MHz, and the right side flows on the back side of the feeding element and the parasitic element and the shaft part at 3400 MHz. A characteristic diagram showing the density of the surface current, the left side of (b) is a characteristic diagram showing the density of the surface current flowing at the surface side of the feeding part and the parasitic element and the shaft portion at 3600 MHz, and the right side is a characteristic chart showing the density of the feeding element and the parasitic element at 3600 MHz It is a characteristic view which shows the density of the surface current which flows into an element and the back surface side of a shaft part. (A) is a diagram in which a perturbation element is provided and a feeding element close to an inverted L-type parasitic element is formed in a straight shape, and (b) is a characteristic diagram showing an actual measurement value of VSWR in the antenna of FIG. is there. (A) is a figure for verifying the line | wire width of a feed element, (b) is a characteristic figure which shows the measured value of VSWR in the antenna of Fig.11 (a). (A) is a figure which shows the example of a change of a perturbation element, (b) is a characteristic figure which shows the measured value of VSWR in the antenna of Fig.12 (a). (A) is a figure which shows the example of a change of a perturbation element, (b) is a characteristic figure which shows the measured value of VSWR in the antenna of Fig.13 (a). (A) is a figure which shows the relationship between the standing degree of a perturbation element, and a feed element, (b) is a characteristic figure which shows the measured value of VSWR in the antenna of Fig.14 (a). (A) is a perspective view showing a mounting example of a perturbation element, (b) is a perspective view seen through a state in which the perturbation element is held on the support portion of the clip piece, (c) is a cross-sectional view showing an attachment state by the clip piece, (D) is sectional drawing which shows the fitting state of a convex piece and a groove | channel. (A) is the perspective view which shows the mounting state of the perturbation element by a thin diameter pipe, (b) is the perspective view which looked at the crimping state of the small diameter pipe from the back surface of the board | substrate. (A) is a front view showing a modified example of the shaft portion, (b) is a back view showing a modified example of the parasitic element, and (c) is a characteristic diagram showing actually measured VSWR.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
The multiband antenna according to the first embodiment of the present invention is intended for a multiband antenna corresponding to a transmission / reception wave of a multi-frequency broadband. By using a single power feeding unit 1, multi-frequency broadband transmission / reception is performed. Is what you do. As shown in FIGS. 1A and 1B, the multiband antenna according to Embodiment 1 of the present invention branches from a single shaft portion 2 connected to a single power feeding portion 1 and the shaft portion 2. And asymmetric parasitic elements 5 a and 5 b separated from the shaft portion 2, and these elements are provided on the same substrate 4.
In FIG. 1A, in order to show the mutual relationship between the shaft portion 2, the feed elements 3a, 3b and the parasitic elements 5a, 5b, the shaft portion 2, the feed elements 3a, In addition to 3b and the parasitic element 5a, the parasitic element 5b formed on the back surface 4b side of the substrate 4 is shown as seen through from the substrate surface side. Similarly, in FIG. 1B, a parasitic element 5b formed on the back surface 4b side of the substrate 4 is added to show the mutual relationship between the shaft portion 2, the feeding elements 3a and 3b and the parasitic elements 5a and 5b. The shaft 2, the feed elements 3a and 3b, and the parasitic element 5a formed on the surface 4a side of the substrate 4 are shown in a state seen through from the substrate surface side. The illustrated embodiment shown in FIGS. 1A and 1B is similarly followed in FIGS. 3 to 9, FIGS. 10 to 14, and 17.

  Furthermore, in the multiband antenna according to Embodiment 1 of the present invention, the line width of the shaft portion 2 is L1, the line widths of the feed elements 3a and 3b are L2 and L3, and the line widths of the parasitic elements 5a and 5b are set. Assuming L4 and L5, the line width L1 of the shaft portion 2 is wider than the line widths L2 to L5 of the power feeding elements 3a and 3b and the parasitic elements 5a and 5b, or the power feeding elements 3a and 3b and the parasitic power. The line widths L2 to L5 of the elements 5a and 5b are set to be the same.

  In the first embodiment of the present invention, the line width L1 of the shaft portion 2 is wider than the line widths L2 to L5 of the feeding elements 3a and 3b and the parasitic elements 5a and 5b, or the feeding elements 3a and 3b and the parasitic element 5a. , 5b are set to be the same as the line widths L2 to L5, the density of the surface current flowing through the feed elements 3a, 3b, the parasitic elements 4a, 4b, and the shaft portion 2 can be set to the low frequency band, the intermediate frequency band, and the high frequency band. It is different for each frequency band and corresponds to the low frequency band, the intermediate frequency band, and the high frequency band, as is apparent from the actual measurement values shown in FIGS. The actual measurement values shown in FIGS. 6 to 9 are cases where the line width L1 of the shaft portion 2 is set wider than the line widths L2 to L5 of the feed elements 3a and 3b and the parasitic elements 5a and 5b. Even when the line width L1 of 1 is set to be the same as the line widths L2 to L5 of the feeding elements 3a and 3b and the parasitic elements 5a and 5b, the same actual measurement value is obtained.

More specifically, in the first embodiment of the present invention shown in FIGS. 1A and 1B, the patterns of the feeding elements 3a and 3b and the parasitic elements 5a and 5b are formed on the dielectric substrate 4 by etching. Forming. The structure of the multiband antenna according to the first embodiment after etching will be described.
In FIGS. 1A and 1B, the lengths of the asymmetric feeding elements 3 a and 3 b are different from each other, and the feeding elements 3 a and 3 b are formed on the surface 4 a of the substrate 4. The asymmetric parasitic elements 5a and 5b are different in length. The parasitic elements 5b having a short length are formed on the surface 4a of the substrate 4, and the parasitic elements 5a having a long length are formed on the substrate 4. The back surface 4b is formed separately.
The feeding elements 3a and 3b and the parasitic elements 5a and 5b formed on the surface 4a of the substrate 4 are provided with different pattern halftone dots to identify each other. In addition, the parasitic elements 5b formed on the back surface 4b of the substrate 4 are marked with a one-dot chain line to distinguish between the elements on the front and back surfaces 4a and 4b of the substrate 4.

  As shown in FIGS. 1A and 1B, the shaft portion 2 is connected to the power feeding portion 1 and rises to be formed on the surface 4 a side of the substrate 4. The feeding elements 3a and 3b are branched from the shaft portion 2 and formed on the front surface 4a of the substrate 4. The parasitic elements 5a and 5b are separated from the shaft portion 2 and separated from the front surface 4a and the back surface 4b of the substrate 4. It is formed separately. The feeding elements 3a and 3b are directly coupled to the shaft portion 2 and mechanically coupled, and the parasitic elements 5a and 5b are electrically coupled to the shaft portion 2 (electrostatic coupling or electromagnetic coupling).

  In the first embodiment shown in FIGS. 1A and 1B, the long feeding element 3a and the long parasitic element 5a are formed on the surface 4a of the left substrate 4 with the shaft portion 2 as the center, and the short feeding element 3b. The short parasitic element 5b is formed on the surface 4a of the right substrate 4 with the shaft portion 2 as the center. The long feeding element 3a and the long parasitic element 5a may be formed on the right side of the shaft part 2, and the short feeding element 3b and the short parasitic element 5b may be formed on the left side of the shaft part 2, respectively.

The feed elements 3a and 3b and the parasitic elements 5a and 5b are formed as antenna elements having an asymmetric structure, respectively, and the configuration will be specifically described.
As shown in FIGS. 1 (a) and 1 (b), the long feeding element 3a is formed by pulling out from the top of the shaft portion 2 in the left lateral direction, leading out the tip downward, and then bending it to the right lateral. ing. As shown in FIGS. 1A and 1B, the short feeding element 3b is formed by pulling out from the shaft portion 2 to the right side, pulling out the tip upward, and then bending the tip to the left side. Yes. Further, the short power feeding element 3b is formed in a meander shape at a portion drawn from the shaft portion 2 to the right side.
As shown in FIGS. 1 (a) and 1 (b), the long parasitic element 5a is formed by pulling it out in the lateral direction on the left side with respect to the shaft 2, pulling out the tip downward, and then bending it to the right lateral side. doing. As shown in FIGS. 1A and 1B, the short parasitic element 5b is pulled out to the right side with respect to the shaft portion 2, its tip is pulled out upward, and then the tip is bent to the right side. It is formed as an inverted L-type antenna element.

In the first embodiment of the present invention, as described above, the line width of the shaft portion 2 is made to correspond to the low frequency band, the intermediate frequency band, and the high frequency band by changing the surface current density for each frequency band. Is L1, the line width of the feed elements 3a and 3b is L2, and the line width of the parasitic elements 5a and 5b is L3, the line width L1 of the shaft portion 2 is the feed elements 3a and 3b and the parasitic elements. 5a and 5b wider than the line widths L2 to L5 (L1> L2 to L5), or the line width L1 of the shaft portion 2 is equal to the line widths L2 to L5 of the feeding elements 3a and 3b and the parasitic elements 5a and 5b. The same (L1 = L2 to L5) is set. The line widths L1, L2 to L5 of the shaft portion 2, the feeding elements 3a and 3b, and the parasitic elements 5a and 5b described above mean dimensions at the widest portion of these elements.
That is, the shaft portion 2 rises with the root side and the top side set to the same line width, and the line width L1 is the dimension of the portion indicated by the arrows on the root side and the top side. The line width L2 is the dimension of the portion indicated by the arrow drawn to the left side from the shaft 2 of the long feed element 3a, and the line width L3 is the arrow bent to the left side with respect to the shaft 2 of the short feed element 3b. It is the dimension of the part shown by. The line width L4 is the dimension indicated by the arrow drawn to the left side from the shaft 2 of the long parasitic element 5a, and the line width L5 is bent to the left side with respect to the shaft 2 of the short parasitic element 5b. It is the dimension of the part shown with the arrow.

  Next, the relationship with the ground plate 6 combined with the antenna elements 3a, 3b, 5a, 5b described above will be described. The single power feeding portion 1 is connected to the end portion 2 a of the shaft portion 2 on the ground plate 6 side and the ground plate 6. The parasitic element 5b formed on the surface 4a of the substrate 4 rises from the ground plate 6 and has an inverted L shape. The parasitic element 5 a formed on the back surface 4 b of the substrate 4 rises from the ground plate 6. A horizontally long impedance matching piece 7 is formed on the surface 4 a of the substrate 4, one end portion 7 a of the impedance matching piece 7 is joined to the end portion 2 a on the ground plate 6 side of the shaft portion 2, and the ground plate 6 The other end 7 b of the impedance matching piece 7 along the edge is joined to the ground plate 6. In this case, a gap S <b> 1 is secured between the impedance matching piece 7 and the edge of the ground plate 6. For this reason, impedance matching is achieved by avoiding contact other than the other end of the impedance matching piece 7 with the ground plate. The impedance matching piece 7 is used for better VSWR improvement, and it has been confirmed that there is no practical problem even if these impedance matching pieces 7 are unnecessary. . Although the ground plate 6 is formed on a part of the substrate 4 by etching, the ground plate 6 may be combined with the ground plate 6 forming a common electrode of the notebook personal computer, and the ground plate 6 is formed on the substrate 4. It is not a necessary and sufficient condition.

  Next, VSWR with the antenna structure shown in FIGS. 1 (a) and 1 (b) was measured. The result is shown in FIG. In FIG. 2, the horizontal axis represents frequency, and the vertical axis represents VSWR.

  As shown in FIG. 2, it can be seen that resonance occurs in the vicinity of 850 MHz in the low frequency band, resonance in the vicinity of 1900 MHz and 2600 MHz in the intermediate frequency band, and resonance in the vicinity of 3100 MHz and 3600 MHz in the high frequency band.

  As described above, according to the antenna structure shown in FIGS. 1A and 1B, the line width of the shaft portion is set wider than the line width of the feed element and the parasitic element or the same as the line width of these elements. By doing so, it is possible to cope with the low frequency band, the intermediate frequency band, and the high frequency band as is apparent from FIG. This corresponds to the low frequency band, the intermediate frequency band, and the high frequency band because the density of the surface current flowing through the feeding element, the parasitic element, and the shaft is different for each of the low frequency band, the intermediate frequency band, and the high frequency band. It is thought that it was possible.

  As described above, according to the structure shown in FIGS. 1A and 1B, the line width of the shaft portion is set wider than the line width of the feeding element and the parasitic element or the same as the line width of these elements. As is apparent from FIG. 2, the object of corresponding to the low frequency band, the intermediate frequency band, and the high frequency band could be achieved.

  Furthermore, the density of the surface current flowing through the feeding element, the parasitic element, and the shaft portion is varied for each frequency band by the combination of the element and the shaft portion, so that a multi-frequency broadband from a low frequency band to a high frequency band can be obtained. In order to cope with this, it is possible to reduce the prescribed electrical lengths of these feeding elements and parasitic elements, and it is possible to achieve further miniaturization.

(Embodiment 2)
According to the first embodiment, the purpose of corresponding to the low frequency band, the intermediate frequency band, and the high frequency band can be achieved. However, since there is a shift in the intermediate frequency band, it is necessary to improve this. . In the second embodiment, an attempt is made to improve the shift in the intermediate frequency band.

Since it is common to shift the frequency to the low frequency side using a perturbation element, the case where this technique is applied to the present invention as it is was considered. The consideration will be described with reference to FIGS.
FIG. 3A is a diagram illustrating a case where the plate-like perturbation element P1 is provided in the long power feeding element 3a. As shown in FIG. 3A, in the structure in which the perturbing element P1 is provided in the long power feeding element 3a, it is clear from comparison between FIG. 2 and FIG. 3B that the intermediate frequency band has not been improved. . FIG. 4A is a diagram showing a case where the plate-like perturbation element P shown in FIG. 3A is changed to a prismatic perturbation element P2 and the prismatic perturbation element P2 is provided in a long feeding element 3a. . As shown in FIG. 4A, in the structure in which the perturbation element P2 is provided in the long power feeding element 3a, it is clear from comparison between FIG. 2 and FIG. 4B that the intermediate frequency band has not been improved. .

  In the second embodiment, the structure shown in FIG. 5A is developed by analyzing the structures of the perturbation elements P1 and P2 shown in FIGS. That is, in Embodiment 2, asymmetrical perturbation elements 8 and 9 are provided in the upper feed elements 3a and 3b, respectively. The side 3c along the inverted L-type parasitic element 5b of the short feeding element (inverted L-type antenna element) 3b is formed in a meander shape. Although the entire side 3c of the feeding element 3b has a meander shape, as shown in FIGS. 6 to 9, a part having a large line width may be provided on a part of the side 3c, and both ends thereof may be in a meander shape. Is.

The asymmetrical perturbation elements 8 and 9 are provided along the feeding elements 3a and 3b with different lengths. That is, a long perturbation element 8 is provided for the long feed element 3a, and a short perturbation element 9 is provided for the short feed element 3b. Further, the perturbing element 8 provided in the upper long feeding element 3 a is provided to extend to the shaft portion 2. In this case, the length of the perturbation element 9 provided in the short power feeding element 3b is limited to the length of the power feeding element 3b.
The other configurations of the second embodiment described above are configured in the same manner as the first embodiment.

Next, the perturbation elements 8 and 9 are provided in the upper feed elements 3a and 3b, the thick part of the line width is provided in a part of the side 3c, and both ends thereof are formed in a meander shape, and the line width L1 of the shaft part 2 is further provided. Is set wider than the line widths L2 to L5 of the feeding elements 3a and 3b and the parasitic elements 5a and 5b, the density of the surface current flowing through the feeding elements 3a and 3b, the parasitic elements 5a and 5b, and the shaft portion 2 can be reduced. The simulation shown in FIG. 6 to FIG. 9 shows whether the low frequency band, the intermediate frequency band, and the high frequency band are changed to correspond to the low frequency band, the intermediate frequency band, and the high frequency band and the intermediate frequency band is improved. Verify based on the results of.
The measured values in FIGS. 6 to 9 are the same measured values even if the line width L1 of the shaft portion 1 is set to be the same as the line widths L2 to L5 of the feeding elements 3a and 3b and the parasitic elements 5a and 5b. It has gained.

  6 (a) (b) (c), FIG. 7 (a) (b) (c), FIG. 8 (a) (b) and FIG. 9 (a) (b) shown in FIG. 9, the density of the surface current flowing through the feeding elements 3a and 3b, the parasitic elements 5a and 5b, and the shaft portion 2 is made different for each of the low frequency band, the intermediate frequency band, and the high frequency band. , The current is flowing in the ground plate 6 because the main purpose is to show that it corresponds to the intermediate frequency band and the high frequency band, but the density distribution of the surface current flowing in the ground plate 6 is omitted. Similarly, the impedance matching piece 7 is omitted.

FIG. 6A shows the result of simulation with the intention of 698 MHz, which is the lower limit frequency of the low frequency band. The left side of FIG. 6A is a view of the simulation result from the front surface 4 a of the substrate 4, and the right side of FIG. 6A is a view of the simulation result from the back surface 4 b of the substrate 4. In FIG. 6A, a region having a high surface current density and a region having a relatively high surface current are indicated by hatching.
As is apparent from the simulation result of FIG. 6A, the surface current density of the long feeding element 3a and the long parasitic element 5a shows the maximum, and the whole shaft portion 2, the short feeding element 3b, and the short parasitic element are shown. A part having a relatively high surface current density is also found in a part of the element 5b. At this frequency of 698 MHz, it is considered that the long feeding element 3a and the long parasitic element 5a indicated by oblique lines mainly contribute to the resonance.

FIG. 6B shows a result of simulation intended for 1000 MHz which is near the upper limit frequency of the low frequency band. Note that the left side of FIG. 6B is a view of the simulation result from the front surface 4 a of the substrate 4, and the right side of FIG. 6B is a view of the simulation result from the back surface 4 b of the substrate 4. In FIG. 6B, the region where the surface current density is high and the region where the surface current density is relatively high are indicated by hatching.
As is apparent from the simulation result of FIG. 6B, the surface current density of the long feeding element 3a and the long parasitic element 5a shows the maximum, and the entire shaft portion 2, the short feeding element 3b, and the short parasitic element are shown. A part having a relatively high surface current density is also found in a part of the element 5b. At this frequency of 698 MHz, it is considered that the long feeding element 3a and the long parasitic element 5a indicated by diagonal lines mainly contribute to the resonance, and other regions contribute to the resonance complementarily. The result of this simulation substantially coincides with the result of the simulation shown in FIG. 6A, and the long feeding element 3a and the long parasitic element shown by hatching for the range of 6987 MHz to 960 MHz in the low frequency band. It can be seen that 5a corresponds.

FIGS. 6C to 8B are simulated with the intention of the intermediate frequency bands 1428 MHz to 1595 MHz, 1710 MHz to 2170 MHz, and 2500 MHz to 2700 MHz.
FIG. 6C shows the result of simulation with the intention of 1400 MHz, which is near the lower limit frequency of the intermediate frequency band. Note that the left side of FIG. 6C is a view of the simulation result from the front surface 4a of the substrate 4, and the right side of FIG. 6C is a view of the simulation result from the back surface 4b of the substrate 4. In FIG. 6C, the region where the surface current density is high and the region where the surface current density is relatively high are indicated by hatching.
As apparent from the simulation result of FIG. 6C, the surface that is substantially uniform in the shaft portion 2, the long feeding element 3a and the long parasitic element 5a, the short feeding element 3b, and the short parasitic element 5b. At this frequency of 1400 MHz, the shaft portion 2, the long feed element 3a, the long parasitic element 5a, the short feed element 3b, and the short parasitic element 5b, which are indicated by diagonal lines, contribute to the resonance. This element is considered to correspond to a frequency of 1400 MHz.

FIG. 7A shows the result of simulation with the intention of an intermediate frequency band of 1595 MHz. The left side of FIG. 7A is a view of the simulation result from the front surface 4 a of the substrate 4, and the right side of FIG. 7A is a view of the simulation result from the back surface 4 b of the substrate 4. In FIG. 7A, a region having a high surface current density and a region having a relatively high surface current are indicated by hatching.
As is clear from the simulation result of FIG. 7A, the surface that is substantially uniform in the shaft portion 2, the long feeding element 3a and the long parasitic element 5a, the short feeding element 3b and the short parasitic element 5b. The current density appears, and at this frequency of 1595 MHz, the shaft portion 2, the long feed element 3a, the long parasitic element 5a, the short feed element 3b, and the short parasitic element 5b, which are indicated by diagonal lines, contribute to the resonance. This element is considered to correspond to a frequency of 1595 MHz.

FIG. 7B shows the result of simulation with the intention of an intermediate frequency band of 1700 MHz. The left side of FIG. 7B is a view of the simulation result from the front surface 4 a of the substrate 4, and the right side of FIG. 7B is a view of the simulation result from the back surface 4 b of the substrate 4. In FIG. 7B, a region having a high surface current density and a region having a relatively high surface current are indicated by hatching.
As apparent from the simulation result of FIG. 7B, the surface that is substantially uniform in the shaft portion 2, the long feeding element 3a and the long parasitic element 5a, and the short feeding element 3b and the short parasitic element 5b. At this frequency of 1700 MHz, the shaft portion 2, the long feed element 3a, the long parasitic element 5a, the short feed element 3b, and the short parasitic element 5b, which are shown by diagonal lines, contribute to the resonance. These elements are considered to correspond to a frequency of 1700 MHz.

FIG. 7C shows the result of simulation with the intention of an intermediate frequency band of 2200 MHz. The left side of FIG. 7C is a view of the simulation result from the front surface 4 a of the substrate 4, and the right side of FIG. 7C is a view of the simulation result from the back surface 4 b of the substrate 4. In FIG. 7C, the region where the surface current density is high and the region where the surface current density is relatively high are indicated by hatching.
As is apparent from the simulation result of FIG. 7C, the surface that is substantially uniform in the shaft portion 2, the long feeding element 3a and the long parasitic element 5a, the short feeding element 3b, and the short parasitic element 5b. At this frequency of 2200 MHz, the shaft portion 2, the long feed element 3a, the long parasitic element 5a, the short feed element 3b, and the short parasitic element 5b, which are indicated by diagonal lines, contribute to the resonance. This element is considered to correspond to a frequency of 2200 MHz.

FIG. 8A shows the result of simulation with the intention of an intermediate frequency band of 2500 MHz. The left side of FIG. 8A is a view of the simulation result from the front surface 4 a of the substrate 4, and the right side of FIG. 8A is a view of the simulation result from the back surface 4 b of the substrate 4. In FIG. 8A, a region having a high surface current density and a region having a relatively high surface current are indicated by hatching.
As is clear from the simulation result of FIG. 8A, the surface that is substantially uniform in the shaft portion 2, the long feeding element 3a and the long parasitic element 5a, the short feeding element 3b, and the short parasitic element 5b. At this frequency of 2500 MHz, the shaft portion 2, the long feed element 3a, the long parasitic element 5a, the short feed element 3b, and the short parasitic element 5b, which are indicated by diagonal lines, contribute to the resonance. This element is considered to correspond to a frequency of 2500 MHz.

FIG. 8B shows the result of simulation with the intention of an intermediate frequency band of 2700 MHz. The left side of FIG. 8B is a view of the simulation result from the front surface 4 a of the substrate 4, and the right side of FIG. 8B is a view of the simulation result from the back surface 4 b of the substrate 4. In FIG. 8B, a region with a high surface current density is indicated by hatching, and a subsequent region is indicated by dots.
As is apparent from the simulation results of FIG. 8B, the surface that is substantially uniform in the shaft portion 2, the long feeding element 3a and the long parasitic element 5a, and the short feeding element 3b and the short parasitic element 5b. At this frequency of 2700 MHz, the shaft portion 2, the long feed element 3a, the long parasitic element 5a, the short feed element 3b, and the short parasitic element 5b, which are shown by diagonal lines, contribute to the resonance. This element is considered to correspond to a frequency of 2700 MHz.

FIG. 9A shows the result of a simulation intended for a high frequency band of 3400 MHz. Note that the left side of FIG. 9A is a view of the simulation result from the front surface 4a of the substrate 4, and the right side of FIG. 9A is a view of the simulation result from the back surface 4b of the substrate 4. In FIG. 9A, a region having a high surface current density and a region having a relatively high surface current are indicated by hatching.
As is apparent from the simulation result of FIG. 9A, surface current density mainly appears in the shaft portion 2, the short feeding element 3b, and the long parasitic element 5a, and this frequency 3400 MHz is indicated by hatching. The shaft portion 2, the short feed element 3b, and the long parasitic element 5a mainly contribute to resonance, and these elements are considered to correspond to a frequency of 3400 MHz.

FIG. 9B shows the result of simulation with the intention of a high frequency band of 3600 MHz. Note that the left side of FIG. 9B is a view of the simulation result from the front surface 4 a of the substrate 4, and the right side of FIG. 9B is a view of the simulation result from the back surface 4 b of the substrate 4. In FIG. 9B, a region having a high surface current density and a region having a relatively high surface current are indicated by hatching.
As is apparent from the simulation result of FIG. 9B, surface current density mainly appears in the shaft portion 2, the short feeding element 3b, and the long parasitic element 5a, and this frequency 3600 MHz is indicated by hatching. The shaft portion 2, the short feeding element 3b, and the long parasitic element 5a mainly contribute to resonance, and it is considered that these elements correspond to a frequency of 3600 MHz.

  As shown in FIG. 5A, even if the antenna structure has perturbation elements 8 and 9 provided in the upper feed elements 3a and 3b and the entire side 3c has a meander shape, the antenna structure is shown in FIGS. The result is similar to the simulation.

The asymmetrical perturbation elements 8 and 9 are provided in the asymmetric upper feed elements 3a and 3b shown in FIG. 5A, and the VSWR is measured in an antenna structure in which the entire side 3c is formed in a meander shape. Shown in 5 (b).
When the measured value of VSWR in FIG. 5B is compared with the measured value of VSWR in FIG. 2, the provision of the perturbation elements 8 and 9 contributes to improvement of characteristics in the intermediate frequency band and expansion of the bandwidth. I understand that.
Further, by adopting the meander shape shown in FIGS. 5A and 6, the parasitic element 5 b is affected by electrical coupling (electromagnetic coupling or electrostatic coupling) due to the current flowing through the feeding element 3 b. It was found that this contributes to the improvement of the characteristics in the intermediate frequency band and the expansion of the bandwidth. In this case, the meander shape shown in FIG. 5 (a) may be employed in order to exert a great influence by the electrical coupling.

  As described above, according to the second embodiment, the density of the surface current flowing through the feeding element, the parasitic element, and the shaft portion is varied for each frequency band as shown in FIGS. In addition to being able to cope with the intermediate frequency band and the high frequency band, it is possible to obtain a remarkable effect that it can contribute to improvement of characteristics and expansion of the bandwidth in the intermediate frequency band.

  Furthermore, the density of the surface current flowing through the feeding element, the parasitic element, and the shaft portion is varied for each frequency band by the combination of the element and the shaft portion, so that a multi-frequency broadband from a low frequency band to a high frequency band can be obtained. In order to cope with this, the electrical lengths of these feeding elements and parasitic elements can be shortened, and further miniaturization can be realized.

  According to the second embodiment shown in FIG. 5A, as shown in FIG. 5B, resonance occurs in the vicinity of 1500 MHz, so that the intermediate frequency band can be improved and the high frequency band is also improved. There is an advantage that you can.

(Embodiment 3)
In the embodiment shown in FIG. 1A and FIG. 5A, an example is shown in which the side 3c along the inverted L-type parasitic element 5b of the short feeding element (inverted L-type antenna element) 3b is formed in a meander shape. However, in Embodiment 3 shown in FIG. 10A, the side 3c of the short feeding element 3b is changed to a straight shape. In this case, it is assumed that the perturbation elements 8 and 9 shown in FIG.
The other configuration of the third embodiment described above is configured similarly to the configuration of the first embodiment.
As is apparent from a comparison between FIG. 10B and FIG. 5B, even if the side 3c of the short feeding element 3b is changed from the meander shape D1 indicated by the alternate long and short dash line to the straight shape D2 indicated by the solid line, FIG. As shown in b), it resonates in the vicinity of 1500 MHz, and there is an advantage that the intermediate frequency band can be improved and the high frequency band can also be improved.

(Embodiment 4)
In FIG. 11A, the VSWR was measured when the line width L21 of the side 3d along the long parasitic element 5a of the long feed element 3a was wide and the line width L22 on the opposite side was narrowed. As is apparent from a comparison between FIG. 11B and FIG. 2, it can be seen that the antenna characteristics of the low frequency band and the intermediate frequency band are deteriorated by widening the side 3d of the feeding element 3a and narrowing the opposite side. .
From this consideration, as shown in FIGS. 1A and 5A, the line width L21 of the side 3d along the long parasitic element 5a of the long feed element 3a is narrowed and the line width L22 on the opposite side is widened. It turns out that is necessary. Other configurations of the fourth embodiment described above are configured in the same manner as the configuration of the first embodiment.

(Embodiment 5)
In FIG. 12A, the perturbation element 9 shown in FIG. The flange 9a is provided on the short feeding element 3b side. In the fifth embodiment, the band on the high frequency side is improved as apparent from the comparison between FIG. 5B and FIG. 12B because the flange 9a electromagnetically affects the feeding element 3b. I understand that. Other configurations of the fifth embodiment described above are the same as the configurations of the first embodiment.

In the above embodiment, the example is shown in which the perturbation elements 8 and 9 are mechanically coupled by being directly coupled to the power feeding elements 3a and 3b. However, the present invention is not limited to this. As shown in FIG. 13A, the perturbation elements 8 and 9 are slightly lifted from the feed elements 3a and 3b and arranged with a gap (about 0.1 mm) S2, thereby disposing the perturbation elements 8 and 9 to the feed element 3a. , 3b may be electrically joined (electromagnetic coupling or electrostatic coupling). When the gap S is opened, a structure in which a dielectric is interposed in the gap S2, and the perturbation elements 8 and 9 are supported by the dielectric and attached to the power feeding elements 3a and 3b may be employed.
The structure shown in FIG. 13 (a) is a VSWR having a gap S2 indicated by a solid line with respect to the VSRD 3 having no floating indicated by a one-dot chain line, as is clear when FIG. 13 (b) is compared with FIG. 5 (b). Although it slightly changes on the lower limit side of the intermediate frequency band, it is practically used as a whole. From this, the perturbation elements 8 and 9 and the feed elements 3a and 3b can be mounted by selecting either mechanical coupling or electrical coupling.

(Embodiment 6)
The example shown in FIG. 14A is an example in which the case where the rising angle θ of the perturbation elements 8 and 9 with respect to the power feeding elements 3a and 3b is adjusted is considered. In FIG. 14A, the standing angle θ of the perturbation elements 8 and 9 with respect to the power feeding elements 3a and 3b is adjusted to 45 °. The VSWR is shown in FIG.
In FIG. 14B, a case where the rising angle θ is 90 ° is indicated by a one-dot chain line V1, and a case where the rising angle θ is 45 ° is indicated by a solid line V2.
As is apparent from comparing the VSWR indicated by the one-dot chain line V1 and the VSWR indicated by the solid line V2 in FIG. 14B, it can be seen that the VSWR from the low frequency band to the high frequency band can be adjusted by the rising angle θ. In FIG. 14 (b), the VSWR when the rising angle θ is 45 ° and 90 ° is taken up and the change tendency is shown, and the VSWR can be changed by the rising angle θ. It is possible to stand up with. Other configurations of the sixth embodiment described above are the same as the configurations of the first embodiment.

(Embodiment 7)
Next, a structure in which the perturbation elements 8 and 9 are mounted on the power feeding elements 3a and 3b by a clip structure will be described with reference to FIGS.
The clip structure shown in FIGS. 15A to 15D is a structure in which the substrate 4 is sandwiched and mounted by the clip piece 10. The clip piece 10 is made of a dielectric, and has a tongue piece 10a and a support portion 10b.
The tongue piece 10a protrudes in a direction intersecting with the support portion 10b, has a spring property, and sandwiches the substrate 4 in the plate thickness direction.
The support portion 10b has an inverted U-shaped pipe shape in which both ends for inserting the perturbation elements 8 and 9 and the bottom side are opened, and the tongue portion 10a holds the substrate 4 between the shaft portion 2 and the feeding element 3b. A partition 10c is provided so as to correspond to the gap, and the perturbation elements 8 and 9 are supported while being press-fitted into the inside from the left and right sides and in contact with the partition 10c. The two perturbation elements 8 and 9 are electrically insulated from each other by a partition 10c.
One perturbation element 8 is press-fitted into the support portion 10b beyond the length of the feed element 3a to a position where it is joined to the shaft portion 2, and the other perturbation element 9 is within the support portion 10b within the length range of the feed element 3b. It is press-fitted into. The inner wall of the support portion 10b has a protrusion 10d protruding inward as shown in FIG. 15B, and the protrusion 10d comes into close contact with the perturbation elements 8 and 9 press-fitted into the support portion 10b. Is blocking.
Further, as shown in FIG. 15B, the substrate 4 is provided with a groove 4c between the shaft portion 2 and the power feeding element 3b, and the tongue piece 10a is provided with a convex piece 10e that fits into the groove 4c. ing.

In order to mount the perturbation elements 8 and 9 on the power feeding elements 3a and 3b with the clip piece 10 shown in FIG. 15, as shown in FIGS. 15 (a) and 15 (b), the perturbation elements 8 and 9 are press-fitted and insulated from each other by a partition 10c.
Next, as shown in FIGS. 15A, 15B, and 15C, the base plate 4 is sandwiched between the shaft portion 2 and the feeding element 3b by the tongue piece 10a, and the spring property of the tongue piece 10a is utilized. Then, the perturbation element 8 in the support portion 10b is crimped to the feed element 3a, and the perturbation element 9 is crimped to the feed element 3b.
Further, as shown in FIG. 15 (d), the protruding piece 10e of the support portion 10b is press-fitted into the groove 4c of the substrate 4 to position the perturbing element 8 and the feeding element 3a, and the perturbing element 9 and the feeding element 3b. Do.

As described above, according to the clip structure shown in FIG. 15, the two perturbation elements 8 and 9 are held in the pipe-shaped support portion 10 b and are sandwiched between the tongue pieces 10 a and the substrate 4. Are provided in the power feeding elements 8 and 9, respectively, so that the perturbation elements 8 and 9 can be assembled by a one-touch method, and the assembling productivity can be improved.
Further, since the feed elements 3a and 3b and the perturbation elements 8 and 9 are positioned by the fitting of the groove 4c and the convex piece 10d, the multi-frequency by the combination of the perturbation elements 8 and 9 and the feed elements 3s and 3b. Broadband transmission / reception performance can be maintained.
Furthermore, it is known that, in the antenna, when a dielectric is superposed on the antenna element, it contributes to the improvement of VSWR. In this embodiment, when the perturbation elements 8 and 9 are attached, the dielectric tongue 10a is provided. Since it is interposed between the shaft portion 2 and the feed element 3b, there is an advantage that the attachment of the perturbation elements 8 and 9 and the improvement of the VSWR can be performed at once.

  The clip structure shown in FIG. 16 is a structure using a thin pipe. As shown in FIG. 16A, a hole 11 that penetrates the perturbing elements 8 and 9 toward the feeding elements 3a and 3b is provided, and as shown in FIG. The feed elements 3a and 3b are provided with holes 12 penetrating in the plate thickness direction.

  In order to mount the perturbation elements 8 and 9 on the power feeding elements 3a and 3b using the small-diameter pipe shown in FIG. 16A, the perturbation elements 8 and 9 are mounted as shown in FIGS. A small-diameter pipe 13 is passed through the through-hole 11 and the through-holes 12 of the power feeding elements 3a and 3b, and the tip of the pipe 13 protrudes from the hole 12 of the substrate 4 to the back surface 4b. The perturbation elements 8 and 9 are brought into close contact with the power feeding elements 3a and 3b by (clipping force).

According to the clip structure shown in FIG. 16, the through holes 11 and 12 are provided in the perturbation elements 8 and 9 and the feeding elements 3 a and 3 b, but these through holes 11 and 12 are filled with the pipe 13, It is possible to avoid affecting the functions of the perturbation elements 8 and 9 and the feed elements 3s and 3b, and to maintain the transmission / reception performance of a multi-frequency broadband.
The clip structure shown in FIG. 16 has the advantage that the perturbation elements 8 and 9 can be mounted on the power feeding elements 3a and 3b by press fitting the pipe 13 into the through holes 11 and 12 and crimping. ing.
Other configurations of the present embodiment described above are configured in the same manner as the configuration of the first embodiment.

(Embodiment 8)
FIGS. 17A and 17B show examples of further improving the VSWR in the antenna structure shown in FIG.
As shown in FIG. 17 (a), the portion branching from the shaft portion 2 to the feeding element 3a is enlarged (enlarged portion 14). Similarly, as shown in FIG. 17B, the portion where the parasitic element 5a on the back surface 4b side of the substrate 4 rises from the ground plate 6 is enlarged (enlarged portion 15).
The other configuration of the eighth embodiment described above is configured in the same manner as the configuration of the first embodiment.

As shown in FIGS. 17A and 17B, by providing the enlarged portion 14 and the enlarged portion 15, the current between the shaft portion 2 and the feeding element 3a, and between the ground plate 6 and the parasitic element 5a. As shown in FIG. 17C, there is an advantage that the VSWR can be improved from the low frequency band to the high frequency band and the bandwidth can be increased.
Although it is most effective to provide the two enlarged portions 14 and 15 as in the present embodiment, it has been confirmed that an effect in a practical range can be obtained by providing only one of them.

  The present invention is compatible with multi-frequency broadband transmission and reception and can contribute to the realization of miniaturization.

DESCRIPTION OF SYMBOLS 1 Feed part 2 Shaft part 3a, 3b Feed element 5a, 5b Parasitic element 8, 9 Perturbation element 9a 庇 10 Clip piece 10a Tongue piece 10b Supporting part 13 Small diameter pipe

Claims (6)

A multiband antenna that supports multi-frequency broadband transmission and reception,
A shaft common to the low and intermediate frequency bands and the high frequency band; and
A single feeding portion connected to the shaft portion and the ground plate;
An upper feeding element that branches off from the shaft and is asymmetrical;
An asymmetric lower parasitic element separated from the shaft portion,
A multiband antenna, wherein an asymmetrical perturbation element is provided in each of the upper feed elements. The multiband antenna according to claim 1,
The line width of the shaft portion is equal to or wider than the line width of the feeding element and the parasitic element,
A multiband antenna, wherein the perturbation element provided in the upper long feed element is extended to the shaft portion. The multiband antenna according to claim 1 or 2,
A multiband antenna, wherein the perturbation element is coupled to the feed element in a clip structure. The multiband antenna according to claim 1,
The upper feeding element and the lower parasitic element are different in length from each other, and a part of the short feeding element along the short parasitic element is formed in a meander shape. Band antenna. The multiband antenna according to claim 1,
The upper feeding element and the lower parasitic element are different in length from each other, and a part of the short feeding element along the short parasitic element is formed in a straight shape. Band antenna. A multiband antenna that supports multi-frequency broadband transmission and reception,
A shaft common to the low and intermediate frequency bands and the high frequency band; and
A single feeding portion connected to the shaft portion and the ground plate;
An upper feeding element that branches off from the shaft and is asymmetrical;
An asymmetric lower parasitic element separated from the shaft portion,
The multiband antenna, wherein a line width of the shaft portion is equal to or wider than line widths of the feeding element and the parasitic element.

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