JP2011120107A - Antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna device which actualizes a low profile and miniaturization, maintaining the impedance matching of a monopole antenna device equipped with a top loading type electrode. <P>SOLUTION: The antenna device includes a ground conductor plate, a rectangular top loading electrode plate arranged to face the ground conductor plate, a monopole antenna electrically connected to the roughly central portion of the top loading electrode plate, and a plurality of short-circuit conductors which are arranged in each roughly central portion of a plurality of sides of the top loading electrode plate and short-circuits between the top loading electrode plate and the ground conductor. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an antenna device, and more particularly to an antenna device provided with a top loading electrode plate at the tip of a monopole antenna.

  The monopole antenna device requires a quarter wavelength or more. For example, when applied to a frequency of 2.6 GHz, the height is about 30 mm, the size is large, and it is not possible to meet the demand for a low attitude. Therefore, there is a top loading monopole antenna device as a monopole antenna device having a low profile. An example of the top loading monopole antenna device is shown in FIG. A top-loading monopole antenna device 10 shown in FIG. 17 is provided with a top-loading electrode 1 (hereinafter referred to as an electrode 1) and the electrode 1 so as to be opposed to the electrode 1. The ground conductor 5, the linear element 3 that electrically connects the center of the electrode 1 and a feeding point (not shown), and the point on the electrode 1 that is different from the center of the electrode 1 and the ground conductor 5 are electrically connected. And a short-circuit conductor 2 to be configured. Here, the central conductor of the feeding coaxial cable 4 is connected to the feeding point, and the grounding conductor of the feeding coaxial cable 4 is connected to the grounding conductor 5.

  This top loading type monopole antenna device 10 is configured by connecting a circular flat plate-shaped electrode 1 to the top of the monopole antenna device. By using the electrode 1 having a circular flat plate shape, when applied to a frequency of 2.6 GHz, for example, the height can be lowered to 10 mm and 0.087λ.

  Moreover, there exists an antenna apparatus described in patent document 1 as what makes a monopole antenna apparatus low-profile. This antenna device includes a radiating element that is disposed opposite to the conductor plate and is partially short-circuited to the conductor plate. The antenna device has a widened shape from the feed point to the radiating element, and has a height of 0.0625λ. Low profile. In this antenna device, a short pin for short-circuiting the radiating element is provided, and two or more short pins are provided at equal intervals on the circumference centering on the feeding point.

  Furthermore, there is an antenna device described in Patent Document 2 as a device that lowers the posture of another monopole antenna device. In this antenna device, an M-type antenna is used as a basic structure, and as shown in FIG. 1 in Patent Document 2, a radiation electrode portion 22 having a square planar outer shape is disposed facing the ground plate 10. The power supply pin 14 is electrically connected to a substantially central portion of the square planar outer shape of the radiation electrode portion 22, and the radiation electrode 22 and the ground plate 10 are positioned at substantially intermediate positions of two opposing sides of the square planar outer shape of the radiation electrode portion 22. A short pin 16 is provided for electrically short-circuiting. This antenna device resonates in a λ / 2 in-phase mode with a current path having a total length of (a + b + 2 × c + d + e) based on the length of each part indicated as a, b, c, d, and e in the figure. To do. With this configuration, the resonance frequency is lowered without increasing the height and planar shape of the radiation electrode portion 22.

JP 2008-219853 A JP 2007-221774 A

  In the antenna device described in Patent Document 1, short-circuit plates are arranged at equal intervals on the circumference centered on the feeding point. In this case, if the distance between the top loading electrode and the ground conductor is shortened in order to lower the posture, it is necessary to increase the number of short-circuit plates and enlarge the top loading electrode. This is not desirable from the viewpoint of miniaturization.

  In addition, when the top loading electrode has a rectangular shape, the shorting plate is arranged at the edge of the square according to the arrangement of the shorting plate at equal intervals on the circumference, and the interval between the top loading electrode and the ground conductor is 0.05λ or less. When trying to do so, there is a problem that the input impedance is lowered and the matching between the feeding coaxial cable and the antenna cannot be achieved.

  Further, in the antenna device described in Patent Document 2, the resonance frequency is lowered without increasing the height and planar shape of the radiation electrode portion 22 by the configuration shown in FIG. However, the dimension of one side of the square of the radiation electrode portion 22 was as large as 124 mm, and impedance matching could not be achieved unless the height was set to 0.074λ. Further, when simulation was performed with the height set to 0.043λ, sufficient impedance matching could not be obtained.

  In view of the above problems, an object of the present invention is to provide an antenna device that maintains impedance matching of a monopole antenna device including a top-loading type electrode and realizes a low profile and a small size.

  An antenna device according to an embodiment of the present invention includes a grounding conductor plate, a rectangular toploading electrode plate disposed opposite to the grounding conductor plate, and an electrical connection at a substantially central portion of the toploading electrode plate. And a plurality of short-circuit conductors that are disposed at substantially central portions of a plurality of sides of the top loading electrode plate and electrically short-circuit between the top loading electrode plate and the ground conductor plate And. According to this antenna device, it is possible to reduce the posture and size while maintaining matching of the input impedance.

  In addition, the number of the plurality of short-circuit conductors is three, and the short-circuit conductors may be arranged at substantially central portions on three sides of the top loading electrode plate. According to this antenna device, good radiation characteristics can be obtained without using a complicated structure.

  An antenna device according to an embodiment of the present invention includes a ground conductor plate, a rectangular top loading electrode plate, a monopole antenna electrically connected to a substantially central portion of the top loading electrode plate, and the top An antenna unit having a plurality of short-circuit conductors that are disposed at substantially central portions of a plurality of sides of the loading electrode plate and electrically short-circuit between the top loading electrode plate and the ground conductor plate; and the ground conductor And an array antenna having a plurality of the antenna portions arranged on a plate. According to this antenna device, the array antenna can be lowered and miniaturized while maintaining matching of the input impedance.

  In addition, the number of the plurality of short-circuit conductors is three, and the short-circuit conductors may be arranged at substantially central portions on three sides of the top loading electrode plate. According to this antenna device, good radiation characteristics can be obtained without using a complicated structure.

  In the array antenna, the plurality of antenna portions may be arranged with the sides on which the short-circuit conductors are arranged facing each other. According to this antenna device, the coupling characteristics of the array antenna can be improved.

  A plurality of dielectrics may be disposed between the plurality of antenna portions. According to this antenna device,

  ADVANTAGE OF THE INVENTION According to this invention, the antenna apparatus which implement | achieves the low attitude | position and size reduction of a monopole antenna provided with a top loading electrode plate can be provided, maintaining the matching of input impedance.

1 is a perspective view showing a schematic configuration of an antenna device according to a first embodiment of the present invention. FIG. 6 is a graph showing changes in input impedance Zin when the height H of the antenna apparatus of FIG. 1 is set to 0.061λ and the number of short-circuit conductors is changed between edge short-circuit and center short-circuit. It is the graph which showed the change of the input impedance Zin at the time of setting the height H of the antenna apparatus of FIG. 1 to 0.043 (lambda), and changing the number of short circuit conductors by an edge short circuit and a center short circuit. 6 is a graph showing a change in VSWR when the height H of the antenna device 100 of FIG. 1 is set to 0.061λ and 0.043λ, and the number of short-circuited conductors is changed between an edge short circuit and a center short circuit. The height H of the antenna device of FIG. 1 is set to 0.061λ and 0.043λ, and the length W1 [λ] of one side of the top loading electrode plate when the number of short-circuited conductors is changed by edge short circuit and center short circuit. It is the graph which showed the change. 2 is a graph showing a change in resonance frequency fc and a change in frequency bandwidth BW when VSWR is 2 or less when the width W2 [λ] of the short-circuit conductor in FIG. 1 is changed. It is the graph which compared the radiation pattern of the horizontal surface of the antenna apparatus which concerns on 1st Embodiment, and the antenna apparatus which has the conventional top loading electrode plate. It is a perspective view which shows schematic structure of the antenna device which concerns on the 2nd Embodiment of this invention. FIG. 9 is a graph obtained by measuring the coupling characteristics in the X direction, the Y direction, and the diagonal direction between four antenna units of the antenna device of FIG. 8 while varying the frequency. It is a perspective view which shows schematic structure of the antenna apparatus of the comparative example which concerns on 2nd Embodiment. 11 is a graph obtained by measuring the coupling characteristics in the X direction, the Y direction, and the diagonal direction between four antenna units of the antenna device of FIG. 10 while varying the frequency. It is a perspective view which shows schematic structure of the antenna device which concerns on the 3rd Embodiment of this invention. 13 is a graph showing each VSWR characteristic when the antenna device shown in FIG. 12 and the antenna device shown in FIG. 8 are operated with the center frequency set to 2.6 GHz. It is a perspective view which shows schematic structure of the antenna apparatus of the comparative example which concerns on 3rd Embodiment. It is a graph which shows each VSWR characteristic at the time of operating the antenna apparatus shown in FIG. 14 and the antenna apparatus shown in FIG. 10 by setting a center frequency to 2.6 GHz. It is a perspective view which shows schematic structure of the antenna device which concerns on other embodiment of this invention. It is a figure which shows schematic structure of the conventional top loading type | mold monopole antenna apparatus.

  Hereinafter, an antenna device according to an embodiment of the present invention will be described in detail with reference to the drawings.

(First embodiment)
An antenna device 100 according to a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a perspective view illustrating a schematic configuration of an antenna device 100 according to the first embodiment. In FIG. 1, the antenna device 100 includes a ground conductor plate 101, a monopole antenna 102, a plurality of short-circuit conductors 103 a to 103 c, a top loading electrode plate 104, and a power feeding unit 105.

  The ground conductor plate 101 is formed of, for example, a rectangular conductor plate. A monopole antenna 102 having a reduced length (for example, 0.1λ or less) is disposed on a substantially central portion of the ground conductor plate 101. A power feeding unit 105 is electrically connected to the lower end of the monopole antenna 102. In the present embodiment, the height H of the monopole antenna 102 is set to 0.043λ, for example. Note that λ represents a wavelength of a desired frequency for operating the antenna device 100.

  For example, a coaxial cable for power feeding is used as the power feeding unit 105, and the central conductor is electrically connected to the lower end of the monopole antenna 102 while being insulated from the ground conductor plate 101.

  The top loading electrode plate 104 is formed of, for example, a rectangular conductor plate, and its substantially central portion is electrically connected to the upper end portion of the monopole antenna 102. In the present embodiment, the top loading electrode plate 104 is, for example, a square plate having a side length W1 of 0.273λ.

  The short-circuit conductors 103 a to 103 c are disposed at the central portions of the three sides of the top loading electrode plate 104. The short-circuit conductors 103a to 103c electrically short-circuit the top loading electrode plate 104 and the ground conductor plate 101. In the present embodiment, the width W2 of the short-circuit conductors 103a to 103c is set to 0.0087λ, for example.

  For example, when the center frequency is 2.6 GHz, the length W1 of one side of the top loading electrode plate 104 is 31.5 mm, the width W2 of the short-circuit conductors 103a to 103c is 1 mm, and the height H is 5 mm. In FIG. 1, a configuration including the monopole antenna 102, the short-circuit conductors 103 a to 103 c, the top loading electrode plate 104, and the power feeding unit 105 is an antenna unit 110.

  Next, the operating characteristics of the antenna device 100 according to the first embodiment will be described with reference to the graphs shown in FIGS. 2 to 7 show characteristics when the antenna apparatus 100 is operated with the center frequency set to 2.6 GHz.

  FIG. 2 is a graph showing changes in the input impedance Zin when the height H of the antenna device 100 is set to 0.061λ and the number of short-circuit conductors is changed. In FIG. 2, the number of short-circuit conductors is changed from one to four, and the positions of the short-circuit conductors are arranged at the end portions (indicated by “E” in the drawing) of the top loading electrode plate 104 and the sides. The change of each input impedance Zin when arranged in the central part (indicated by “C” in the figure) is divided into a real part E_Re, C_Re and an imaginary part E_Im, C_Im. In the following, a short-circuit conductor disposed at the end of each side of the top loading electrode plate 104 is referred to as “edge short circuit”, and a short-circuit conductor disposed at the center of each side of the top loading electrode plate 104 is referred to as “center It will be called “short circuit”. In FIG. 2, changes E_Re and E_Im of the input impedance Zin when the edge is short-circuited are indicated by ◯ and dotted lines, and changes C_Re and C_Im of the input impedance Zin when the center is short-circuited are indicated by ● and a solid line.

  Here, conditions for matching the input impedance Zin of the antenna device 100 to 50Ω are extracted from the graph shown in FIG. When the edge is short-circuited, the number of short-circuit conductors whose input impedance Zin including E_Re and E_Im can be matched with 50Ω is four. In this edge short circuit, the length W1 of one side of the top loading electrode plate 104 when the number of short-circuit conductors is four is 0.312λ. In addition, when the center is short-circuited, the number of short-circuit conductors that can match the input impedance Zin including C_Re and C_Im with 50Ω is two and three. In this central short circuit, the length W1 of one side of the top loading electrode plate 104 when the number of short-circuit conductors is two is 0.22λ. Therefore, in FIG. 2, by setting the height H of the antenna device 100 to 0.061λ and applying the center short circuit, the size of the top loading electrode plate 104 can be reduced, and the number of short circuit conductors can be reduced. There was found.

  FIG. 3 is a graph showing changes in the input impedance Zin when the height H of the antenna device 100 is set to a low posture with 0.043λ and the number of short-circuit conductors is changed. In FIG. 3, the number of short-circuit conductors is changed from one to four, and each input impedance when edge short-circuiting (indicated by “E” in the figure) and central short-circuiting (indicated by “C” in the figure) are performed. The change of Zin is divided into a real part E_Re, C_Re and an imaginary part E_Im, C_Im. In FIG. 3, changes E_Re and E_Im of the input impedance Zin when the edge is short-circuited are indicated by ◯ and dotted lines, and changes C_Re and C_Im of the input impedance Zin when the center is short-circuited are indicated by ● and a solid line.

  FIG. 4 shows changes in VSWR (Voltage Standing Wave Ratio) when the height H of the antenna device 100 is set to 0.061λ and 0.043λ and the number of short-circuit conductors is changed. It is a graph. In FIG. 4, the number of short-circuit conductors is changed from one to four, the change in VSWR when the height H is 0.043λ in the edge short circuit is indicated by Δ and a dotted line, and the height H in the edge short circuit is The change of VSWR when 0.061λ is indicated by a circle and a dotted line, the change of VSWR when the height H is 0.043λ at the middle short is indicated by a solid line with ●, and the height H is 0. The change in VSWR in the case of 061λ is indicated by ■ and solid line. The antenna device 100 is desirably used at VSWR <2.

  Here, conditions for matching the input impedance Zin of the antenna device 100 to 50Ω are extracted from the graphs shown in FIGS. 3 and 4. When the edge is short-circuited, the input impedance Zin including E_Re and E_Im does not become higher than 40Ω, and the VSWR cannot secure a frequency bandwidth of 2 or less. In addition, when the center is short-circuited, the number of short-circuit conductors that can match the input impedance Zin including C_Re and C_Im to 50Ω is 3 and 4, and the VSWR can also secure a frequency bandwidth of 2 or less. . Therefore, even when the height H of the antenna device 100 is set to 0.043λ and set to a low posture, it has been found that the center short circuit can provide better characteristics than the edge short circuit.

  FIG. 5 shows changes in the length W1 [λ] of one side of the top loading electrode plate 104 when the height H of the antenna device 100 is set to 0.061λ and 0.043λ and the number of short-circuit conductors is changed. It is a graph. In FIG. 5, the change in W1 when the number of short-circuit conductors is changed from 1 to 4 and the height H is 0.043λ in the edge short-circuit is shown by ▲ and a dotted line, and the height H is changed in the edge short-circuit. The change of W1 when 0.061λ is indicated by a dot-dash line with ◯, the change of W1 when the height H is 0.043λ in the middle short circuit is indicated by a solid line with ●, and the height H is 0 in the middle short circuit The change of W1 when .061λ is set is indicated by □ and a two-dot chain line.

  Referring to FIG. 5, when the number of short-circuit conductors is increased at the edge short-circuit heights of 0.061λ and 0.043λ, W1 in each of the numbers is almost the same value, and at the center short-circuit height H When the number of short-circuit conductors is increased by 0.061λ and 0.043λ, the increase in W1 in each number is about 0.05λ. Therefore, in the antenna device 100 employing the center short circuit, even if the number of short-circuit conductors is reduced to three and the height H is lowered to 0.043λ, the input impedance Zin for 50Ω can be matched. This is advantageous for downsizing. On the other hand, in the antenna device adopting the edge short circuit, when the number of short-circuit conductors is reduced to three and the height H is lowered to 0.043λ, the VSWR can also secure a frequency bandwidth of 2 or less. In addition, the input impedance Zin for 50Ω cannot be matched. In an antenna device employing edge short-circuiting, if the height H is set to 0.061λ and the number of short-circuiting conductors is set to 4, the frequency bandwidth of VSWR can be secured to 2 or less, and the input impedance Zin for 50Ω. However, since the height H is higher and the length W1 of one side of the top loading electrode plate 104 is larger than that of the antenna device 100 employing the center short circuit, it is disadvantageous for lowering the posture and reducing the size. It is.

  FIG. 6 is a graph showing a change in the resonance frequency fc and a change in the frequency bandwidth BW when the VSWR is 2 or less when the width W2 [λ] of the short-circuit conductor is changed. In this graph, even when the width W2 [λ] of the short-circuit conductor is changed from 0.005λ to 0.026λ, the change in the resonance frequency fc is small, and the change in the frequency bandwidth BW with VSWR of 2 or less is also small. For this reason, it turned out that the freedom degree of the attachment method of the grounding conductors 130a-130c shown in FIG. 1 is large.

  FIG. 7 is a graph showing a radiation pattern on the horizontal plane of the antenna device 100 according to the first embodiment and a conventional antenna device having a top loading electrode plate. According to this graph, it has been found that the radiation pattern of the antenna device 100 is omnidirectional.

  As described above, according to the antenna device 100 according to the first embodiment, the central short circuit in which the short-circuit conductors 103a to 103c are arranged at the central part of the three sides of the square-shaped flat top loading electrode plate 104 is adopted. Accordingly, the configuration in which the radiation pattern on the horizontal plane has a non-directional characteristic can be reduced in size and reduced in size without taking a complicated structure. By applying this antenna device 100 to a small radio communication base station, it is possible to increase the degree of design freedom and reduce the development cost.

(Second Embodiment)
An antenna device according to a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, an example will be described in which the antenna unit 110 shown in the first embodiment is used to configure an array antenna in which a plurality of antenna units 110 are arranged on the upper surface of a ground conductor plate. 8 and 9 show a configuration example in which the four antenna portions 110A to 110D are arranged with the sides where the short-circuit conductors 103a to 103c are arranged facing each other, and their coupling characteristics. In FIGS. 10 and 11, A configuration example in which the four antenna portions 110A to 110D are arranged with their sides where the short-circuit conductors 103a to 103c are not arranged facing each other, and their coupling characteristics are shown as a comparative example.

  FIG. 8 is a perspective view showing a schematic configuration of the antenna device 200 according to the second embodiment in which no dielectric is disposed. In FIG. 8, the same components as those of the antenna device 100 shown in FIG.

  In FIG. 8, the antenna device 200 has four antenna portions 110 </ b> A to 110 </ b> D arranged on the upper surface of the ground conductor plate 201. The antenna units 110A to 110D have the same configuration as the antenna unit 110 shown in FIG. These four antenna units 110 constitute an array antenna 202. The four antenna portions 110A to 110D are arranged such that the sides on which the short-circuit conductors 103a to 103c are arranged face each other. That is, in FIG. 8, the antenna unit 110A and the antenna unit 110B are arranged with the sides where the short-circuit conductors 103a to 103c are arranged facing each other in the X direction shown in the figure, and the antenna unit 110A and the antenna unit 110C are shown in the figure. The sides where the short-circuit conductors 103a to 103c are arranged in the Y direction shown are arranged so as to face each other, and the sides where the short-circuit conductors 103a to 103c are arranged in the X direction shown in FIG. The antenna unit 110B and the antenna unit 110D are arranged such that the sides where the short-circuit conductors 103a to 103c are arranged face each other in the Y direction shown in the drawing. The antenna units 110 </ b> A to 110 </ b> D are each provided with a power feeding port (not shown) at the lower end (not shown) of the monopole antenna 102. The feeding port of the antenna unit 110A is Port1, the feeding port of the antenna unit 110B is Port2, the feeding port of the antenna unit 110C is Port3, and the feeding port of the antenna unit 110D is Port4.

  Next, the coupling characteristics of the antenna device 200 will be described with reference to FIG. FIG. 9 is a graph showing a simulation result by varying the frequency for each of the coupling characteristics in the X direction, the Y direction, and the diagonal direction between the four antenna units 110 </ b> A to 110 </ b> D of the antenna device 200.

  As shown in FIG. 9, the coupling characteristics in the X direction (Port2-Port1, Port4-Port3) between the antenna unit 110A and the antenna unit 110B, and between the antenna unit 110C and the antenna unit 110D, and the antenna unit The coupling characteristics in the Y direction (Port4-Port2, Port3-Port1) between 110A and the antenna part 110C and between the antenna part 110B and the antenna part 110D show similar coupling characteristics. Further, as shown in FIG. 9, the coupling characteristics in the diagonal directions (Port3-Port2, Port4-Port1) between the antenna unit 110A and the antenna unit 110D and between the antenna unit 110B and the antenna unit 110C are as follows. The coupling characteristics in the X direction and the Y direction are low.

(Comparative example)
Next, a comparative example for the antenna device 200 shown in FIG. 8 will be described with reference to FIGS. 10 and 11. FIG. 10 is a perspective view showing a schematic configuration of the antenna device 300 for comparison with the coupling characteristics of the antenna device 200 shown in FIG. In FIG. 10, the same components as those of the antenna apparatus 100 shown in FIG.

  The configuration of the antenna device 300 shown in FIG. 10 is different from the configuration of the antenna device 200 shown in FIG. 8 in that the four antenna portions 110A to 110D have the sides where the short-circuit conductors 103a to 103c are not disposed facing each other. The components are the same as those of the antenna device 200 shown in FIG. The four antenna units 110 </ b> A to 110 </ b> D constitute an array antenna 302.

  Next, the coupling characteristics of the antenna device 300 will be described with reference to FIG. FIG. 11 is a graph obtained by measuring the coupling characteristics in the X direction, the Y direction, and the diagonal direction between the four antenna units 110 </ b> A to 110 </ b> D of the antenna device 300 while varying the frequency. Each coupling characteristic in the X direction, the Y direction, and the diagonal direction shown in FIG. 11 is a result of simulation in the same direction as the X direction, the Y direction, and the diagonal direction shown in FIG.

  When the coupling characteristics of the antenna device 200 shown in FIG. 9 and the coupling characteristics of the antenna device 300 shown in FIG. 11 are compared, each coupling characteristic in the X direction, the Y direction, and the diagonal direction has four antenna portions. It has been found that the antenna device 200 shown in FIG. 9 in which the portions where the short-circuit conductors 103a to 103c are arranged so as to face each other 110A to 110D is better.

  Therefore, when an array antenna is configured using the four antenna portions 110A to 110D, the coupling characteristics can be reduced by arranging the sides where the short-circuit conductors 103a to 103c are arranged facing each other. In the antenna device 200 according to the second embodiment, the four antenna units 110A to 110D have the same configuration as the antenna unit 110 shown in FIG. Low profile and small size are possible. Thereby, the antenna device 200 can improve performance such as MIMO (Multiple-Input Multiple-Output) and beam homing. Moreover, by applying the antenna device 200 to a base station such as MIMO, it is possible to contribute to the promotion of downsizing and the improvement of the degree of freedom of design.

(Third embodiment)
An antenna device according to a third embodiment of the present invention will be described with reference to FIGS. A configuration example in which a dielectric is disposed between the four antenna units 110A to 110D shown in the second embodiment will be described. In FIG. 12, the same components as those of the antenna device shown in FIGS. 1 and 8 are denoted by the same reference numerals, and the description of the configuration is omitted.

  The configuration of the antenna device 400 shown in FIG. 12 is different from the configuration of the antenna device 200 shown in FIG. 8 in that a dielectric 403 is disposed between the antenna unit 110A and the antenna unit 110B, and the antenna unit 110C and the antenna unit are arranged. This is that a dielectric 404 is arranged between the antenna device 110D and each component part is the same as the antenna device 200 shown in FIG. The four antenna units 110110A to 110D constitute an array antenna 402.

  Next, the VSWR characteristics of the antenna device 400 will be described with reference to FIG. FIG. 13 is a graph showing each VSWR characteristic when the antenna device 400 shown in FIG. 12 and the antenna device 200 shown in FIG. 8 are operated with the center frequency set to 2.6 GHz.

  Referring to FIG. 13, the VSWR at 2.6 GHz is about 1.2 for the antenna device 200 in which no dielectric is disposed, and is about 1.2 for the antenna device 400 in which the dielectrics 403 and 404 are disposed. From this, it was found that the VSWR characteristics of the antenna device 200 and the antenna device 400 are equivalent. That is, when the four antenna portions 110A to 110D are arranged with the sides where the short-circuit conductors 103a to 103c are arranged facing each other, even if the dielectrics 403 and 404 are arranged like the antenna device 400, the influence on the VSWR characteristics is not affected. It was found that almost no VSWR characteristics were maintained.

(Comparative example)
Next, a comparative example for the antenna device 400 shown in FIG. 12 will be described with reference to FIGS. 14 and 15. FIG. 14 is a perspective view showing a schematic configuration of antenna apparatus 500 for comparison with the VSWR characteristics of antenna apparatus 400 shown in FIG. In FIG. 14, the same components as those of the antenna device shown in FIGS. 1 and 8 are denoted by the same reference numerals, and the description of the configuration is omitted.

  The configuration of the antenna device 500 shown in FIG. 14 is different from the configuration of the antenna device 400 shown in FIG. 12 in that the four antenna portions 110A to 110D have the sides where the short-circuit conductors 103a to 103c are not disposed facing each other. Each component is the same as the antenna device 400 shown in FIG. The four antenna units 110 </ b> A to 110 </ b> D constitute an array antenna 502.

  Next, the VSWR characteristic of the antenna device 500 will be described with reference to FIG. FIG. 15 is a graph showing each VSWR characteristic when the antenna device 500 shown in FIG. 14 and the antenna device 300 shown in FIG. 10 are operated with the center frequency set to 2.6 GHz.

  Referring to FIG. 15, the VSWR at 2.6 GHz is about 1.2 for the antenna device 300 on which no dielectric is disposed, and about 1.4 for the antenna device 500 on which the dielectrics 403 and 404 are disposed. From this, it was found that the antenna device 500 in which the dielectrics 403 and 404 are arranged has a VSWR characteristic that is deteriorated as compared with the antenna device 200.

  From the above, the dielectric 403 is disposed between the antenna unit 110A and the antenna unit 110B, the dielectric 404 is disposed between the antenna unit 110C and the antenna unit 110D, and the four antenna units 110A to 110D are short-circuited. It has been found that when the sides on which the conductors 103a to 103c are arranged are arranged to face each other, there is almost no change compared to the VSWR characteristics of the antenna device 200 in which no dielectric is arranged. In addition, a dielectric 403 is disposed between the antenna unit 110A and the antenna unit 110B, a dielectric 404 is disposed between the antenna unit 110C and the antenna unit 110D, and the four antenna units 110A to 110D are short-circuited conductors 103a to 103D. It has been found that when the sides where the 103c is not arranged are arranged to face each other, the VSWR characteristics of the antenna device 300 without the dielectric are deteriorated.

  Accordingly, when an array antenna is configured using the four antenna units 110A to 110D, even when a dielectric is disposed between the antenna units 110A to 110D, the short antennas 103a to 103c are disposed on the four antenna units 110A to 110D. The VSWR characteristics are better when the arranged sides face each other. Thereby, the antenna device 400 can improve performance such as MIMO (Multiple-Input Multiple-Output) and beam homing. In the antenna device 400 according to the third embodiment, the four antenna units 110A to 110D have the same configuration as the antenna unit 110 illustrated in FIG. Low profile and small size are possible. By applying the antenna device 400 to a base station such as MIMO, it is possible to contribute to the promotion of downsizing and the improvement of design freedom.

  In the antenna device 100 shown in FIG. 1, the top loading electrode plate 104 has a rectangular shape, but the shape is not limited to this. For example, the top loading electrode plate 104 is top like the antenna device 600 shown in FIG. 16. The shape of the loading electrode plate 604 may be changed. The top loading electrode plate 604 has a portion protruding from a side connecting adjacent short-circuit conductors 103a to 103c with a straight line. In this antenna device 600, the components other than the top loading electrode plate 604 are the same as those of the antenna device 200 shown in FIG. In the first to third embodiments, the height H of the monopole antenna 102 shown in the antenna devices 100, 200, and 400, the length W1 of one side of the top loading electrode plate 104, and the width W2 of the short-circuit conductors 103a to 103c. Shows an example of the case where the frequency is 2.6 GHz, and these dimensions may be appropriately changed according to the frequency to be used.

  100, 200, 300, 400, 500, 600 ... antenna device, 101, 201 ... ground conductor plate, 102 ... monopole antenna, 103a-103c ... short-circuit conductor, 104, 604 ... top loading electrode plate, 105 ... power feeding section, 110, 110A to 110D: antenna portion, 202, 302, 402, 502 ... array antenna.

Claims (6)

A grounding conductor plate;
A rectangular top loading electrode plate disposed opposite to the ground conductor plate;
A monopole antenna electrically connected to a substantially central portion of the top loading electrode plate;
A plurality of short-circuit conductors that are disposed at substantially central portions of a plurality of sides of the top-loading electrode plate and electrically short-circuit between the top-loading electrode plate and the ground conductor plate;
An antenna device comprising:   2. The antenna device according to claim 1, wherein the number of the plurality of short-circuit conductors is three, and the plurality of short-circuit conductors are arranged at substantially central portions on three sides of the top loading electrode plate. A grounding conductor plate;
A rectangular top loading electrode plate; a monopole antenna electrically connected to a substantially central portion of the top loading electrode plate; and the top disposed at a substantially central portion of each of a plurality of sides of the top loading electrode plate. A plurality of short-circuit conductors that electrically short-circuit between the loading electrode plate and the ground conductor plate, an antenna unit,
An array antenna having a plurality of the antenna portions disposed on the ground conductor plate;
An antenna device comprising:   4. The antenna device according to claim 3, wherein the number of the plurality of short-circuit conductors is three, and the plurality of short-circuit conductors are arranged at substantially central portions on three sides of the top loading electrode plate.   5. The antenna device according to claim 3, wherein the array antenna includes the plurality of antenna units arranged such that sides on which the short-circuit conductors are arranged face each other. 6. The antenna device according to claim 3, wherein a plurality of dielectrics are disposed between the plurality of antenna units.