JP4734655B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device having a thin plate shape and capable of beam scanning in its spreading direction.

  Conventionally, a PC (Personal Computer) card (previously used as a PCMCIA card) has been widely used as an expansion slot for computers. This card has a thin plate shape, and in most notebook computers, it is inserted in parallel with a keyboard installed on a desk or knee, that is, the upper and lower surfaces of the PC card are substantially horizontal. .

The inventors have disclosed a proposal of an antenna device applicable to a thin plate shape such as a PC card in the following document.
Junichi Iigusa and Hiroshi Harada, Proposal of Variable Reactor-Loaded Slot Array Antenna and Basic Examination of Beam Scanning Capabilities, Communication Technology, AP2006-94, pp.101-106, October 2006, IEICE

  In the technique disclosed in the above document, a conductor is applied to the surface of a rectangular parallelepiped having a thin plate shape, and three parallel strip-shaped conductors from the upper surface of the rectangular parallelepiped (one of the two surfaces having the largest area). And three gaps (slots) are formed on the upper surface.

  A power supply unit is provided across one opposing long side of the slot, a variable reactor is loaded across the opposing long sides of the remaining two slots, and a DC (Direct Current) voltage applied to the variable reactor is set. By changing it, the directivity is changed.

  On the other hand, in the field of wireless ad hoc communication or the like, when communicating between terminals, the height of the wireless with respect to the ground is considered to be substantially equal, so a function capable of scanning the beam on a horizontal plane is required.

  Therefore, when using a combination of a notebook computer and a PC card as a terminal for the above wireless ad hoc communication, a small antenna device having a thin plate shape and capable of efficiently scanning a beam in the spreading direction is strongly desired. It is rare.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an antenna device having a thin plate shape and capable of beam scanning in the spreading direction.

  In order to achieve the above object, the following invention is disclosed in accordance with the principle of the present invention.

  An antenna device according to a first aspect of the present invention includes a conductor part, a power feeding part, a variable reactor, and a control part, and is configured as follows.

  That is, the conductor portion has a shape obtained by removing a plurality of band-like regions (hereinafter referred to as “slots”) from the upper surface to one of the side surfaces to the lower surface on the substantially rectangular parallelepiped surface.

  On the other hand, the power feeding portion is connected to the vicinity of each of the opposing points on two sides in the longitudinal direction of one of the plurality of slots (hereinafter referred to as “power feeding slot”) in the conductor portion.

  Furthermore, the variable reactor has a slot other than the power supply slot (hereinafter referred to as “loading slot”) of the plurality of slots, and each of the opposing points on the two sides in the longitudinal direction of the load slot. Connected in the vicinity.

  And a control part changes each reactance value of a variable reactor, and controls directivity.

  In the antenna device of the present invention, the substantially rectangular parallelepiped has a plate shape, and the lengths of the sides of the upper surface and the lower surface are both longer than the distance between the upper surface and the lower surface. Can be configured.

  In the antenna device of the present invention, the longitudinal directions of the plurality of slots are substantially parallel to each other and arranged at equal intervals, and the longitudinal directions of the plurality of slots are disposed perpendicular to one of the side surfaces, The distances from one of the side surfaces of the longitudinal end points of the slots can be configured to be equal.

  In the antenna device of the present invention, the plurality of slots may be three, and the feeding slot may be arranged so as to be sandwiched between the two loading slots.

  In the antenna device of the present invention, the variable reactor is a pair of varactors connected in anti-series, and the control unit changes the series voltage applied to the pair of varactors so as to change the reactance value. Can be configured.

  According to the present invention, it is possible to provide an antenna device having a thin plate shape and capable of beam scanning in the spreading direction.

  An embodiment of the present invention will be described below. In addition, embodiment described below is for description and does not limit the scope of the present invention. Therefore, those skilled in the art can employ embodiments in which each or all of these elements are replaced with equivalent ones, and these embodiments are also included in the scope of the present invention.

  FIG. 1 is an explanatory view illustrating the shape of a conductor used in the antenna device according to the present embodiment. Hereinafter, a description will be given with reference to FIG.

  As shown in the figure, the general shape of the conductor 102 covers the surface of a thin rectangular parallelepiped. Accordingly, the inside of the rectangular parallelepiped is not filled with a conductor, but is filled with a hollow or an insulator (dielectric). Here, the two surfaces having the largest area are the upper surface 151 and the lower surface 152, one of the four side surfaces is the front surface 153, and the side surface facing this is the back surface 154.

  In this figure, three belt-like regions extending from the upper surface 151 to the lower surface 152 through the front surface 153 are indicated by alternate long and short dash lines. This band-like area is an area for the slot 161. In the present embodiment, the number of the slots 161 is three, all of which have the same shape, the longitudinal directions thereof are parallel to each other, the longitudinal direction thereof is perpendicular to the front surface 153, and the front surface 153 to the end point of the slot 161 The distance is the same on the upper surface 151 and the lower surface 152.

  Although the outline of the conductor part 102 is shown in this figure, the actual shape of the conductor part 102 is as follows. That is, among the conductors covering the surface of the rectangular parallelepiped shown in this drawing, the shape of the actual conductor portion 102 is obtained by removing the conductor from the region for the slot 161. As described above, the hollow conductor portion 102 having a gap (which may be filled with an insulator inside) functions as a thin planar resonator.

  Such a structure can be configured by bending a conductor plate or conductor foil, pressing and shaping, or combining them, and then removing unnecessary areas as appropriate, or using techniques such as etching in a printed wiring board. It is also possible to configure by applying.

  In the present embodiment, the central slot 161 is defined as a power feeding slot 181, and the two slots 161 sandwiching this are defined as loading slots 182.

  FIG. 2 is an explanatory diagram showing a schematic configuration of the antenna device according to the present embodiment. Hereinafter, a description will be given with reference to FIG.

  The conductor portion 102 that defines the thin plate shape of the antenna device 101 has one feeding slot 181 and two loading slots 182.

  In the power supply slot 181, a power supply point is defined so as to straddle the longitudinal direction, and the power supply unit 103 is connected. When the antenna device 101 is used for transmission, an RF (Radio Frequency) voltage is applied by the power supply unit 103. However, the antenna device 101 can also be used for reception due to reversibility of transmission and reception. is there. When used for reception, the power supply unit 103 acquires a signal by detecting a change in voltage between connection points.

  Each loading slot 182 has a connection point defined across the longitudinal direction, and the variable reactor 104 is connected thereto. The control unit 105 changes the DC voltage applied to the variable reactor 104 to change its reactance value (electric capacity).

  In this figure, for easy understanding, the power feeding unit 103 and the variable reactor 104 are illustrated outside the rectangular parallelepiped that is the shape of the conductor unit 102. However, as described above, the conductor unit 102 is hollow or dielectric. Since the body is a conductor filled with the body, it is typical to arrange the power feeding unit 103 and the variable reactor 104 in the inside thereof to reduce the size of the antenna device.

  When power is supplied to the power supply unit 103, along the longitudinal direction of the power supply slot 181 and the loading slot 182, from the upper surface 151 to the lower surface 152 via the front surface 153, or from the lower surface 152 to the upper surface 151 via the front surface 153, Magnetic current flows. By changing the magnetic current, electromagnetic waves are radiated.

  Since the magnetic current flowing on the upper surface 151 and the magnetic current flowing on the lower surface 152 cancel each other, the main contribution to the radiation of electromagnetic waves is the magnetic current flowing from the top 153 to the bottom or from the bottom to the top. Current. Therefore, the electromagnetic wave is radiated in a direction parallel to the upper surface 151 and the lower surface 152.

  However, the upper surface 151 and the lower surface 152 of the power supply slot 181 and the loading slot 182 are necessary for exciting the magnetic current. Therefore, the total length in the longitudinal direction of the power supply slot 181 and the loading slot 182, that is, the distance from the end point of the upper surface 151 to the end point of the lower surface 152 through the front surface 153 is about half a wavelength of the radiated electromagnetic wave. It is desirable.

  By changing the reactance value of the variable reactor 104, the intensity of the electromagnetic wave radiated from each of the power supply slot 181 and the loading slot 182 changes, but the direction in which each electromagnetic wave is radiated depends on the upper surface 151 and the lower surface 152. Therefore, by changing the reactance value, the directivity of the electromagnetic wave can be scanned in the spreading direction of the thin plate shape of the antenna device 101.

As shown in the figure, in this embodiment,
(1) The size of the upper surface 151 and the lower surface 152 is a × b,
(2) The size of the front surface 153 and the back surface 154 is a × h,
(3) The power supply slot 181 is arranged in the center so that the side of the length a is divided into two,
(4) The distance between the feeding slot 181 and the loading slot 182 is d,
(5) The distances from the front surface 153 to the end points of the power supply slot 181 and the loading slot 182 are L on the upper surface 151 and the lower surface 152,
(6) The width of the power feeding slot 181 and the loading slot 182 is w.
(7) The distance (feed point offset) between the power feeding unit 103 and the front surface 153 is L _f ,
(8) the distance between the variable reactor 104 and the front 153 (loading point offset) is L _r.

In the following description, it is assumed that the wavelength of the electromagnetic wave is λ ₀ and L = 0.217λ ₀ is assumed as an example for design.

  FIG. 3 is a circuit diagram showing one of the variable reactors 104 according to this embodiment. Hereinafter, a description will be given with reference to FIG.

  The variable reactor 104 is obtained by connecting two varactors (sometimes referred to as variable capacitance diodes or varicaps) 301 in anti-series, and the DC voltage by the control unit 105 is passed through the high resistance 302 and the varactor 301. Are applied to the points connected in anti-series. The resistor 302 is for preventing the RF current from flowing through the DC voltage control line.

  Here, since the conductors on the opposite sides in the longitudinal direction of the loading slot 182 have the same potential in terms of DC voltage, a DC voltage cannot be applied even if only one varactor 301 is loaded. A DC voltage can be applied only when an anti-series pair is used as shown in the figure.

  Further, by utilizing such reverse connection, harmonic distortion can be reduced, and the reactance value variable width with respect to the applied DC voltage is twice the variable width when the single varactor 301 is used. There is an advantage.

  FIG. 4 is a circuit diagram showing a rough circuit configuration of the antenna device according to the present embodiment. Hereinafter, a description will be given with reference to FIG.

One end of the conductor part 102 of the antenna device 101 is grounded, and the voltage v ₀ of the power feeding part 103 is an RF voltage between power feeding slots 181 provided in the conductor part 102.

Also, the DC voltages v ₁ and v ₂ controlled by the control unit 105 are applied between the varactors 301, thereby reactance values X ₁ and X _{2 of} the variable reactor 104 loaded in the loading slot 182. Changes.

(Example of design)
Hereinafter, a simulation method for designing the directivity characteristics of the antenna device 101 will be described.

  For simulation of the antenna characteristics, simulation software IE3D (trademark) by the moment method is used.

  By using the equivalent steering vector model, the far electric field E (θ, φ) by the antenna device 101 can be expressed as follows.

  Here, φ represents an angle along the upper surface 151 and the lower surface 152 from the axis from the back surface 154 to the front surface 153 of the antenna device 101, and θ is from the axis from the back surface 154 to the front surface 153 of the antenna device 101. Represents an angle perpendicular to the upper surface 151 and the lower surface 152.

  Here, M = 2, the subscript m = 0 means a port by the power supply unit 103, and the subscripts m = 1, 2 mean a port by the variable reactor 104.

Further, u _m ^(v) (θ, φ) is a structural parameter and does not depend on the reactance value X _m , so it is only necessary to calculate all of them. As described above, the structural parameters can be analyzed by simulation software based on the moment method.

Z _{m, n} is the impedance between the port m and the port n, the open circuit voltage v _{s provided} by the power feeding circuit to the power feeding unit 103, and the internal impedance Z _s of the power feeding circuit, the following calculation is performed. Is possible.

Here, since Z _{m, n} is a structural parameter that does not depend on the reactance X _m , if it is calculated once before iterative calculation by IE3D together with u _m ^(v) (θ, φ), the rest is a constant. Can be treated as

Based on these, the maximum gain Ga (absolute gain not including mismatch loss) in the horizontal plane can be calculated as follows. Here, r is the distance from the antenna, Z _o is the free space impedance, and Z _in is the input impedance.

Since the maximum gain Ga and the input impedance Z _in is not dependent on Z _s, in the above calculation, as Z _s = 0, calculation can be simplified.

  The operation gain Gw including the reflection coefficient Γ, the voltage standing wave ratio vswr, and the mismatch loss can be calculated by the following equation.

Further, in the main beam direction, φ _max is a direction of φ in which the maximum gain Ga (0, φ) in the horizontal plane is maximized.

In this antenna apparatus 101, since the directivity is changed using the variable reactor 104, the matching also changes when the directivity is changed. If a variable function for matching is not provided in the power feeding unit 103 in order to reduce cost, it is necessary to use an actual value as Z _s , and when connecting a coaxial cable to the antenna device 101, Z _s = This gives a fixed value of 50Ω.

  Since the relationship between the reactance value and the various antenna characteristics as described above is non-linear, and the realizable antenna control state is unknown, it is difficult to analytically determine the optimal control state.

Therefore, the antenna characteristics are visualized by displaying contour lines so that the reactance values X ₁ and X ₂ are coordinate values. From this contour map, a global optimum control state can be found, and reactance value control for scanning the beam can be obtained as a trajectory.

  Since the reactance value dependency of the antenna characteristic does not depend on the frequency, the same contour map can be used for any frequency band as long as the antenna has the same dimensions when considered in terms of the wavelength ratio. .

  FIG. 5 is an explanatory diagram showing specifications of the size of the antenna device used in the design example. Hereinafter, a description will be given with reference to FIG. As shown in the figure, seven types from type 1 to type 7 were prepared as the sizes of the antenna device 101. Each is discussed below.

  These specifications are applicable when the antenna device 101 is arranged at the tip of the PC card and used in the 5.2 GHz band. In this case, the specifications of the antenna portion are a = 43.3 mm , B = 12.5mm, h = 1mm.

(Basic characteristics)
Type 1 and type 2 differ in feeding point offset L _f . FIG. 6 is a contour map comparing the characteristics of type 1 and type 2. (A-1), (a-2), (a-3), and (a-4) show vswr, Ga, Gw, and φ _max of type 1 when X ₁ and X ₂ are changed. These diagrams (b-1), (b-2), (b-3), and (b-4) show vswr and Ga of type 2 when X ₁ and X ₂ are changed. , Gw, φ _max is a contour map. Hereinafter, a description will be given with reference to FIG.

As shown in the figure, there is almost no change in directivity even when the feed point offset _Lf is changed, but it can be seen that the matching changes greatly. In addition, it can be seen from this figure that by adjusting the feeding point to about 0.154 wavelength, it is possible to adjust the matching reactance region and the region where a high directivity gain can be obtained. .

In the drawings (b-3) and (b-4), the point A (X ₁ = 300, X ₂ = −300) to the point B (X ₁ = 0, X ₂ = 0) to the point A ′ (X ₁ = 300, X ₂ = 300). Looking at the state of the contour lines passing at this time, it can be seen that the beam directivity can be scanned from about -45 degrees to about 45 degrees.

  FIG. 7 is an explanatory diagram showing the results of calculating the operating gain characteristics at points A and B by IE3D. Hereinafter, a description will be given with reference to FIG.

It can be seen that the operating gain Gw _max shown in this figure and the main beam direction φ _max are in good agreement with the results shown in FIG. 6 and that a beam with an operating gain Gw _max of about 4 dBi can be formed. Although this value is not very large, it can be considered that there is sufficient gain considering that the projection of the antenna in the horizontal direction is equivalent to a 0.75 wavelength dipole.

  It can also be seen that there are large side lobes and a plurality of nulls can be formed. Since null is effective in suppressing interference wave signals, the capability of null scanning is also an important characteristic.

  In addition, it can be seen that the radiation is strong in the back (back 154) direction, and communication with the back direction is possible.

  When the beam is scanned, the beam gain formed in the front direction (point B) is about 1 dBi, and there is a gain change of about 3 dB in the 45 degree direction.

  This can reduce such a decrease in operating gain if a matching adjustment function is provided by applying a method such as loading a variable reactor to the power supply unit 103.

  In addition, the points A and A ′ are almost matched. Therefore, the directivity diversity effect can be obtained by switching only the polarity of the DC voltage using only the point A and the point A ′.

  When the point A and the point A are switched, the square of the absolute value of the correlation coefficient ρ of the directivity in the horizontal plane is 0.11.

  The half-value angle of the beam at point B is about 80 degrees, but at point A, the half-value angle is about 55 degrees, indicating that the beam is narrowed.

(Resonator thickness dependence)
In type 3, the thickness h is twice that of type 2. FIG. 8 is an explanatory diagram showing type 3 antenna characteristics. Hereinafter, a description will be given with reference to FIG.

  As shown in this figure, even if the thickness h is changed, the change in alignment and the change in directivity are small.

  From this figure (b), it can be seen that a design in which the maximum value of the directivity gain Ga exceeds 5 dBi is possible.

  From this figure (c), it can be seen that the reactance variable width required for beam scanning from −45 degrees to 45 degrees is slightly narrowed by increasing the thickness h. However, since these improvements are small compared to doubling the thickness, the advantage of compactness is selected, and in this design example, type 2 is the basic configuration.

(Reactance loading position dependency)
In type 4, the loading point offset L _r is larger than type ₂ . FIG. 9 is an explanatory diagram showing type 4 antenna characteristics. Hereinafter, a description will be given with reference to FIG.

It can be seen that the reactance region in which the value of the operating gain Gw increases and the reactance region necessary for beam scanning approach the symmetry axis of X ₁ = X ₂ .

When reactance control is performed so as to pass through a locus passing from point C (X ₁ = −7, X ₂ = −93) to point C ′ (X ₁ = −93, X ₂ = −7) in the figure, −40 degrees It can be seen that beam scanning of 40 degrees can be realized. That is, the above beam scanning width can be realized in a reactance variable range of −7Ω to −93Ω.

  FIG. 10 is a graph showing the operational gain directivity at point C. In FIG. Hereinafter, a description will be given with reference to FIG.

As can be seen from the figure, the beam is formed in the direction of 40 degrees, the operating gain is 4.06 dBi, and the half-value angle is about 59 degrees. The square of the correlation coefficient ρ when the values of X ₁ and X ₂ are exchanged is 0.0734.

  The reactance variable width becomes narrower as the frequency becomes higher. The reactance value X can be expressed as 1 / (ωC) using the capacitance C and the communication angular frequency ω. However, when C changes from 0.7 pF to 9 pF, the variable width of the varactor anti-series pair is 500 MHz. About 840Ω in the band, about 180Ω in the 2.5 GHz band, and about 87Ω in the 5.2 GHz band.

  That is, it can be seen that even in the 5.2 GHz band, a reactance variable width of −7Ω to −93Ω can be realized, and thus an antenna capable of beam scanning of −40 ° to 40 ° can be realized.

(Slot interval dependency)
In type 5, the slot interval d is reduced to half that of type 2 and the size is reduced, and the feed point offset L _f is increased more than type 2 in order to achieve matching in a reactance region where an absolute gain can be obtained. FIG. 11 is an explanatory diagram illustrating type 5 antenna characteristics. Hereinafter, a description will be given with reference to FIG.

  As shown in this figure, it is understood that a gain of about 4 dBi can be realized with type 5, but the reactance variable width necessary for beam scanning becomes large.

(Depends on top and bottom size)
In type 6, the length (resonator width) a of the upper surface 151 and the lower surface 152 on the side in contact with the front surface 153 is reduced to a half wavelength to reduce the size. FIG. 12 is an explanatory diagram showing type 6 antenna characteristics. Hereinafter, a description will be given with reference to FIG.

  As shown in the figure, the maximum gain is as low as about 3.5 dBi.

  From these analyses, it is understood that the slot interval d and the width a of the resonator are important for gain improvement.

(Influence of distance between front and back)
In type 7, the length (resonator depth) b of the upper surface 151 and the lower surface 152 not contacting the front surface 153 is longer than the slot size L, and the antenna device 101 of the present invention is attached to the tip of the PC card. Is considered to be grounded and a PC card conductor case is also disposed in the remaining portion.

  FIG. 13 is an explanatory diagram illustrating type 7 antenna characteristics. Hereinafter, a description will be given with reference to FIG.

  As shown in this figure, it can be seen that as the length of the conductor at the rear of the antenna increases, both the matching characteristics and the directivity are affected. The angle range in which the beam can be scanned also decreases from −35 degrees to 35 degrees. Therefore, although beam scanning is possible, it turns out that the design which considered structures other than the antenna front-end | tip part is required.

  As described above, design and analysis using contour lines can be performed from various specifications, and specifications of the antenna device 101 that satisfy a desired condition can be determined.

  In the above embodiment, the number of loading slots 182 is two, but the number is not limited to this, and any number may be adopted as long as it is one or more.

  In addition, the length of the upper surface 151 and the length of the lower surface 152 of each slot 161 are designed to be equal to L, but these lengths may be changed as appropriate.

  Further, as can be seen from the difference between type 2 and type 7, the end of the slot 161 may reach the back surface 154 (L = b), and is arranged halfway between the back surface 154 and the front surface 153 (L <b) It is also good.

  Further, the loading offset may be a different value in each loading slot 182. Further, it is possible to connect one variable reactor 104 to the upper surface 151 side and connect another variable reactor 104 to the lower surface 152 side.

  In addition, the slots 161 do not necessarily have to be parallel, and the strip shape of each slot 161 does not have to be linear, and various arrangements such as preparing a plurality of slots can be employed. .

  The conductor 102 is not only a thin plate shape that functions as a resonator, but also a waveguide-like shape that works on a principle similar to that of a resonator, and a cylindrical shape that does not operate as a resonator. It's also good. That is, the shape of a substantially rectangular parallelepiped includes a shape having rounded corners.

  As described above, according to the present invention, it is possible to provide an antenna device having a thin plate shape and capable of beam scanning in the spreading direction.

It is explanatory drawing explaining the shape of the conductor part used with the antenna apparatus which concerns on this embodiment. It is explanatory drawing which shows schematic structure of the antenna device which concerns on this embodiment. It is a circuit diagram which shows one of the variable reactors which concern on this embodiment. It is a circuit diagram which shows the rough circuit structure of the antenna apparatus which concerns on this embodiment. It is explanatory drawing which shows the item of the size of the antenna apparatus used by the design example. It is a contour map which compares the characteristics of type 1 and type 2. It is explanatory drawing which shows the result of having calculated the operation gain characteristic in the point A and the point B by IE3D. It is explanatory drawing which shows the antenna characteristic of type 3. It is explanatory drawing which shows the antenna characteristic of type 4. 6 is a graph showing an operational gain directivity at a point C. It is explanatory drawing which shows the antenna characteristic of type 5. It is explanatory drawing which shows the antenna characteristic of type 6. It is explanatory drawing which shows the antenna characteristic of type 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Antenna apparatus 102 Conductor part 103 Feeding part 104 Variable reactor 105 Control part 151 Upper surface 152 Lower surface 153 Front surface 154 Rear surface 161 Slot 181 Feeding slot 182 Loading slot 301 Varactor 302 Resistance

Claims (6)

A conductor portion having a shape obtained by removing a plurality of band-like regions (hereinafter referred to as “slots”) from the upper surface to one of the side surfaces to the lower surface on the surface of the substantially rectangular parallelepiped;
In the conductor portion, a power feeding portion connected in the vicinity of each of opposing points on two sides in the longitudinal direction of one of the plurality of slots (hereinafter referred to as “power feeding slot”),
Of each of the plurality of slots, each of the slots other than the power supply slot (hereinafter referred to as “loading slot”) is connected to the vicinity of the opposing points on the two sides in the longitudinal direction of the load slot. Reactor,
A control unit for controlling directivity by changing each reactance value of the variable reactor ;
An antenna device, wherein the inside of the substantially rectangular parallelepiped is hollow or filled with an insulator . The antenna device according to claim 1,
The substantially rectangular parallelepiped has a plate shape, and the lengths of the sides of the upper surface and the lower surface are both longer than the distance between the upper surface and the lower surface. The antenna device according to claim 1 or 2,
The longitudinal directions of the plurality of slots are substantially parallel to each other and arranged at equal intervals,
The longitudinal direction of the plurality of slots is arranged perpendicular to one of the side surfaces,
The distance between the end points in the longitudinal direction of the plurality of slots from one of the side surfaces is the same. The antenna device according to any one of claims 1 to 3,
The plurality of slots is three,
The power supply slot is arranged so as to be sandwiched between the two loading slots ,
The antenna device is characterized in that the direction of the directivity scans a spreading direction parallel to the upper surface and the lower surface of the substantially rectangular parallelepiped when the control unit changes a reactance value of the variable reactor . The antenna device according to any one of claims 1 to 4, wherein
The variable reactor is a pair of varactors connected in anti-series,
The said control part changes the series voltage applied to the pair of the said varactor, and changes the said reactance value. The antenna apparatus characterized by the above-mentioned. The antenna device according to any one of claims 1 to 5,
The total length of the slot from the upper surface to the lower surface through the side surface is about half the wavelength of the electromagnetic wave used for communication.

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