JP2008141661A - Antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna device, or the like, which selects any one from among the frequency bands of a plurality of radio services to operate, and which can be reduced in size. <P>SOLUTION: A plurality of inverted-F antennas 101 of the antenna device 11 share a feed line 102, in common, and the longitudinal direction of each standard antenna 103 is parallel. The feed line 102 and each short-circuit line 104 are vertical to the longitudinal direction of the standard antenna 103, a grounding conductor 201 has a substantially rectangular and substantially rectangular solid shape; and its one side is parallel to the longitudinal direction of the standard antenna 103 and is connected to the feed line 102 via a feed port 251. A short-circuit line 104a of an inverted-F antenna 101a, which is one among the plurality of inverted-F antennas 101 is directly connected to the grounding conductor 201, and short-circuit lines 104b, 104c, 104d of other inverted-F antennas 101b, 101c, 101d are connected to a grounding conductor 251 via a reactor 105. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a miniaturizable antenna device that operates by selecting one from a plurality of frequency bands of wireless services.

  Currently, an antenna called an inverted F antenna is widely used. The inverted F antenna is an antenna in which a conductor is arranged in an F shape, and an F-shaped vertical line corresponds to an aerial line, one of the F-shaped horizontal lines corresponds to a feed line used for transmission and reception, and the other corresponds to a short-circuit line for grounding. . Here, which of the F-shaped horizontal lines is used as a power supply line and which is used as a short-circuit line, that is, whether the power supply point is an end point of the aerial line or in the middle, can be appropriately changed depending on the application.

  Furthermore, a technique for adjusting antenna characteristics by loading a reactor whose reactance value changes when the applied DC voltage is changed has been proposed.

Such techniques are disclosed in the following documents.
JP 2001-160710 A J. Cheng, Y. Kamiya and T. Ohira, Adaptive beamforming of ESPAR antenna based on steepest gradient algorithm, IEICE Trans. Commun., Vol. E84-B, no. 7, pp. 1790-1800, July 2001.

  [Patent Document 1] proposes an array antenna using an inverted-F antenna, and [Non-Patent Document 1] proposes a method of calculating reactance values for obtaining desired antenna performance using the steepest gradient method. Has been.

  On the other hand, in cognitive radio, which has been attracting attention in recent years, frequency and communication methods are selected according to the radio wave environment to improve frequency utilization efficiency. To realize cognitive radio, multiple radio services An antenna that operates in the frequency band of is required.

  As a method of realizing such an antenna, a method of preparing a plurality of pairs of antennas and frequency filters and switching them using an RF switch, or a method of switching using a RF switch by connecting a plurality of frequency filters to a broadband antenna. And so on.

  However, in the method of providing an RF switch, a plurality of antennas cannot be combined into one, and downsizing is difficult. Therefore, there is a strong demand for a miniaturizable antenna device that operates by selecting one of a plurality of frequency bands for wireless services.

  The present invention solves the above-described problems, and an object of the present invention is to provide a miniaturizable antenna device that operates by selecting any one of frequency bands of a plurality of wireless services.

  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 plurality of inverted F antennas and a ground conductor, and is configured as follows.

  That is, the plurality of inverted-F antennas share a feed line, and the longitudinal direction of each antenna line is parallel, and the feed line and each short-circuit line are perpendicular to the longitudinal direction of the antenna line.

  On the other hand, the ground conductor has a substantially rectangular shape or a substantially rectangular parallelepiped shape, and one side thereof is parallel to the longitudinal direction of the antenna line, and is connected to the power supply line via a power supply port.

Further, among the plurality of inverted F antennas,
(A) The short-circuit wire of any one inverted F antenna is directly connected to the ground conductor,
(B) Each of the other short-circuited wires of the inverted F antenna is connected to the ground conductor through the reactor.

  In addition, the antenna device of the present invention can be configured such that any surface of the ground conductor and the plurality of F-shaped antennas are arranged on the same plane.

  That is, this antenna device has a planar structure.

  Further, the antenna device of the present invention can be configured such that the feed line is perpendicular to any surface of the ground conductor, and a plurality of F-shaped antennas are arranged on a plane including the feed line. .

  That is, the antenna device has a three-dimensional structure, but the plurality of inverted F antennas are arranged in a plane orthogonal to the ground conductor and are parallel to each other.

  An antenna device according to another aspect of the present invention includes a plurality of inverted F antennas and a ground conductor, and is configured as follows.

  In other words, the plurality of inverted F antennas are a plurality of inverted F antennas sharing a feeder line, and the longitudinal direction of each antenna line is arranged in a plane parallel to each other, and the feeder line and each short-circuited line are arranged. Is perpendicular to the longitudinal direction of the antenna.

  On the other hand, the ground conductor has a substantially rectangular shape or a substantially rectangular parallelepiped shape, and one surface thereof is parallel to the plane parallel to each other and is perpendicular to the power supply line, and is connected to the power supply line via a power supply port. Connected.

Further, among the plurality of inverted F antennas,
(A) The short-circuit wire of any one inverted F antenna is directly connected to the ground conductor,
(B) Each of the other short-circuited wires of the inverted F antenna is connected to the ground conductor through the reactor.

  That is, in this antenna device, the antenna lines of the plurality of F-shaped antennas are all parallel to the ground conductor, but the antenna lines are not necessarily parallel to each other, and the antenna lines may be arranged in a fan-shaped manner around the feeder line. Is possible.

  An antenna device according to another aspect of the present invention includes a plurality of inverted F antennas sharing a feeder line and a ground conductor connected to the feeder line via a feeder port, and is configured as follows.

That is, among a plurality of inverted F antennas,
(A) The short-circuit wire of any one inverted F antenna is directly connected to the ground conductor,
(B) Each of the other short-circuited wires of the inverted F antenna is connected to the ground conductor through the reactor.

  Then, the reactance of the reactor is adjusted to match any one of the plurality of inverted F antennas with a desired frequency band.

  The present invention corresponds to a more general embodiment of the above invention. In general, the antennas of the inverted F antenna do not need to be parallel to the ground conductor, need not be parallel to each other, and are not short-circuited or fed. The electric wire does not need to be perpendicular to the ground conductor, and the ground conductor does not need to have a rectangular or rectangular parallelepiped shape, and can have any shape.

  In the antenna device of the present invention, the lengths of the antennas of the plurality of inverted F antennas can be different from each other.

  In the antenna device of the present invention, the antenna of at least one of the inverted F antennas may be L-shaped, U-shaped, or a lightning pattern. it can.

  With this configuration, it is possible to increase the length of the antenna. In addition, the lightning pattern is a spiral as a whole while the line is bent at a right angle. In the U-shape, the lengths of the U-shaped vertical bars may be different from each other.

  In the antenna device of the present invention, the reactor loaded on at least one of the plurality of inverted F antennas is connected in anti-series, and a DC voltage is applied to the anti-series connection point. The reactance value of the reactor can be adjusted by changing the DC voltage.

  A varactor is an electronic element sometimes called a variable capacitance diode or a varicap.

  In the antenna device of the present invention, the reactor loaded on any one of the plurality of inverted F antennas includes a capacitor to which a DC voltage is applied and a varactor connected in series to the capacitor. The reactance value of the reactor can be adjusted by changing the DC voltage.

  In the antenna device of the present invention, the reactor loaded on any one of the plurality of inverted F antennas includes a capacitor to which a DC voltage is applied and a varactor connected in series to the capacitor. The reactance value of the reactor can be adjusted by changing the DC voltage, and the reactor loaded on at least one other inverted F antenna among the plurality of inverted F antennas is inverted. The varactor includes two varactors connected in series and applied with a DC voltage to the connection point. The reactance value of the reactor can be adjusted by changing the DC voltage.

  That is, it corresponds to a combination of the above inventions.

  In the antenna device of the present invention, among the plurality of inverted F antennas, in the inverted F antenna in which the reactor includes the capacitor and the varactor, the varactor is connected in the middle of the feeder line, and the capacitor is It can comprise so that it may be connected between the said ground wire and the said ground conductor.

  In the present invention, the electronic circuit constituting the reactor is not necessarily arranged in the short-circuit line, and can be arranged in any place as described above. According to the present invention, the degree of freedom in circuit arrangement is increased. Can be increased.

  In the antenna device of the present invention, the power feeding port and the power feeding line can be configured to be connected via a capacitor.

  In the antenna device of the present invention, the ground conductor can be configured to be a liquid crystal display.

  In the antenna device of the present invention, the ground conductor can be configured to be a casing of a wireless communication device.

  ADVANTAGE OF THE INVENTION According to this invention, the antenna apparatus which can be reduced in size which operate | moves by selecting either from the frequency band of several radio | wireless services can be provided.

  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 diagram showing a relationship between one inverted F antenna and a ground conductor used in the antenna device according to the present invention. Hereinafter, a description will be given with reference to FIG.

  As shown in the figure, the inverted-F antenna 101 has an aerial line 103 extending in the longitudinal direction and a midpoint of the aerial line 103 as a feed point. Therefore, the feed line 102 connected at right angles to the aerial line 103 and the end points of the aerial line 103 are directly connected. In order to be grounded to the ground conductor 201 intentionally or indirectly, it is composed of a short-circuit line 104 which is parallel to the feeder line 102 and connected to the antenna line 103 at a right angle.

  The ground conductor 201 is typically a liquid crystal display included in a housing of a communication device or various portable terminals, both of which have a substantially rectangular shape or a substantially rectangular parallelepiped shape.

  A power supply port 251 is prepared between the power supply line 102 and the ground conductor 201 via a capacitor 252 serving as a capacitor.

  This figure (a) has shown a mode that the short circuit wire 104 is directly connected to the ground conductor 201. FIG. As will be described later, the antenna device according to the present embodiment uses a plurality of inverted F antennas 101. One of the features is that one inverted antenna in which the short-circuit wire 104 is directly connected to the ground conductor 201 is provided. .

  This figure (b) has shown a mode that the reactor 105 is inserted between the short circuit wire 104 and the ground conductor 201. FIG. In general, the reactor 105 often employs one whose electric capacity varies depending on the potential difference (voltage) with respect to the ground conductor 201, but any other reactor can be used as long as the reactance can be adjusted as appropriate. It can also be adopted.

  This figure (c) shows the position which can arrange | position the electric element which comprises the reactor 105 separately. It is possible to arrange an electric element constituting the reactor 105 at a position 107 surrounded by a dotted line in the figure. If this position 107 is in the middle of a loop that returns from the ground conductor 201 to the ground conductor 201 through the feeder line 102, the aerial line 103, and the short-circuit line 104, the position 107 should be arranged according to the structure of the electronic circuit composed of electrical elements. Is also possible. Moreover, when it consists of a several electric element, it can also divide | segment and arrange | position.

  FIG. 2 is a schematic diagram illustrating a schematic configuration of the antenna device according to the present embodiment. Hereinafter, a description will be given with reference to FIG. In the drawing, the dimensions of each part are appropriately deformed for easy understanding.

  In the antenna apparatus 11 shown in this figure, four inverted F antennas 101 are used, and these feeders 102 are common.

  The short-circuit wire 104a of the inverted F antenna 101a is directly connected to the ground conductor 201.

  The short-circuit wire 104b of the inverted F antenna 101b is connected to the ground conductor 201 via a DC voltage source 301b having a high internal resistance, and a large-capacitance capacitor 252 (capacitor) is connected between the short-circuit wire 104b and the ground conductor 201. ) Is connected. This is for cutting a direct current.

  In addition, a varactor 302 b is loaded in the middle of the feeder line 102. The reactance of the varactor 302b can be adjusted by changing the voltage of the DC voltage source 301b. The varactor 302b may be disposed in the middle of the short-circuit line 104b. In addition, the tip of the antenna 103b of the inverted F antenna 101b is bent in a lightning pattern (or a U-shape with different lengths of vertical bars) to reduce the arrangement space. It may be left stretched.

  Further, in the reverse F antennas 101c and 101d, the ground conductor 201 and the short-circuit wires 104c and 104d are connected to the reverse connection varactors 303c and 303d, and the voltage applied to the reverse connection varactors 303c and 303d is adjusted. DC voltage sources 301c and 301d are prepared.

  FIG. 3 is a circuit diagram in which a configuration related to the inverted-F antenna 101a is extracted from the antenna device of this embodiment. Hereinafter, a description will be given with reference to FIG.

  As shown in the figure, a large capacity capacitor 252 (capacitor) is connected to the power supply port 251, and signals are exchanged through the power supply port 251. The capacitor 252 (capacitor) is for preventing a DC voltage from being applied to the power supply port 251. Further, the short-circuit line 104a is grounded to the ground conductor 201.

  FIG. 4 is a circuit diagram in which a configuration related to the inverted-F antenna 101b is extracted from the antenna device of the present embodiment. Hereinafter, a description will be given with reference to FIG.

  As shown in the figure, the DC voltage source 301b is variable in voltage, but the internal resistance 353 is high. Further, by connecting a large-capacitance capacitor 252 in parallel with the DC voltage source 301b, a DC voltage is applied to the varactor 302b and a DC current is cut.

  FIG. 5 is a circuit diagram in which a configuration related to the inverted F antenna 101c is extracted from the antenna device of the present embodiment. FIG. 6 is a circuit diagram in which a configuration related to the inverted-F antenna 101d is extracted from the antenna device of this embodiment. Hereinafter, description will be given with reference to these drawings.

  As shown in the figure, the DC voltage source 301c is variable in voltage, but the internal resistance 353 is high. Also, by connecting the reverse connection points of the reverse connection varactors 303c and 303d and the DC voltage source 301c, the reactance is adjusted, the harmonic distortion generated in the varactor is suppressed, and the reactance variable width is doubled. ing.

  As shown in FIGS. 2, 4, 5, and 6, since the DC voltage sources 301b, 301c, and 301d can be disposed in the vicinity of the ground conductor 201, the DC voltage control wiring can be suppressed to the shortest. Further, the positions of the varactor 302b and the reverse connection varactors 303c and 303d may be disposed in the vicinity of the ground conductor 201, or are sandwiched between the short-circuit line 104 and the power supply line 102 in the middle of the power supply line 102, in the middle of the short-circuit line 104. It can be arranged at various places such as in the middle of the antenna 103.

  In other words, the reactor is disposed in any of the closed loops from the power supply port 251 to the ground conductor 201 via the power supply line 102, the aerial line 103, and the short-circuit line 104. Thereby, the arbitraryness of element arrangement | positioning can be improved.

  The number of inverted F antennas 101 can be arbitrary. Moreover, various shapes can be adopted by arranging the antennas 103 so as not to contact each other.

  Below, the design example of the item of the antenna apparatus 11 which concerns on this embodiment is further demonstrated.

(Design example)
Since the characteristics of the inverted F antenna 101 change depending on the size of the ground conductor 201, it is necessary to individually design the inverted F antenna 101 according to the applied device. Below, the example which implement | achieves the antenna apparatus of this embodiment with a printing technique on the dielectric substrate (relative dielectric constant 2.17, thickness 0.8mm) of a size of 150 mm x 100 mm is demonstrated. The frequency band of the wireless service is the following three.
Terrestrial digital broadcasting (470-770 MHz, specific bandwidth 48.8%);
Mobile phone (1920-2170MHz, specific bandwidth 12.2%);
Wireless LAN (5150-5350MHz, specific bandwidth 3.8%)

  At the time of designing, it is desirable that the dimensions of the inverted F antenna 101 adopt the order of determining a low frequency band first and then determining a next higher frequency band. This is because the high frequency band inverted F antenna 101 is smaller than the low frequency band inverted F antenna 101, and therefore, even if a high frequency band antenna is added, the influence on the low frequency characteristics is small.

  In this embodiment, since the feeder line 102 is shared by the plurality of inverted F antennas 101, it may be assumed that the input admittance is substantially added when the inverted F antenna 101 in a high frequency band is added. This is because the voltage of the power supply port 251 is common, and the port current is the sum of the currents flowing through the inverted F antennas 101.

  Therefore, for the inverted F antenna 101 for the low frequency band, if the input impedance in the high frequency band is controlled to be almost open, the input impedance in the single state of the newly added inverted F antenna in the high frequency band is almost the same. realizable.

  Actually, although there is mutual coupling between the inverted F antennas 101, adjustment is necessary, but the presence of the ground conductor 201 is considered to reduce the mutual coupling. This is because the antenna 103 of the inverted F antenna 101 is parallel to the ground conductor 201 and a canceling current flows through the ground conductor 201.

  Note that, when the input impedance in the high frequency band of the low frequency band inverted F antenna 101 is small, it is expected that matching by the added high frequency band inverted F antenna 101 is difficult. Therefore, in this case, the dimensions of the inverted F antenna 101 in the low frequency band must be redesigned.

  In addition, for the inverted F antenna 101 in the low frequency band, if the input impedance in the high frequency band is close to the characteristic impedance of the feeder circuit (generally 50Ω when a coaxial cable is employed), the high frequency band Matching is possible without adding the inverted F antenna 101. However, if matching is achieved in the two frequency bands, the antenna device 11 does not function as a frequency filter.

  Therefore, even in such a case, assuming that the reactance is controlled so that matching is achieved in one radio service frequency band and matching is not achieved in the other, the size of the inverted F antenna 101 in the high frequency band is set. You may decide.

In this example, the frequency ratio band for receiving terrestrial digital broadcasting, which is the lowest frequency band, is as wide as about 50%. Thus, two inverted F antennas 101 a and 101 b are used, and a varactor 302 b (X ₃ ) is provided in the middle of the feeder line 102.

  Since one varactor 302b is used as a reactor, harmonic distortion may remain. However, when used for terrestrial digital broadcasting, since it is dedicated to reception, even if this distortion remains, there is no problem. . In addition, the reactance value variable width is smaller than when the reverse connection varactor is used. However, since it is originally for a low frequency band, the variable range of the frequency band is wide even if the variable width of the same reactance value is used. So it doesn't matter.

For the inverted F antenna 101a, the short-circuit wire 104a is directly connected to the ground conductor 201, and for the inverted F antenna 101b, the DC voltage source 301b (v ₃ ) is connected between the short-circuit wire 104a and the ground conductor 201. Yes.

  This corresponds to the relationship between the inverted F antenna 101 and the ground conductor 201 shown in FIGS.

  After determining the dimensions of the inverted F antennas 101a and 101b in this way, the dimensions of the inverted F antenna 101c in the 2 GHz band and then the inverted F antenna 101d in the 5 Hz band are determined.

In these inverted F antennas 101c and 101d, the reverse connection varactors 303c (X ₁ ) and 303d (X ₂ ) are loaded to adjust the voltages applied by the DC voltage sources 301c (v ₁ ) and 301d (v ₂ ). This corresponds to the case where the reactance is changed and a large current flows.

  These aspects correspond to the relationship between the inverted F antenna 101 and the ground conductor 201 shown in FIGS.

In this embodiment, four inverted F antennas 101 are used, and one of them is directly connected to the ground conductor 201. Therefore, by determining the reactance values X ₁ , X ₂ , and X ₃ for the remaining three, The antenna characteristics can be adjusted. Actually, the applied voltages v ₁ , v ₂ and v ₃ are adjusted.

Generally, the reactance value X _1, ..., when there are M reactor X _M, a voltage v ₀ is applied to the power supply port 251, and a voltage v ₁ applied to each of the reactors, ..., the relationship v _M is It can be determined as follows.

Here, v _s represents the open-circuit voltage of the feed port 251 when transmission is considered, Z _s represents the characteristic actual impedance of the feed line, and Z _{m, n} represents the mth and nth ports (the reactor is loaded). I _m represents the current flowing through the m-th port.

  Since these are structural parameters determined by the shape, they can be considered as constants in each frequency band. Therefore, it can be determined by, for example, the moment method (IE3D).

Further, the input impedance Z _in , reflection coefficient Γ, and voltage standing wave ratio (Voltage Standing Wave Ratio) vswr have the following relationship.

In the present embodiment, since M = 3, the reactance values X ₁ , X ₂ , and X ₃ are matched in the frequency band in which the corresponding inverted F antenna 101 uses the inverted F antenna 101. To control.

Here, the optimum reactance value can be obtained by using the steepest gradient method as shown in [Non-Patent Document 1]. However, there are the following problems.
(1) The convergence value depends on the initial value.
(2) The convergence value and the number of iterations until convergence depend on the step width and the difference width.
(3) The convergence value may be out of the reactable variable range that can be realized.

  Therefore, in the present embodiment, the dependence of the reactance value of vswr on the contour map is shown, and the entire contour map is looked over to find the optimum reactance value set within the feasible control range. In this embodiment, since the number of reactors is three, a plurality of candidate values are prepared for any one reactance value, fixed to each candidate value, a plurality of two-dimensional contour maps are drawn, The optimum reactance value set is predicted from these.

  A reactance value set that minimizes vswr globally can be calculated by applying the steepest gradient method with the reactance value found in this way as an initial value.

  In most cases, a reactance value set that minimizes vswr and a reactance value set that ensures matching in a wide band do not match, but a reactance value having a wide band characteristic can also be predicted from a contour map.

Generally, there is a limit to the variable width of the electric capacity of the varactor 302b and the reverse connection varactors 303c and 303d. When a varactor whose electric capacitance changes from 9 pF to 0.7 pF when the applied DC voltage changes from 0 V to 20 V is adopted, the reactance variable range that can be realized in each frequency band is as follows for the varactor 302 b: In the reverse connection varactors 303c and 303d, this is doubled.
0.47 GHz ... -479Ω to -33.3Ω;
0.77 GHz ... -288Ω to -15.9Ω;
1.92 GHz--201Ω to 17.0Ω;
2.17 GHz ... -169Ω to 23.8Ω;
5.15 GHz ... 6.84Ω-88.3Ω;
5.35 GHz ... 13.8 Ω to 92.2 Ω

  Since the variable width is almost inversely proportional to the frequency, the higher the frequency, the lower the degree of freedom of control. Although the variable range can be expanded by connecting varactors in series, it is sometimes not suitable for miniaturization because the applied voltage needs to be increased.

  With respect to the converged values as described above, it is confirmed whether the range of reactance values that can be matched with vswr ≦ 3 is within the respective control ranges. If not, the inverted F antenna 101 Change the dimensions of and adjust again.

From here on, the antenna dimensions will be examined in more detail with respect to an embodiment employing the following specifications.
L = 150 mm;
L0 = 13 mm;
L1 = 14.3 mm;
L2 = 41 mm;
L4 = 74.5 mm;
L31 = 10 mm;
L32 = 14.5 mm;
H = 100 mm;
w = 1 mm;
H1 = 2 mm;
H2 = 4.5 mm;
H4 = 14.5 mm;
H3 = 19.5mm

  FIG. 7 is a contour diagram showing the reactance value dependence of vswr at the lowest frequency, the center frequency, and the highest frequency of each frequency band. Hereinafter, a description will be given with reference to FIG.

  In this figure, the reactance value of the reactor loaded on the inverted F antenna 101 for the frequency band is displayed in a contour map, and the reactance variable range is drawn with a rectangular area of a broken line. From these, a combination of reactance values with which vswr is 3 or less is selected.

  Black circles A, B, and C in the figure are points selected so that matching can be achieved at the minimum frequency, the center frequency, and the maximum frequency.

FIG. 8 is a table showing the reactance values X ₁ , X ₂ , and X _{3 of} A, B, and C, and the electric capacity values Cx ₁ , Cx ₂ , and Cx ₃ of the varactor at that time, It is a graph which shows the frequency characteristic of vswr in each frequency band.

  As seen from these figures, matching is achieved at the frequency within the design target. In particular, in the 5 GHz band, vswr ≦ 3 is matched in the band by one reactance value set. It can be seen that in the UHF band, only by the three reactance value sets, there is a portion where matching of vswr ≦ 3 cannot be achieved in each band.

In addition, from this simulation, the region where matching can be achieved in the 2 GHz band is strongly dependent on X ₂ (the inverted F antenna 101 loaded with this is a 2 GHz band resonant element), and the region where matching can be achieved in the UHF band is , X ₃ (the inverted F antenna 101 on which it is loaded is a resonant element in the UHF band).

  As described above, there is a band that cannot be matched if the reactance value is fixed. Therefore, it is necessary to control the reactance value depending on the frequency so that matching can be achieved at an arbitrary frequency included in a desired frequency band.

In order to obtain an optimum reactance value for a desired frequency, it is sufficient to determine an initial value by drawing a contour map and use the steepest gradient method as described above. However, the structural parameter Z _{m, n} changes depending on the frequency. Therefore, it is necessary to calculate the structural parameter Z _{m, n} for many frequencies. However, _{in order} to calculate the structural parameter Z _{m, n} when a dielectric is present, the calculation time is often long.

  Therefore, the tendency of the change in the shape of the contour map is investigated from the three contour maps of the minimum frequency, the center frequency, and the maximum frequency of a certain frequency band, and a reactance region in which matching can be obtained at a frequency between other frequencies is predicted. .

  FIG. 10 is a graph showing combinations of reactance value sets and electric capacities. FIG. 11 is a graph showing vswr values in the reactance value set.

From these graphs, it can be seen that, in most cases, matching can be achieved at a desired frequency by dynamically adjusting the reactance value even in the UHF band and the 2 GHz band. In the UHF band, it is necessary to control three reactance values, but there are mainly _two control objects, X ₁ and X ₂ .

  It can also be seen that by using the contour map, it is possible to predict with a high degree of accuracy by predicting the overall tendency of the matching characteristics, saving calculation time and obtaining a desired set of reactance values.

  Next, the directivity and polarization of the antenna device 11 for which the reactance value is determined in this way will be examined.

  As shown in FIG. 2, the coordinate system sets the x-axis in the longitudinal direction of the ground conductor 201 so that the plane of the surface of the ground conductor 201 is stretched between the x-axis and the y-axis. Set to the vertical direction.

  Further, the rotation angle of polar coordinates is set by the rotation amount φ from the x axis to the y axis and the rotation amount θ from the z axis.

  FIGS. 12, 13, and 14 are graphs showing operational gain directivities at the center frequencies of the UHF band, the 2 GHz band, and the 5 GHz band, respectively. Hereinafter, a description will be given with reference to FIG.

  The graphs in these figures show the operational gain directivity of the θ = 90 ° plane at the upper left, the φ = 0 ° plane at the upper right, and the φ = 90 ° plane at the lower center. The broken line is vertical polarization, and the solid line is horizontal polarization.

  According to these, it can be seen that the horizontal plane (xy plane) is substantially horizontally polarized but has a vertically polarized component other than in the horizontal direction.

  Since liquid crystal displays of personal computers and portable terminals are often arranged obliquely with a certain angle with respect to the ground, when a liquid crystal display is used as the ground conductor 201, horizontal polarization coming from the horizontal direction・ It is thought that both vertical polarization can be transmitted and received.

  In the above description, an example of the antenna device 11 in which a plurality of inverted F antennas 101 and ground conductors 201 are configured on a printed board and arranged in a substantially planar shape is taken up. An embodiment of an antenna device having a structure in which the inverted F antenna 101 and the ground conductor 201 are three-dimensionally arranged will be described.

  FIG. 15 and FIG. 16 are explanatory views showing the appearance of a three-dimensional antenna device. Hereinafter, a description will be given with reference to FIG. Also in this figure, the dimensions of each part are deformed.

  In the antenna apparatus shown in FIGS. 15 and 16, the feed line 102 of the inverted F antenna 101 is arranged in the normal direction of the rectangular ground conductor 201. The antenna 103 of the inverted F antenna 101 is arranged in parallel with the rectangular shape of the ground conductor 201. Actually, the distance between the antenna 103 and the ground conductor 201 is shorter than shown in the figure.

  From the end point of each antenna line 103, a short-circuit line 104 is drawn perpendicular to the ground conductor 201, and is connected to the ground conductor 201 via the reactor 105 or directly.

  In the shape shown in FIG. 15, the antenna lines 103 of the inverted F antenna 101 are also arranged in parallel. In the shape shown in FIG. 16, the antenna lines 103 of the inverted F antenna 101 are in a twisted relationship with each other, and the angle at which the antennas 103 are arranged is slightly shifted. It has become.

  Since the antenna 103 corresponding to the longitudinal direction of the inverted F antenna is parallel to the ground conductor 201, for example, when the ground conductor 201 is a liquid crystal display, on the printed circuit board having a multilayer structure arranged parallel to the ground conductor 201 It can be said that the aerial wire 103 is disposed by etching, and the power supply line 102 and the short-circuit wire 104 are disposed in a through hole passing through the multilayer structure printed board.

  As described above, the arrangement of the inverted-F antenna 101 is extremely high as long as it is parallel to the ground conductor 201 in any direction, and thus antenna devices having various shapes can be provided depending on the application.

  In the above embodiment, the ground conductor 201 is substantially rectangular, the feed line 102 is perpendicular to the ground conductor 201, and the antenna 103 of the inverted F antenna 101 is parallel to the ground conductor 201. The restriction is for facilitating calculation when the structural parameter is obtained by simulation, and it is not always necessary to impose these restrictions.

  FIGS. 17, 18, and 19 are explanatory diagrams illustrating a schematic arrangement of the antenna device in which the restrictions on the shapes of the feeder line 102, the antenna line 103, the short-circuit line 104, and the ground conductor 201 are relaxed. Hereinafter, a description will be given with reference to FIG.

  In the antenna device 11 shown in FIG. 17, the feed line 102 and the short-circuit line 104 are not perpendicular to the side of the ground conductor 201.

  In the antenna device 11 shown in FIG. 18, the antenna line 103 is not parallel to the side of the ground conductor 201 and is not parallel to each other.

  In the antenna device 11 shown in FIG. 19, the feeder line 102, the aerial line 103, and the short-circuit line 104 have a general curved shape, and the ground conductor 201 has a figure surrounded by an arbitrary curve.

  When these shapes are adopted, the structural parameters may be obtained by simulation after design, but the calculation may take time. In this case, after manufacturing an actual machine, a combination of reactance values of each reactor is actually applied, a contour map similar to the above embodiment is drawn, and a set of reactance values at a desired frequency is determined. good.

  According to this embodiment, it is possible to greatly increase the degree of freedom of the shape of the antenna device.

  As described above, according to the present invention, it is possible to provide a miniaturizable antenna device that operates by selecting one from a plurality of frequency bands of wireless services.

It is explanatory drawing which shows the relationship between one reverse F antenna and ground conductor which are utilized with the antenna apparatus which concerns on this invention. It is a mimetic diagram showing an outline composition of an antenna device concerning this embodiment. It is the circuit diagram which extracted the structure relevant to the reverse F antenna 101a from the antenna apparatus of this embodiment. It is the circuit diagram which extracted the structure relevant to the reverse F antenna 101b from the antenna apparatus of this embodiment. It is the circuit diagram which extracted the structure relevant to the reverse F antenna 101c from the antenna apparatus of this embodiment. It is the circuit diagram which extracted the structure relevant to the reverse F antenna 101d from the antenna apparatus of this embodiment. FIG. 6 is a contour diagram showing the reactance value dependence of vswr at the lowest frequency, the center frequency, and the highest frequency in each frequency band. ₄ is a table showing reactance values X ₁ , X ₂ , and X ₃ for A, B, and C, and values Cx ₁ , Cx ₂ , and Cx ₃ of varactors at that time. It is a graph which shows the frequency characteristic of vswr in each frequency band. It is a graph which shows the combination of a reactance value set and an electric capacity. It is a graph which shows vswr value in a reactance value set. It is a graph showing the operational gain directivity at the center frequency of the UHF band. It is a graph showing the operational gain directivity at the center frequency of 2 GHz band. It is a graph showing the operational gain directivity at the center frequency of the 5 GHz band. It is explanatory drawing which shows the external appearance of the antenna apparatus comprised in three dimensions. It is explanatory drawing which shows the external appearance of the antenna apparatus comprised in three dimensions. It is explanatory drawing which shows schematic arrangement | positioning of the antenna apparatus which eased the restriction | limiting of the shape which concerns on a feeder line, an aerial line, a short circuit line, and a ground conductor. It is explanatory drawing which shows schematic arrangement | positioning of the antenna apparatus which eased the restriction | limiting of the shape which concerns on a feeder line, an aerial line, a short circuit line, and a ground conductor. It is explanatory drawing which shows schematic arrangement | positioning of the antenna apparatus which eased the restriction | limiting of the shape which concerns on a feeder line, an aerial line, a short circuit line, and a ground conductor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Antenna apparatus 101 Reverse F antenna 102 Aerial line 103 Feed line 104 Short circuit line 105 Reactor 107 Position which can arrange | position a reactor 201 Ground conductor 251 Feed port 252 Capacitor 301 DC voltage source 302 Varactor 303 Reverse connection varactor 352 Terminal 353 Internal resistance

Claims (14)

A plurality of inverted F antennas sharing a feeder line, wherein the longitudinal direction of each antenna line is parallel, and the feeder line and each short-circuit line are a plurality of inverted F antennas perpendicular to the longitudinal direction of the antenna line. An antenna,
It has a substantially rectangular or substantially rectangular parallelepiped shape, one side of which is parallel to the longitudinal direction of the antenna, and is connected to the power supply line via a power supply port;
With
Among the plurality of inverted F antennas,
(A) The short-circuit wire of any one inverted F antenna is directly connected to the ground conductor,
(B) Each of the other short-circuit wires of the inverted-F antenna is connected to the ground conductor via a reactor. The antenna device according to claim 1,
Any one surface of the ground conductor and the plurality of F-shaped antennas are arranged on the same plane. The antenna device according to claim 1,
The feed line is perpendicular to any surface of the ground conductor, and the plurality of F-shaped antennas are arranged on a plane including the feed line. A plurality of inverted-F antennas sharing a feeder line, wherein the longitudinal direction of each antenna line is arranged in a plane parallel to each other, and the feeder line and each short-circuit line are perpendicular to the longitudinal direction of the antenna line A plurality of inverted F antennas,
A substantially rectangular or substantially rectangular parallelepiped shape, one surface of which is parallel to the planes parallel to each other and perpendicular to the feeder line, and is connected to the feeder line via a feeder port; ,
With
Among the plurality of inverted F antennas,
(A) The short-circuit wire of any one inverted F antenna is directly connected to the ground conductor,
(B) Each of the other short-circuit wires of the inverted-F antenna is connected to the ground conductor via a reactor. A plurality of inverted F antennas sharing a feed line;
A ground conductor connected to the feed line via a feed port;
With
Among the plurality of inverted F antennas,
(A) The short-circuit wire of any one inverted F antenna is directly connected to the ground conductor,
(B) Each of the other short-circuited wires of the inverted F antenna is connected to the ground conductor via a reactor,
An antenna device characterized by adjusting a reactance of the reactor to match any one of the plurality of inverted F antennas with a desired frequency band. The antenna device according to any one of claims 1 to 5,
The antenna apparatus characterized in that the antennas of the plurality of inverted F antennas have different lengths. The antenna device according to any one of claims 1 to 5,
Among the plurality of inverted F antennas, an antenna of at least one of the inverted F antennas is L-shaped, U-shaped, or a lightning pattern. The antenna device according to claim 6 or 7, wherein
The reactor loaded on at least one of the plurality of inverted F antennas is composed of two varactors that are connected in anti-series and a DC voltage is applied to the anti-series connection point. An antenna device characterized in that a reactance value of the reactor can be adjusted by changing a DC voltage. The antenna device according to claim 6 or 7, wherein
A reactor loaded on at least one of the plurality of inverted F antennas is:
An antenna device comprising: a capacitor to which a DC voltage is applied; and a varactor connected in series to the capacitor, wherein the reactance value of the reactor can be adjusted by changing the DC voltage. The antenna device according to claim 6 or 7, wherein
A reactor loaded on at least one of the plurality of inverted F antennas includes a capacitor to which a DC voltage is applied and a varactor connected in series to the capacitor. The reactance value of the reactor can be adjusted by changing
A reactor loaded on at least one other inverted F antenna among the plurality of inverted F antennas is composed of two varactors connected in anti-series and having a DC voltage applied to the connection point. An antenna device, wherein the reactance value of the reactor can be adjusted by changing a voltage. The antenna device according to claim 9 or 10, wherein
Among the plurality of inverted F antennas, in the inverted F antenna in which the reactor is composed of the capacitor and the varactor, the varactor is connected in the middle of the feeder line, and the capacitor includes the ground line and the ground conductor. An antenna device characterized by being connected between the two. The antenna device according to any one of claims 1 to 11,
The antenna device, wherein the power supply port and the power supply line are connected via a capacitor. The antenna device according to any one of claims 1 to 12,
The antenna device is characterized in that the ground conductor is a liquid crystal display. The antenna device according to any one of claims 1 to 12,
The antenna device, wherein the ground conductor is a housing of a wireless communication device.

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