JP3981678B2 - Self-complementary antenna device - Google Patents

Description

  The present invention relates to a self-complementary antenna apparatus capable of changing radiation characteristics.

  In recent years, wireless terminals equipped with a plurality of wireless systems such as mobile phones and wireless LANs have been developed. In these wireless terminals, one antenna is used in a plurality of wireless systems from the viewpoint of device miniaturization. However, since the radio frequency is different for each radio system, the antenna needs to operate at a plurality of frequencies.

  One of antennas operating at a plurality of frequencies is a self-complementary antenna (Non-patent Document 1). The self-complementary antenna is composed of a first conductor plate having a notch portion and a second conductor plate having the same shape as the notch portion of the first conductor plate, and the notch portion of the first conductor plate. And the second conductor plate are arranged in line-symmetric positions. A feeding point is provided between the first conductor plate and the second conductor plate.

  If the self-complementary antenna satisfies the above conditions, the shape of the notch, in other words, the shape of the second conductor plate is not limited. Under this condition, the self-complementary antenna has the property of having an input impedance with a constant impedance of 60πΩ (≈188.4Ω) independent of the frequency. Therefore, since the input impedance of the antenna does not depend on the frequency, it can be used at a plurality of frequencies.

In principle, a self-complementary antenna requires an infinitely large conductor plate. For this reason, the first and second conductor plates are connected to each other with a resistance of 60πΩ, so that they are equivalent to an infinitely large body plate. As a result, a constant impedance of 60πΩ is obtained at all frequencies.
Yasuto Mushiake, Springer, "Self-Complementary Antennas Principle of Self-Complementarity for Constant Impedance"

  However, if the size is reduced using a resistance of 60πΩ, power is consumed at this resistance portion, and the radiation efficiency of the antenna is deteriorated. In particular, when the amount of radio waves radiated from the second conductor plate decreases, the amount of radiation efficiency degradation increases. The amount of radiation decreases when the size of the second conductor plate does not resonate with the frequency of the radiated radio wave.

  As described above, conventionally, when the self-complementary antenna is downsized, the radiation efficiency changes depending on the frequency even if the input impedance is constant without depending on the frequency. It was. In addition, there are problems such as radiation pattern control, miniaturization, and cost reduction.

  An object of the present invention is to provide a self-complementary antenna device that can be miniaturized and can obtain high radiation efficiency at a plurality of frequencies.

  According to one aspect of the present invention, the first conductor plate having a notch with a predetermined shape and the first conductor plate are spaced apart and arranged in a line-symmetric position with the notch. A second conductor plate having substantially the same shape and the same size as the notch, the notch and the second conductor plate are disposed in proximity to each other, and supplies power to the first and second conductor plates. A feeding point; a resistance element connected between the first and second conductor plates; and a first switching circuit capable of short-circuiting or opening two opposing sides of the notch at least at one place. The second conductor plate is separated from each other in proximity to the first and second conductor portions, and the distance from the feeding point is substantially equal to that of the first switching circuit, and the first and second conductor plates are A second switching circuit capable of short-circuiting or opening at least one conductor part of The notch has a shape having two or more branch portions, and the first switching circuit has a plurality of second sides that can short-circuit or open two opposing sides of each of the two or more branch portions. The second conductor plate has a plurality of branch portions that are substantially the same shape and the same size as each of the branch portions of the notch portion and are arranged in close proximity to each other, The second switching circuit includes a plurality of second switching units that are arranged at positions that are substantially equal to the plurality of first switching units, and that are capable of short-circuiting or opening two different branch units. A self-complementary antenna device is provided.

  According to the present invention, since the first or second switching circuit is provided symmetrically on each of the first and second conductive plates constituting the self-complementary antenna, a constant input is obtained without depending on the frequency. Impedance is obtained, and high radiation efficiency is obtained at a plurality of frequencies.

  Hereinafter, an embodiment of the present embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a plan view of a self-complementary antenna device according to the first embodiment of the present embodiment. The self-complementary antenna apparatus of FIG. 1 has a first conductor plate 2 having a notch portion 1 and a second conductor plate 2 that is spaced apart from the first conductor plate 2 and is symmetrical with the notch portion 1. A conductive plate 3, a feeding point 4 for feeding power to the first and second conductive plates 1, 3, a resistance element 5 of 60πΩ connected between the first and second conductive plates 1, 3, And a first switching circuit 6 capable of short-circuiting or opening two opposing sides of the cutout portion 1 at least at one place.

  The second conductor plate 3 has substantially the same shape and the same size as the cutout portion 1. The feeding point 4 is arranged in the vicinity of the symmetry axis between the notch 1 and the second conductor plate 3. More specifically, the feeding point 4 is disposed between the outer end portion of the cutout portion 1 of the first conductor plate 2 and the second conductor plate 3.

  The second conductor plate 3 includes first and second conductor portions 11 and 12 that are arranged adjacent to each other separately from each other, and a second switch that can short-circuit or open the first and second conductor portions 11 and 12. Circuit 13. The second switching circuit 13 is arranged so that the distance from the feeding point 4 is substantially the same as that of the first switching circuit 6.

  Hereinafter, the operation of the self-complementary antenna apparatus of FIG. 1 will be described. The self-complementary antenna device of this embodiment can switch between two types of self-complementary antennas by switching control of the first and second switching circuits 6 and 13. Hereinafter, the two types of self-complementary antennas are referred to as first and second self-complementary antennas.

  The first self-complementary antenna is obtained when the first switching circuit 6 is turned on and the second switching circuit 13 is turned off. In this case, the operating range of the first conductor plate 2 as an antenna is a range from the feeding point 4 to the first switching circuit 6, and the operating range of the second conductor plate 3 as an antenna is the feeding point 4. To the second switching circuit 13.

  By such first and second switching circuits 6 and 13, a self-complementary antenna shown in FIG. 2 can be obtained equivalently. In principle, the input impedance of the self-complementary antenna shown in FIG. 2 does not depend on the frequency. Further, high radiation efficiency can be realized at a frequency that resonates with the length of the cutout portion 1 (the length of the second conductor plate 3) d1. Here, the frequency that resonates at length d1 is a frequency at which the length of d1 is an integral multiple of 1/4 wavelength.

  The second self-complementary antenna is obtained when the first switching circuit 6 is turned off and the second switching circuit 13 is turned on. In this case, the operating range of the first conductor plate 2 as the antenna is the entire cutout portion 1, and the operating range of the second conductor plate 3 as the antenna is from the feeding point 4 to the entire second conductor plate 3. It is.

  By such first and second switching circuits 6 and 13, the self-complementary antenna shown in FIG. 3 can be obtained equivalently. In principle, the input impedance of the self-complementary antenna shown in FIG. 3 does not depend on the frequency. Further, high radiation efficiency can be realized at a frequency that resonates with the length of the cutout portion 1 (the length of the second conductor plate 3) d1 + d2. Here, the frequency that resonates at length d1 + d2 is a frequency at which the length of d1 + d2 is an integral multiple of 1/4 wavelength.

  Next, a simulation result performed to prove the operation principle is shown. The entire length of the notch 1 is 70 mm, d1 is 50 mm, and d2 is 20 mm.

  FIG. 4 is a diagram showing the result of expressing the frequency characteristics of the input impedance on the Smith chart. As can be seen from FIG. 4, the input impedance of each of the first and second self-complementary antennas is substantially constant 60πΩ from the frequency of 0.9 GHz to 1.7 GHz.

  FIG. 5 is a diagram showing frequency characteristics of radiation efficiency. In two states where the first and second switching circuits 13 are switched, a radiation efficiency of almost 100% can be realized at different frequencies.

  In the state of being the first self-complementary antenna, the length of d1 corresponding to 50 mm corresponds to the resonance length. At a frequency of 1.4 GHz, the quarter wavelength is approximately 50 mm, which matches the length of resonance.

  In the state of the second self-complementary antenna, the length of 70 mm of d1 + d2 corresponds to the resonance length. At a frequency of 1 GHz, the quarter wavelength is approximately 70 mm, which is a resonance length. It should be noted that here the resonance wavelength is about 95% shorter than the free space wavelength. This is generally the same principle as designing a half-wave dipole antenna with a length reduced by about 5%.

  As described above, as can be seen from FIGS. 4 and 5, the self-complementary antenna according to the present embodiment has the characteristics that a constant input impedance characteristic can be obtained without depending on the frequency and the characteristics that a high radiation efficiency can be obtained at a plurality of frequencies. It is possible to realize an antenna that satisfies the three characteristics simultaneously.

  Here, the shape of the notch 1 is a rectangle, but any shape other than a rectangle can be adopted. As long as the cutout portion 1 of the first conductor plate 2 and the second conductor plate 3 have the same shape (that is, a self-complementary structure), any shape can be adopted. For example, as shown in FIG. 6, it is effective to provide a L-shaped cutout portion 1 to reduce the posture, in order to realize a small wireless device. Instead of using the L shape, the cutout portion 1 may be curved to reduce the posture.

  Below, the detail of each part of this antenna is demonstrated. Description will be made in the order of the feeding point 4, the resistance of 60πΩ and the switching circuit.

  The feeding point 4 gives a voltage difference between the first conductor plate 2 and the second conductor plate 3, and is close to the notch portion 1 and the second conductor plate 3 of the first conductor plate 2. Arranged. A feed line from a radio (not shown) is connected to the feed point 4. FIG. 7 is a diagram showing an example in which the coaxial line 21 is used as the feed line. The outer conductor of the coaxial line is grounded to the first conductor plate 2, and the feeding point 4 of the antenna is formed by connecting the inner conductor of the coaxial line and the second conductor plate 3 with the linear conductor 22.

  FIG. 8 is a diagram showing an example in which a microstrip line is used as a feed line. In FIG. 8, a dielectric layer 23 is present on the first conductor plate 2 and a microstrip line 24 is present thereon. Then, by connecting the tip of the microstrip line 24 and the second conductor plate 3 with a linear conductor, a feeding point 4 is formed at the connection position. In addition to this, the feed point 4 is formed using an arbitrary feed line.

  Next, the resistance of 60πΩ will be described. The resistance element 5 may be arranged so as to connect the first and second conductor plates 1 and 3 as shown in FIG. 9 using a general two-terminal resistance component. Then, the outer periphery of the first conductor plate 2 different from the feeding point 4 and the boundary portion of the cutout portion 1 are connected to the second conductor plate 3. The resistance element 5 may be a small element called a carbon resistance or a chip resistance. Further, as shown in FIG. 4, in the self-complementary antenna that has been reduced in size, the input impedance of the antenna does not become strictly constant but becomes a substantially constant value due to the fact that the first ground plane becomes finite. is there. Accordingly, a resistance value close to 60πΩ can be substituted, and there is little deterioration in the characteristics other than 60πΩ.

  Next, the first switching circuit 6 will be described. As an element for realizing the on / off characteristics of the switching circuit, a switching circuit using an active element such as a pin diode, a MESFET (Metal Semiconductor Field Effect Transistor), or a MEMS (Micro Electro Mechanical System) element can be used.

  FIG. 10 is a circuit diagram showing an example of the first switching circuit 6. In FIG. 10, the active element 31 is connected to the first conductor plate 2 at two opposite sides of the cutout portion 1 via DC voltage cutting capacitor elements C1 and C2. A DC voltage for switching the operation of the active element 31 is supplied from the voltage source 32 via the inductor elements L1 and L2. With such a configuration, by switching the voltage supplied to the active element 31, the high frequency characteristics are switched, and the on / off operation can be performed. Each component constituting the first switching circuit 6 is disposed on a dielectric.

  Strictly speaking, the on / off operation of the first switching circuit 6 may be designed to switch between an impedance of several Ω and an impedance of several thousand Ω. Further, the active element 31 may be designed at a trade-off with operation speed, operation voltage, current consumption, cost, size, and the like. Further, the capacitor elements C1 and C2 and the inductor elements L1 and L2 may be selected from element values so as to perform a desired operation at a required frequency.

  Next, the second switching circuit 13 will be described. The second switching circuit 13 may be configured in the same manner as the first switching circuit 6. For example, it can be configured as shown in FIG. The circuit of FIG. 11 includes a voltage source 31, inductor elements L1 and L2, capacitor elements C1 and C2, and an active element 31 as in FIG.

  As described above, in the first embodiment, the first or second switching circuit 13 is disposed in the cutout portion 1 and the second conductor plate 3 of the first conductor plate 2, respectively. By switching the operation of the switching circuits 6 and 13, a constant input impedance can be obtained without depending on the frequency, and a highly efficient radiation pattern can be obtained at two frequencies.

  In addition, the self-complementary antenna of the present embodiment is also effective when the second conductor plate 3 is lowered in posture as shown in FIG. In general, when the antenna is lowered, the input impedance changes greatly and impedance mismatch occurs. However, in this embodiment, since the input impedance is constant, the shape of the antenna can be designed without worrying about changes in the input impedance, and high radiation efficiency can be realized at a plurality of frequencies.

  Further, in the present embodiment, the case where two frequencies are switched has been described, but it is also possible to increase the number of switching circuits so as to realize high radiation efficiency at three or more frequencies.

(Second Embodiment)
In the second embodiment, the number of switching circuits is increased so that two types of self-complementary antennas can be switched.

  FIG. 12 is a plan view of a self-complementary antenna according to the second embodiment of the present embodiment. The self-complementary antenna in this embodiment includes a first conductor plate 2 having a branched notch portion 1 and a second conductor plate 3 having the same shape as the notch portion 1 of the first conductor plate 2. An antenna feeding point 4 and a 60πΩ resistive element 5 are connected between the cutout portion 1 of the first conductor plate 2 and the second conductor plate 3.

  The second conductor plate 3 is disposed at a position symmetrical to the first cutout portion 1. The feeding point 4 is disposed between the outer end portion of the cutout portion 1 of the first conductor plate 2 and the second conductor plate 3. In addition to the feeding point 4, the 60πΩ resistive element 5 is disposed so as to connect the outer end portion of the cutout portion 1 of the first conductor plate 2 and the second conductor plate 3. The cutout portion 1 of the first conductor plate 2 is branched into two inside the first conductor plate 2.

  Similarly, the second conductor plate 3 has a shape bifurcated into the same shape and size as the cutout portion 1 of the first conductor plate 2. The first conductor plate 2 has a first switching circuit 41 and a second switching circuit 42 that short-circuit or open a part of the cutout portion 1 in the vicinity of the bifurcated position of the cutout portion 1. .

  The second conductor plate 3 is divided into three parts around a two-branching part, and shorts or opens the connection between the conductor part connected to the feeding point 4 and the two conductor parts not connected to the feeding point 4. A third switching circuit 43 and a fourth switching circuit 44 are provided.

  The first switching circuit 41 and the third switching circuit 43 are arranged at line-symmetric positions, and the second switching circuit 42 and the fourth switching circuit 44 are arranged at line-symmetric positions.

  The self-complementary antenna of this embodiment obtains a constant input impedance characteristic independent of frequency and a plurality of radiation pattern characteristics by switching the first, second, third and fourth switching circuits 41 to 44. be able to.

  Hereinafter, the operation principle of the antenna device of the second embodiment will be described. Note that description of the same components as those in the first embodiment is omitted.

  The self-complementary antenna of the present embodiment can switch between two types of self-complementary antennas under the control of the first, second, third and fourth switching circuits 41 to 44.

  The state of the first self-complementary antenna is as follows: the first switching circuit 41 is turned off (opened), the second switching circuit 42 is turned on (short circuit), the third switching circuit 43 is turned on (short circuit), This is a case where the switching circuit 44 is turned off (opened).

  In this case, the range of the cutout portion 1 of the first conductor plate 2 that operates as an antenna includes a portion from the feed point 4 to the second branch and a cutout on the side where the first switching circuit 41 exists. Part 1. The range of the second conductor plate 3 that operates as an antenna is a conductor portion that is connected by the third switching circuit 43 to a portion from the feeding point 4 to the second branch.

  By switching the first to fourth switching circuits 41 to 44 as described above, an operation equivalent to that of the self-complementary antenna as shown in FIG. 13 can be realized. Therefore, in the self-complementary antenna shown in FIG. 13, the input impedance can obtain a constant value without depending on the frequency, and the shapes of the cutout portion 1 and the second conductor plate 3 of the first conductor plate 2 are obtained. A first radiation pattern characteristic determined by

  On the other hand, in the state of the second self-complementary antenna, the first switching circuit 41 is turned on (short circuit), the second switching circuit 42 is turned off (opened), and the third switching circuit 43 is turned off (opened). This is a case where the fourth switching circuit 44 is turned on (short circuit).

  In this case, of the cutout portion 1 of the first conductor plate 2, the range of operation as an antenna is the portion from the feed point 4 to the point where it branches into two and the cutout on the side where the second switching circuit 42 exists. This is a portion of the notch portion 1. The range of the second conductor plate 3 that operates as an antenna is a moving body portion that is connected by the fourth switching circuit 44 to a portion from the feeding point 4 to the second branch.

  By switching the first to fourth switching circuits 41 to 44 as described above, an operation equivalent to that of the self-complementary antenna as shown in FIG. 14 can be realized. Therefore, in the self-complementary antenna shown in FIG. 14, the input impedance has a constant value that does not depend on the frequency, and is determined by the shape of the cutout portion 1 of the first conductor plate 2 and the second conductor plate 3. A second radiation pattern characteristic is obtained.

  As a result, in the self-complementary antenna of this embodiment, the self-complementary antenna shown in FIGS. 13 and 14 can be realized by performing the switching operation of the first to fourth switching circuits 41 to 44. Although these two self-complementary antennas have different radiation patterns, the input impedances have the same value.

  Here, in general, when changing the radiation pattern of the antenna, it is necessary to change the current distribution on the conductor plate which is the source of radiation. Here, when the current distribution changes, there is a problem that the input impedance of the antenna changes, as can be seen from Ohm's law. That is, generally, when an operation that changes the radiation pattern of the antenna is performed, the input impedance of the antenna also changes together. Therefore, it is necessary to take measures such as reducing the degree of freedom of the radiation pattern to be changed and inserting a matching circuit corresponding to the changed impedance.

  On the other hand, in the self-complementary antenna of this embodiment, in order to realize an arbitrary radiation pattern, the shape of the cutout portion 1 of the first conductor plate 2, in other words, the shape of the second conductor plate 3 is used. However, even if it has an arbitrary shape, the input impedance has a very excellent feature that it has a constant value, there are few restrictions on the radiation pattern that can be realized, and no matching circuit is required.

  Therefore, when used for a small wireless device, the input impedance does not change according to the present embodiment even if the antenna installation space is limited and the antenna shape is limited. Moreover, when using for a small radio | wireless machine, since two radiation patterns are realizable, it can be used as a diversity antenna.

  Thus, in the second embodiment, two radiation patterns can be realized, and the input impedance of the antenna does not change.

  Similarly to the first embodiment, by setting the length of the notch 1 to a length that resonates at the frequency to be operated, two types of radiation pattern characteristics with high radiation efficiency can be obtained with the same input impedance. Can be realized.

  In addition, the case where the two types of self-complementary antennas of FIGS. 13 and 14 are switched has been described. However, the first switching circuit 41 is turned off, the second switching circuit 42 is turned off, and the third switching circuit 43 is turned on. By turning on the fourth switching circuit 44, the entire cutout portion 1 and the entire second conductor plate 3 can be operated as an antenna, and the third radiation pattern can be realized.

  On the other hand, the first switching circuit 41 is turned on, the second switching circuit 42 is turned on, the third switching circuit 43 is turned off, and the fourth switching circuit 44 is turned off. The fourth radiation pattern can be realized by operating the cutout portion from 4 to the front of the second branch and the second conductor plate 3 from the feed point 4 to the front of the second branch.

  Further, in the present embodiment, the description has been given on the case of two branches, but the same can be applied to the case of three branches. In this case, by increasing the number of switching circuits, it is possible to realize three or more types of radiation patterns, and at this time, it has an excellent feature that the impedance of the antenna does not change.

(Other embodiments)
In the first and second embodiments, the method of realizing a plurality of self-complementary antennas by placing switching circuits equidistant from the feeding point 4 has been described. However, when the self-complementary antenna is mounted on a small portable wireless device, the vicinity of the antenna may be held by hand. When the antenna portion is covered with a hand, the apparent wavelength of the current flowing through the antenna or the magnetic current changes, and the resonance frequency changes. In particular, when the hand is close to the first conductor plate 2 and the hand is not close to the second conductor plate 3, the cutout portion 1 minute of the first conductor plate 2 and the second conductor plate 3 In some cases, the wavelength may be different.

In such a case, as shown in FIG. 15, a plurality of switching circuits may be used to adjust the locations where the short circuit or the open circuit is made between the first conductor plate 2 and the second conductor plate 3, respectively. it can. At this time, although it does not physically have a self-complementary antenna structure, it becomes a self-complementary antenna from an electrical point of view, and a certain input impedance characteristic can be obtained.

  In particular, in the case of a mobile phone, there is a possibility that the antenna portion is always held by hand, and such a method is considered to be effective.

  In addition, since a certain input impedance characteristic and high radiation efficiency characteristic can be realized at a plurality of frequencies, it can also be used as an antenna of a device other than a wireless terminal performing wireless communication. For example, it can be used for an antenna for a radio wave monitoring device. In radio wave monitoring, radio waves of multiple frequencies may be monitored, and it is necessary to detect weak radio waves. Therefore, the input impedance is constant at the multiple frequencies of this embodiment, and high radiation efficiency characteristics are also achieved. It is effective to use an antenna.

  Further, the antenna of this embodiment can be applied to an apparatus using a plurality of antennas such as an adaptive antenna, a smart antenna, a phased array antenna, and MIMO (Multiple Input Multiple Output). When using a plurality of antennas, inter-antenna coupling may occur, and the resonance frequency of the antenna may change. However, if the self-complementary antenna according to the present embodiment is used, there is a problem that the resonance frequency is changed because the input impedance of the antenna is constant with respect to the frequency. In addition, there is a feature that can realize high radiation efficiency in a plurality of frequency bands. In addition, when using a plurality of antennas, it may be necessary to reduce the size of the antenna for the convenience of installation space. In the self-complementary antenna of this embodiment, since the degree of freedom of the antenna shape is large, it is possible to easily downsize the antenna shape without changing the antenna characteristics when the element spacing must be made extremely small. Can do.

The top view of the self-complementary antenna apparatus which concerns on 1st Embodiment of this embodiment. The equivalent diagram at the time of turning on the 1st switching circuit 41 and turning off the 2nd switching circuit 42. FIG. The equivalent diagram at the time of turning off the 1st switching circuit 41 and turning on the 2nd switching circuit 42. FIG. The figure which shows the result which represented the frequency characteristic of the input impedance on the Smith chart. The figure which shows the frequency characteristic of radiation efficiency. The top view of the antenna device which provided the L-shaped notch part 1. FIG. The figure which shows the example which used the coaxial line for the feed line. The figure which shows the example which used the microstrip line for the feed line. The figure which shows the example of arrangement | positioning of a resistive element. The circuit diagram which shows an example of the detailed structure of a 1st switching circuit. The circuit diagram which shows an example of the detailed structure of a 2nd switching circuit. The top view of the self-complementary antenna which concerns on 2nd Embodiment of this embodiment. FIG. 6 is an equivalent diagram when the first switching circuit is turned off, the second switching circuit is turned on, the third switching circuit 43 is turned on, and the fourth switching circuit 44 is turned off. FIG. 6 is an equivalent diagram when the first switching circuit is turned on, the second switching circuit is turned off, the third switching circuit 43 is turned off, and the fourth switching circuit 44 is turned on. The top view of the antenna device which provided the some switching circuit and enabled it to control the switching position of these switching circuits arbitrarily.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Notch part 2 1st conductor board 3 2nd conductor board 4 Feeding point 5 Resistance element 6 1st switching circuit 11 1st conductor part 12 2nd conductor part 13 2nd switching circuit

Claims (5)

A first conductor plate having a notch of a predetermined shape;
A second conductor plate that is spaced apart from the first conductor plate and is positioned in line symmetry with the notch, substantially the same shape and size as the notch,
A feeding point that is disposed adjacent to the notch and the second conductor plate and feeds power to the first and second conductor plates;
A resistance element connected between the first and second conductor plates;
A first switching circuit capable of short-circuiting or opening two opposing sides of the notch at least at one location;
The second conductor plate is
First and second conductor portions arranged in close proximity to each other;
The distance from the feeding point substantially equal to said first switching circuit, have a, a second switching circuit that can be short or open at least one location the first and second conductor portions,
The notch has a shape having two or more branches,
The first switching circuit has a plurality of first switching units capable of short-circuiting or opening two opposing sides for each of the two or more branch portions,
The second conductor plate has a plurality of branch portions that are substantially the same shape and the same size as each of the branch portions of the notch, and are arranged in close proximity to each other.
The second switching circuit is disposed at a position where the distance from the feeding point is substantially equal to the plurality of first switching units, and a plurality of second switching units capable of short-circuiting or opening two different branch units. self-complementary antenna apparatus characterized by having a.   The self-complementary antenna apparatus according to claim 1, wherein the resistance element is 60π ohm.   By switching control of the first and second switching circuits, the first conductor portion resonates at a frequency that is an integral multiple of a quarter wavelength, or the first and second conductor portions are The self-complementary antenna device according to claim 1 or 2, wherein the combined length resonates at a frequency that is an integral multiple of a quarter wavelength.   The self-complementary antenna device according to any one of claims 1 to 3, wherein the notch and the second conductor plate are bent or curved at at least one place.   5. The self-complementary antenna according to claim 1, further comprising: a coaxial line or a microstrip line that is disposed on the first and second conductive plates and feeds power to the feeding point. 6. apparatus.

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