JP4534948B2 - Array antenna - Google Patents

Description

The present invention relates to an array antenna (leakage wave antenna) having a strip line formed by periodically and repeatedly arranging a predetermined unit pattern made of a conductor on the front side of a dielectric substrate having a ground plate on the back surface. In particular, the present invention relates to an antenna having controllable directivity.
The present invention is useful for radars and communication devices that transmit or receive electromagnetic waves in the millimeter wave band or microwave band, and is very useful for reducing the size of antennas or the space required for installation.

  A configuration example of a conventional strip array antenna (leakage wave antenna) having a CRLH (Composite Right and Left Handed) transmission line on a dielectric substrate is illustrated in FIG. The CRLH line is provided with a gap that periodically divides the transmission line (main line in the X-axis direction), a stub branched from the transmission line, and the like. In this antenna, the direction of the group velocity and the phase velocity of transmitted electromagnetic waves can be opposite to each other in a certain frequency band by the action of the capacitance provided by the gap and the inductance provided by the stub. As a result, the frequency of the transmitted electromagnetic wave can be changed, so that the direction of the electromagnetic wave propagates on the main line is inclined from the positive z-axis direction to the negative x-axis direction in the figure. Electromagnetic waves can be emitted even in the angle region where θ <0. As a result, when the direction of the radiation beam is changed, the scanning range of the radiation beam can be widened. Such a principle that the phase velocity and the group velocity are opposite to each other is disclosed in detail in, for example, Non-Patent Document 1 below. However, in the prior art, unless the frequency is changed greatly, it is difficult to give the radiation beam directivity in the direction inclined in the angle region where θ <0 as described above.

  Non-Patent Document 2 below discloses a control method for variably controlling the radiation angle of a radiation beam based on predetermined electronic control while fixing the frequency of an electromagnetic wave input from a feeding point to a constant value. . In this radiation angle control system, for example, the varactor diodes are arranged close to the individual gaps and stubs of the wiring pattern shown in FIG. 11 and the capacitance of each varactor diode is variably controlled to radiate the radiation beam. Is variably controlled.

  Patent Document 1 below discloses a beam scanning antenna using a reflector having an EBG structure (Electrical Band Gap structure) in which a metal patch 1 having a via in the center is periodically arranged on a dielectric substrate (FIG. 12-). A, -B) has been proposed. This beam scanning antenna changes the capacitance between the metal patches (1, 2) of the reflector to change the traveling direction of the reflected wave of the electromagnetic wave incident on the reflector from a predetermined direction, that is, the direction of reflection. The capacitance between the metal patches (1, 2) is variably controlled by moving the movable plate 3 to which the metal patch 2 is attached in the horizontal direction.

  In addition, as another control method, for example, the dielectric constant of the material through which the electromagnetic wave propagates is variably controlled by electrically controlling the permeability of the material using ferrite or the like. There is a method for variably controlling the above. That is, as such a control method, for example, the dielectric constant of the dielectric substrate constituting the target antenna is variably controlled by voltage, and thereby the radiation angle of the radiation beam of the array antenna is variably controlled to a desired angle. A control method can be considered. Examples of such a dielectric substrate material whose dielectric constant is variably controlled include liquid crystal and ferroelectric.

In the field of electromagnetic wave sensing or wireless communication, it is desirable to control the directivity of the radiation beam of the antenna without changing the frequency of the radiated electromagnetic wave.
Tatsuo Ito and two others, 'CHARACTERISTICS AND APPLICATIONS OF PLANAR NEGATIVE REFRACTIVE INDEX MEDIA', MWE2003, WS02-03 Tatsuo Ito and two others, 'Electronically-Controlled Metamaterial-Based Transmission Line as a Continuous-Scanning Leaky-Wave Antenna', 2004 IEEE MTT-S Digest TU1D-4. US Patent: US 6,552,696 B1

  However, the conventional array antenna described in Non-Patent Document 1 cannot variably control the radiation angle of the radiation beam of the antenna while keeping the frequency of the electromagnetic wave input from the feeding point constant. For this reason, an antenna that employs this method is not suitable for an antenna that emits or receives electromagnetic waves of a certain frequency, such as a millimeter wave radar.

In the conventional array antenna described in Non-Patent Document 2, a varactor diode is used as a variable capacitor. However, since a varactor diode generally has a large transmission loss, a varactor is used in a frequency band of several GHz or more. It is difficult to operate the diode as a desired variable capacitor. For this reason, this prior art cannot be used for an array antenna that handles electromagnetic waves in a frequency band of several GHz or more.
Further, even in a frequency band of 1 GHz or less in which the radiation angle can be variably controlled, it is not always easy to ensure a sufficiently large capacity displacement ratio (change rate) with respect to a standard capacity (predetermined reference capacity) in a varactor diode. Therefore, it is not always easy to ensure a large variation range of the radiation angle.

Further, the conventional beam scanning antenna (FIGS. 12A and 12B) described in Patent Document 1 has the following problems relating to productivity, controllability, downsizing and thinning.
(1) As shown in FIGS. 12A and 12B, a beam scanning antenna is configured using a reflector having an EBG structure. Therefore, another feeding antenna for irradiating the reflector with electromagnetic waves is separately provided. It is necessary to prepare.
(2) Although the directivity of the radiation beam of the antenna can be variably controlled by moving the movable plate 3 in the horizontal direction, each metal patch has strong theoretical and physical restrictions on the periodic positional relationship. Therefore, the position of each metal patch cannot be controlled independently. For this reason, it is impossible to introduce a beam shaping technique such as variably controlling the beam width and beam pattern to the conventional beam scanning antenna.

  Further, as described above, the dielectric constant or permeability of the dielectric substrate constituting the target antenna is variably controlled by an actively controlled electric field or magnetic field, whereby the radiation angle of the array antenna radiation beam is controlled. A control method that can be variably controlled to a desired angle can be considered, but when using a material such as a ferroelectric or ferrite whose dielectric constant changes, the power loss of the electromagnetic wave propagating through the antenna is very large. Therefore, it is difficult to ensure a large antenna gain.

The present invention has been made to solve the above-described problems, and its purpose is to provide a beam directivity scanning range that can be used in a high frequency band of 1 GHz or higher without changing the frequency. This is to realize a wide and small array antenna. A further object of the present invention is to provide these small array antennas with at least one of the following functions.
(Function 1) Function to freely change the beam width of the antenna (Function 2) Function to suppress the amount of radiation of unnecessary side lobes (Function 3) Function to form a null in a desired direction

  However, the individual objects described above may be achieved individually by at least one of the individual means of the present invention, and therefore the individual invention of the present application (the individual means described below) is not necessarily All of the above-mentioned problems may not be solved simultaneously.

In order to solve the above problems, the following means are effective.
That is, the first means of the present invention comprises a dielectric substrate, a strip line formed by arranging a plurality of identical or similar unit patterns made of conductors in a predetermined direction on the front side of the dielectric substrate, and a dielectric In an array antenna having a ground plate made of a conductor formed on the back surface of a substrate, each unit pattern has a transmission line, a gap that divides the transmission line in the middle, and a stub that branches off from the transmission line. It is a pattern that becomes a left-handed system at the frequency, and is disposed in proximity to each gap of each unit pattern, and is composed of a dielectric, a magnetic material, a metal conductor, or a composite thereof, position, orientation, size, or shape can variably controlled, the capacitance of each gap, until the unit pattern is a non-operating state as an antenna, respectively, independently, vary Each of the first variable control members that can be arranged, and the positions, orientations, and sizes of the first and second variable control members that are disposed in proximity to the stubs of the unit patterns and that are composed of a dielectric material, a magnetic material, a metal conductor, or a composite thereof. Each of the second variable control members can be controlled in a variable manner, and the inductance of each stub can be changed independently until each unit pattern is inoperative as an antenna, position of the acts mechanically to the variable control member each variable control member, orientation, size, or shape, respectively, and each of the first actuator to vary independently, in each second variable control member A second actuator that mechanically acts on each variable control member to independently change the position, orientation, size, or shape of each variable control member, and each first actuator. And each of the second actuator, each independently, a array antenna, characterized in that a control means for applying a voltage.

Array antenna of the present invention may be a single line antenna strip line may be a planar antenna comprising a plurality of strip lines. The directivity in the direction perpendicular to the strip line on the dielectric substrate surface can be controlled by controlling the phase of power supplied to each strip line. The stubs may be on only one side of the strip line, on both sides at the same position, or the side provided along the traveling direction may be alternately reversed. The stub is usually provided at a right angle to the strip line, but the angle is arbitrary. The opposing portions of the strip line constituting the gap may be widened in order to increase the capacitance.

  In addition, when the variable control member is composed of a composite of a dielectric and a metal conductor or a composite of a magnetic and a metal conductor, a metal conductor is provided on the surface of the dielectric or magnetic body. Alternatively, a metal conductor may be provided inside the dielectric or magnetic material. Further, the variable control member and the actuator may be provided inside the dielectric substrate, or may be provided above the dielectric substrate, that is, above the strip line. Further, a thin film may be provided between the variable control member and the material constituting the strip line or the dielectric substrate to facilitate movement.

This onset Ming, by variably controlling the position or attitude of the variable control member, and realizes desired functions 1-3 above.

According to a second means of the present invention, in the first means, the control means continues from the end of the array antenna until each of the first actuators and the respective actuators are inactivated with a predetermined number of unit patterns as antennas. By controlling the second actuator, the effective length of the array antenna is variably controlled.
However, the effective length is the length of the portion of the array of unit patterns constituting the antenna that actually acts effectively as an antenna. This length is the length of each unit pattern. It can be determined based on each radiation amount.
According to a third means of the present invention, in the first means, when the control means divides the plurality of unit patterns into two groups of the first group and the second group, the unit patterns belonging to the first group Applies a voltage to each of the first actuators and each of the second actuators so that the unit patterns belonging to the second group are operated in a right-handed system so as to suppress the level of side lobes in the array antenna. It is characterized as a means.
That is, the side lobe level of the antenna can be suppressed by controlling the distribution to an appropriate distribution that exhibits a side lobe suppressing action such as the well-known Taylor distribution.

According to a fourth means of the present invention, in the first means, when the control means divides the plurality of unit patterns into two groups of the first group and the second group, the unit patterns belonging to the first group Applies a voltage to each of the first actuators and each of the second actuators so that the unit pattern belonging to the second group operates in a right-handed system so that the unit pattern belonging to the second group operates in the right-handed system. It is characterized by being means for variably controlling.

  However, for example, when controlling the directivity of unit patterns in two different directions, each unit pattern belonging to a set of unit patterns to be radiated in one direction is not necessarily continuous on the unit pattern array. There is no need to arrange them together. That is, unit patterns that give different directivities may be arranged alternately, or a set of unit patterns that radiate in one direction may be combined into a continuous set on the array. The plurality of directions may be three directions or four or more directions.

According to a fifth means of the present invention, in any one of the first to fourth means, the variable follow-up mechanism that is displaced or deformed in accordance with the displacement or deformation of the actuator includes the variable control member and the actuator. The position of the variable control member is indirectly controlled by the actuator via the variable follow-up mechanism.

According to a sixth means of the present invention, in the fifth means described above, the variable follow-up mechanism acts on a fulcrum that is a fixed point, a power point that receives a driving force from an actuator, and a variable control member. And an action point.

Further, the variable control member may be disposed on the dielectric substrate.
By the above means of the present invention, the above-mentioned problem can be effectively or rationally solved.

  The effects obtained by the above-described means of the present invention are as follows.

According to any one of the first to fourth means of the present invention, the above-described variable control member is mechanically moved to change the equivalent dielectric constant in the vicinity of the gap or stub, The electrical length of the inductor provided by the stub can be changed. That is, the gap capacitance and the stub inductance can be changed by mechanically moving the variable control member. For this reason, the intensity | strength, phase distribution, etc. of the electromagnetic waves radiated | emitted from an array antenna can be freely controlled. Accordingly, at least one of the functions 1 to 3 described above can be realized based on the control of the position and orientation of the variable control member.

In addition, according to any one of the first to fourth means of the present invention, the directivity of the radiation beam can be variably controlled based on the minute displacement of each variable control member, so that the orientation of the entire array antenna can be controlled by the machine. Therefore, a desired array antenna can be formed more compactly than in the case where the directivity is variably controlled by changing the directivity.

In particular, according to the second aspect of the present invention, by using an actuator on reporting, since the capacitance component and inductance component of the stub of the gap can be variably controlled, thereby, the predetermined portion of the unit pattern The frequency can be controlled to be inactive. In this case, since the band gap can be formed by the unit patterns in the non-operating state, the effective length of the array antenna can be variably controlled by this action. At that time, the shorter the effective length of the array antenna, the wider the beam width of the array antenna. Therefore, according to the second means of the present invention, it becomes possible to variably control the beam width of the antenna. .

According to the third aspect of the present invention, by using an actuator on reporting, the distribution of each radiation amount of the unit patterns, such as such as well-known Taylor distribution, suitable to achieve the sidelobe suppression effect Therefore, the amount of radiation of the side lobes of the array antenna can be suppressed to be small.

According to the fourth aspect of the present invention, by using an actuator on reporting, by controlling the respective directivity plurality of different orientations of the unit pattern, a null in a direction deviated from their orientation forming can do. Therefore, according to the fourth means of the present invention, it is possible to form a null in a desired direction, thereby reducing reception of a signal from an arbitrary direction.
For example, when nulls are to be formed in the front direction of the antenna, the beam direction of half of the unit pattern is directed toward the backward wave (ie, the direction of the left-handed beam) and the remaining half of the unit pattern The pattern beam may be directed toward the forward wave (ie, the direction of the right-handed beam). Thereby, reception of the signal from the front direction can be reduced.

Further, according to the fifth means of the present invention, the direction of the displacement of the actuator is changed to a desired direction, the magnitude of the displacement of the actuator is enlarged or reduced by the above-described variable follow-up mechanism (compliance mechanism). Alternatively, the correspondence between the actuator and the variable control member can be set to one-to-many correspondence.

For example, the configuration in which the magnitude of the displacement of the actuator is enlarged is effective when it is difficult to obtain a large displacement of the actuator. In addition, when the displacement amount of the actuator can be obtained sufficiently large but the displacement accuracy of the actuator is difficult to obtain, it is effective to adopt a configuration that reduces the displacement of the actuator.
Further, in order to obtain such an enlargement action or reduction action, for example, the above-described sixth means of the present invention may be employed. That is, the sixth means of the present invention has an effect of changing the magnitude of the displacement of the actuator by a constant multiple. The sixth means of the present invention can also provide an action of arbitrarily changing the direction and direction of displacement of the actuator and the position of the action point.

Further, according to the seventh means of the present invention, there is no need to embed an actuator in the dielectric substrate, and therefore the array antenna of the present invention can be manufactured relatively easily.

  As for the above unit patterns, which are constituent elements of the strip line, it is more desirable in terms of design easiness to arrange them periodically using the same pattern, but it is necessary to use only the same pattern. There is no need to arrange them periodically. Therefore, for example, the above unit pattern that is a constituent element of the strip line may not have the same dimensions such as the thickness and the length of each part such as the transmission line and the stub, and the gap and the like may not be uniform. good.

  Moreover, as a material of said variable control member, a material with a large dielectric constant is desirable, for example, ceramics, such as an alumina, are useful. In addition, as the dielectric substrate, a material having a small relative dielectric constant such as tetrafluoroethylene resin is desirable. The larger the relative dielectric constant difference between the two dielectrics, the more easily the capacitance provided by the gap and the inductance provided by the stub change, and as a result, a larger beam for a given amount of movement of the variable control member. A direction swing width can be obtained.

  The actuator material is preferably one that can be directly electronically controlled. For example, a piezoelectric element can be used. The material constituting the variable follow-up mechanism (compliance mechanism) may be arbitrary. However, for example, when a resin such as polyethylene is used, a desired operation can be easily or effectively realized in many cases.

In addition, the frequency of the electromagnetic wave radiated or received by the array antenna of each example illustrated below is assumed to be a substantially fixed frequency in the range of 10 GHz to 300 GHz (millimeter wave band and quasi-millimeter wave band). Of course, the pattern formation period when the unit pattern is repeatedly formed in the x-axis direction may be determined according to the frequency as in the conventional case. However, the operations and effects that can be obtained by the present invention are not necessarily limited to the array antenna that handles electromagnetic waves in the above frequency band.
The array antennas of the embodiments illustrated below are designed assuming a scanning frequency of about several times per second over the entire scanning range (all scanning angles θ). Of course, the frequency may be arbitrarily set as required.

Hereinafter, the present invention will be described based on specific examples.
However, the embodiments of the present invention are not limited to the following examples.

  FIG. 1 is a plan view of the array antenna 10 of the first embodiment. On the front side of the dielectric substrate 15 made of tetrafluoroethylene resin, predetermined unit patterns constituting a conductor wiring pattern are periodically arranged in the x-axis direction for 16 periods. It comprises a main line 11 (transmission line) running in the x-axis direction and a stub 12 branched from the main line 11 in the y-axis direction. On the dielectric substrate 15 having this wiring pattern, a variable control member 13 and a variable control member 14 each made of ceramics (alumina) having a relative dielectric constant of 10 are periodically arranged corresponding to each unit pattern. These are connected to the actuators 17 'and 17 via the compliance mechanisms 18' and 18 (variable follow-up mechanism) formed of a resin (eg, polyethylene) that operates in the y-axis direction, respectively. Has been. Each actuator 17 ', 17 can be comprised from well-known piezoelectric materials, such as piezoelectric ceramics, for example.

FIG. 2 is a plan view of the wiring pattern constituting the strip line of the array antenna 10. Reference numerals p ₁ and p ₂ denote a feeding point and a termination point of the antenna, respectively. Each unit pattern U has a gap G1 composed of a narrow gap formed by the facing part 11a and the facing part 11b whose longitudinal direction coincides with the y-axis direction. By this gap G1, the main line 11 is periodic. It is divided into two. The end portion of the stub 12 is formed to be slightly thicker than the branch portion in the middle of branching from the main line 11 in the y-axis direction.
The gap G1 functions as a capacitor, and the stub 12 functions as an inductor.

FIG. 3 is a cross-sectional view of the array antenna 10 taken along the line AA ′. However, in this cross-sectional view, the voltage variable control circuit C and the lead electrode L are additionally written. A ground plate 16 (FIG. 3) made of a conductor is provided on the entire back surface of the dielectric substrate 15. Electrodes 17a and 17b made of a metal film are formed on both the front and back surfaces of the piezoelectric material 17c constituting the main body portion of the actuator 17, and the electrode 17a has a lead electrode L formed on the front side of the dielectric substrate 15. To the anode side of the battery E. The electrode 17b is connected to the cathode side of the battery E via the variable resistor R _v. That is, the voltage variable control circuit C is configured by connecting the battery E and the variable resistor _Rv in series.

Further, the variable resistor R _v, using the IC chip, it is possible to digital electronic control of the computer (CPU) is configured to facilitate construction. In the first embodiment, the voltage variable control circuit C corresponds to the effective length variable control means in the first means of the present invention, and such a variable resistor _Rv is provided for each actuator 17 '. , 17 for each one. However, it goes without saying that one battery E can be shared by each variable resistor R _v .
Based on the voltage variable action by the variable resistor R _v and the piezoelectric action of the actuator 17, the position (y-axis coordinate) of each variable control member (13, 14) is appropriately variably controlled.

  FIG. 4 illustrates the operation of the array antenna 10 described above. Due to the variable control of the voltage variable control circuit C, in each unit pattern U in the left half of FIG. 4, the positions of the variable control members 14 are each moved in the positive direction of the y axis by D (= 0.8 mm). ing. As a result, the stub 12 is completely covered with the variable control member 14 including the branch portion in the middle. Similarly, in each unit pattern U in the left half of FIG. 4, each variable control member 13 is similarly driven by each actuator 17 ′ and moved by kD in the negative direction of the y-axis. . Here, k is an appropriate proportionality constant. The gap G1 of each unit pattern U is completely covered with the variable control member 13. These controls can be performed individually for each variable control member (13, 14).

  By performing such an operation, each unit pattern U in which the stub 12 and the gap G1 are covered with a dielectric (variable control members 13 and 14) does not operate as a minute antenna. For this reason, a band gap is formed in the left half of the antenna. As a result, the effective length of the array antenna 10 is substantially halved.

FIG. 5 illustrates the beam shape (azimuth-gain characteristic) of the array antenna 10. Each graph of the beam shape schematically shows the result of verification by simulation with the operating frequency f being 76 GHz for each of the following cases a to c.
(A) In the state of FIG. 1 in which the number of minute antennas (unit pattern U) to be deactivated by the above operation is zero (b) Minute antennas to be deactivated by the above operation ( In the state of FIG. 4 in which only eight unit patterns U) are provided from the end point p ₂ side. (C) A minute antenna (unit pattern U) that is disabled by the above operation is provided on the end point p ₂ side. When only 12 are provided

From the result of FIG. 5, D = 0.0 mm, that is, the above-described operation of covering the stub 12 and the gap G1 with the dielectric (variable control members 13 and 14) was not performed, and it was close to the feeding point p ₁ . The effective length of the array antenna 10 is approximately proportional to the number of unit patterns U, and the beam width of the array antenna 10 is monotonous with respect to the number of unit patterns U near the feed points (effective length of the array antenna 10). It can be seen that the number decreases. For example, in the case of (b) above, the beam width (half-value angle) is expanded by about 1.4 times compared to the case of (a) above.
Thus, by variably controlling the number of unit patterns U with D = 0.0 mm, the beam width of the antenna can be variably controlled.

FIG. 6A is a graph illustrating the beam shape of the array antenna 10 in the case of (a) above. FIG. 6B is a graph illustrating the beam shape of the array antenna 10 in the case of (b). However, the angle θ (Theta; degree) on the horizontal axis of these graphs is the same as FIG. 11, and the direction from the positive z-axis direction to the positive x-axis direction is a positive direction.
In each of these graphs, f0 = 76 GHz, and simulation was performed for two cases of f = f0 and f = 1.04 × f0. From this result, in both cases (a) and (b), the azimuth angle of the highest sensitivity peak of the radiation beam of the antenna can be obtained by simply changing the operating frequency f to about 4%. It was found that the left and right can be controlled greatly.

6A and 6B, the antenna operating frequency f is variably controlled by about 4% while the beam width is variably controlled to an arbitrary width based on the effective length variable control means of the present invention. The directivity of the entire array antenna is controlled by this, but by placing an arbitrary number of unit patterns in a substantially non-operating state with weak excitation state, for example, on the termination point side, that is, for example, the non-measurement measured from the termination point. Since the effective length variable control means of the present invention can be realized by arbitrarily setting the length of the operation portion, this effective length variable control can be achieved even when the operating frequency f of the array antenna is kept constant. Variable voltage directivity control means capable of operating simultaneously in parallel with the voltage control means, for example, the voltage variable action of the voltage variable control circuit C or the like (ie, dielectric constant variable control means based on an actuator) It can be configured based on.
A means for variably controlling the directivity of the entire array antenna while keeping the operating frequency f of the array antenna constant will be exemplified in Example 3 described later.

  In the array antenna of the second embodiment, the relative dielectric constants of the variable control members 13 and 14 of the array antenna 10 are changed from 10 to 4.5, respectively, and other device configurations are the same as those of the first embodiment. This is the same as the array antenna 10 (FIGS. 1 to 4). FIG. 7 is a graph illustrating the beam shape of the array antenna of the second embodiment obtained by improving the array antenna 10 described above. Here, a simulation was performed in which f = f0 (= 76 GHz) was fixed and the case of (a) and the case of (b) were compared. A dielectric (variable control member) having a relative dielectric constant of 4.5 can be configured using, for example, a synthetic material of tetrafluoroethylene resin and ceramics.

For the eight unit patterns U on the power supply side, the beam is directed to the backward side, and for the eight unit patterns U on the termination side, the beam is directed to the forward side. Could be formed. The peak gain hardly changed between the cases (a) and (b).
Note that the orientation of the null formed in this way can be freely variably controlled by changing the displacement D described above. Therefore, in this case, the voltage variable control circuit C can be considered to correspond to the null forming means in the above-described third means of the present invention.

  Further, in the graph relating to f = f0 in FIG. 6B of the first embodiment, the beam width is enlarged as described above, and at the same time, a slightly weak null is formed in the vicinity of −5 °. It can be regarded as. Therefore, the effective length variable control means and the null forming means of the present invention can be considered as means that can be realized simultaneously by the voltage variable control circuit C or the like, for example.

  8A and 8B are plan views of the unit pattern 20 according to the third embodiment (before / after movement of the dielectric). Even when the unit pattern 20 having such a structure is employed, a strip array antenna having the variable control member of the present invention can be configured as in the above-described embodiment. A wiring pattern on the front side of the dielectric substrate 25 of the unit pattern 20 is formed of main lines 21 a and 21 b and a stub 22. The opposing portions of the main lines 21a and 21b that face each other across the gap G2 have wide portions 211a and 211b that are expanded in a T-shape that is inclined sideways. As a result, the width of the capacitor in the y-axis direction is set wide, so that the capacitance can be increased. Further, the stub 22 has a wide portion 211 that is expanded in the x-axis direction in the vicinity of the tip portion thereof. By extending these widths, the capacitance provided by the gap G2, the inductance provided by the stub 22, or the fluctuation range thereof is effectively expanded.

  Also in the third embodiment, the actuators (27, 27 '), the variable follow-up mechanisms (28, 28'), the above-described dielectrics 23, 24, and the like are arranged in the inner region (thickness) of the dielectric substrate 25. ing. The variable follow-up mechanism 28 (compliance mechanism) is formed in a Z-shape that falls sideways, and is a position displaced toward the actuator (27, 27 ') side by a predetermined distance with respect to the midpoint of the length in the x-axis direction. The fulcrum 29, which is a fixed point, is fixed to the ground conductor. Since the variable follow-up mechanism 28 is made of resin (eg, polyethylene), the bending angle can be changed flexibly at each Z-shaped bending point. The actuator 27 formed of a piezoelectric element expands and contracts in the y-axis direction based on a voltage applied from an unillustrated electrode. Hereinafter, the junction point between the actuator 27 and the variable follow-up mechanism 28 is referred to as a force point, and the junction point between the dielectric 23 and the variable follow-up mechanism 28 is referred to as an action point.

The state diagram of FIG. 8B shows a state in which the actuator 27 pushes the variable follow-up mechanism 28 downward (in the negative direction of the y-axis) at the above-described force point with respect to the state of FIG. As a result of this operation, the variable follow-up mechanism 28 rotates around the fulcrum 29, so that the action point moves upward (positive direction of the y-axis), and accordingly, the dielectric 23 also translates upward. . In this unit pattern 20, the distance between the action point and the fulcrum is longer than the distance between the force point and the fulcrum. The moving amount of the body 23 is long. That is, by setting the relationship among the three points of the force point, the fulcrum, and the action point as described above, the variable follow-up mechanism 28 is provided with an amplifying function for amplifying the operation of the actuator 27.
Further, these operations and amplification functions are also realized in the variable follow-up mechanism 28 '.

  FIG. 9 shows an effect (simulation result) when the unit pattern 20 is adopted. This simulation was performed based on the well-known transmission line theory. In this simulation, the metamaterial structure using the unit pattern 20 described above, that is, the unit pattern 20 is arranged in a row in the x-axis direction. The verification was performed on an array antenna prepared by repeating × 16 times periodically. In addition, the constant k in this figure is 1.

  From this simulation result (FIG. 9), by driving the actuators 27 and 27 ′ based on the control of the voltage applied to the actuators 27 and 27 ′, the variable control members (dielectrics 23 and 24) are moved from 0 μm to 45 μm. It can be seen that the beam can be scanned from the negative side of the x-axis to the positive side with an amplitude of about 60 ° in the strip array antenna in which the unit patterns 20 are repeatedly formed in one row × 16 times by moving within the range.

From these results, if such beam directivity control is applied independently for each unit pattern, the beam directions of each unit pattern are grouped into a plurality of sets in substantially the same manner as in the second embodiment. This also shows that the null forming means in the third means of the present invention can be configured.
That is, for example, in an array antenna having the above-described configuration in which unit patterns 20 are provided for 16 periods, the value of displacement D in the eight unit patterns on the right side (feeding point side) is set to 0 μm, and the remaining half eight unit patterns. If the value of the displacement D at 45 is 45 μm, a null can be formed in the front direction (z-axis direction) even by such directivity control. That is, such directivity control can also be used as the null forming means of the present invention.

  Further, according to each of the embodiments described above, the directivity variable control means that fixes the operating frequency f, the effective length variable control means of the present invention, and the null forming means of the present invention include, for example, the voltage variable control circuit described above. It can be seen that the same configuration can be made simultaneously using C or the like. Each of these means (directivity variable control means, effective length variable control means, and null forming means) can be simultaneously and effectively operated on one array antenna according to the present invention.

10A and 10B are plan views of the unit pattern U ′ of the array antenna according to the fourth embodiment. The unit patterns U ′ constitute an array antenna by being periodically arranged in the x-axis direction as in the case of the unit patterns U described above.
In this unit pattern U ′, the variable control members 23 and 24 are made of an artificial dielectric formed by mixing metal particles inside the dielectric, and the variable control member 23 is under a gap that divides the main line. The variable control members 24 are respectively disposed under the stubs branched at right angles from the main line. The variable control member 23 is sandwiched between piezo elements 27 'and 27' in the y-axis direction. The variable control member 24 is sandwiched between piezoelectric elements 27 and 27 in the x-axis direction. Furthermore, each piezo element is sandwiched between two electrodes 29 arranged in two, and by controlling the potential of each of these electrodes, the piezo elements 27 'and 27' are moved in the y-axis direction. 27 and 27 can be freely expanded and contracted in the x-axis direction.

When the volume of the artificial dielectric is changed, the density of the mixed metal particles is changed, so that the dielectric constant of the variable control member is largely changed. Therefore, when the piezoelectric elements 27 ', 27', 27, 27 are deformed by the above-described potential control and the variable control members 23, 24 are compressed in each direction as shown in FIG. The dielectric constant of the control member can be variably controlled.
Also, by configuring such a variable control mechanism, the effective length variable control means, side lobe level suppressing means, null forming means, etc. of the present invention that provide substantially the same operation and effect as the above embodiments are configured. can do.

[Other variations]
The embodiment of the present invention is not limited to the above-described embodiment, and other modifications as exemplified below may be made. Even with such modifications and applications, the effects of the present invention can be obtained based on the functions of the present invention.

(Modification 1)
For example, the voltage variable control circuit C (FIG. 3) can be operated as a side lobe level suppressing means in the second means of the present invention described above. For that purpose, the distribution of each radiation amount of the unit pattern in the antenna may be controlled to the Taylor distribution using the actuator (17, 17 ′ or 27, 27 ′). If such a control means is used to control the radiation amount distribution of the unit pattern to, for example, a well-known Taylor distribution, the radiation amount of the side lobe of the array antenna can be further suppressed. it can.

(Modification 2)
In each of the above embodiments, the dielectric is moved as the variable control member. However, a metal piece may be placed inside these dielectrics. In this case, it is possible to control not only the dielectric constant but also the electrical length of the gap and the stub at the same time, so that the change of the beam angle θ with respect to the movement of the dielectric becomes sensitive. Therefore, by making such a modification, it is possible to secure a wider range of change in the beam direction or to further reduce the size of the actuator.

(Modification 3)
In the above embodiment, the variable control member is translated, but the movement of the variable control member may be a translational reciprocating motion, a rotational motion, or a rotational motion. The gap capacitance and stub inductance can be variably controlled by any form of motion.

  The present invention is useful for wireless communication and electromagnetic wave sensing. For example, an object search for a wireless communication device, an obstacle sensor used in a vehicle accident prevention system, an auto cruise control system, or other objects around the vehicle. It can be used as a means.

Plan view of array antenna 10 of the first embodiment Plan view of wiring pattern constituting strip line of array antenna 10 Sectional view in the AA 'cross section of the array antenna 10 A plan view illustrating the operation of the array antenna 10 A graph illustrating the beam shape (azimuth-gain characteristic) of the array antenna 10 A graph illustrating the beam shape of the array antenna 10 A graph illustrating the beam shape of the array antenna 10 The graph which illustrates the beam shape of the array antenna of Example 2 Plan view of array antenna 20 of Embodiment 3 A plan view illustrating the operation of the array antenna 20 A graph illustrating the beam shape (azimuth-gain characteristic) of the array antenna 20 The top view of unit pattern U 'of the array antenna of Example 4 The top view which illustrates operation of unit pattern U 'of Example 4. Explanatory drawing explaining the characteristic of the conventional strip array antenna The top view of the other conventional beam scanning antenna. Sectional drawing of the other conventional beam scanning antenna.

10: Strip array antenna 11: Transmission line (main line)
12: Stub 13: Variable control member 14: Variable control member 15: Dielectric substrate 16: Ground plate 17: Actuator 18: Compliance mechanism (variable follow-up mechanism)
U: Unit pattern G1: Gap C: Voltage variable control circuit

Claims (6)

From a dielectric substrate, a strip line formed by arranging a plurality of identical or similar unit patterns made of conductors in a predetermined direction on the front side of the dielectric substrate, and a conductor formed on the back surface of the dielectric substrate An array antenna having a ground plate comprising:
Each unit pattern has a transmission line, a gap that divides the transmission line in the middle, and a stub that branches off from the transmission line, and is a pattern that becomes a left-handed system at a used frequency,
The position, orientation, size, or shape of each unit pattern, which is disposed in the vicinity of each gap and is composed of a dielectric, a magnetic material, a metal conductor, or a composite thereof, can be variably controlled. A respective first variable control member capable of independently changing a capacitance of each gap until each unit pattern is inoperative as an antenna;
The position, orientation, size, or shape of each unit pattern, which is disposed in proximity to each stub and is composed of a dielectric material, a magnetic material, a metal conductor, or a composite thereof, can be variably controlled. Each second variable control member capable of independently changing the inductance of each stub until each unit pattern is inoperative as an antenna;
The position of each first variable control member with respect to mechanical action to the respective variable control element, the orientation, size, or shape, respectively, and each of the first actuator to vary independently,
A second actuator that mechanically acts on each second variable control member to independently change the position, orientation, size, or shape of each variable control member;
An array antenna comprising control means for applying a voltage independently to each of the first actuators and each of the second actuators . The control means controls each of the first actuator and the second actuator continuously from an end portion of the array antenna until the predetermined number of unit patterns are used as antennas to be in an inoperative state. 2. The array antenna according to claim 1, wherein the array antenna is means for variably controlling the effective length of the array antenna. When the control unit divides the plurality of unit patterns into two groups of the first group and the second group, the unit patterns belonging to the first group operate in a left-handed system, and the unit patterns belonging to the second group Is means for suppressing the level of the side lobe in the array antenna by applying a voltage to each of the first actuators and each of the second actuators so as to operate in a right-handed system.
The array antenna according to claim 1. When the control unit divides the plurality of unit patterns into two groups of the first group and the second group, the unit patterns belonging to the first group operate in a left-handed system, and the unit patterns belonging to the second group Is means for variably controlling the direction of the directivity null in the array antenna by applying a voltage to each of the first actuators and each of the second actuators so as to operate in a right-handed system. The array antenna according to claim 1. Wherein each of the first Ohen follow-up mechanism for displacement or deformation according to the displacement or deformation of the first actuator has between said respective first variable control member said each first actuator,
Each second variable follow-up mechanism that is displaced or deformed according to the displacement or deformation of each second actuator is provided between each second variable control member and each second actuator,
Wherein each of the first variable control member, said indirectly position control via the respective first Ohen follow-up mechanism by the first actuator,
Wherein each of the second variable control member to any one of claims 1 to 4, characterized in that it is indirectly position control via the respective second Ohen follow-up mechanism by the respective second actuator The described array antenna. Wherein each first Ohen follow-up mechanism, each supporting point is a fixed point, wherein the respective power point receiving a driving force from the first actuator, the respective point of action acting on the respective first variable control member Have
Each of the second variable follow-up mechanisms includes a respective fulcrum that is a fixed point, each power point that receives a driving force from each second actuator, and each point that acts on each second variable control member. array antenna according to claim 5, characterized in that it comprises a.

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