JP5739281B2 - Antenna device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an antenna device used for, for example, a phased array antenna (phased array antenna) and a manufacturing method thereof.

  Conventionally, as a phased array antenna using a dipole element, the one shown in FIG. 11 is known. That is, in the conventional phased array antenna 1, a plurality of dipole elements 2 as radiating elements are arranged on the opening surface side of the dielectric substrate 4, and each dipole element 2 is connected to a feed element 6 such as an amplifier or a phase shifter. It has a configuration. Here, the feed element 6 is disposed on the back side of the dielectric substrate 4, and the dipole element 2 and the feed element 6 are connected by a line such as the coaxial feed line 5. Therefore, a balanced / unbalanced converter (balun) 3 for converting a propagation mode between the dipole element 2 and the coaxial feeder 5 is necessary. As a result, in the conventional phased array antenna 1, as shown in FIG. 12, the distance between the dipole element 2 and the opening surface of the dielectric substrate 4 needs to be about a quarter wavelength. There was a problem that could not be.

  In order to solve this problem, a so-called low-profile antenna has been proposed in which a balun function is provided in the radiating element so that the distance between the radiating element and the aperture surface is much narrower than about a quarter wavelength ( For example, see non-patent documents 1 and 2). The conventional low-profile antenna 7 shown in FIG. 13 includes a dielectric substrate 4, a coaxial feed line 8 provided through the dielectric substrate 4, and a linear conductor 9 joined to the coaxial feed line 8. It is equipped with. The coaxial feeder 8 has a center conductor 8a, an outer conductor 8b, and a bent portion 8c, and a linear conductor 9 is joined to the bent portion 8c. With this configuration, the conventional low-profile antenna 7 realizes the balun function by using the outer conductor 8b of the coaxial feeder 8 as a part of the radiating element.

A. Thunvichit, T. Takano and Y. Kamata, "Ultra Low Profile Dipole Antenna with a Simplified Feeding Structure and a Parasitic Element", Trans. Of Institute of Electronics, Information and Communication and Communication Engineers, vol.89-B, no .2, pp. 576-580, 2006. A. Thunvichit, T. Takano and Y. Kamata, "Characteristics Verification of a Half-wave Dipole Very Close to a Conducting Plane with Excellent Impedance Matching", IEEE Transactions on Antennas and Propagation, Vol.55, No.1, pp. 53-58, 2007.

  However, the conventional low-profile antenna has a configuration in which a coaxial feed line penetrates from the opening surface side to the back surface side of the dielectric substrate, and since a feed element cannot be provided on the opening surface side, the feed element is provided on the back surface side. It was provided. Therefore, the conventional low-position antenna requires a work from the opening surface side and a work from the back surface side, and there is a problem that the work becomes complicated and cannot cope with mass production.

  The present invention has been made in order to solve the conventional problems, and an antenna device that can be manufactured more easily than conventional devices, can cope with mass production, and can achieve a low posture, and a manufacturing method thereof. The purpose is to provide.

  The antenna device of the present invention includes a dielectric substrate, a dipole antenna element formed on one surface of the dielectric substrate and having a length in the longitudinal direction that is a half wavelength of the used radio wave, and the one of the dielectric substrates. A ground plane conductor formed on the back surface of the surface, and the dipole antenna element is a strip line provided on the one surface on one side with respect to an axis perpendicular to the longitudinal direction, A coplanar line provided on the one surface on the other side with respect to the axis, wherein the coplanar line is provided at a predetermined interval from the strip line and extends in the longitudinal direction. A conductor, and a second and third strip conductors connected to the strip line and sandwiching the first strip conductor at a predetermined interval from the first strip conductor. .

  With this configuration, the antenna device of the present invention does not need to be provided with a feed element on the back side of the dielectric substrate, and can be manufactured by work from the opening surface side. In addition to being able to cope, it is possible to achieve a low posture.

  In the antenna device of the present invention, the lengths of the second and third strip conductors in the longitudinal direction are shorter than the length of the first strip conductor, and the second and third strip conductors. The leading end of the conductor has a configuration having a rounded shape.

  With this configuration, the antenna device of the present invention can match the impedance of the antenna element and the impedance of the coaxial feeder by adjusting the lengths of the second and third strip conductors in the longitudinal direction.

  Furthermore, the antenna device of the present invention further includes an electromagnetic field shielding member that covers an upper surface of the coplanar line and the strip line and shields an electromagnetic field, and the electromagnetic field shielding member is shorter than a cutoff wavelength of the used radio wave. It has the structure which has a cross-sectional dimension.

  With this configuration, the antenna device of the present invention can shield the electromagnetic field generated by the feed element when the feed element is provided on the antenna element.

  Furthermore, the antenna device of the present invention further includes a feed element provided on the strip line, and a through hole that penetrates the dielectric substrate and the ground plane conductor from the surface of the strip line and passes the feed line. The feeder element has a configuration including a first terminal connected to the first strip conductor, a second terminal connected to the feeder line, and a ground terminal connected to the strip line. ing.

  With this configuration, the antenna device of the present invention does not need to be provided with a feeding element on the back surface side of the dielectric substrate as in the prior art, and can be manufactured by work from the opening surface side. It can be easily manufactured, can be used for mass production, and can be lowered.

  The antenna device manufacturing method of the present invention includes a step of forming the dipole antenna element on one surface of the dielectric substrate, and a through-hole penetrating the dielectric substrate and the ground plane conductor from the surface of the strip line. Forming, feeding the feeding element on the strip line, connecting the first terminal to the first strip conductor, connecting the second terminal to the feeding line, A step of connecting a ground terminal to the strip line; and a step of covering the coplanar line and the strip line by the electromagnetic field shielding member.

  With this configuration, the antenna device manufacturing method of the present invention does not need to provide a feed element on the back surface side of the dielectric substrate, and can be manufactured by work from the opening surface side, so it can be manufactured more easily than the conventional one, It can cope with mass production and can be lowered.

  The present invention can provide an antenna device that can be manufactured more easily than conventional ones, can cope with mass production, and can be lowered in posture, and a method for manufacturing the antenna device.

It is a block diagram in one Embodiment of the antenna device which concerns on this invention. It is explanatory drawing of the coplanar track | line in one Embodiment of the antenna apparatus which concerns on this invention. It is explanatory drawing of the electric current which flows into the antenna element in one Embodiment of the antenna apparatus which concerns on this invention. It is a figure which shows the modification of the outer side strip | belt-shaped conductor front-end | tip part in one Embodiment of the antenna apparatus which concerns on this invention. It is a figure which shows the structural example of the electromagnetic field shielding member in one Embodiment of the antenna apparatus which concerns on this invention. It is explanatory drawing of the manufacturing method in one Embodiment of the antenna device which concerns on this invention. In one Embodiment of the antenna device which concerns on this invention, it is a figure which shows the simulation model of the antenna device analyzed with the simulator. In one Embodiment of the antenna device which concerns on this invention, it is a figure which shows the data of the frequency characteristic of the reflection loss by simulation analysis. It is a figure which shows the antenna directivity by simulation analysis in one Embodiment of the antenna apparatus which concerns on this invention. FIG. 5 is a diagram illustrating definitions of axes X, Y, and Z and angles θ and φ in a simulation analysis in an embodiment of an antenna device according to the present invention. It is a figure which shows the conventional phased array antenna. It is a block diagram of the dipole element and balun in the conventional phased array antenna. It is a figure which shows the conventional low attitude | position antenna.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the configuration of an antenna device according to an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the antenna device 100 according to this embodiment includes an antenna element 10, a dielectric substrate 20, a ground plane conductor 30, a coaxial feed line 40, and a feed element 50.

  The antenna element 10 includes a central strip conductor 11, outer strip conductors 12 and 13, a strip line 14, and an electromagnetic shielding member 15. The antenna element 10 is formed, for example, by printing on one surface (hereinafter referred to as “opening surface”) 21 of a dielectric substrate 20. A ground plane conductor 30 is formed on the back surface of the opening surface 21 of the dielectric substrate 20. The antenna element 10 constitutes a dipole antenna element according to the present invention. Moreover, the center strip | belt-shaped conductor 11 comprises the 1st strip | belt-shaped conductor which concerns on this invention. The outer strip conductors 12 and 13 constitute the second and third strip conductors according to the present invention, respectively.

  The coaxial power supply line 40 has an impedance of 50Ω to 100Ω, for example, and includes a center conductor 41 and an outer conductor 42.

  The feed element 50 has an input / output terminal 51 and a ground terminal 52 connected to the upstream side (antenna element 10 side), and an input / output terminal 53 and a ground terminal 54 connected to the downstream side (circuit side). Here, the input / output terminals 51 and 53 constitute a first terminal and a second terminal according to the present invention, respectively.

  As shown in FIG. 2, the center strip conductor 11 has a shape sandwiched between the outer strip conductors 12 and 13. That is, the center strip conductor 11 and the outer strip conductors 12 and 13 include a portion configured as a coplanar line (C0-Planar Wave-line: CPW).

  Since the CPW is an unbalanced line, as shown in FIG. 2, the central strip conductor 11 is connected to the central conductor 41 of the coaxial feeder 40, and the outer strip conductors 12 and 13 are connected to the outer conductor 42 of the coaxial feeder 40. It can be configured. In this configuration, current flows as shown in FIG.

That is, as shown in FIG. 3, the current I _B1 flowing through the outer strip-shaped conductor outer edge portions 12a and 13a, which is the outer side of each of the outer strip-shaped conductors 12 and 13 (the side far from the central strip-shaped conductor 11), The outer strip-shaped conductor inner edge portion 12c which is the inner side of the outer strip-shaped conductors 12 and 13 (the side close to the central strip-shaped conductor 11) It flows as _{I B2} to 13c. The current I _A2 flowing through the central strip conductor 11 of the CPW flows as it is regardless of the positions of the outer strip conductor tips 12b and 13b. Therefore, when the outer strip conductor outer edge portions 12a and 13a and the central strip conductor 11 are viewed as one line, this line is a balanced line. Therefore, CPW is acting as a balun.

  The center belt-like conductor 11 includes a portion constituting a strip line in a pair with the ground plane conductor 30 (see FIG. 1) provided on the back surface of the dielectric substrate 20. Hereinafter, this line is referred to as a “small strip line”. The strip line 14 is hereinafter referred to as a “large strip line”. This large strip line is in contact with the outer strip-shaped conductors 12 and 13 of the CPW at the position of the axis 16 orthogonal to the longitudinal direction of the antenna element 10. The center strip conductor 11 is provided at a predetermined interval from the large strip line.

  A current in the same direction flows on the center strip conductor 11, the outer strip conductor outer edges 12a and 13a, and the large strip line. Therefore, if the length of the antenna element 10 in the longitudinal direction is the resonance length, the antenna element 10 functions as a dipole antenna element. In the present embodiment, when the wavelength of the radio wave used for transmission or reception by the antenna element 10 is represented by λ, the length of the large strip line in the longitudinal direction of the antenna element 10 is λ / 4. The total length of the CPW and the small strip line in the same direction is also λ / 4. That is, the length of the antenna element 10 in the longitudinal direction is λ / 2.

  The current of the small strip line composed of the central strip conductor 11 and the ground plane conductor 30 becomes zero at the central strip conductor tip 11a, which is the end of the central strip conductor 11, and the impedance is infinite. Therefore, near the boundary between the CPW and the small strip line, the current of the central strip conductor 11 of the CPW and the current of the central strip conductor 11 of the small strip line can be made equal. The state where both currents are equal is the impedance matching state. Therefore, in the antenna device 100, the outer strip conductors 12 and 13 are made shorter than the central strip conductor 11 and the outer strip conductors 12 and 13 are adjusted to adjust the length of the outer strip conductors 12 and 13 to the coaxial impedance and the entire antenna element 10. The impedance of the electric wire 40 can be matched.

  By performing impedance matching as described above, the antenna device 100 can install the feeding element 50 such as an amplifier or a phase shifter on the antenna element 10, that is, on the opening surface 21 side, as shown in FIG. it can.

  In the above-described embodiment, the outer band-shaped conductor tips 12b and 13b have a straight shape. However, as shown in FIG. 4, each tip has a round shape (for example, an arc shape). (Convex shape).

  In order to connect the feeding element 50 and the antenna element 10, the input / output terminal 51 is connected to the base (large strip line side) of the central strip conductor 11. Further, the ground terminal 52 is connected to a position on the strip line 14 corresponding to a substantially central portion of the antenna element 10.

  On the other hand, in order to connect the power feeding element 50 and the downstream circuit, the input / output terminal 53 needs to be connected to the circuit on the back surface side of the dielectric substrate 20. Therefore, the through-hole 14a is provided in the strip line 14 of the antenna element 10 and the coaxial feed line 40 is passed through, and the central conductor 41 of the coaxial feed line 40 and the input / output terminal 53 are connected. In addition, the ground terminal 54 is connected to a position on the strip line 14 corresponding to the substantially central portion of the antenna element 10.

Next, the electromagnetic field shielding member 15 will be described. The electromagnetic shielding member 15 shields an electromagnetic field generated by the power feeding element 50. As shown in FIG. 5A, the electromagnetic field shielding member 15 is made of, for example, a metal material and has a semicircular cross-sectional shape. If the large strip and the CPW of the antenna element 10 are covered with the electromagnetic field shielding member 15, the current I _A1 flowing on the large strip line flows on the electromagnetic field shielding member 15. Further, the current I _B1 flowing in the outer edge portions 12a and 13a of the outer strip-like conductor of the CPW also flows on the electromagnetic shielding member 15. Therefore, the antenna device 100 does not impair the radiation characteristics of the dipole antenna.

  The cross-sectional shape of the electromagnetic shielding member 15 can be matched to the usage pattern and is not limited to a semicircular shape. For example, as shown in FIG. 5B, the cross-sectional shape may be a rectangle. However, since an electromagnetic field is generated from the feed element 50 inside the electromagnetic shielding member 15, it is not desirable if the electromagnetic field is combined with the antenna element 10 to cause a feedback phenomenon. Therefore, the cross-sectional dimension of the electromagnetic field shielding member 15 needs to be in a state where the waveguide system formed by the electromagnetic field shielding member 15 and the large strip does not transmit (blocks) the electromagnetic field. That is, if the cross-sectional shape of the electromagnetic field shielding member 15 is semicircular (FIG. 5A), the radius is made shorter, and if it is a rectangle (FIG. 5B), the vertical and horizontal dimensions are made shorter than the cutoff wavelength of the used radio wave. It should be noted that the shielding effect can be further enhanced by covering the end face opposite to the CPW side of the two end faces in the longitudinal direction of the electromagnetic shielding member 15 with a shielding material.

  Since the power feeding element 50 is provided in the relatively narrow electromagnetic field shielding member 15, it is important to prevent heat generated from the power feeding element 50 or use it. For example, when the temperature inside the electromagnetic field shielding member 15 exceeds a predetermined temperature due to the heat generation of the power feeding element 50, it is preferable that the electromagnetic field shielding member 15 absorbs heat and conducts it outside the electromagnetic field shielding member 15. For this purpose, it is preferable to provide a material having a relatively high thermal emissivity on the inner surface of the electromagnetic field shielding member 15. Conversely, for example, when the antenna device 100 is used in a cold region, the inside of the electromagnetic field shielding member 15 can be warmed by the heat generated by the feed element 50. For this purpose, it is preferable to provide a substance having a relatively low thermal emissivity inside the electromagnetic field shielding member 15.

  Next, a method for manufacturing the antenna device 100 according to the present embodiment will be described with reference to FIG.

  First, a pattern of the antenna element 10 constituted by the center strip conductor 11, the outer strip conductors 12 and 13, and the strip line 14 is formed on the dielectric substrate 20 using a known printing technique (FIG. 6A). ). It is assumed that a ground plane conductor 30 (see FIG. 1) is formed on the back surface of the dielectric substrate 20.

  Next, a through hole 14a penetrating from the surface of the strip line 14 to the ground plane conductor 30 is formed (FIG. 6B).

  Subsequently, the feeding element 50 is placed on the antenna element 10, and the coaxial feeding line 40 is inserted into the through hole 14a (FIG. 6C).

  The input / output terminal 51 of the feed element 50 is the central strip conductor 11 of the CPW, the input / output terminal 53 of the feed element 50 is the center conductor 41 of the coaxial feed line 40, and the ground terminals 52 and 54 are the strip line 14, respectively. Soldering is performed (FIG. 6D).

  Next, the shielding electromagnetic shielding member 15 is placed on the antenna element 10 (FIG. 6E). Then, the shielding electromagnetic shielding member 15 and the antenna element 10 are electrically connected and fixed by, for example, soldering, conductive adhesive, conductive tape, or the like (FIG. 6F).

  As described above, the antenna device 100 according to the present embodiment can be manufactured more easily than the conventional one, so that it can cope with mass production.

  Next, a simulation analysis result of the antenna device 100 according to this embodiment will be described. An antenna device 100 analyzed by a simulator is shown in FIG. Moreover, the data of the frequency characteristic of the reflection loss by simulation analysis are shown in FIG. 8, and the radiation pattern showing the antenna directivity is shown in FIG. Also, the definitions of the angles θ and φ in FIG. 9 are shown in FIG.

  As shown in FIG. 9, the antenna device 100 has excellent characteristics such as a maximum reflection loss of −15.3 dB and a 3 dB bandwidth of about 10% (about 0.3 GHz). Further, as shown in FIG. 10, the antenna device 100 has a radiation pattern shape that satisfies both the electric field surface and the magnetic field surface.

  Next, characteristics of the prototype of the antenna device 100 according to the present embodiment will be described. The prototype electromagnetic shielding member 15 is made of brass and has a rectangular cross section. Inside the electromagnetic field shielding member 15, a low noise amplifier is inserted as the feed element 50, and the amplification factor is 10.9 dB. In the antenna device 100, no oscillation occurred even when the low noise amplifier was operated. By comparison with a single antenna (no low noise amplifier), it was confirmed that the reception level increased by 10 dB by providing a low noise amplifier. As a result, it was possible to realize an antenna device 100 having an extremely low posture in which the feeding element 50 was integratedly mounted on the antenna element 10 side.

  As described above, the antenna device 100 according to the present embodiment has a configuration in which the feeding element 50 such as an amplifier or a phase shifter is installed on the opening surface 21 side on the antenna element 10. It is not necessary to provide the power feeding element 50 on the back surface side of the substrate 20, and it can be manufactured by work from the opening surface 21 side.

  Therefore, the antenna device 100 according to the present embodiment can be manufactured more easily than the conventional one, can cope with mass production, and can achieve a low posture.

  As a result, the antenna device 100 according to the present embodiment can greatly reduce the manufacturing cost, and can contribute to the application of the phased array antenna to consumer use.

  As described above, the antenna device and the manufacturing method thereof according to the present invention can be manufactured more easily than conventional ones, have the effects of being able to cope with mass production and achieving a low profile, and phase alignment. It is useful as a radio communication radar equipped with an antenna or a phased array antenna.

10 Antenna element (Dipole antenna element)
11 Central strip conductor (first strip conductor)
11a Center strip conductor tip 12 Outer strip conductor (second strip conductor)
12a, 13a Outer strip conductor outer edge portion 12b, 13b Outer strip conductor tip portion 12c, 13c Outer strip conductor inner edge portion 13 Outer strip conductor (third strip conductor)
DESCRIPTION OF SYMBOLS 14 Strip line 14a Through-hole 15 Electromagnetic-field shielding member 16 Axis 20 Dielectric board | substrate 21 Opening surface 30 Ground plane conductor 40 Coaxial feeder 41 Central conductor 42 External conductor 50 Feeding element 51 Input / output terminal (1st terminal)
52, 54 Ground terminal 53 Input / output terminal (second terminal)
100 Antenna device

Claims (5)

A dielectric substrate;
A dipole antenna element formed on one surface of the dielectric substrate, the length in the longitudinal direction being a half wavelength of the used radio wave;
A ground plane conductor formed on the back surface of the one surface of the dielectric substrate,
The dipole antenna element is
A strip line provided on the one surface on one side with respect to an axis perpendicular to the longitudinal direction;
A coplanar line provided on the one surface on the other side with respect to the axis, and
The coplanar track is
A first strip conductor provided at a predetermined interval from the strip line and extending in the longitudinal direction;
An antenna device comprising: second and third strip conductors connected to the strip line and sandwiching the first strip conductor at a predetermined interval from the first strip conductor. Each length in the longitudinal direction of the second and third strip conductors is shorter than the length of the first strip conductor,
2. The antenna device according to claim 1, wherein tips of the second and third strip conductors have a rounded shape. An electromagnetic field shielding member for covering an upper surface of the coplanar line and the strip line and shielding an electromagnetic field;
The antenna device according to claim 1, wherein the electromagnetic shielding member has a cross-sectional dimension shorter than a cutoff wavelength of the used radio wave. A feed element provided on the stripline;
Through the dielectric substrate and the ground plane conductor from the surface of the strip line, further comprising a through hole through which a power supply line passes,
The feeding element is
A first terminal connected to the first strip conductor;
A second terminal connected to the feeder line;
The antenna device according to any one of claims 1 to 3, further comprising a ground terminal connected to the strip line. It is a manufacturing method of the antenna device according to claim 4,
Forming the dipole antenna element on one surface of the dielectric substrate;
Forming a through-hole penetrating the dielectric substrate and the ground plane conductor from the surface of the stripline;
Providing the feeding element on the stripline;
Connecting the first terminal to the first strip conductor;
Connecting the second terminal to the feeder line;
Connecting the ground terminal to the stripline;
Covering the coplanar line and the strip line with the electromagnetic shielding member.

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