JP2010109623A - Slot bow-tie antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wideband circular polarized antenna which is thin, unidirectional, and supplies power by an imbalanced line. <P>SOLUTION: A cross slot bow-tie antenna 11 is provided with a loop conductor 2, a slot conductor 4, and a ground conductor 3. The loop conductor 2 is formed into a loop by bringing one and the other ends close to each other The slot conductor 4 has a dielectric layer between itself and the loop conductor 2 and is placed almost in parallel to the loop conductor 2. The ground conductor 3 is placed opposite to a side where the slot conductor 4 is placed viewed from the loop conductor 2. The slot conductor 4 has a bow-tie slot 4a in the shape in which a plurality of triangles placed with apexes confronting to one another in a radiation shape face the loop conductor 2. The loop conductor 2 and the ground conductor 3 compose a microstrip line. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a configuration of a slot-type bow tie antenna.

  FIG. 15A shows a schematic shape of a known bow tie antenna. The bow tie antenna 90 shown in FIG. 15 (a) has a pair of radiation conductors 91 formed in an isosceles triangle shape, and is configured in a bow tie shape as shown in the figure. The bow tie antenna 90 can be considered as a planarized version of a known biconical antenna, and is characterized by having a wideband characteristic. A balanced line is used for power supply, and a point between the vertices of the two triangles is a power supply point. The directivity of the bow tie antenna 90 is bidirectional.

As described above, the bow tie antenna requires balanced power feeding. For this reason, in order to supply electric power through an unbalanced line such as a coaxial line or a microstrip line, a balun as a converter is required, and the power supply system becomes complicated. In this regard, Patent Documents 1 to 3 disclose a slot-type bow tie antenna that can be directly connected to an unbalanced line by using a parasitic element without providing a balun. This slot-type bow tie antenna is characterized in that it has a wide bandwidth and is bidirectional, like the ordinary bow tie antenna shown in FIG.
JP 2003-78345 A JP 2003-87050 A Japanese Patent Laid-Open No. 2004-289592

  On the other hand, a cross slot antenna with a cavity as shown in FIG. 15B is also known. In the cross-slot antenna 93 shown in the figure, two orthogonal slots 94 are formed, and circular polarization can be generated by one-point feeding by making the lengths of the two slots longer and shorter. Furthermore, by changing the position of the feeding point 95, it is possible to generate right-handed circularly polarized wave and left-handed circularly polarized wave. In addition, since the cavity 96 is provided on the back surface of the slot 94, back radiation can be suppressed and directivity can be made unidirectional.

  As described above, the directionality of the slot-type bow tie antenna having the configuration of Patent Documents 1 to 3 is bidirectional. For this reason, in order to make this unidirectional, it is necessary to provide a reflector at a position of a quarter wavelength from the radiation conductor, and it is difficult to reduce the thickness. Furthermore, although the slot-type bow tie antennas of Patent Documents 1 to 3 have broadband properties, they cannot generate circularly polarized waves.

  On the other hand, two conventional bow tie antennas shown in FIG. 15 (a) are arranged so as to be orthogonal to each other, and are configured so that the feeding phase difference to the two bow tie antennas is 90 degrees. It can also be generated. However, in this case, since the 90-degree phase difference is given, the power feeding system is further complicated. Further, as in the case of Patent Documents 1 to 3, it is difficult to reduce the thickness because it is necessary to provide a reflecting plate at a position of a quarter wavelength from the radiation conductor in order to suppress backside radiation.

  In this regard, the cross slot antenna with a cavity shown in FIG. 15B does not require a reflector for realizing unidirectionality, and thus can be formed thin, and can generate circularly polarized waves. it can. However, since it is a single-point feed type, the circular polarization band has been narrowed.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wide-band circularly polarized antenna that can be thin and unidirectional and can be fed by an unbalanced line.

Means and effects for solving the problems

  The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

  According to an aspect of the present invention, a slot bow tie antenna having the following configuration is provided. That is, the slot bow tie antenna includes a loop conductor, a slot conductor, and a ground conductor. The loop conductor is formed in a loop shape with one end and the other end being close to each other. The slot conductor is disposed substantially parallel to the loop conductor with a dielectric layer sandwiched between the slot conductor. The ground conductor is disposed on the side opposite to the side on which the slot conductor is disposed when viewed from the loop conductor. The slot conductor is formed with a bow tie slot having a shape in which a plurality of triangles are arranged in a radial pattern with their apexes facing each other at a position facing the loop conductor. The loop conductor and the ground conductor constitute a microstrip line.

  With the above configuration, by transmitting electromagnetic waves to the microstrip line formed by the loop conductor and the ground conductor, power can be supplied to the slot conductor via electromagnetic coupling. Therefore, for example, a balanced-unbalanced converter such as a balun is not required at the time of power feeding, and the power feeding system can be configured very simply. Furthermore, by radiating from a triangular slot, it is possible to ensure the wide bandwidth characteristic of the bowtie antenna. In addition, since the backside radiation can be suppressed by the ground conductor without providing a separate reflector, a compact unidirectional antenna can be configured.

  In the slot bow tie antenna, one end of the loop conductor is connected to the feeding portion, the other end is connected to the matching termination portion, and the length of one loop of the loop conductor is approximately one wavelength. It is preferable. Note that “the length of one loop of the loop is approximately one wavelength” means that the length of one loop of the loop when viewed electrically is approximately one wavelength.

  Thereby, by supplying power to the loop conductor, it is possible to supply power while giving a feeding phase difference to each part of the slot conductor via electromagnetic coupling from the loop conductor. Accordingly, circularly polarized waves can be generated, and power can be supplied by one-point power supply while maintaining the broadband property of the bow tie antenna. In addition, surplus power that has not contributed to radiation can be absorbed by the matching termination.

  In the slot bow tie antenna, it is preferable that the bow tie slot is formed in a shape in which four isosceles triangles are arranged in a substantially cross shape so that apex angles are abutted.

  As a result, a feeding phase difference of about 90 degrees can be given from the loop conductor to the portion corresponding to the four isosceles triangles of the slot conductor, and the circularly polarized wave can be generated satisfactorily.

  Next, embodiments of the invention will be described with reference to the drawings. FIG. 1 is an external perspective view of a cross slot bow tie antenna 11 as a slot bow tie antenna according to a first embodiment of the present invention. 2 is a plan view of the cross slot bow tie antenna 11, and FIG. 3 is a cross-sectional view taken along the line AA in FIG.

  The cross slot bow tie antenna 11 of the present embodiment shown in FIGS. 1 to 3 mainly includes a loop conductor 2, a ground conductor 3, and a slot conductor 4.

  The loop conductor 2 is configured as a flat metal member having a certain thickness. Further, the loop conductor 2 is formed in a substantially C-shaped (circular shape with a part cut) with one end and the other end thereof close to each other, and is configured so that the line width of the loop is constant. Yes. A flat ground conductor 3 is arranged below the loop conductor 2 so as to be parallel to a plane including the C-shape (loop shape). As shown in FIG. 3, a dielectric layer 8 composed of a gap (air) is formed between the loop conductor 2 and the ground conductor 3. With the above configuration, a microstrip line is formed by the loop conductor 2 and the ground conductor 3.

  Further, a dielectric layer 9 made of a gap is sandwiched between the upper side of the loop conductor 2 (opposite side of the ground conductor 3 when viewed from the loop conductor 2) so as to be parallel to a plane including the C-shaped loop of the loop conductor 2. A flat slot conductor 4 is disposed on the surface. A part of the slot conductor 4 is cut out to form a bowtie-shaped slot (bowtie slot 4a). Specifically, as shown in FIG. 2, the bow tie slot 4a has a shape in which a plurality of triangles are arranged radially so that their vertices abut each other (more specifically, four isosceles triangles are spaced at 90 ° intervals. It is arranged in a substantially cross shape and is formed in a shape in which the apex angles of each isosceles triangle are abutted. The bow tie slot 4a is formed so that the center portion of the cross shape (the position where the apex angle of the isosceles triangle is abutted) is a position corresponding to the center position of the loop of the loop conductor 2. The bow tie slot 4a and the loop conductor 2 are configured to face each other.

  Since the bow tie slot 4a is formed in such a shape that the two slot-type bow tie antennas are arranged so as to be orthogonal to each other, the cross slot bow tie antenna 11 has a characteristic of a wide band characteristic that the bow tie antenna has. Further, since the backside radiation is suppressed by the ground conductor 3 provided in the microstrip line, unidirectionality can be realized without providing a reflector.

  A side conductor 5 is disposed between the four sides of the slot conductor 4 and the four sides of the ground conductor 3. The four sides of the slot conductor 4 and the ground conductor 3 are short-circuited by being connected by the side conductor 5. As a result, the slot conductor 4, the ground conductor 3, and the side conductor 5 form a rectangular parallelepiped cavity (cavity) as shown in the figure. The loop conductor 2 is arranged inside the cavity.

  Next, a configuration for supplying power to the loop conductor 2 and the bow tie slot 4a will be described. A first connection portion 2a is formed at one end of the loop conductor 2, and a second connection portion 2b is formed at the other end. Further, as shown in FIG. 3, on the back side of the ground conductor 3 (the surface opposite to the side where the loop conductor 2 is disposed), a feeding port (feeding portion) 6 and a matching termination port (matching termination portion) 7 are provided. Is arranged.

  The feeding port 6 and the matching termination port 7 are configured as a known coaxial cable. The feeding port 6 is connected to a power supply device (not shown), and the matching termination port 7 is connected to a matching load (not shown). This matching load is for absorbing excess power that did not contribute to radiation. The coaxial cable of the power feeding port 6 includes a center conductor 6a, a coaxial outer conductor 6b disposed coaxially around the center conductor 6a, and an unillustrated insulator disposed between the center conductor and the coaxial outer conductor. And. Similarly, the coaxial cable of the matching termination port 7 includes a center conductor 7a, a coaxial outer conductor 7b, and an insulator (not shown).

  An insertion hole (not shown) is formed at a position corresponding to the first connection portion 2a and the second connection portion 2b of the ground conductor 3. Then, the center conductor 6a of the power feeding port 6 and the center conductor 7a of the matching termination port 7 are passed through the insertion hole from the back surface of the ground conductor 3 to the surface (the surface on the side where the loop conductor 2 is disposed). The center conductor 6a is electrically connected to the first connection portion 2a, and the center conductor 7a is electrically connected to the second connection portion 2b. The central conductors 6a and 7a pass through the insertion hole in a non-contact manner and are configured not to be connected to the ground conductor 3.

  The coaxial outer conductor 6b of the power feeding port 6 and the coaxial outer conductor 7b of the matching termination port 7 are electrically connected to the ground conductor 3, respectively.

  With the above configuration, a traveling wave can be propagated to the loop conductor 2 by supplying a high-frequency current from the power feeding device. The loop conductor 2 and the ground conductor 3 constitute a microstrip line as described above, and power can be supplied from the loop conductor 2 to the slot conductor 4 via electromagnetic coupling. Then, by making the electrical length of one loop of the loop conductor 2 substantially coincide with the wavelength, the feeding phase at a position corresponding to each of the four isosceles triangles constituting the bow tie slot 4a is about 90. Power can be supplied to shift by degrees.

  Therefore, by supplying power to the loop conductor 2, power is supplied so as to give a 90-degree phase difference to the four isosceles triangles constituting the bow tie slot 4a by electromagnetic coupling via the dielectric layer 9, and the slot conductor 4 can generate circularly polarized waves.

  Next, the configuration of the cross slot bow tie antenna 11 of the present embodiment will be described more specifically. The cross slot bow tie antenna 11 of this embodiment is configured as a right-hand circularly polarized slot bow tie antenna of 5.8 GHz band. Of course, the dimensions and shape of the cross slot bow tie antenna 11 described below can be changed as appropriate according to the band to be used.

  Hereinafter, description will be made mainly with reference to FIG. The loop conductor 2 has a constant thickness, and is formed such that the line width W1 in the diameter direction of the C-shaped loop formed by the loop conductor 2 is 4 mm and has a constant arc shape (C-shape). The C-shaped inner diameter D1 is 13 mm, and the outer diameter D2 is 21 mm.

  The ground conductor 3 and the slot conductor 4 each have a vertical width L1 and a horizontal width L2 of 28 mm. The size of the dielectric layer 9 (height h1 shown in FIG. 3) is 2 mm, and the size of the dielectric layer 8 (height h2 shown in FIG. 3) is 1 mm.

  The bow tie slot 4a formed in the slot conductor 4 is formed so that each of the four isosceles triangles has a base length L3 of 9.5 mm and a height L4 of 11.5 mm.

  With the configuration as described above, the electrical length of one turn of the loop conductor 2 is approximately one wavelength in the 5.8 GHz band. As a result, power is supplied from the loop conductor 2 to the bow tie slot 4a through the dielectric layer 9 using electromagnetic coupling, thereby giving a 90 degree phase difference to the four isosceles triangles constituting the bow tie slot 4a. Waves can be generated.

  Next, characteristics when the cross slot bow tie antenna 11 of the present embodiment is used will be described with reference to FIGS.

  FIG. 4 is a graph showing a simulation result of the axial ratio frequency characteristic in the zenith direction of the cross slot bow tie antenna 11 of the present embodiment. The vertical axis of the graph is the axial ratio between the major axis and the minor axis of circularly polarized wave, and the axial ratio of perfect circularly polarized wave in which the length of the major axis coincides with the length of the minor axis is 0 dB. In general, the axial ratio capable of obtaining good characteristics as a circularly polarized antenna is 3 dB or less. As shown in FIG. 4, the optimum axial ratio of the cross slot bow tie antenna 11 of this embodiment is 0.1 dB, which is very good. Further, the bandwidth where the axial ratio is 3 dB or less is 40% in the specific band, and it can be seen that broadband circular polarization characteristics are obtained.

  FIG. 5 is a graph showing simulation results of directivity characteristics of the right-handed circularly polarized wave (main polarization) component and the left-handed circularly polarized wave (orthogonal polarization) component at 5.8 GHz of the cross slot bow tie antenna 11 of the present embodiment. It is. In a bow tie antenna configured to generate circular polarization, the main polarization component in the zenith direction and the orthogonal polarization component in the back direction are radiated with the same intensity. For this purpose, a reflector was necessary. In this regard, in the cross slot bow tie antenna 11 of the present embodiment, as shown in FIG. 5, the left-handed circularly polarized component is compared with the radiation of the right-handed circularly polarized component in the zenith direction (0 ° direction in the figure). The radiation in the back direction (−180 ° direction in the figure) is about 11.2 dB smaller. Therefore, it is possible to satisfactorily suppress backside radiation without providing a reflector.

  FIG. 6 is a graph showing a simulation result of the input impedance (VSWR: voltage standing wave ratio) characteristic of the cross slot bow tie antenna 11 of the present embodiment. The vertical axis is VSWR, and generally VSWR is 2 or less within the practical range. Since the cross slot bow tie antenna 11 of the present embodiment is configured by a microstrip line in which the feeding system is matched, good characteristics are obtained over a very wide band (the bandwidth with a VSWR of 2 or less). 50% or more in the band).

  FIG. 7 is a graph showing a simulation result of the gain frequency characteristic of the cross slot bow tie antenna 11 of the present embodiment. The vertical axis represents the gain (unit: dBi) in the zenith direction. As shown in the figure, the bandwidth that is 3 dB lower than the gain peak of the right-handed circularly polarized wave (main polarization) component is a very wide band of 33% in the specific band.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 8 is an external perspective view of a cross slot bow tie antenna 12 as a slot bow tie antenna according to the second embodiment of the present invention. FIG. 9 is a plan view of the cross slot bow tie antenna 12, and FIG. 10 is a side view of the cross slot bow tie antenna 12. In the following description, the same or similar configurations as those in the first embodiment may be denoted by the same reference numerals in the drawings, and the description thereof may be omitted.

  The cross slot bow tie antenna 12 of the present embodiment has a side conductor removed from the cross slot bow tie antenna 11 of the first embodiment, and a loop conductor 2, a ground conductor 3, and a slot conductor 4 are configured on a dielectric substrate. .

  As shown in FIG. 8 and the like, the cross slot bow tie antenna 12 includes a first dielectric substrate 21 and a second dielectric substrate 22, and the first dielectric substrate 21 and the second dielectric substrate 22 are parallel to each other. It is arranged to be.

  A slot conductor 4 is formed on the surface of the first dielectric substrate 21 (the surface facing away from the second dielectric substrate 22). The slot conductor 4 is formed with a bow tie slot 4a as in the first embodiment. The slot is formed only in the slot conductor 4, and no slot is formed in the first dielectric substrate 21 itself.

  A loop conductor 2 is formed on the surface of the second dielectric substrate 22 (the surface facing the first dielectric substrate 21). As shown in FIG. 10, the ground conductor 3 is formed on the back surface (the surface opposite to the surface on which the loop conductor 2 is formed) of the second dielectric substrate 22. With the above configuration, the loop conductor 2 and the ground conductor 3 constitute a microstrip line.

  Further, as shown in FIG. 10, a gap 23 is provided between the first dielectric substrate 21 and the second dielectric substrate 22. That is, a dielectric layer is formed between the loop conductor 2 and the slot conductor 4 by the gap 23 and the first dielectric substrate 21 instead of the dielectric layer 9 by the gap in the first embodiment.

  Further, the power feeding port 6 and the matching termination port 7 are disposed on the back surface side of the second dielectric substrate 22. The second dielectric substrate 22 and the ground conductor 3 are formed with insertion holes (not shown) at positions corresponding to the first connection portion 2 a and the second connection portion 2 b of the loop conductor 2. Thereby, the center conductor 6a can be connected to the 1st connection part 2a through the surface from the back surface of the 2nd dielectric substrate 22. FIG. Similarly, the central conductor 7a can be passed from the back surface to the front surface of the second dielectric substrate 22 and connected to the second connection portion 2b.

  Next, the configuration of the cross slot bow tie antenna 12 of the present embodiment will be described more specifically. The cross slot bow tie antenna 12 of this embodiment is configured as a right-hand circularly polarized slot bow tie antenna of 5.8 GHz band. Of course, the dimensions and shape of the cross slot bow tie antenna 12 described below can be changed as appropriate according to the band to be used.

  Hereinafter, description will be made mainly with reference to FIG. The loop conductor 2 has a constant thickness and is formed to have a constant arc shape (C shape) with a line width W2 in the diameter direction of the C-shaped loop formed by the loop conductor 2 being 1.2 mm. . The C-shaped inner diameter D3 is 8 mm, and the outer diameter D4 is 10.4 mm.

  The first dielectric substrate 21 and the second dielectric substrate 22 each have a vertical width L5 and a horizontal width L6 of 28 mm. Further, the thickness t1 of the first dielectric substrate 21 shown in FIG. 10 is 1 mm, and the thickness t2 of the second dielectric substrate 22 is 0.6 mm, and the first dielectric substrate 21 and the second dielectric substrate have a thickness t2. The size of the gap 23 (height h3 shown in FIG. 10) is 0.5 mm.

  The slot conductor 4 has a vertical width L7 and a horizontal width L8 of 25 mm. The bow tie slot 4a formed in the slot conductor 4 is formed so that each of the four isosceles triangles has a base length L9 of 8.7 mm and a height L10 of 10.5 mm.

  Next, characteristics when the cross slot bow tie antenna 11 of the present embodiment is used will be described with reference to FIGS.

  FIG. 11 is a graph showing a simulation result of the axial ratio frequency characteristic in the zenith direction of the cross slot bow tie antenna 12 of the present embodiment. The vertical axis of the graph is the axial ratio between the major axis and the minor axis of circular polarization. As shown in FIG. 11, the optimum axial ratio of the cross slot bow tie antenna 12 of this embodiment is 0.6 dB, which is favorable. Further, the bandwidth where the axial ratio is 3 dB or less is 40% in the specific band, and it can be seen that broadband circular polarization characteristics are obtained.

  FIG. 12 is a graph showing simulation results of directivity characteristics of the right-handed circularly polarized wave (main polarization) component and the left-handed circularly polarized wave (orthogonal polarization) component at 5.8 GHz of the cross slot bow tie antenna 12 of the present embodiment. It is. As shown in the figure, the radiation of the left-handed circularly polarized component in the back direction (-180 ° direction in the figure) compared to the radiation of the right-handed circularly polarized component in the zenith direction (0 degree direction in the figure) Is about 17.2 dB smaller. Therefore, it is possible to satisfactorily suppress backside radiation without providing a reflector.

  FIG. 13 is a graph showing a simulation result of the input impedance (VSWR: voltage standing wave ratio) characteristic of the cross slot bow tie antenna 12 of the present embodiment. The vertical axis is VSWR. Since the cross slot bow tie antenna 12 of the present embodiment is configured by a microstrip line in which the feeding system is matched, good characteristics can be obtained over a very wide band (the bandwidth with a VSWR of 2 or less). 50% or more in the band).

  FIG. 14 is a graph showing a simulation result of the gain frequency characteristic of the cross slot bow tie antenna 12 of the present embodiment. The vertical axis represents the gain (unit: dBi) in the zenith direction. As shown in the figure, the bandwidth that is 3 dB lower than the gain peak of the right-handed circularly polarized wave (main polarization) component is 12% in the specific band.

  As described above, the cross slot bow tie antennas 11 and 12 of the above embodiment include the loop conductor 2, the slot conductor 4, and the ground conductor 3. The loop conductor 2 is formed in a loop shape with one end and the other end being close to each other. The slot conductor 4 is disposed substantially parallel to the loop conductor 2 with a dielectric layer interposed between the slot conductor 4 and the loop conductor 2. The ground conductor 3 is disposed on the side opposite to the side on which the slot conductor 4 is disposed when viewed from the loop conductor 2. In the slot conductor 4, a bow tie slot 4 a having a shape in which a plurality of triangles are arranged radially with their vertices abutting each other is formed at a position facing the loop conductor 2. The loop conductor 2 and the ground conductor 3 constitute a microstrip line.

  With the above configuration, the electromagnetic wave is transmitted to the microstrip line formed by the loop conductor 2 and the ground conductor 3, whereby power can be supplied to the slot conductor 4 through electromagnetic coupling. Therefore, for example, a balanced-unbalanced converter such as a balun is not required at the time of power feeding, and the power feeding system can be configured very simply. Furthermore, by radiating from a triangular slot, it is possible to ensure the wide bandwidth characteristic of the bowtie antenna. Further, since the backside radiation can be suppressed by the ground conductor 3 without providing a separate reflector, a compact unidirectional antenna can be configured.

  In the cross slot bow tie antennas 11 and 12 of the above embodiment, one end of the loop conductor 2 is connected to the feeding port 6 and the other end is connected to the matching termination port 7, and the loop conductor 2 The electrical length of one round is approximately one wavelength.

  Thus, by supplying power to the loop conductor 2, it is possible to supply power from the loop conductor 2 to each part of the slot conductor 4 via electromagnetic coupling while giving a feeding phase difference. Accordingly, circularly polarized waves can be generated, and power feeding by one-point power feeding can be realized while maintaining the broadband property of the cross slot bow tie antennas 11 and 12. In addition, surplus power that has not contributed to radiation can be absorbed by the matching termination port 7.

  Moreover, in the cross slot bow tie antennas 11 and 12 of the above embodiment, the bow tie slot 4a is formed in a shape in which four isosceles triangles are arranged in a substantially cross shape so that the apex angles are abutted.

  As a result, a feeding phase difference of about 90 degrees is given from the loop conductor to the portion corresponding to the four isosceles triangles of the slot conductor 4, and circularly polarized waves can be generated satisfactorily.

  Although the preferred embodiment of the present invention has been described above, the above configuration can be changed as follows, for example.

  The shape of the loop conductor 2 constituting the microstrip line is not limited to a circle (C-shape) as in the above embodiment, as long as the circumference is electrically about one wavelength. However, it is preferable that the bow tie slot has a shape capable of giving a phase difference of 90 degrees.

  In the cross slot bow tie antenna 12 of the second embodiment, the air gap 23 may be eliminated, and the dielectric layer may be configured only with a dielectric substrate. Also, in the cross slot bow tie antenna 11 of the first embodiment, the portion formed by the gap may be filled with a dielectric.

  The bow tie slot 4a is not limited to a shape in which four isosceles triangles are arranged at equal intervals as in the above embodiment. For example, it is not necessary to be strictly an isosceles triangle, and the four triangles need not be congruent. Further, it is only necessary that the triangles are formed in a shape in which the apexes are abutted and arranged radially, and they are not necessarily substantially cross-shaped (that is, the triangles are not necessarily arranged at equal intervals). Further, the number of triangles is not limited to four, and three or five or more can generate circularly polarized waves.

  The feeding method may be a coaxial feeding from the back surface of the ground conductor 3 or a coplanar feeding method on the same plane as the loop conductor 2.

  Although the configuration as a transmission antenna has been described in the above embodiment, the cross slot bow tie antennas 11 and 12 can function as reception antennas by connecting a reception circuit to the first connection unit 2a instead of the power feeding device.

1 is an external perspective view of a cross slot bow tie antenna according to a first embodiment of the present invention. The top view of the cross slot bow tie antenna of a 1st embodiment. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2. The graph which showed the simulation result of the axial ratio frequency characteristic of the cross slot bow tie antenna of a 1st embodiment. The graph which showed the simulation result of the directivity of the cross slot bow tie antenna of a 1st embodiment. The graph which showed the simulation result of VSWR of the cross slot bow tie antenna of 1st Embodiment. The graph which showed the simulation result of the gain frequency characteristic of the cross slot bow tie antenna of a 1st embodiment. The external appearance perspective view of the cross slot bow tie antenna concerning a 2nd embodiment of the present invention. The top view of the cross slot bowtie antenna of 2nd Embodiment. A side view of a cross slot bow tie antenna of a 2nd embodiment. The graph which showed the simulation result of the axial ratio frequency characteristic of the cross slot bow tie antenna of 2nd Embodiment. The graph which showed the simulation result of the directivity of the cross slot bow tie antenna of a 2nd embodiment. The graph which showed the simulation result of VSWR of the cross slot bow tie antenna of 2nd Embodiment. The graph which showed the simulation result of the gain frequency characteristic of the cross slot bow tie antenna of a 2nd embodiment. (A) The schematic diagram which showed the structure of the bow-tie antenna of a prior art. (B) The perspective view which showed the structure of the cross slot antenna with a cavity of a prior art.

Explanation of symbols

11,12 Cross slot bow tie antenna (slot bow tie antenna)
2 Loop conductor 3 Ground conductor 4 Slot conductor 4a Bowtie slot 5 Side conductor 6 Feed port (feed section)
7 Matching termination port (matching termination)
9 Dielectric layer

Claims (3)

A loop conductor formed in a loop shape by bringing one end and the other end close to each other;
A dielectric layer sandwiched between the loop conductor and a slot conductor disposed substantially parallel to the loop conductor;
A ground conductor disposed on the side opposite to the side on which the slot conductor is disposed when viewed from the loop conductor;
With
The slot conductor is formed with a bow tie slot having a shape in which a plurality of triangles are arranged radially with the apexes facing each other at a position facing the loop conductor,
The slot bow tie antenna, wherein the loop conductor and the ground conductor constitute a microstrip line. The slot bow tie antenna according to claim 1,
The loop conductor has one end connected to the power supply unit and the other end connected to the matching termination unit,
A slot bow tie antenna, wherein the length of one loop of the loop conductor is approximately one wavelength. The slot bow tie antenna according to claim 1 or 2,
4. The slot bow tie antenna according to claim 1, wherein the bow tie slot is formed in a shape in which four isosceles triangles are arranged in a substantially cross shape so that apex angles thereof are abutted.

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