JP2008092396A - Antenna system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna system changing, in simple configuration, a radiation direction of electromagnetic waves continuously over a wide range at 90° or more. <P>SOLUTION: An antenna system 1 includes a pole-like dielectric rod antenna 11 which propagates electromagnetic waves in a slow-wave mode and a helical member 12, made of a dielectric or conductor, helically wound around the dielectric rod antenna 11. A lower end of the helical member 12 is fixed in a power feeding section 13 and an upper end thereof is fixed in a hollow member 15 through a hollow part of which the dielectric rod antenna 11 is passed. A fixing position of the hollow member 15 is moved and an extension/contraction amount of the helical member 12 is adjusted, so that the radiation direction of electromagnetic waves is changed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antenna device, and more particularly to an antenna device capable of continuously changing the radiation direction of electromagnetic waves over a wide range even with a simple structure.

  When performing large-capacity wireless transmission such as transmission / reception of video signals between cameras and receivers of wireless camera systems used in broadcast station program production, and transmission / reception of data via wireless LAN, a wide-band millimeter wave band is applied. The

  The antenna mounted on the millimeter-wave band wireless transmission system applied to the usage environment where the relative position of the transmitting antenna and the receiving antenna changes greatly shall be able to change the radiation direction of electromagnetic waves in a wide range according to the usage environment. Is desirable.

  Further, in order to attach the antenna to the millimeter-wave band wireless transmission device itself, the space is generally limited, so the antenna needs to have a small and simple configuration.

  As a millimeter-wave band antenna having a small and simple configuration, there is a surface wave antenna or a leaky wave antenna. A typical surface wave antenna can be a dielectric rod antenna composed of a dielectric rod, and a typical leaky wave antenna is a dielectric leaky wave composed of a dielectric line having a periodic structure. An antenna can be mentioned.

  The dielectric rod antenna radiates a radio wave from the end of the dielectric rod antenna in the propagation direction of the radio wave of the dielectric rod antenna, and the leaky wave antenna radiates a radio wave in a direction different from the propagation direction of the radio wave on the dielectric line.

  Dielectric rod antenna devices and leaky wave antenna devices that can change the radiation direction of radio waves have already been proposed (see, for example, Patent Document 1 and Patent Document 2).

  As shown in FIG. 4, the conventional dielectric rod antenna device disclosed in Patent Document 1 is provided with a reflecting member 42 along the dielectric rod antenna 41 to change the radiation direction of the radio wave to the dielectric rod antenna. It is possible to incline about 15 degrees with respect to the 41 axis.

  The conventional leaky wave antenna device disclosed in Patent Document 2 includes a propagation path in which a ground plane conductor 51 and a dielectric substrate 52 are arranged in parallel via a spacer 53 as shown in FIG.

  A plurality of metal strips 54 are provided on the upper surface of the dielectric substrate 52 at predetermined intervals. Further, a metal plate 55 is disposed above the dielectric substrate 52 at a predetermined interval and perpendicular to the propagation direction of the radio wave, and the metal plate 55 rotates within a predetermined angle in a plane perpendicular to the propagation direction of the radio wave. It is possible.

The radio wave propagates from the metal plate 55 toward the metal strip 54, leaks from the metal strip 54, and is radiated into the air. Then, by changing the inclination of the metal plate 55, it is possible to control the radiation direction of radio waves.
Japanese Patent Laid-Open No. 06-244628 ([0007], FIG. 1) JP 2003-338706 A ([0031], FIG. 1)

  In order to transmit a large amount of information stably, it is necessary to increase the ratio of received power and noise power (CN ratio), but in order to increase the CN ratio, it is radiated from the transmitting antenna to the receiving antenna. It is necessary to increase the transmission power as much as possible, that is, to increase the antenna gain.

  However, the higher the gain of the antenna, the sharper the directivity of the antenna. Therefore, when shooting while moving with a wireless camera, the transmitting antenna emits more power in the direction of the receiving antenna. It is desirable that the radio wave radiation direction can be continuously changed.

  In addition, when using the wireless camera indoors, it is often the case that the receiving antenna is installed above the wireless camera to ensure visibility, and when used outdoors, the receiving antenna is often installed horizontally with respect to the wireless camera. In consideration, it is desirable that the transmitting antenna can change the radio wave radiation direction by 90 degrees or more.

  However, the dielectric rod antenna disclosed in Patent Document 1 has a problem that the radiation direction of radio waves cannot be changed according to the use environment.

  The dielectric leaky wave antenna disclosed in Patent Document 2 has a problem that the range of change is limited, although the direction of radio wave radiation can be changed according to the usage environment.

  Although it is possible to expand the radio wave radiation range using both surface wave antennas and leaky wave antennas, it is necessary to have a configuration that can switch the feed circuit that supplies radio waves to each antenna, and the structure is complicated It cannot be avoided.

  The present invention has been made to solve the above-described conventional problems, and the radiation direction of electromagnetic waves can be changed over a wide range of 90 degrees or more with a simple configuration, or the radiation direction of electromagnetic waves can be continuously changed. An object of the present invention is to provide an antenna device that can be used.

  The antenna device according to the present invention includes a columnar dielectric rod antenna that propagates electromagnetic waves in a slow wave mode, and a spiral member that spirally winds around the dielectric rod antenna.

  With this configuration, the radiation direction of radio waves can be changed in a wide range with a simple configuration, or the radiation direction of electromagnetic waves can be continuously changed.

  In the antenna device according to the present invention, the spiral member may be made of a dielectric.

  In the antenna device according to the present invention, the spiral member may be made of a conductor.

  The antenna device according to the present invention includes a fixing portion that fixes one end of the spiral member to the dielectric rod antenna, a hollow member that penetrates the hollow portion through the dielectric rod antenna, and the other end of the spiral member is fixed. including.

  With this configuration, the amount of expansion and contraction of the spiral member can be appropriately adjusted to change the radiation direction of the radio wave over a wide range, or the radiation direction of the electromagnetic wave can be continuously changed.

  The present invention can change the radiation direction of radio waves in a wide range with a simple configuration by changing the amount of expansion and contraction of the spiral member that spirally winds around the dielectric rod antenna, or the radiation direction of electromagnetic waves is continuous. It is possible to provide an antenna device having an effect that it can be changed automatically.

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

  FIG. 1 is a perspective view of an antenna device 1 according to an embodiment of the present invention, in which a columnar dielectric rod antenna 11 that propagates electromagnetic waves in a slow wave mode, and a periphery of the dielectric rod antenna 11 are spirally wound. A rotating spiral member 12.

  The spiral member 12 may be made of a dielectric or a conductor.

  As shown in the enlarged perspective view of FIG. 2A, the power supply unit 13 installed at the base of the dielectric rod antenna 11 includes a first waveguide 131 in which a waveguide 14 having a rectangular cross section is attached to the peripheral wall. And a tapered portion 132 and a second waveguide 133 into which the dielectric rod antenna 11 is inserted.

  One end, for example, the lower end 12D of the spiral member 12 is fixed to the power feeding unit 13, and the other end, for example, the upper end 12U is fixed to the hollow member 15 through which the dielectric rod antenna 11 passes through the hollow portion.

  The hollow member 15 may be made of a dielectric or a conductor.

  The hollow member 15 is provided with at least one screw hole, and a bolt 16 having a pointed end is fitted into the screw hole. As a result, the spiral member 12 can be adjusted to an arbitrary length by pressing the tip of the bolt 16 against the dielectric rod antenna 11 and fixing the hollow member 15 to the rod antenna.

  Hereinafter, the operation of the antenna device according to the embodiment will be described. The cross-sectional shapes of the dielectric rod antenna 11 and the power feeding unit 13 are circular.

A radio wave propagating through the waveguide 14 in the TE ₁₀ mode is first supplied to the first waveguide 131 and converted into the TM ₀₁ mode. The TE ₁₀ mode is a mode having no electric field component in the Y-axis direction and having only a magnetic field distribution. In the TM ₀₁ mode, the lines of magnetic force are distributed concentrically within the cross section of the first waveguide 131, and the amplitude of the magnetic field. The phase is a mode in which the phase is symmetrically distributed with respect to the central axis (Z-axis direction) of the first waveguide 131.

The radio wave fed from the rectangular waveguide 14 to the first circular waveguide 131 and converted into the TM ₀₁ mode propagates in the first waveguide 131 in the Z-axis direction and passes through the tapered portion 132 to the first wave. Propagated to the second waveguide 133. The tapered portion 132 is installed to expand the diameter of the first waveguide 131 to the diameter of the dielectric rod antenna 11.

  A radio wave propagating through the second waveguide 133 is fed to the dielectric rod antenna 11. Here, it is desirable that the insertion end portion of the dielectric rod antenna 11 into the second waveguide 133 is formed in a tapered shape in order to suppress reflection of radio waves.

The second waveguide 133 may have a funnel portion 134 that opens in the axial direction (Z-axis direction) of the dielectric rod antenna 11 as shown in FIG. By providing the funnel portion 134, it is possible to efficiently transmit the radio wave propagating through the second waveguide 133 in the TM ₀₁ mode to the dielectric rod antenna 11.

  FIG. 3 is a perspective view of the antenna device 1 according to the present invention, in a state (a) in which the spiral member 12 is compressed and the spiral member is brought into close contact, and the hollow member 15 is fixed to the upper end of the dielectric rod antenna 11. The state (b) which extended the spiral member 12 to the maximum length is shown.

In the state where the spiral member 12 is in close contact (FIG. 3A), the spiral member 12 does not function as a periodic structure, so that the radio wave is not perturbed, and the dielectric rod antenna 11 remains in the TM ₀₁ mode. It propagates and is emitted from the upper end of the dielectric rod antenna 11 as a conical beam having a null in the Z direction. The radiation direction (Q) of the conical beam is about 20 degrees around the Z axis.

  As shown in FIG. 1, when the hollow member 15 is fixed approximately in the middle of the dielectric rod antenna 11 and the spiral member 12 is extended to an intermediate length, the spiral member 12 functions as a periodic structure of the first period. Perturbs the radio wave propagating through the dielectric rod antenna 11 in the slow wave mode. As a result, the radio wave propagating through the dielectric rod antenna 11 in the slow wave mode is converted into the fast wave mode, and is omnidirectional with respect to the Z axis in the first direction (Q ′) different from the radiation direction (Q) of the conical beam. Radiated.

  In the state in which the spiral member 12 is extended to the maximum length (FIG. 3B), the spiral member 12 functions as a periodic structure of the second period and perturbs the radio wave propagating through the dielectric rod antenna 11. give. As a result, the radio wave is converted to the fast wave mode and radiated omnidirectionally with respect to the Z axis in the second direction (Q ″) different from the radiation direction (Q) of the conical beam and the first direction (Q ′).

  As described above, in the antenna device 1 according to the embodiment of the present invention, the radiation direction of the radio wave is changed by changing the expansion / contraction state of the spiral member 12 wound around the columnar dielectric rod antenna 11. It becomes possible to do.

  The spiral member 12 can be attached to and detached from the dielectric rod antenna 11, and when the spiral member 12 is attached to the dielectric rod antenna 11 and when the spiral member 12 is detached from the dielectric rod antenna 11, The radiation direction may be changed.

In the embodiment described above, the radio wave propagating through the waveguide 14 is converted to the TM ₀₁ mode by the first waveguide 131, but is converted to the TE ₀₁ mode or the TE ₁₁ mode. It is good. However, when converted to the TE ₁₁ mode, the radiation direction of radio waves is not omnidirectional with respect to the axial direction (Z-axis direction) of the dielectric rod antenna 11.

If the feeding mode to the dielectric rod antenna 11 is the TM ₀₁ mode, the radio wave radiated from the dielectric rod antenna 11 in a plane direction perpendicular to the axial direction (Z-axis direction) of the dielectric rod antenna 11 is vertically polarized. If the power feeding mode to the dielectric rod antenna 11 is the TE ₀₁ mode or the TE ₁₁ mode, it becomes a horizontally polarized wave.

  In the above embodiment, the electromagnetic wave is a millimeter wave band radio wave, but the present invention can be applied to an electromagnetic wave other than the millimeter wave band. In particular, in the case of millimeter wave radio waves, a phase shifter is conventionally required to control the antenna directivity, which not only complicates the antenna structure but also increases the power loss. If the antenna device according to the above is applied, the directivity can be controlled by using a low-loss antenna as well as a simple structure and a small size.

  Moreover, although the case where the antenna device according to the present invention is a transmission antenna has been described above, it is obvious that the antenna device according to the present invention can also be applied as a reception antenna.

  As described above, the antenna device according to the present invention has an effect that the radiation direction of electromagnetic waves can be changed over a wide range of 90 degrees or more with a simple configuration, or the radiation direction of electromagnetic waves can be continuously changed. It is effective as a device.

The perspective view of the antenna device which concerns on embodiment of this invention The perspective view of the electric power feeding part of the antenna apparatus which concerns on this invention The perspective view of the antenna device which concerns on embodiment of this invention Perspective view of a conventional dielectric rod antenna device A perspective view of a conventional leaky wave antenna device

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Dielectric rod antenna 12 Spiral member 13 Feeding part 14 Waveguide 15 Hollow member 16 Bolt

Claims (4)

A columnar dielectric rod antenna that propagates electromagnetic waves in slow wave mode;
An antenna device including a spiral member that spirally winds around the dielectric rod antenna. The antenna device according to claim 1, wherein the spiral member is made of a dielectric. The antenna device according to claim 1, wherein the spiral member is made of a conductor. A fixing portion for fixing one end of the spiral member to the dielectric rod antenna;
The antenna device according to any one of claims 1 to 3, further comprising: a hollow member through which the dielectric rod antenna passes and a second end of the spiral member is fixed.

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