JP2005167606A - Slot antenna system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slot antenna system that can easily be downsized and suitably used even for a circularly polarization antenna system. <P>SOLUTION: The slot antenna system 10 is provided with: a dielectric board 11; a high frequency circuit 12 arranged to a bottom side of the dielectric board 11; a ground conductor layer 13 patterned to an upper side of the dielectric board 11; and a shield case 14 for supporting the dielectric board 11 and covering the high frequency circuit 12, a slot 15 is formed to the ground conductor layer 13, and a feeding line 16 crossing the slot 15 in the width direction is formed to the bottom side of the dielectric board 11. The feeding line 16 is connected to a feeding circuit, which feeds power to around both ends of the slot 15 in the width direction by electromagnetic coupling to the feeding line 16 to excite the slot 15, resulting in that the slot 15 emits a linearly polarized wave. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a slot antenna device for exciting a slot provided in a conductor member by a feed line.

  The slot antenna device includes a conductor member made of a metal foil, a metal plate, or the like in which a slot of a predetermined dimension is formed, and a circuit board on which a high-frequency circuit including an amplifier, an oscillator, and the like is disposed. By feeding power to an appropriate position of the conductor member via power feeding means such as a power feeding line connected to the substrate, the slot can be excited to emit linearly polarized waves. As a conventional example of this type of slot antenna device, one having a configuration in which an antenna portion is provided on one side of a circuit board is widely known (for example, see Patent Document 1).

FIG. 6 is a plan view of a main part of such a conventional slot antenna apparatus, and shows an antenna section 2 provided on one side of a substrate 1 made of a dielectric or the like. In the figure, a conductor layer 4 having a slot 3 is formed on one surface of a substrate 1, and a power supply line 5 is formed on the other surface of the substrate 1 so as to cross the slot 3 in the width direction. An unillustrated extension portion of the substrate 1 is a circuit portion 6 in which a high-frequency circuit is disposed. The conductor layer 4 and the power supply line 5 are formed by patterning a copper foil or the like, and a straight opening surrounded by the conductor layer 4 is a slot 3. The slot 3 has a longitudinal dimension set to about one half of the resonance wavelength λ. The feed line 5 is a microstrip line led out from the circuit unit 6, and the slot 3 can be excited by feeding power to the vicinity of both ends in the width direction of the slot 3 through the feed line 5.
Japanese Patent Laying-Open No. 2003-234615 (page 3-4, FIG. 3)

  However, since the conventional slot antenna device shown in FIG. 6 uses the extended portion (one side portion) of the substrate 1 on which the high-frequency circuit is disposed as the region of the antenna portion 2, the area of the substrate 1 is small. There is a problem that it is difficult to downsize the entire apparatus.

  In FIG. 6, another slot extending in the direction orthogonal to the longitudinal direction of the slot 3 is provided in the vicinity of the slot 3, and the other slot is excited with a phase difference of about 90 degrees with respect to the resonance mode of the slot 3. In this case, it is possible to obtain a circularly polarized slot antenna device. In this case, however, a large space is required for the antenna unit 2, so that it is more difficult to reduce the size of the entire device.

  The present invention has been made in view of the actual situation of the prior art, and an object of the present invention is to provide a slot antenna device that can be easily miniaturized and is suitable for circular polarization.

  In order to achieve the above-described object, in the slot antenna device of the present invention, a dielectric substrate, a high-frequency circuit disposed on one surface of the dielectric substrate, and a ground conductor layer formed on the other surface of the dielectric substrate. And a slot is provided in the ground conductor layer, and a power supply line is provided on the one surface or intermediate layer of the dielectric substrate so as to cross the slot in the width direction, and the slot is excited by the power supply line. .

  The slot antenna device configured as described above is provided with a high frequency circuit and its ground conductor layer on both surfaces of the dielectric substrate, and a slot is provided in this ground conductor layer, so that the size of the dielectric substrate is increased. This eliminates the need for the device, and promotes downsizing of the entire device. The power supply line may be provided on the same surface as the high-frequency circuit when the dielectric substrate is a single layer, and may be provided on the intermediate layer when the dielectric substrate is a multilayer substrate.

  In the slot antenna device having such a configuration, the slot is formed as a cross-shaped opening in which the first slot and the second slot are orthogonal to each other, and the first slot is crossed in the width direction as the feed line. By providing one power supply line and a second power supply line that crosses the second slot in the width direction, and connecting a 90-degree phase difference circuit to either one of the first and second power supply lines, It can also be operated as a circularly polarized antenna.

  Further, in the slot antenna device having such a configuration, when the closed end portion of the slot is formed wider than the other portion, the resonance frequency is lower than when the closed end portion is the same width as the other portion. Therefore, the downsizing of the entire apparatus can be further promoted.

  The slot antenna device of the present invention is provided with a high frequency circuit and a ground conductor layer on both surfaces of a dielectric substrate and excites slots provided in the ground conductor layer. Miniaturization is easy. This slot antenna device can also be used for circularly polarized waves by making the slot a cross-shaped opening.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a slot antenna apparatus according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of the slot antenna apparatus.

  A slot antenna device 10 shown in these drawings is patterned on a dielectric substrate 11, a high-frequency circuit 12 including an amplifier and an oscillator disposed on the bottom surface of the dielectric substrate 11, and the top surface of the dielectric substrate 11. A grounding conductor layer 13 made of copper foil or the like and a sheet metal shield case 14 that holds the dielectric substrate 11 and covers the high-frequency circuit 12 are provided. A slot 15 is formed at the center of the grounding conductor layer 13. Has been. In addition, on the bottom surface of the dielectric substrate 11, a power supply line 16 that crosses the slot 15 in the width direction is formed.

  The slot 15 is an I-shaped opening, and its closed end portion (both ends in the longitudinal direction) is a wide portion 15a cut out wider than the other portion. The power supply line 16 is a microstrip line derived from a power supply circuit. When a signal current is supplied to the power supply line 16, the ground conductor layer 13 is supplied near the both ends in the width direction of the slot 15 by electromagnetic coupling. The slot 15 can be excited to emit linearly polarized waves. Since the high-frequency circuit 12 is covered by the shield case 14, it is shielded from external radio waves and high reliability is ensured.

  As described above, the slot antenna device 10 according to the present embodiment is provided with the high frequency circuit 12 and the ground conductor layer 13 on both surfaces of the dielectric substrate 11, and the slot 15 opened in the ground conductor layer 13 is excited by the feed line 16. Therefore, there is no need to increase the size of the dielectric substrate 11. In addition, since the width of the slot 15 is widened at the closed end, which is the magnetic field region (maximum current region), and the resonance frequency can be lowered with an increase in the current path length, the resonance is performed at a specific frequency. The longitudinal dimension of the slot 15 required for this is shortened. As a result, the slot antenna device 10 is significantly reduced in size as compared with the conventional product. Further, since the bottom plate portion 14a of the shield case 14 functions as a reflector that reflects radio waves radiated downward from the slot 15, the slot antenna device 10 is expected to have good directivity due to the strong radio waves radiated upward. it can.

  In the present embodiment, the slot 15 is formed in an I shape in order to promote downsizing, but it may be a slot having a constant width as in the conventional example shown in FIG. Further, as shown in the plan view of FIG. 3, a notch-type slot 17 whose one end in the longitudinal direction is an open end may be formed by providing a cut at one end of the ground conductor layer 13.

  FIG. 4 is a cross-sectional view of the slot antenna device according to the second embodiment of the present invention, and the same reference numerals are given to portions corresponding to those in FIG. The slot antenna device 20 shown in FIG. 4 is greatly different from the first embodiment described above in that the dielectric substrate 11 is a multilayer substrate and the feed line 16 is provided in the intermediate layer. When a multilayer substrate is employed as the dielectric substrate 11 in this manner, the occupied space of the power supply line 16 does not have a possibility of adversely affecting the mounting space of the high-frequency circuit 12, so that the degree of freedom in design is improved and the overall size of the apparatus can be promoted. .

  FIG. 5 is a plan view of a slot antenna apparatus according to the third embodiment of the present invention, and the same reference numerals are given to portions corresponding to those in FIG. In the slot antenna device 30 shown in FIG. 5, the slot is formed as a cross-shaped opening in which the first slot 31 and the second slot 32 are orthogonal to each other. Further, as the power supply line, a first power supply line 33 that crosses the first slot 31 in the width direction and a second power supply line 34 that crosses the second slot 32 in the width direction are provided. The line 33 is connected to the 90-degree phase difference circuit 35.

  In the slot antenna device 30 adopting such a configuration, the first slot 31 is excited by the first feed line 33 and the second slot 32 spatially orthogonal to the first slot 31 is provided. Although excited by the second feed line 34, a phase difference of about 90 degrees is generated in the resonance mode of each of the slots 31 and 32, so that it can be operated as a circularly polarized antenna.

1 is a perspective view of a slot antenna device according to a first embodiment of the present invention. It is sectional drawing of this slot antenna apparatus. It is a top view which shows the modification of this slot antenna apparatus. It is sectional drawing of the slot antenna apparatus which concerns on the 2nd Example of this invention. It is a top view of the slot antenna apparatus which concerns on the 3rd Example of this invention. It is a principal part top view of the slot antenna apparatus which concerns on a prior art example.

Explanation of symbols

10, 20, 30 Slot antenna device 11 Dielectric substrate 12 High frequency circuit 13 Ground conductor layer 14 Shield case 15, 17 Slot 15a Wide portion 16 Feed line 31 First slot 32 Second slot 33 First feed line 34 First 2 feed lines 35 90 degree phase difference circuit

Claims (3)

  A dielectric substrate; a high-frequency circuit disposed on one surface of the dielectric substrate; and a ground conductor layer formed on the other surface of the dielectric substrate. A slot is provided in the ground conductor layer, and the dielectric A slot antenna device, wherein a feed line that crosses the slot in the width direction is provided on the one surface or intermediate layer of the body substrate, and the slot is excited by the feed line.   2. The first slot according to claim 1, wherein the slot is a cross-shaped opening formed by orthogonally intersecting the first slot and the second slot, and the first slot crossing the first slot in the width direction as the power supply line. And a second power feed line that crosses the second slot in the width direction, and a 90 ° phase difference circuit is connected to one of the first and second power feed lines, thereby providing a circular polarization. A slot antenna device which is operated as a wave antenna. 3. The slot antenna device according to claim 1, wherein a closed end portion of the slot is formed wider than other portions.

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