JP2012235337A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device having a receiver circuit structure hard to be adversely affected by an external noise.SOLUTION: A UHF antenna 1, a reverse F-shaped planar antenna, is formed on a master substrate 20 having a plane portion 10 in such a manner that the plane portion 10 covers the entire surfaces of a receiver circuit 21 in a plan view. The UHF antenna 1 includes a feed end portion 11 and a short circuit end portion 12 that extend downward from a predetermined edge of the plane portion 10 and shield end portions 13a-13d. The shield end portions 13a-13d are respectively connected to a GND portion 25. A feeding-to-shield distance between each shield end portion 13a-13d and the feed end portion 11 is set twofold or greater than a feeding-to-short circuit distance between the feed end portion 11 and the short circuit end portion 12.

Description

  The present invention relates to an antenna device having a planar antenna on a substrate having a receiving circuit.

  As a planar antenna used by a device having a receiving circuit such as a cellular phone, for example, there is an “inverted L type” planar antenna disclosed in Patent Document 1. The planar antenna disclosed in Patent Document 1 is provided separately from the substrate, reducing the problem of antenna detuning caused by the user.

Japanese Patent No. 4611299

  The receiving circuit has a property that the receiving sensitivity deteriorates when receiving noise having an adverse effect from the outside. However, the conventional planar antenna as disclosed in Patent Document 1 has a problem in that no countermeasure is taken against deterioration in reception performance of a receiving circuit provided on a substrate that is affected by external noise.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an antenna device having a structure in which a receiving circuit is hardly affected by external noise.

  According to a first aspect of the present invention, there is provided an antenna device according to the first aspect of the present invention, comprising: a receiving circuit; a substrate having a stub portion grounded via a predetermined length of wiring; and a ground portion on the surface; And an inverted F-shaped planar antenna having a planar portion that covers the entire surface of the receiving circuit in plan view, and each planar antenna extends downward from the planar portion. The power feeding unit is connected to the receiving circuit, the short circuit unit is connected to the stub unit, the power feeding unit and the short circuit unit have a predetermined distance, and the planar antenna Further includes at least one shield portion extending downward from the planar portion, wherein the at least one shield portion is connected to the grounding portion, and each of the at least one shield portion and The distance between the serial feeding portion is set to be more than twice said predetermined distance.

  A second aspect of the present invention is the antenna device according to the first aspect, wherein the planar portion has at least one opening.

  A third aspect of the present invention is the antenna device according to the first or second aspect, wherein the at least one shield part is connected to the ground part via a capacitor.

  In the antenna device according to the first aspect of the present invention, the planar antenna further includes at least one shield portion extending downward from the planar portion.

  For this reason, the receiving circuit under the plane part can be effectively protected from the noise by escaping the noise received from the outside to the ground part via the plane part and at least one shield part.

  In addition, since the distance between the power supply unit and at least one shield unit is set to be twice or more the predetermined distance between the power supply unit and the short-circuit unit, the presence of the shield unit does not affect the antenna function. .

  As a result, the antenna device according to the first aspect of the present invention has an effect that the receiving circuit can exhibit a structure that is hardly affected by external noise.

  In this invention of Claim 2, by providing at least 1 opening part in the plane part of a planar antenna, the fine tuning of the tuning frequency by a planar antenna can be performed and the improvement of a tuning frequency precision can be aimed at.

  In the present invention of claim 3, by connecting at least one shield part to the grounding part via a capacitor, at least one shield part exhibits a filter function having an excellent noise removal function for each specific frequency. be able to.

  As a result, by setting the capacitance value of at least one capacitor appropriately and selectively removing only the noise that affects the receiving circuit, the antenna function of the planar antenna is hardly affected. The receiving circuit below the unit can be effectively protected from noise.

It is a perspective view which shows typically the structure of the UHF antenna which is a planar antenna of the "inverted F character" in the antenna apparatus which is Embodiment 1 of this invention. 1 is a perspective view schematically showing an overall configuration of an antenna device according to a first embodiment. 3 is a plan view schematically showing a planar view positional relationship and an electrical connection relationship between a UHF antenna and a planar portion in the antenna device of the first embodiment. FIG. It is a perspective view which shows typically the structure of the UHF antenna used with the antenna apparatus of Embodiment 2 of this invention. It is a perspective view which shows typically the electrical connection relation of the UHF antenna used in Embodiment 3 of this invention.

<Embodiment 1>
(UHF antenna 1)
FIG. 1 is a perspective view schematically showing a configuration of a UHF antenna which is an “inverted F-shaped” planar antenna in the antenna apparatus according to the first embodiment of the present invention.

  As shown in the figure, the UHF antenna 1 includes a plane portion 10, a feeding end portion 11, a short-circuit end portion 12, and shield end portions 13a to 13d.

  The planar portion 10 has a rectangular planar shape, and has a width that completely covers a receiving circuit described later in plan view. The planar portion 10 is bent at a right angle from the front edge 10f in the figure, and extends downward to be provided with a power feeding end portion 11. Similarly, it is bent at a right angle from the edge 10f and extends downward to provide a short-circuit end 12.

  For example, a distance D1 (predetermined distance) between the feeding end portion 11 and the short-circuiting end portion 12 is relatively close, for example, 20 mm or less. The feeding end 11 is electrically connected to a receiving circuit 21 to be described later, and the short-circuited end 12 is electrically connected to a GND connecting stub 22 (short wiring that branches like a branch) to be described later.

  On the other hand, it is bent at a right angle from an edge 10r located on the right side in the figure with respect to the edge 10f, and extends downward to provide a shield end 13a. Furthermore, from edge 10b which opposes edge 10f, each bends at right angle and it extends below, and shield end part 13b-13d is provided. The tips of the shield end portions 13 a to 13 d are in contact with the surface of the parent substrate 20.

  The shield end portions 13a to 13d are electrically connected to a GND (ground) portion 25 described later. In addition, as will be described in detail, the distances D2a to D2d between the power supply end 11 and the shield ends 13a to 13d are set to a length that is at least twice the distance D1 between the power supply and the short circuit.

(overall structure)
FIG. 2 is a perspective view schematically showing the overall configuration of the antenna device of the first embodiment. As shown in the figure, a receiving circuit 21, a GND connection stub 22, an IC unit 23, a power supply circuit 24 and a GND unit 25 are provided on the surface of the parent substrate 20. Furthermore, the UHF antenna 1 is arranged so that the tips of the feeding end 11, the short-circuiting end 12 and the shield ends 13 a to 13 d are brought into close contact with the surface of the parent substrate 20, and the planar portion 10 is disposed above the receiving circuit 21. Provided on the parent substrate 20.

  FIG. 3 is a plan view schematically showing the positional relationship and electrical connection relationship between the UHF antenna 1 and the planar portion 10.

  As shown in the figure, the planar portion 10 of the UHF antenna 1 is provided so as to cover the entire surface of the receiving circuit 21 in plan view. In addition, the feeding end 11 is electrically connected to the receiving circuit 21, and the short-circuited end 12 is grounded via a GND connection stub 22. The GND connection stub 22 including the grounded portion is simply referred to as a “stub portion”.

  On the other hand, the shield end portion 13d is electrically connected to the GND portion 25, respectively. For the convenience of explanation, the GND portion 25 is shown as a single region, but it is of course possible to use a general GND wiring or the like as the GND portion 25.

  By providing the UHF antenna 1 in this manner, the tuning frequency of the UHF antenna 1 is determined mainly by the shape of the flat surface portion 10, the distance D1 between the feeding and short circuit, and the wiring length of the GND connection stub 22 in the stub portion. Necessary gain can be obtained. Further, the UHF antenna 1 can have a high gain and a wide frequency band of the antenna by having the plane portion 10 having a relatively wide shape.

  In FIG. 2, the power supply / shield distances D2a to D2d between the power supply end portion 11 and the shield end portions 13a to 13d are equal to the power supply / short circuit distance D1 between the power supply end portion 11 and the short-circuit end portion 12 as described above. Since the length is set to be twice or more, the shield end portions 13 a to 13 d hardly participate in the antenna function of the UHF antenna 1.

  Since the shield end portions 13a to 13d can release noise from the outside to the GND portion 25 via the plane portion 10 and the shield end portions 13a to 13d, the receiving circuit 21 below the plane portion 10 is effectively protected from noise. be able to. That is, the UHF antenna 1 can exhibit a shield function that protects the reception circuit 21 from noise by the plane portion 10 and the shield end portions 13a to 13d. At this time, the UHF antenna 1 can have a higher shielding effect by having the relatively wide planar portion 10.

  As described above, in the antenna device according to the first embodiment, the UHF antenna 1 includes the shield end portions 13a to 13d extending downward from the plane portion 10, and the shield end portions 13a to 13d are respectively connected to the GND portion 25. It is connected.

  For this reason, it is possible to effectively protect the receiving circuit 21 below the planar portion 10 from noise by escaping noise received from the outside to the GND portion 25 via the planar portion 10 and the shield end portions 13a to 13d.

  Further, the power supply / shield distances D2a to D2d between the power supply end portion 11 and the shield end portions 13a to 13d are set to be twice or more the power supply / short circuit distance D1 between the power supply end portion 11 and the short-circuit end portion 12. Therefore, the presence of the shield end portions 13a to 13d does not affect the antenna function.

  As a result, the antenna device according to the first embodiment can have a structure in which the receiving circuit 21 is not easily affected by external noise.

<Embodiment 2>
FIG. 4 is a perspective view schematically showing the structure of the UHF antenna 2 used in the antenna apparatus according to the second embodiment of the present invention. As shown in the figure, the planar portion 10 is provided with a plurality of openings 14. The other structure of the UHF antenna 2 and the arrangement and electrical connection relationship of the UHF antenna 2 in the antenna device are the same as those in the first embodiment shown in FIGS.

  As described above, in the antenna device according to the second embodiment, by providing the plurality of openings 14 in the plane portion 10 of the UHF antenna 2, the tuning frequency can be finely adjusted by the UHF antenna 2, and the tuning frequency accuracy can be improved. Improvements can be made.

<Embodiment 3>
FIG. 5 is a perspective view schematically showing an electrical connection relationship of the UHF antenna 3 used in Embodiment 3 of the present invention. As shown in the figure, capacitors C13a to C13d are interposed between the shield end portions 13a to 13d and the GND portion 25. And each capacitance value is changed between the capacitors C13a to C13d. The structure of the UHF antenna 3, the arrangement in the antenna device, and other electrical connection relations are the same as those in the first embodiment shown in FIGS.

  As described above, in the antenna device of the third embodiment, the shield end portions 13a to 13d and the capacitors C13a to C13d are specified by connecting the shield end portions 13a to 13d to the GND portion 25 through the capacitors C13a to C13d. The noise with respect to the frequency can be released to the GND unit 25.

  As a result, by appropriately setting the capacitance values of the capacitors C13a to C13d and selectively removing only the noise that affects the receiving circuit 21, the antenna function of the UHF antenna 3 is hardly affected. The receiving circuit 21 below the plane portion 10 can be effectively protected from noise.

  In the antenna device of the second embodiment shown in FIG. 4, it is of course possible to connect the shield end portions 13a to 13d to the GND portion 25 via the capacitors C13a to C13d as in the third embodiment. Is possible. In this case, in addition to the effect of the third embodiment, the effect of the antenna device of the third embodiment can be further exhibited.

<Others>
The receiving circuit 21 shown in the present embodiment and covered entirely in plan view by the UHF antennas 1 to 3 generally comprises a filter, an amplifier, a transmitter, a mixer, a detector, a signal converter, and the like. It means a receiving circuit comprising an amplifier, an oscillator, a mixer, a detector and a signal converter, including all possible receiving circuits and excluding at least filters.

  In the present embodiment, UHF antennas 1 to 3 are shown as antennas, but it goes without saying that antennas other than “UHF” can also be used.

DESCRIPTION OF SYMBOLS 1-3 UHF antenna 10 Plane part 11 Feeding end part 12 Short-circuit end part 13a-13d Shield end part 14 Opening part 20 Parent board 21 Receiver circuit 22 GND connection stub 25 GND part C13a-C13d Capacitor

Claims (3)

A receiving circuit, a substrate having a stub portion to be grounded via a predetermined length of wiring and a ground portion on the surface;
An inverted F-shaped planar antenna provided on the substrate and having a planar portion disposed above the receiving circuit, the planar portion covering the entire surface of the receiving circuit in plan view;
The planar antenna includes a feeding part and a short-circuit part each extending downward from the planar part, the feeding part is connected to the receiving circuit, the short-circuit part is connected to the stub part, The power feeding part and the short-circuit part present a predetermined distance,
The planar antenna further includes at least one shield part extending downward from the planar part, and the at least one shield part is connected to the ground part, and the at least one shield part and the The distance to the power feeding unit is set to be twice or more the predetermined distance.
Antenna device. The antenna device according to claim 1,
The planar portion has at least one opening,
Antenna device. The antenna device according to claim 1 or 2,
Each of the at least one shield part is connected to the ground part via a capacitor,
Antenna device.

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