JPH0641213U - Directional variable antenna - Google Patents

Abstract

(57) [Summary] [Object] To provide a directional variable antenna for mobile communication, which is lightweight and compact, and which can obtain a sufficient gain for radio waves coming from the horizontal direction or 45 ° direction. A pair of antenna elements 4 and 7 in which conductors having a predetermined electrical length are respectively arranged and are separated by a predetermined distance L of a wavelength of a center frequency to be used, and a pair of these antenna elements 4 , 7 each having a phase control circuit 50 for inputting in-phase signals or signals that cause a phase difference of the predetermined distance with each other. [Effect] The structure is simple, lightweight and compact. By switching the directivity of the antenna characteristics, it is possible to obtain a sufficient gain for radio waves coming from the horizontal direction or the 45 ° direction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a mobile communication antenna suitable for mobile phones and so-called sign posts, and more particularly to a directional variable antenna whose directivity can be arbitrarily changed.

[0002]

[Prior art]

 Recently, mobile communication has been widely used, such as a mobile phone and a so-called sign post (Vehicle Information and Communication System) that sends information from the roadside to a moving body such as a moving vehicle. . At this time, for example, in-vehicle antennas used for this mobile communication are often used as flat antennas from the viewpoint of the appearance of the vehicle body, etc., but in the horizontal or 45 ° direction such as the above-mentioned mobile phones or sign posts. From the viewpoint of directivity, there were cases where sufficient gain could not be obtained for radio waves arriving from, or noise was added during voice conversion. Therefore, in order to obtain a sufficient gain, it has been possible to prevent noise by combining two or more planar antennas so that they have different directivities, or by arraying the planar antennas to have directivity. Attempts have been made to obtain a sufficient gain, but the problem is that the shape of the antenna becomes large.

[0003]

[Problems to be solved by the device]

 Therefore, the present invention has been made in view of the above problems, and it is possible to prevent noise by reducing the weight and size and changing the directivity even for the radio waves coming from the horizontal direction or the 45 ° direction. The aim is to provide a variable directivity antenna that can obtain a sufficient gain.

[0004]

[Means for Solving the Problems]

 The present invention has been made in order to achieve the above-mentioned object, and a pair of antennas in which conductors having a predetermined electric length are respectively arranged and are separated by a predetermined distance of a wavelength of a center frequency to be used. A directional variable antenna comprising an element and a phase control circuit for inputting a signal of the same phase or a signal which causes a phase difference of the predetermined distance to each conductor of the pair of antenna elements is configured.

[0005]

[Action]

 According to the present invention, the first and second antenna elements arranged at a distance of about 1/4 or about 1/2 of the wavelength λ of the center frequency to be used are provided with about 1 wavelength of the center frequency λ 1. By inputting a signal through a phase control circuit configured to generate a phase delay of / 4 or a phase delay of about 1/2, or by giving a signal of the same phase with no phase delay to the second antenna element, The resulting antenna characteristics, that is, the generation direction of the approximately four-leaf-shaped isoelectric field strength curve or the two-leaf-shaped isoelectric field strength curve can be made variable, which allows a signal coming from the horizontal direction or 45 ° direction to have a sufficient gain. Can be obtained. Therefore, by providing such an antenna, for example, in the rear tray section of an automobile and controlling the phase of the signal input to the antenna element, it is possible to change the generation direction of the equal electric field strength curve, that is, the directivity. Strong directivity can be generated in the front-rear direction or both sides of the vehicle. As a result, the variable directivity antenna according to the present invention can obtain a sufficient gain for radio waves coming from the horizontal direction or the 45 ° direction.

[0006]

【Example】

 Hereinafter, one embodiment of the directional variable antenna according to the present invention will be described with reference to the drawings. However, the present invention is not limited to this embodiment, and various modifications can be made within the concept of the present invention. . 1 is a perspective view of an embodiment of the variable directivity antenna according to the present invention, and FIG. 2 is a circuit diagram of the variable directivity antenna shown in FIG. 3 (A), (B), and (C) are a plan view, a front view, and a right side view, respectively, in one operating state of the directional variable antenna shown in FIG. 1, and FIG. , (B), (C) are a plan view, a front view, and a right side view, respectively, of the variable directivity antenna shown in FIG. 1 in different operating states. 5 (A), 5 (B), and 5 (C) are a plan view, a front view, and a right side view, respectively, in different operating states of another embodiment of the variable directivity antenna according to the present invention. 6 (A), 6 (B), and 6 (C) are a plan view, a front view, and a right side view, respectively, of the variable directivity antenna shown in FIG. 5 in different operating states. 1 to 6, the same parts will be described with the same reference numerals. The dotted lines shown in FIG. 3 to FIG. 6 indicate equal electric field strength curves.

Referring to FIG. 1, the first antenna element 4 and the second antenna element 7 are, for example, about a quarter, a third, or a eighth of the wavelength λ of the center frequency used. It has the meandering conductors 2 and 5 having the electric length of 5 and these conductors 2 and 5 are printed or embedded in the plate-shaped insulators 3 and 6. The first and second antenna elements 4 and 7 are arranged on one side of a printed circuit board 8 on the back surface of which a metal foil strip line is printed, in a substantially orthogonal direction and in a substantially parallel relationship with each other. At that time, as shown in FIG. 1, the separation distance L between the first and second antenna elements is arranged so as to have either one quarter or one half of the wavelength λ of the center frequency. ing. Although a conductive layer 10 such as a metal foil is provided on the upper surface of the print substrate 8, only the portion 17 where the first antenna element 4 is arranged and the portion 18 where the second antenna element 7 is arranged are made conductive. Layer 10 has been removed. The outer conductor 22 of the coaxial cable 20 is connected to the conductive layer 10.

Here, the stripline structure of the back surface of the printed circuit board 8 will be described. As shown in FIG. 2, the stripline structure is such that the internal conductor (not shown) of the coaxial cable 20 shown in FIG. A terminal a to be connected, a power supply wire 70 arranged between the terminals a to b, a power distribution circuit 60 arranged between the terminals b to c and terminals b to d, and arranged between the terminals i to j. In addition to having the phase control circuit 50, the first antenna element 4 is connected to the terminal c side through an impedance matching circuit 31 formed by a strip line, and the phase selection switch S and impedance matching are connected to the terminal d side. The second antenna element 7 is connected via the circuit 32. As shown in the figure, the switch S has switch pieces 41 and 42, and when the switch S is in the off state, the switch S is connected to the terminals e-f-g-h to connect the antenna elements 4 and 7 and the phase control circuit 50. The electrical connection between the antenna elements 4 and 7 and the phase control circuit 50 is electrically connected by disconnecting the electrical connection and connecting to the terminals e-i-j-h when the switch S is on. By connecting the antennas 4 and 7 with the phase control circuit 50, the phase of the signal input to the phase control circuit 50 can be selectively output to the antenna elements 4 and 7. The impedance matching circuits 31 and 32 are for matching the impedance of the strip lines with the conductors 2 and 5 of the antenna elements 4 and 7.

The operation of the above embodiment having the above-mentioned configuration will be described below. First, the separation distance L between the antenna elements 4 and 7 is about a quarter of the wavelength λ of the center frequency used, and the phase control circuit 50 determines the phase of a quarter of the wavelength λ of the center frequency used. The operation of the antenna characteristic of the directional variable antenna 1 when configured to cause a delay will be described with reference to FIGS. 2 to 4.

Now, when a power source (not shown) is turned on and the flat directional variable antenna 1 having the above-mentioned configuration is in an operating state, the switch S is turned off, and the first and second antenna elements 4 are fed from the power source (not shown). , 7 to which in-phase signals are supplied, the variable directivity antenna 1 has an almost four-leaf-shaped isoelectric field intensity curve as shown by the dotted lines in FIGS. Produces an antenna characteristic that has. Next, when the switch S is turned on, the phase control circuit 50 and the second antenna element 7 are connected to each other, and the second antenna element 7 is divided into four quarter wavelengths λ of the center frequency than the first antenna element 4. The signal having a phase delay of 1 is input, and the variable directivity antenna 1 is biased toward the second antenna element 7 as shown by the dotted lines in (A) to (C) of FIG. An antenna characteristic having an equal electric field strength curve is generated. Further, at this time, the meeting angle, that is, the elevation angle θ of these equal electric field strength curves is printed especially when the electrical length of the conductors 2 and 5 is 5/8 of the wavelength λ of the center frequency used. Since it is diffused in the range of about 15 to 60 degrees from the upper surface of the substrate 8, the equal electric field strength curve extends far.

As a result, the variable directivity antenna 1 can arbitrarily obtain the antenna characteristics shown in FIGS. 3 and 4 by switching the switch S between the on and off states. In this way, the isoelectric field strength curve can be extended in the horizontal direction by changing the antenna characteristics, that is, the generation direction of the isoelectric field strength curve, and a sufficient gain can be obtained even for signals coming from the horizontal direction or 45 ° direction. Can be obtained.

[0012]

[Effect of device]

 As described above, according to the present invention, it is not necessary to form an array of antennas in order to obtain a sufficient gain as in a conventional antenna, and therefore the antenna is not bulky, and the structure is simple and lightweight. In addition to being small, the directivity of the antenna characteristics can be switched by a simple operation of selectively using the phase control circuit with a switch, so that sufficient gain can be obtained for signals coming from the horizontal direction or 45 ° direction. be able to. Therefore, if it is used for a mobile phone or a sign post, it will be lightweight and compact, and stable communication will be possible.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a directional variable antenna according to the present invention.

FIG. 2 is a circuit diagram for supplying power to the variable directivity antenna shown in FIG.

FIG. 3 is a diagram showing one operating state of the variable directivity antenna shown in FIG. 1, (A) a plan view thereof, (B) a front view thereof,
(C) Right side view

4A and 4B are diagrams showing another operating state of the variable directivity antenna shown in FIG. 1, in which FIG. 4A is a plan view thereof, and FIG.
(C) Right side view

5A and 5B are views showing an operating state of another embodiment of the variable directivity antenna according to the present invention, in which FIG. 5A is a plan view thereof, FIG. 5B is a front view thereof, and FIG.

6 is a diagram showing another operating state of the variable directivity antenna shown in FIG. 5, (A) a plan view thereof, (B) a front view thereof,
(C) Right side view

[Explanation of symbols]

 1 directional variable antenna 2, 5 conductors 3, 6 insulator 4 first antenna element 7 second antenna element 8 printed circuit board 31, 32 matching circuit 41, 42 switch piece 50 phase control circuit 60 power distribution circuit 70 power supply line L separation distance S switch

Claims (1)

[Scope of utility model registration request] 1. A pair of antenna elements in which conductors having a predetermined electrical length are respectively arranged and are separated from each other by a predetermined distance of a wavelength of a center frequency to be used, and each of the pair of antenna elements. A directional variable antenna comprising: a conductor; and a phase control circuit for inputting in-phase signals or signals that cause a phase difference of the predetermined distance from each other.