JP2001345625A - Dual band antenna and constitution method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dual band antenna which is small in size, lightweight, possessed of an excellent VSWR, a high separation performance, and moreover equipped with two coaxial cables. SOLUTION: A member 1 and member 2 are lined vertical by straight and separated from each other in a vertical direction by a certain space to constitute a λa dipole antenna. The above member 2 is used in common to constitute a λb inverse F antenna utilizing the member 2 as its base plate. A reverse F antenna element is represented by a code 3 and resonates with λb. A trap 5 having an electrical length of λb/2 is provided so as to prevent high-frequency signals of λb from leaking out into a high-frequency circuit of λa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a dual-band antenna capable of simultaneously transmitting and receiving each type of radio wave, and a method of configuring the dual-band antenna, and more particularly to a dual-band antenna suitable for use in a frequency band used for a mobile radio device. is there.

[0002]

2. Description of the Related Art In the modern radio wave industry, the division of labor of various devices constituting a radio device, for example, ICs, wiring boards, antennas, etc., has been almost established. Mass production is taking place. Under these technical backgrounds, from an antenna manufacturer's point of view, what is demanded of a dual-band antenna is that a required VSWR (voltage constant) is required for two operating frequency bands designated by a general radio manufacturer. Wave ratio) and the required degree of separation.
Creating and supplying lightweight, low cost products.

[0003]

When a dual band antenna tuned to the wavelengths λa and λb is constructed based on the prior art, an antenna element tuned to the wavelength λa and an antenna element tuned to the wavelength λb are used. Unless the distance between them is increased, the degree of separation cannot be improved. However, if the two antenna elements are largely separated from each other, the overall size of the dual-band antenna becomes large, and thus the weight becomes large. Many of the conventional dual band antennas have only one coaxial cable for connection to a high frequency circuit of a wireless device. However, in such a case, it is necessary to provide a circuit for separating the two high-frequency signals carried by the one coaxial cable, so that two coaxial cables for the wavelengths λa and λb are provided. Is desirable. VSWR
In order to form a dual band having both excellent degree of separation and excellent antenna gain, the structure becomes complicated, so that the size, the weight and the cost must be increased. It is unlikely that it would be possible to solve all of these conditions all at once in a short period of time, but the inventor's desire was to make it somewhat closer than in the prior art. An object of the present invention is to provide a VSWR, a directional characteristic, and an antenna gain equivalent to those of a conventional single frequency band (non-dual band) antenna, and Each band has a coaxial cable, and there is no need to provide a "circuit for separating the signal of the wavelength λa and the signal of the wavelength λb" on the high frequency circuit side. Another object of the present invention is to provide a dual band antenna having a small increase in external dimensions as compared with a conventional single antenna, and a method of configuring the dual band antenna.

[0004]

The basic principle of the present invention created to achieve the above object will be briefly described with reference to FIG. 2 corresponding to the embodiment. That is, in order to provide a dual-band antenna that is small, lightweight, has excellent VSWR and excellent separation performance, and further includes two coaxial cables, the members denoted by reference numerals 1 and 2 are vertically moved. And a vertical dipole antenna for λa. The member denoted by reference numeral 2 is shared to constitute an inverted F antenna for λb using this as the ground plane. The reverse F is indicated by reference numeral 3.
An antenna element that resonates at λb / 4. λ
In order to prevent the high frequency signal b from leaking to the high frequency circuit λa, a trap 5 having an electrical length λb / 2 is provided.

[0005] Based on the principle described above, the construction of the method according to the first aspect of the present invention is to provide a dual band antenna having two tuning wavelength bands, around a wavelength λa and near a wavelength λb shorter than the wavelength λa. In the configuration method, a pair of dipole antenna elements having an electrical length of λa / 4 are arranged on substantially the same straight line in the vertical direction to configure a dipole antenna near the tuning wavelength range λa.
The lower dipole antenna element of the pair of dipole antenna elements is formed in a strip shape, and the strip-shaped antenna element is shared to constitute an inverted-F antenna near the tuning wavelength range λb using this as the ground plane. , Said 1
The lower end of the upper dipole antenna element of the pair of dipole antenna elements is connected to the core wire of the coaxial cable, and the outer conductor of the coaxial cable is connected to the ground plate of the inverted F antenna at a location immediately near the connection point. A trap that is connected to the lower dipole antenna element that is also used and that resonates at a wavelength λb is provided in the vicinity of a connection point between the core wire of the coaxial cable and the dipole antenna element.
The transmission and reception of radio waves of wavelength λa by the dipole antenna and the transmission and reception of radio waves of wavelength λb by the inverted F antenna are performed independently of each other. According to the method of the first aspect described above, the VSWR, the directional characteristics, and the antenna gain are the same as those of a single antenna, the degree of separation between frequency bands is excellent, and the conventional single unit antenna is used. A dual-band antenna whose external dimensions are not significantly increased as compared with the antenna can be configured at low cost. Since the lower dipole antenna element of the pair of dipole antenna elements constituting the dipole antenna is also used as the ground plane of the inverted F antenna, the number of components can be reduced. Since the lower antenna element of the pair of upper and lower dipole antenna elements has an elongated plate shape, it effectively functions as the ground plane of the inverted F antenna. By sharing one of the dipole antenna elements as the ground plane of the inverted-F antenna as described above, not only the number of components can be reduced, but also the space for arranging two types of antennas is reduced, and The band antenna is configured to be small as a whole. As described above, since the antenna element for the wavelength λa and the antenna element for the wavelength λb are extremely close to each other, there is a fear of interference between the two antennas. It has been confirmed theoretically and experimentally that the leakage to the high-frequency circuit having the wavelength λb is very small, and can be ignored in practical use. Conversely, there is no danger that the high-frequency signal of the shorter wavelength λb leaks into the high-frequency circuit of the longer wavelength λa. However, in the method of the present invention, a trap resonating at the wavelength λb is provided. Therefore, the feeding point of the dipole antenna element having the wavelength λa is always in a “zero voltage” state with respect to the high frequency having the wavelength λb, and does not leak into the high frequency circuit having λa. As described above, since the antenna of the tuning wavelength λa and the antenna of the tuning wavelength λb are prevented from mutual interference and function independently of each other, they exhibit the same VSWR, antenna gain, and directivity as in a single antenna. I do. Therefore, the separation between the two wavelengths is also sufficient to be practically perfect. Further, since coaxial cables are connected to the antenna element of the wavelength λa and the antenna element of the wavelength λb, the radio wave of the wavelength λa and the radio wave of the wavelength λb are transmitted and received as mutually independent high-frequency signals. There is no need to provide.

According to a second aspect of the present invention, in addition to the components of the second aspect of the present invention, the upper half of the pair of dipole antenna elements is located on the upper side of the pair of dipole antenna elements. By forming at least a part of the zigzag or helical shape, and by assembling a top heavy composite antenna element, the mechanical length of the dipole antenna near the tuning wavelength range λa is made shorter than the electrical length. It is characterized by doing. According to the method of the second aspect described above, the upper dipole antenna element of the pair of upper and lower dipole antenna elements constituting the dipole antenna must have an electrical length of λa / 4. Since the mechanical length is shorter than λa / 4, it is effective to shorten the length of the entire dual band antenna. The zigzag antenna element and the helical antenna element applied to the method of the second aspect of the present invention are both suitable for industrial production, and can supply a large number of products of uniform quality at low cost. . The manufacturing method of the zigzag-shaped antenna element according to the present invention is not limited.
A light-weight product with uniform electrical characteristics can be formed at low cost. In addition, by supporting the portion of the substrate member where the zigzag conductive pattern is not formed, the zigzag conductive pattern can be reliably positioned and supported. For example, even if the cordless telephone in which the dual-band antenna is installed is accidentally dropped and subjected to an impact, the zigzag conductive member is tightly fixed to the substrate, so that there is no danger of damage such as deformation. . Also, the method of manufacturing the dipole antenna element having the helical portion according to the present invention is not limited, but, for example, if the wire is formed by plastic working,
A product having an arbitrary shape and size can be easily mass-produced with uniform quality, and the finished helical portion can be easily modified. Moreover, since the helical shaped antenna element made of wire has elasticity, there is no danger of being permanently deformed even when subjected to an impact due to negligence of the user, and is excellent in durability. Considering these together, according to the method of the present invention,
Without including a complicated and fragile component, the mechanical external dimensions can be reduced more than the electrical length of the antenna element, and the entire dual-band antenna can be reduced in size.

According to a third aspect of the present invention, in addition to the constituent features of the first or second aspect of the present invention, the wavelength λa is set so that “the value obtained by rounding off the fractional part is 1 GHz to 4 GHz. Frequency, and the wavelength λb is the wavelength λa set as described above.
About 1/2 of the above. According to the method of the third aspect described above, the overall length of the dual-band antenna including the dipole antenna for the wavelength λa and the inverted-F antenna for the wavelength λb is reduced as a mobile radio antenna, particularly a cordless antenna. Since it is about several centimeters to about 20 centimeters, which is suitable as a telephone antenna, its application range is wide and its practical value is high. Moreover,
Since the wavelength λa is about twice the wavelength λb, the electrical length of the dipole antenna element having the electrical length of λa / 4 is substantially equal to λb / 2.

[0008] For this reason, the dimensional relationship between the lower dipole antenna element of the pair of upper and lower wavelength λa / 4 dipole antenna elements is matched so that the lower dipole antenna element is used as the ground plane of the inverted F antenna of wavelength λb. The gist of the invention method of claim 1, which is a basic invention on which this claim 3 is dependent, is further summarized in "Common use of lower element of dipole antenna and ground plate of inverted F antenna and installation of wavelength λb trap". is there. Therefore, the practical effect of facilitating electrical matching by setting the length dimension λa / 4 of the dipole antenna element to の of the tuning wavelength λb of the inverted-F antenna is great.

According to a fourth aspect of the present invention, in addition to any one of the first to third aspects of the present invention, the inverted F antenna near the tuning wavelength band λb is rectangular. A conductive plate-like member similar to the above is supported substantially parallel to the ground plate, and one of four corners of the rectangle is extended and connected to the ground plate to form a ground point, and A power supply point is set at a position apart from one corner of the rectangular plate member in both the width direction and the length direction of the rectangle, and an output end of the high-frequency circuit is connected to the power supply point.
It is characterized by conducting. According to the method of the fourth aspect described above, a high-performance inverted-F antenna can be configured as a component of the dual-band antenna. That is, excellent VSWR around wavelength λb
It is possible to configure an inverted-F antenna having characteristics, excellent separation properties with respect to the wavelength λa, high antenna gain, and having a wide tuning wavelength range near the wavelength λb. The reason why such an effect can be obtained is mainly that “the feed point of the conventional inverted F antenna is farther away from the ground point in either the length direction or the width direction of the antenna element”. This is due to the fact that the feeding point of the inverted-F antenna according to the present invention is separated in both the length direction and the width direction of the plate-shaped antenna element.

The method according to the fifth aspect of the present invention is characterized in that the wavelength λ
a and a pair of dipole antenna elements having an electrical length of λb / 4 in a vertical direction in a method of constructing a dual band antenna having two tuning wavelength ranges, ie, near a and near a wavelength λb shorter than the wavelength λa. To form a dipole antenna in the vicinity of the tuning wavelength range λb, and positioned below the dipole antenna and along the coaxial cable connected to the dipole antenna to form a tuning wavelength range. Inverse F of about λa
An antenna is arranged, and the coaxial cable of the dipole antenna and the coaxial cable of the inverted-F antenna are individually connected to a high-frequency circuit to transmit and receive radio waves of wavelength λb by the dipole antenna and the wavelength by the inverted-F antenna. The transmission and reception of the radio wave of λa are performed without mutual interference. According to the method of the present invention described above, the dipole antenna for the wavelength λb and the inverted F antenna for the wavelength λa are antennas of different types, and are vertically deviated from each other in a straight line in the vertical direction. Since the antennas are opposed to each other, each antenna functions independently without causing any interference without a large interval. The dipole antenna located above has a characteristic of 3
It has uniform directional characteristics in the 60-degree direction, and has extremely low sensitivity in the vertical and vertical directions. The inverted-F antenna is located at the “lower sensitivity”. Metaphorically speaking, since the inverted F antenna is in the blind spot of the dipole antenna, they do not interfere with each other. Since they do not interfere with each other, there is no need to keep a large distance between both antennas, and therefore, the overall length of the dual band antenna is reduced. Along with this, the attached members such as the antenna cover are also small and lightweight, so that the overall external dimensions of the dual band antenna are reduced and the weight is reduced. As described above, the dipole antenna having the wavelength λb and the inverted-F antenna having the wavelength λa function independently, so that the same VSWR, antenna gain, and directional characteristics as those of a single antenna are obtained, and the functions are independent. The separation performance is good. As described above, since the antenna element for the wavelength λa and the antenna element for the wavelength λb are arranged without using any special connecting means, the structure is simple and the manufacturing cost is low. When the construction method of the present invention is applied to industrial production, high accuracy is not required for relative positioning between the dipole antenna and the inverted-F antenna, so that the assembling process can be performed easily and quickly, and furthermore, the manufacturing process can be easily performed. In the final stage of adjustment and inspection, it is sufficient to individually inspect the characteristics of the dipole antenna and the inverted-F antenna, and it is not necessary to consider the electrical coupling state (for example, capacitive coupling) between both antennas. Is also good.

A dual band antenna according to a sixth aspect of the present invention is a dual band antenna having two tuned wavelength bands near a wavelength λa and near a wavelength λb shorter than the wavelength λa. A pair of
A dipole antenna element having an electrical length of about λa / 4 is provided, and the lower dipole antenna element of the pair of dipole antenna elements is used in common to form an electrical length of about λb / 4 inverted F antenna elements are provided, and the core wire of one coaxial cable of the two coaxial cables is connected to the upper dipole antenna element of the pair of dipole antenna elements, and An outer conductor of a coaxial cable is connected to the common ground plane, and a core wire of the other coaxial cable of the two coaxial cables is connected to a feed point of the inverted F antenna element,
An outer conductor of the other coaxial cable is connected to the common ground plane, and a trap resonating at a wavelength of λb is connected to a location immediately near a connection point between the core wire of the one coaxial cable and the dipole antenna element. It is characterized by having been done. According to the dual band antenna of claim 6 described above, the same V
A low-cost dual-band antenna having SWR, directional characteristics, and antenna gain, having excellent frequency band separation, and having no remarkable increase in external dimensions as compared with the conventional single antenna. Can be. The lower dipole antenna element of the pair of dipole antenna elements constituting the dipole antenna is
Since it is also used as the ground plane of the inverted F antenna, the number of components can be reduced. Since the lower antenna element of the pair of upper and lower dipole antenna elements has an elongated plate shape, it effectively functions as the ground plane of the inverted F antenna. By sharing one of the dipole antenna elements as the ground plane of the inverted-F antenna as described above, not only the number of components can be reduced, but also the space for arranging two types of antennas is reduced, and The band antenna is configured to be small as a whole. As described above, since the antenna element for the wavelength λa and the antenna element for the wavelength λb are extremely close to each other, there is a fear of interference between the two antennas. Leakage into the high-frequency circuit of the shorter wavelength λb has been confirmed theoretically and experimentally to be insignificant, and can be ignored in practical use. On the contrary, although there is no danger that the high-frequency signal of the shorter wavelength λb leaks into the high-frequency circuit of the longer wavelength λa, the antenna according to claim 6 is provided with a trap that resonates at the wavelength λb. Therefore, the feeding point of the dipole antenna element of the wavelength λa is always in a “zero voltage” state with respect to the high frequency of the wavelength λb, and does not leak into the high frequency circuit of λa. Then, as described above, the antenna of the tuning wavelength λa and the antenna of the tuning wavelength λb are prevented from mutual interference and function independently of each other.
It exhibits the same VSWR, antenna gain, and directivity as a single antenna. Therefore, the separation between the two wavelengths is also sufficient to be practically perfect. further,
Since a coaxial cable is connected to each of the antenna element of the wavelength λa and the antenna element of the wavelength λb, the radio wave of the wavelength λa and the radio wave of the wavelength λb are transmitted and received as mutually independent high-frequency signals. No need.

According to a seventh aspect of the present invention, in addition to the configuration of the sixth aspect, the trap resonating at the wavelength λb is constituted by using a coaxial cable as a main material or a coaxial cable. And (a) the electrical length is about λb
/ (B) at one end, the core of the trap is connected to the "connection point between the core of the one coaxial cable and the dipole antenna", and (c) at the one end, An outer conductor of the trap is connected to an outer conductor of the one coaxial cable, and (d) at the other end of the trap, the core wire and the outer conductor are connected to have zero electrical resistance. According to the seventh aspect of the present invention described above, the trap of the wavelength λb can be configured quickly, easily and at low cost by using a coaxial cable which is industrially mass-produced and supplied at low cost. When resonance is performed at a half wavelength with the end of the core wire of the coaxial cable dropped to the ground, the voltage at the base end is always zero. When viewed from the base end side with respect to the wavelength λb, the impedance is infinite, and the high-frequency signal of the wavelength λb does not affect the high-frequency circuit of the wavelength λa, and the coaxial cable (general off-the-shelf or similar product) is flexible. Therefore, it is easy to insert and store the antenna element including the trap into the pipe-shaped antenna cover, and since it is flexible, it is excellent in impact resistance. In the coaxial cable, the outer periphery of the outer conductor is coated with an electrically insulating material, so that the outer conductor of the trap can be brought into contact with another component (for example, an inverted-F antenna element) by simply using the outer conductor. This is convenient because there is no danger of doing so.

According to an eighth aspect of the present invention, the upper dipole antenna element of the pair of dipole antenna elements has a zigzag shape in at least a part thereof, preferably an upper half or an upper end. Or at least a part, preferably an upper half or an upper end, is formed in a helical shape. According to the eighth aspect of the present invention described above, the upper dipole antenna element of the pair of upper and lower dipole antenna elements constituting the dipole antenna must have an electrical length of λa / 4. Since the mechanical length is shorter than λa / 4, it is effective to reduce the length of the dual band antenna as a whole. The zigzag antenna element and the helical antenna element applied to the invention of claim 8 are:
All of them are suitable for industrial production and can supply a large quantity of products of uniform quality at low cost. The manufacturing method of the zigzag-shaped antenna element according to the present invention is not limited. However, when a known technique for forming a wiring board is applied, a light-weight product having the same shape and dimensions, uniform electrical characteristics, and low weight can be obtained. Can be configured at cost. In addition, by supporting the portion of the substrate member where the zigzag conductive pattern is not formed, the zigzag conductive pattern can be reliably positioned and supported. For example, even if the cordless telephone in which the dual-band antenna is installed is accidentally dropped and subjected to an impact, the zigzag conductive member is tightly fixed to the substrate, so that there is no danger of damage such as deformation. . Also, the method of manufacturing the dipole antenna element having a helical portion according to the present invention is not limited. For example, if a wire is formed by plastic working, a product having an arbitrary shape and size can be easily produced in large quantities with uniform quality. In addition to being able to be produced, it is easy to modify the resulting helical part. Moreover, since the helical shaped antenna element made of wire has elasticity, there is no danger of being permanently deformed even when subjected to an impact due to negligence of the user, and is excellent in durability. Considering all of these considerations, according to the antenna of the present invention, it is possible to reduce the mechanical external dimensions rather than the electrical length of the antenna element without including complicated and fragile components, The whole antenna can be reduced in size.

According to a ninth aspect of the present invention, in addition to the constitutional requirements of the sixth aspect of the present invention, the lower dipole antenna shared with the ground plane of the inverted F antenna element includes the inverted dipole antenna. It is characterized in that it is extended upward from the ground point of the F antenna element by an electrical length of about λb / 4, and the extended portion functions as a λb / 4 ground plane dedicated to the inverted F antenna.

According to the ninth aspect of the present invention described above,
Since the inverted F antenna used near the wavelength λb is provided with the dedicated ground plane having an electrical length of λb / 4, the electrical characteristics of the inverted F antenna are further improved. That is, the antenna gain is increased, the VSWR is improved, and the isolation of the wavelength λa from the high frequency is further improved. The invention of claim 9 can be applied to any of claims 6 to 8 and has the above-mentioned effects. However, it is particularly suitable to be applied to the invention of claim 8, for the following reason. Like. That is, the upper dipole antenna element of the pair of dipole antenna elements according to the eighth aspect of the present invention has a so-called top heavy shape, and the upper half thereof is formed in a zigzag or helical shape. Therefore, the lower half of the upper dipole antenna element can be formed as a linear antenna. Therefore, the exclusive ground plate having an electrical length of λb / 4 according to the ninth aspect of the present invention can be properly placed in a narrow space along the linear portion so as not to interfere with the zigzag portion or the helical portion. it can. In this case, if the wavelength λb is set to about half of the wavelength λa, the electrical length (substantially equal to the mechanical length) of the dedicated ground plane of λb / 4 of the inverted F antenna is roughly λa It is half the mechanical length of a / 4 dipole antenna. For this reason, interference with the zigzag portion or the helical portion formed in the upper half of the λa / 4 dipole antenna is avoided, and the half length is formed in the space beside the linear portion formed in the lower half thereof. Can be provided with a special ground plate.

According to a tenth aspect of the present invention, in addition to the constituent features of the sixth to ninth aspects, the inverted F antenna element has a substantially L-shaped conductive member. And one of the two sides having an L-shape is connected to and connected to the base plate, and the other of the two sides has an elongated plate shape. And the feeding point of the inverted-F antenna element is substantially parallel to the ground plane, and the feeding point of the inverted F antenna element is located in the elongated plate-shaped portion on the other side, and extends in the length direction from the L-shaped bending point. Are also separated in the width direction.

According to the antenna of the tenth aspect described above, a high-performance inverted-F antenna can be configured as a component of the dual band antenna. That is,
An inverted-F antenna having excellent VSWR characteristics near the wavelength λb, excellent isolation from the wavelength λa, high antenna gain, and having a wide tuning wavelength band near the wavelength λb can be configured. . The reason why such an effect can be obtained is mainly that “the feed point of the conventional inverted F antenna is farther away from the ground point in either the length direction or the width direction of the antenna element”. This is due to the fact that the feeding point of the inverted-F antenna according to the present invention is separated in both the length direction and the width direction of the plate-shaped antenna element.

The dual-band antenna according to the eleventh aspect of the present invention is a dual-band antenna having two tuning wavelength ranges of about a wavelength λa and near a wavelength λb shorter than the wavelength λa. A pair of electric lengths of approximately λb, which are opposed to each other on a straight line and spaced apart from each other,
/ 4 dipole antenna element, a coaxial cable connected to the pair of dipole antenna elements, an inverted F antenna arranged along the coaxial cable and having a tuning wavelength range of about λb, and an inverted F antenna. And a separate coaxial cable connected to the F antenna. The dual-band antenna according to the eleventh aspect described above has excellent antenna characteristics, and is small, lightweight, and low-cost.

[0019]

FIG. 2 is a schematic front external view showing an embodiment of a dual-band antenna according to the present invention, in which both a mechanical configuration and an electrical configuration are illustrated. FIG. 10 is a diagram corresponding to claim 1 and claim 6. The present embodiment is configured for a cordless telephone, and the performance parameters (target quality) targeted for development are as follows. Working frequency band corresponding to λa 900 to 930 MHz Working frequency band corresponding to λb 1.85 to 1.99 G
Hz Antenna gain and directional characteristics are equivalent to those of conventional single antennas, output cables are provided for each frequency band, and the degree of isolation between antennas is sufficient for cordless telephones. The overall length of the antenna should not be significantly larger than a conventional single antenna.

When the present invention is applied, the value is not necessarily limited to the above-mentioned tuning frequency band.
If the wavelength corresponding to the frequency is λa and the wavelength corresponding to the frequency whose rounded value is 2 GHz is λb, a sufficient effect can be obtained. A dipole antenna tuned to the wavelength λa is indicated by the reference symbol a, and a pair of dipole antenna elements having an electrical length λa are arranged along a straight line in the vertical direction, and are opposed and separated vertically. is there. The dual band antenna of the present invention
It is sufficiently possible to use this in an oblique position, and the above "up and down" is a name for convenience of explanation,
It does not limit the technical scope of the present invention. In FIGS. 1, 2, 3, 7, 8, and 9, “up and down” for convenience corresponds to the upper and lower sides of the drawing, but does not match in FIG. 4.

The member denoted by reference numeral 1 has an electrical length λ.
a dipole antenna element constituted by a line of a / 4, and a member denoted by reference numeral 2 is an elongated plate-like member having an electrical length of λa / 4, and acts as a dipole antenna element; In cooperation with the dipole antenna element 1, a dipole antenna having a wavelength λa is formed. The above-mentioned elongated plate-shaped member 2 is used in common, and the inverted F antenna b for λb is provided by using this as the ground plane. The member denoted by reference numeral 3 is an inverted F antenna element. The detailed structure of the inverted F antenna element 3 will be described later with reference to FIG. 6 is λ
a coaxial cable of the dipole antenna a, the core wire of which is connected and conductive to the feeding point (lower end) of the dipole antenna element 1, and the outer conductor of the coaxial cable is shared by the above-mentioned "member 2", i.e. Connected to the ground plate and dipole antenna element.

Reference numeral 6 'denotes a coaxial cable of the .lambda.b inverted-F antenna b, the outer conductor of which is connected to the common ground plane 2, and whose core is connected to the feeding point s of the inverted-F antenna element 3.
Is electrically connected. The detailed structure near the feeding point s will be described later with reference to FIG. The trap denoted by reference numeral 5 is a trap that resonates at the wavelength λb. The trap 5 of this embodiment cuts the coaxial cable to an electrical length of about λb / 2, and connects one end (upper end in the figure) of the core to “connection between the core of the coaxial cable 6 and the λa dipole antenna element 1”. And the upper end of the outer conductor is connected and connected to the outer conductor of the coaxial cable 6 at the ground point E ". In FIG. 2, the structure is slightly expanded for easier reading. , The ground point E, the ground point E ', and the ground point E "are apart from each other, but these ground points E, E', and E" are substantially the same point. At the lower end of the cable trap 5, the core wire 5b is short-circuited 5c to the outer conductor 5a so that the ohmic resistance becomes zero.

FIG. 3 is a schematic view illustrating various types of traps. FIG. 3B is a half view similar to that shown in FIG.
The wavelength trap, (A) is a 波長 wavelength trap, and (C) is a ／ wavelength trap. It is also possible to apply the quarter-wave trap shown in FIG. 3A instead of the half-wave trap shown in FIG. 3B. Although the weight is reduced, in the embodiment of FIG. 2 described above, since these advantages are not so important, a 1/2 wavelength (λb / 2) trap having a stable trapping function is used. FIG. 1 is a partially cutaway perspective view schematically illustrating the dual-band antenna according to the embodiment shown in FIG. 2 described above, and claims 1, 2, 6, 7, 8, and 9. Nine configurations have appeared. However, the distance between the coaxial cable and the trap is enlarged, and is not a sketch. The dipole antenna element 1 for λa is a composite type, and the lower half 1a is a linear antenna element 1
a, and the upper half is formed by a zigzag antenna element 1b. A helical shape can be used instead of the zigzag shape. However, the zigzag shape has higher industrial productivity and is suitable for mass production at low cost by applying printed circuit board technology. As mentioned above,
When a so-called top heavy type is used, the mechanical length is reduced as compared with the electrical length, and the size and weight of the entire dual band antenna can be reduced. Utilizing the space beside the linear antenna element 1a, λa,
The λb common ground plane 2 is extended above the ground point E ′ by an electrical length λb / 4 to form a 波長 wavelength ground plane dedicated to the inverted F antenna. When such a λb / 4 ground plane 4 is provided, the characteristics of the inverted-F antenna are improved, and its operation is stabilized.

FIG. 4 is a view for explaining an inverted-F antenna. FIG. 4A is a principle diagram of the inverted-F antenna.
(B) is a perspective view schematically depicting a conventional example of the inverted-F antenna, and (C) is a perspective view schematically depicting the embodiment, and corresponds to claims 4 and 10. ing.
(See FIG. 4A.) The inverted-F antenna element 3 has an L-shape, is electrically connected to the ground plane 8, and resonates at a quarter wavelength. The output terminal of the high-frequency circuit 7 is connected to the feeding point s of the inverted-F antenna element 3 and is conducted. This is reverse F
This is a basic configuration of an antenna. (See FIG. 4 (B).) In the conventional inverted F antenna element 3 ', a portion parallel to the base plate 8 is formed in a "rectangular plate shape having a width W and a length L", and a feeding point s' Is set at a position away from the ground point E in the width direction. (See FIG. 4C.) When only the inverted F antenna element 3 of the present embodiment is extracted and considered, it has a shape similar to that of the conventional inverted F antenna element 3 '. However, the portion parallel to the base plate 8 does not necessarily need to be exactly rectangular, and any shape similar to a rectangle is sufficient. The feeding point s of the inverted F antenna according to the present embodiment is set at a position away from the ground point E in both the width direction (W) and the length direction (L). Thereby, an inverted-F antenna having good antenna characteristics is configured.

FIG. 5 shows the characteristics of the dipole antenna of the embodiment shown in FIGS. 1 and 2 described above, and FIG.
VSWR of the 00 MHz dipole antenna, (B) is isolation. Around 900MHz, 875-9
At 50 MHz, the VSWR is 3 or less. Further, the isolation also indicates a good degree of separation.

FIGS. 6A and 6B show the characteristics of the 1.9 GHz inverted-F antenna. FIG. 6A shows the VSWR, and FIG. 6B shows the isolation. As can be seen from FIG. 6A, the inverted-F antenna of the present embodiment (FIGS. 1 and 2) has a VSWR of 3 or less in the used frequency band (1.85 to 1.99 GHz), and has a wide tuning frequency. It has a band. When the trap 5 for λb is removed from the dual band antenna of the embodiment of FIGS. 1 and 2, the curve in FIG. 6B becomes a dotted line, and when the trap 5 for λb is attached, it becomes a solid line. This shows that the trap is extremely effective in improving the degree of separation.

FIG. 7 is a schematic front view showing an embodiment different from those of FIGS. 1 and 2 described above.
And the sixth configuration. FIG. 8 corresponds to FIG.
FIG. 2 is a schematic perspective view illustrating the dual band antenna according to the embodiment shown in FIG. Reference numerals 9a and 9b denote dipole antenna elements each having an electrical length of λb / 4. The dipole antenna elements are arranged on one straight line in the vertical direction, are vertically opposed to each other, are connected to the coaxial cable 6, and are connected to the dipole for the wavelength λb. Make up the antenna. A ground plane 11 for an inverted-F antenna is arranged along the coaxial cable 6, and an inverted-F antenna element 10 is connected to and connected to the ground plane 11, thereby forming an inverted-F antenna for a wavelength λa.
Reference numeral 6 ″ denotes a coaxial cable of the inverted F antenna for λa, the core wire of which is connected and connected to the feeding point s, and the outer conductor is connected and connected to the ground plane 11. The dipole antenna elements 9a and 9b are provided. The λb dipole antenna has, as characteristics common to the linear dipole antenna, a uniform sensitivity of 180 degrees in the horizontal direction and almost zero sensitivity in the vertical direction. Since the inverted F antenna for λa is positioned in the direction, the dipole antenna for λb and the inverted F antenna for λa function independently as a single antenna without interfering with each other.

For this reason, the dual band antenna of the present embodiment (FIGS. 7 and 8) has a wavelength λb
Can exhibit the same characteristics as a single antenna. Moreover, its simple structure makes it lightweight,
Small size and low manufacturing cost.

FIG. 9 is an overall view of a state in which the dual-band antenna according to the present invention is housed in an antenna cover and is supported by an antenna cover holder so as to be rotatable. FIG. 1 and the dual band antenna of the embodiment shown in FIGS. 7 and 8 are drawn by hidden lines, respectively.

As described above, λa = 900 MHz,
λb = 1.9 GHz, and in this case, the dimension La from the rotation center line XX ′ of the antenna to the tip of the antenna cover
Is 160 mm and Lb is 170 mm.

[0031]

As described above, according to the embodiment of the present invention, the configuration and function of the present invention are clarified.
A low-cost dual-band antenna with directional characteristics and antenna gain, excellent degree of separation between frequency bands, and with no significant increase in external dimensions compared to the conventional single antenna Can be. Since the lower dipole antenna element of the pair of dipole antenna elements constituting the dipole antenna is also used as the ground plane of the inverted F antenna, the number of components can be reduced. Since the lower antenna element of the pair of upper and lower dipole antenna elements has an elongated plate shape, it effectively functions as the ground plane of the inverted F antenna.
By sharing one of the dipole antenna elements as the ground plane of the inverted-F antenna as described above, not only the number of components can be reduced, but also the space for arranging two types of antennas is reduced, and The band antenna is configured to be small as a whole. As described above, since the antenna element for the wavelength λa and the antenna element for the wavelength λb are extremely close to each other, there is a fear of interference between the two antennas. It has been confirmed theoretically and experimentally that the leakage to the high-frequency circuit having the wavelength λb is very small, and can be ignored in practical use. Conversely, the high-frequency signal of the shorter wavelength λb has the longer wavelength λa
However, in the method of the present invention, since a trap resonating at the wavelength λb is provided, the feed point of the dipole antenna element having the wavelength λa is set at the wavelength λb. Is always "zero voltage", and does not leak into the high frequency circuit of λa. As described above, since the antenna of the tuning wavelength λa and the antenna of the tuning wavelength λb are prevented from mutual interference and function independently of each other, they exhibit the same VSWR, antenna gain, and directivity as in a single antenna. I do. Therefore, the separation between the two wavelengths is also sufficient to be practically perfect. Further, since coaxial cables are connected to the antenna element of the wavelength λa and the antenna element of the wavelength λb, the radio wave of the wavelength λa and the radio wave of the wavelength λb are transmitted and received as mutually independent high-frequency signals. There is no need to provide.

According to the second aspect of the present invention, the upper dipole antenna element of the pair of upper and lower dipole antenna elements constituting the dipole antenna is:
The electrical length must be λa / 4, but the mechanical length is shorter than λa / 4, which is effective in shortening the length of the dual band antenna as a whole. The zigzag antenna element and the helical antenna element applied to the method of the second aspect of the present invention are both suitable for industrial production, and can supply a large number of products of uniform quality at low cost. . The manufacturing method of the zigzag-shaped antenna element according to the present invention is not limited. However, when a known technique for forming a wiring board is applied, a light-weight product having the same shape and dimensions, uniform electrical characteristics, and low weight can be obtained. Can be configured at cost. In addition, by supporting the portion of the substrate member where the zigzag conductive pattern is not formed, the zigzag conductive pattern can be reliably positioned and supported. For example, even if the cordless telephone in which the dual-band antenna is installed is accidentally dropped and subjected to an impact, the zigzag conductive member is tightly fixed to the substrate, so that there is no danger of damage such as deformation. . Also, the method of manufacturing the dipole antenna element having the helical portion according to the present invention is not limited. For example, if a wire is formed by plastic working, a product having an arbitrary shape and size can be easily mass-produced with uniform quality. And it is easy to modify the resulting helical portion. Moreover, since the helical shaped antenna element made of wire has elasticity, there is no danger of being permanently deformed even when subjected to an impact due to negligence of the user, and is excellent in durability. Considering these together, according to the method of the present invention, it is possible to reduce the mechanical length dimension rather than the electrical length of the antenna element without including complicated and fragile components, The entire dual band antenna can be reduced in size.

According to the third aspect of the present invention, the overall length of the dual band antenna including the dipole antenna for the wavelength λa and the inverted F antenna for the wavelength λb is set as an antenna for a mobile radio device, particularly a cordless telephone. Since it is about several centimeters to 20 centimeters, which is suitable as a dexterous antenna, the applicable range is wide and the practical value is high. In addition, since the wavelength λa is about twice as large as the wavelength λb, the electrical length of the dipole antenna element having the electrical length of λa / 4 is substantially equal to λb / 2.
For this reason, the dimensional relationship between the pair of upper and lower wavelength λa / 4 dipole antenna elements is matched so that the lower dipole antenna element of the pair of upper and lower wavelength λa / 4 dipole antenna elements is used as the ground plane of the inverted F antenna of wavelength λb. The gist of the invention method of claim 1, which is a basic invention on which this claim 3 is dependent, is further summarized in "Common use of lower element of dipole antenna and ground plate of inverted F antenna and installation of wavelength λb trap". is there. Therefore, the practical effect of facilitating electrical matching by setting the length dimension λa / 4 of the dipole antenna element to の of the tuning wavelength λb of the inverted-F antenna is great.

According to the method of the present invention, an inverted-F antenna having good performance can be formed as a component of the dual band antenna. That is, to constitute an inverted-F antenna having excellent VSWR characteristics near the wavelength λb, excellent separation properties for the wavelength λa, high antenna gain, and having a wide tuning wavelength range near the wavelength λb. Can be. The reason why such an effect can be obtained is mainly that “the feed point of the conventional inverted F antenna is farther away from the ground point in either the length direction or the width direction of the antenna element”. This is due to the fact that the feeding point of the inverted-F antenna according to the present invention is separated in both the length direction and the width direction of the plate-shaped antenna element.

According to the fifth aspect of the present invention, the dipole antenna for the wavelength λb and the inverted F antenna for the wavelength λa are different types of antennas, and are vertically opposed to each other in a straight line in the vertical direction. Therefore, each antenna functions independently without causing interference even without a large interval. The dipole antenna located above is a characteristic of the dipole antenna,
In a horizontal plane, the directional characteristics are uniform in the 360-degree direction, and the sensitivity in the vertical and vertical directions is extremely low. The inverted-F antenna is located at the “lower sensitivity”. Metaphorically speaking, since the inverted F antenna is in the blind spot of the dipole antenna, they do not interfere with each other. Since they do not interfere with each other, there is no need to keep a large distance between both antennas, and therefore, the overall length of the dual band antenna is reduced. Along with this, the attached members such as the antenna cover are also small and lightweight, so that the overall external dimensions of the dual band antenna are reduced and the weight is reduced. As described above, the wavelength λ
b, and the inverted-F antenna of wavelength λa function independently of each other, so that the same VSWR, antenna gain, and directional characteristics as those of a single antenna are obtained. Is good. As described above, since the antenna element for the wavelength λa and the antenna element for the wavelength λb are arranged without using any special connecting means, the structure is simple and the manufacturing cost is low. When the construction method of the present invention is applied to industrial production, high accuracy is not required for relative positioning between the dipole antenna and the inverted-F antenna, so that the assembling process can be performed easily and quickly, and furthermore, the manufacturing process can be easily performed. In the final stage of adjustment and inspection, it is sufficient to individually inspect the characteristics of the dipole antenna and the inverted-F antenna, and it is not necessary to consider the electrical coupling state (for example, capacitive coupling) between both antennas. Is also good.

According to the dual band antenna of the sixth aspect, the antenna has the same VSWR, directional characteristics, and antenna gain as those of the single antenna, has excellent frequency band separation, and has the same characteristics as the conventional single antenna. In comparison, a dual-band antenna whose external dimensions are not significantly increased can be configured at low cost. Since the lower dipole antenna element of the pair of dipole antenna elements constituting the dipole antenna is also used as the ground plane of the inverted F antenna, the number of components can be reduced. Since the lower antenna element of the pair of upper and lower dipole antenna elements has an elongated plate shape, it effectively functions as the ground plane of the inverted F antenna.
By sharing one of the dipole antenna elements as the ground plane of the inverted-F antenna as described above, not only the number of components can be reduced, but also the space for arranging two types of antennas is reduced, and The band antenna is configured to be small as a whole. As described above, since the antenna element for the wavelength λa and the antenna element for the wavelength λb are extremely close to each other, there is a fear of interference between the two antennas. Leakage into the high-frequency circuit of the shorter wavelength λb has been confirmed theoretically and experimentally to be insignificant, and can be ignored in practical use. On the contrary, although there is no danger that the high-frequency signal of the shorter wavelength λb leaks into the high-frequency circuit of the longer wavelength λa, the antenna according to claim 6 is provided with a trap that resonates at the wavelength λb. Therefore, the feeding point of the dipole antenna element of the wavelength λa is always in a “zero voltage” state with respect to the high frequency of the wavelength λb, and does not leak into the high frequency circuit of λa. As described above, since the antenna of the tuning wavelength λa and the antenna of the tuning wavelength λb are prevented from mutual interference and function independently of each other, they exhibit the same VSWR, antenna gain, and directivity as in a single antenna. I do. Therefore, the separation between the two wavelengths is also sufficient to be practically perfect. Further, since the coaxial cable is connected to each of the antenna element of the wavelength λa and the antenna element of the wavelength λb, the radio wave of the wavelength λa and the radio wave of the wavelength λb are transmitted and received as mutually independent high-frequency signals. There is no need to provide

According to the seventh aspect of the present invention, using a coaxial cable which is industrially mass-produced and supplied at a low cost,
A trap of wavelength λb can be configured quickly, easily and at low cost. When resonance is performed at a half wavelength with the end of the core wire of the coaxial cable dropped to the ground, the voltage at the base end is always zero. That is, the trap configured as described above has an infinite impedance when viewed from the base end side with respect to the wavelength λb, and the high-frequency signal of the wavelength λb does not affect the high-frequency circuit of the wavelength λa. Moreover,
The coaxial cable (general off-the-shelf product or similar product) is flexible, and the operation of inserting the antenna element including the trap into the pipe-shaped antenna cover and storing it therein is easy. In addition, since it is flexible, it has excellent impact resistance. Further, in the coaxial cable generally supplied, since the outer periphery of the outer conductor is coated with an electrically insulating material, the outer conductor of the trap is used as it is, and the outer conductor of the trap is made up of another component (for example, an inverted F antenna element). This is convenient because there is no danger of contact conduction with.

According to the eighth aspect of the present invention, the upper dipole antenna element of the pair of upper and lower dipole antenna elements constituting the dipole antenna must have an electrical length of λa / 4. Since the actual length is shorter than λa / 4, it is effective to shorten the length of the entire dual band antenna. The zigzag antenna element and the helical antenna element applied to the invention of claim 8 are both suitable for industrial production, and can supply a large number of products of uniform quality at low cost. The manufacturing method of the zigzag-shaped antenna element according to the present invention is not limited. However, when a known technique for forming a wiring board is applied, a light-weight product having the same shape and dimensions, uniform electrical characteristics, and low weight can be obtained. Can be configured at cost. In addition, by supporting the portion of the substrate member where the zigzag conductive pattern is not formed, the zigzag conductive pattern can be reliably positioned and supported. For example, even if the cordless telephone in which the dual-band antenna is installed is accidentally dropped and subjected to an impact, the zigzag conductive member is tightly fixed to the substrate, so that there is no danger of damage such as deformation. . Also, the dipole antenna element having the helical portion according to the present invention is not limited to the manufacturing method,
For example, if the wire is formed by plastic working, a product having an arbitrary shape and size can be easily mass-produced with uniform quality, and the finished helical portion can be easily corrected. Moreover, since the helical shaped antenna element made of wire has elasticity, there is no danger of being permanently deformed even when subjected to an impact due to negligence of the user, and is excellent in durability. Considering all of these considerations, according to the antenna of the present invention, it is possible to reduce the mechanical external dimensions rather than the electrical length of the antenna element without including complicated and fragile components, The whole antenna can be reduced in size.

According to the ninth aspect of the present invention, the inverted F antenna used near the wavelength λb is provided with the dedicated ground plane having an electrical length of λb / 4, so that the electrical characteristics of the inverted F antenna are further improved. . That is, the antenna gain is increased, the VSWR is improved, and the isolation of the wavelength λa from the high frequency is further improved. The invention of claim 9 can be applied to any of claims 6 to 8 and has the above-mentioned effects. However, it is particularly suitable to be applied to the invention of claim 8, for the following reason. Like. That is,
The upper dipole antenna element of the pair of dipole antenna elements according to the invention of claim 8 described above has a so-called top heavy shape, and its upper half is formed in a zigzag or helical shape. The lower half of the upper dipole antenna element can be formed as a linear antenna. Therefore, the exclusive ground plate having an electrical length of λb / 4 according to the ninth aspect of the present invention can be properly placed in a narrow space along the linear portion so as not to interfere with the zigzag portion or the helical portion. it can.
In this case, if the wavelength λb is set to about half of the wavelength λa, the electrical length (substantially equal to the mechanical length) of the dedicated ground plane of λb / 4 of the inverted F antenna is roughly λa / 4
Half the mechanical length of the dipole antenna. For this reason, interference with the zigzag portion or the helical portion formed in the upper half of the λa / 4 dipole antenna is avoided, and the half length is formed in the space beside the linear portion formed in the lower half thereof. Can be provided with a special ground plate.

According to the antenna of the tenth aspect, an inverted-F antenna with good performance can be configured as a component of the dual band antenna. That is, to constitute an inverted-F antenna having excellent VSWR characteristics near the wavelength λb, excellent separation properties for the wavelength λa, high antenna gain, and having a wide tuning wavelength range near the wavelength λb. Can be. The reason why such an effect can be obtained is mainly that “the feed point of the conventional inverted F antenna is farther away from the ground point in either the length direction or the width direction of the antenna element”. This is due to the fact that the feeding point of the inverted-F antenna according to the present invention is separated in both the length direction and the width direction of the plate-shaped antenna element. The dual band antenna according to the eleventh aspect of the present invention has excellent antenna characteristics, and is small, lightweight,
And low cost.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view schematically illustrating a dual band antenna according to an embodiment shown in FIG. 2, which will be described later. Nine configurations have appeared. However, the distance between the coaxial cable and the trap is enlarged, and is not a sketch.

FIG. 2 is a schematic front external view illustrating an embodiment of a dual band antenna according to the present invention, which is drawn so as to express both a mechanical configuration and an electrical configuration. FIG. 13 is a diagram corresponding to item 6.

FIG. 3 is a schematic view illustrating various traps,
(B) is a 波長 wavelength trap similar to that shown in FIG. 2, (A) is a 波長 wavelength trap, and (C) is a ／ wavelength trap.

FIG. 4 is a view for explaining an inverted F antenna,
(A) is a principle diagram of an inverted-F antenna, (B) is a perspective view schematically depicting a conventional example of an inverted-F antenna, and (C)
Is a perspective view schematically depicting the embodiment, and
And the tenth configuration.

5A and 5B show characteristics of the dipole antenna of the embodiment shown in FIGS. 1 and 2 described above, wherein FIG. 5A shows the VSWR of a 900 MHz dipole antenna, and FIG. 5B shows the isolation.

FIG. 6 shows the characteristics of a 1.9 GHz inverted-F antenna;
(A) is VSWR, (B) is isolation.

FIG. 7 is a schematic front view showing an embodiment different from FIGS. 1 and 2 described above, and corresponds to the configuration of claims 5 and 6;

FIG. 8 is a schematic perspective view illustrating the dual-band antenna according to the embodiment shown in FIG. 7 described above.

FIG. 9 is an overall view of a state in which the dual-band antenna according to the present invention is housed in an antenna cover and supported by an antenna cover holder so as to be rotatable and undulating;
(A) depicts the dual-band antenna of the embodiment shown in FIG. 1 above, and (B) depicts the dual-band antenna of the embodiment shown in FIGS. 7 and 8 with hidden lines.

[Explanation of symbols]

1 ... Dipole antenna element for λa, 2 ... λa,
λb common ground plane, 3 ... λb inverted F antenna element,
3 ′: inverted F antenna element, 4: λb / 4 ground plane, 5
... trap for λb, 5a ... outer conductor, 5b ... core wire, 5c
... short circuit connection, 6 ... coaxial cable, 7 ... high frequency circuit, 8 ...
Ground plate, 9a, 9b ... dipole antenna element for λb, 10 ... inverted F antenna element for λa, 11 ... λa
Ground plane.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01Q 13/08 H01Q 13/08 21/30 21/30

Claims (11)

[Claims] 1. A method for constructing a dual band antenna having two tuning wavelength bands, around a wavelength λa and near a wavelength λb shorter than the wavelength λa, comprising: The dipole antenna elements are arranged substantially on the same straight line in the vertical direction to form a dipole antenna near the tuning wavelength range λa, and the lower dipole antenna element of the pair of dipole antenna elements is formed into a strip shape. Forming an inverted-F antenna in the vicinity of the tuning wavelength range λb using the strip-shaped dipole antenna as a ground plane, and forming a lower end of the upper dipole antenna element of the pair of dipole antenna elements. Connect to the core of the coaxial cable, and at the point near this connection point, the outer conductor of the coaxial cable. A trap that is connected to the “lower dipole antenna element also serving as the ground plane of the inverted F antenna” and that resonates at a wavelength λb immediately near the connection point between the core wire of the coaxial cable and the dipole antenna element. Preventing the high-frequency signal of the wavelength λb from leaking to the high-frequency circuit of the wavelength λa, and independently performs transmission and reception of the radio wave of the wavelength λa by the dipole antenna and transmission and reception of the radio wave of the wavelength λb by the inverted F antenna. A method for configuring a dual-band antenna. 2. A zigzag or helical shape of at least a part of an upper half of the dipole antenna element located on the upper side of the pair of dipole antenna elements to form a top heavy composite antenna element. 2. The method according to claim 1, wherein the mechanical length of the dipole antenna in the vicinity of the tuning wavelength band λa is shorter than the electrical length. 3. The wavelength λa is a wavelength corresponding to “a frequency at which a value rounded off to the nearest decimal point is 1 GHz to 4 GHz”, and the wavelength λb is about 1 of the wavelength λa set as described above.
The method according to claim 1 or 2, wherein the ratio is set to / 2. 4. The inverted F antenna in the vicinity of the tuning wavelength range λb supports a conductive plate-like member that is similar to a rectangle substantially parallel to a ground plane and one of four corners of the rectangle. A grounding point is formed by extending and connecting the vicinity to the ground plane, and a power supply point is set at a location separated from one corner of the rectangular plate-like member in both the width direction and the length direction of the rectangle. The method according to any one of claims 1 to 3, wherein an output terminal of the high-frequency circuit is connected to and electrically connected to the feed point. 5. A method for constructing a dual band antenna having two tuning wavelength bands near a wavelength λa and near a wavelength λb shorter than the wavelength λa, comprising: a pair of dipole antennas having an electrical length of λb / 4. The elements are arranged substantially on the same straight line in the vertical direction to constitute a dipole antenna near the tuning wavelength range λb, and are positioned below the dipole antenna, and
An inverted-F antenna having a tuning wavelength range of about λa is arranged along the coaxial cable connected to the dipole antenna, and the coaxial cable of the dipole antenna and the coaxial cable of the inverted F antenna are individually connected to a high-frequency circuit. And transmitting and receiving radio waves having a wavelength of λb by the dipole antenna and transmitting and receiving radio waves having a wavelength of λa by the inverted F antenna without interfering with each other. 6. A dual-band antenna having two tuning wavelength ranges near a wavelength λa and near a wavelength λb shorter than the wavelength λa, wherein a pair of vertically opposed electric lengths of about λa / 4 dipole antenna elements are provided, and an inverted F antenna element having an electrical length of about λb / 4 and using the lower dipole antenna element of the pair of dipole antenna elements as a ground plate is provided. The core wire of one of the two coaxial cables is connected to the upper dipole antenna element of the pair of dipole antenna elements, and the outer conductor of the one coaxial cable is connected to the outer conductor of the one coaxial cable. The inverted F antenna is connected to a common ground plane, and the core of the other coaxial cable of the two coaxial cables is connected to the inverted F antenna. Element, and the outer conductor of the other coaxial cable is connected to the common ground plane, and at a location near the connection point between the core wire of the one coaxial cable and the dipole antenna element, A trap resonating at a wavelength λb is connected,
Dual band antenna. 7. The trap resonating at the wavelength λb,
It is composed of a coaxial cable as a main material or has a structure similar to a coaxial cable, and (a) has an electrical length of about λb / 2, and (b)
At one end, the core wire of the trap is “the connection point between the core wire of the one coaxial cable and the dipole antenna”.
And (c) at one end,
An outer conductor of the trap is connected to an outer conductor of the one coaxial cable, and (d) at the other end of the trap, the core wire and the outer conductor are connected to have zero electrical resistance. The dual band antenna according to claim 6, wherein 8. An upper dipole antenna element of the pair of dipole antenna elements has at least a part thereof, preferably an upper half or an upper end formed in a zigzag shape, or the at least one part preferably has a zigzag shape. The dual-band antenna according to claim 6, wherein the upper half or the upper end is formed in a helical shape. 9. A lower dipole antenna shared with a ground plane of the inverted-F antenna element has an electrical length of approximately λb / 4 from the ground point of the inverted-F antenna element.
And this extension is λ dedicated to the inverted F antenna.
9. The dual band antenna according to claim 6, wherein the dual band antenna functions as a b / 4 ground plane. 10. The inverted-F antenna element has a substantially L-shaped conductive member, and one of two L-shaped sides is connected to the ground plane. While being conducted, the other of the two sides has an elongated plate shape, is substantially parallel to the ground plane, and the feeding point of the inverted F antenna element is Characterized in that it is located in the elongated plate-like portion of the side and is separated from the L-shaped bending point in both the length direction and the width direction,
A dual band antenna according to any one of claims 6 to 9. 11. A dual band antenna having two tuned wavelength ranges near a wavelength λa and near a wavelength λb shorter than the wavelength λa. One
A pair of dipole antenna elements each having an electrical length of about λb / 4, a coaxial cable connected to the pair of dipole antenna elements, and a tuning wavelength band disposed along the coaxial cable; A dual-band antenna, comprising: an inverted-F antenna having a wavelength of λb; and a coaxial cable separate from the antenna connected to the inverted-F antenna.