JPH1051224A - Antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna system that is resonated for a plurality of frequency bonds and used in common to a plurality of systems. SOLUTION: The antenna system in resonance with a plurality of frequencies or provided with a linear feeding element 1 having length is L1 and a linear loop-back element 2 placed close to the feeding element 1 whose one end is short circuited to the feeding element 1 and whose length is L2 , the difference (L1 -L2 ) of the length between the feeding element 1 and the loop-back element 2 is set to be in resonance with higher frequencies and the length L1 of the feeding element 1 is set, in resonance with lower frequencies in cooperation with the loop-back element 2. Multi-resonance at a plurality of frequencies is attained, and the antenna is used in common for radio equipments in a plurality of systems.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device used for a portable telephone, a mobile radio, and the like, and more particularly, to an antenna device capable of resonating in a plurality of frequency bands.

[0002]

2. Description of the Related Art In recent years, mobile communication systems have been diversified,
Along with that, the frequency band used is 800 MHz
Band, 1.5 GHz band, 1.9 GHz band, and so on. 2. Description of the Related Art In mobile phones and mobile wireless devices, an antenna device having reception characteristics suitable for a band of a used system is used.

[0003] In a conventional portable telephone, a whip antenna using a housing of the telephone as a ground plane is used.
As shown in FIG. 7, the whip antenna is pulled out of the wireless device housing 6 during a call, and is stored in the wireless device housing 6 during standby, as shown in FIG. This antenna is formed by integrally forming a helical antenna 9 disposed at the tip, a sleeve 13 electrically connected to the helical antenna 9, a rod-shaped monopole antenna 15, a sleeve 13 and the monopole antenna 15. Insulator 14
The sleeve 13 and the monopole antenna 15 are electrically disconnected.

A matching circuit 4 for matching impedance between the wireless circuit 5 and an antenna is provided in a wireless device housing 6.
And a connection spring for connecting the matching circuit 4 to the whip antenna
The connection spring 16 is connected to the monopole antenna 15 when the whip antenna is extended (FIG. 7), and is connected to the sleeve 13 when the whip antenna is stored (FIG. 8).

The impedance of the matching circuit 4 when viewing the monopole antenna 15 from the matching circuit 4 is Z ₁ , the impedance when the matching circuit 4 is viewed from the monopole antenna 15 is Z _2, and the helical antenna When the impedance when the matching circuit 4 is viewed from 9 is Z ₃ , Z ₁
It is configured such that ≒ Z ₂ ≒ Z ₃ .

When the whip antenna is extended, the power is fed from the radio circuit 5 through the matching circuit 4 to the monopole antenna 15 only through the connection spring 16 and its length (this length is not a mechanical length but a mechanical length). , The electrical length, that is, the length in terms of wavelength, and even if the mechanical length is the same, the electrical length also changes when the wavelength changes due to the material or the like. It operates as a monopole antenna having a substantially equivalent electrical length of １ ／ wavelength, ／ wavelength, １ ／ wavelength, or the like according to the “substantially equivalent electrical length”.

When the whip antenna is housed, power is supplied only to the helical antenna 9 from the wireless circuit 5 through the matching circuit 4 via the connection spring 15 so that the の wavelength, 実 質 wavelength, 波長 wavelength, etc. It operates as a helical antenna with an equivalent electrical length.

[0008]

The mobile communication system has been diversified, and the operating frequency band is 800 MHz band and 1.5G.
Hz band and 1.9 GHz band are increasing.
In the market, there is a demand for a mobile wireless device that can be shared by systems having different frequencies.

[0009] However, the conventional monopole antenna supports only one frequency band, and if it is made to have multiple resonances so that it can be shared by a plurality of systems, its characteristics are significantly deteriorated.

The helical antenna containing the whip antenna has a narrow operating band. Therefore, in an 800 MHz band system in which a large frequency difference is provided (double separated) between the transmission band and the reception band, high-quality mobile communication cannot be performed, and a single helical antenna is not provided. It is extremely impossible to realize a multi-resonant antenna that can be shared by multiple systems.

The present invention solves such a conventional problem, and resonates in a plurality of frequency bands, can be shared by a plurality of systems, and can ensure stable communication quality. It is intended to provide.

[0012]

The present invention SUMMARY OF] is an antenna device resonates in a plurality of frequencies, and the feed element linear having a length L _1, is arranged close to the feed element, in the feeding element and one end a linear folded element having a short length L ₂ provided, the length L ₂ of the folded element, set so as to resonate to the higher frequency is L ₁ -L _2, the length of the feed element and L ₁ is,
At the lower frequency, it is set to a length that works with the folded element and resonates at this frequency.

In this antenna device, L ₁ −L _{2, which} is obtained by subtracting the length L ₂ of the return element from the length L ₁ of the feed element, resonates with the higher frequency, and the lower frequency is used. On the other hand, the impedance of L ₁ -L ₂ is loaded with an impedance composed of two parallel lines of the short-circuited tip of the folded element and the feed element, and the combined impedance resonates.

Therefore, multiple resonances at a plurality of frequencies are possible.

[0015]

DETAILED DESCRIPTION OF THE INVENTION According to a first aspect of the present invention provides an antenna apparatus resonates in a plurality of frequencies, and a linear feed element having a length L _1, is arranged close to the feed element , and a linear folded element having a length L ₂ which is short-circuited at the feed element and the one end,
The folded element length L _2, is set so as to resonate to the higher frequency in the L ₁ -L _2, the length L ₁ of the feed element, in the lower the frequency,
It is set to a length that resonates with this frequency by acting together with the folding element, so that multiple resonances at a plurality of frequencies are possible, and it can be used for a shared radio of a plurality of systems.

According to a second aspect of the present invention, the length of the folded element is set to a substantially equivalent electrical length of 1/4 wavelength of an arbitrary frequency higher than the lower frequency. At higher frequencies, folded elements are equivalently eliminated.

According to a third aspect of the present invention, the feed element and the folded element are configured by a helical antenna, and a narrow band of the helical antenna can be corrected.

According to a fourth aspect of the present invention, the feed element and the folded element are formed by concentrically arranged helical antennas having different diameters.
A helical antenna capable of multi-resonance at a plurality of frequencies is obtained.

According to a fifth aspect of the present invention, the feed element and the folded element are formed of helical antennas having the same diameter and wound alternately.
This helical antenna can be manufactured by plating or the like, and is easy to manufacture.

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

(First Embodiment) As shown in FIG. 1, an antenna device according to a first embodiment includes a radio circuit 5 operating at a first frequency and a second frequency in a radio device housing 6; A whip antenna 3 of a wireless device in which a matching circuit 4 for impedance matching with an antenna is housed, and includes a feed element 1 fed through the matching circuit 4 and a folded element 2 from the feed element 1. .

Feeding element 1 and folded element 2
Means that they are close to each other and parallel to each other so that the distance between them is sufficiently smaller than the substantially equivalent electrical length of one wavelength of the frequency that resonates in the feed element 1.

The whip antenna 3 may be formed as a cylindrical whip antenna by molding the linear feed element 1 and the folded element 2 or by forming the feed element 1 and the folded element 2 by a strip line. , May be formed as a flat antenna.

The element length of the feeding element 1 is L ₁ ,
The element length of the folded element 2 is L ₂ (<L ₁ )
, The element length L _{2 of the} folded element ₂
It is set to substantially equivalent electrical length of a quarter wavelength of any frequency f ₃ higher than the first frequency (λ _3/4).

[0025] At this time, the impedance Zin viewed from the tip of the folded element 2, from the two parallel lines of a short-circuited end, when the characteristic impedance _{Z 0 Zin = j · Z 0} · tan (β · l) ( Equation 1 ). Where l is the length of the folded element, β
Is a propagation coefficient depending on frequency, and has a relation of β = 2π / λ.

[0026] In this case, when _{l = λ 3/4, Zin} → ∞
Therefore, as shown in FIG.
The portion of the feed element 1 parallel to the folded element 2 is equivalently eliminated, and operates as an equivalent element 8 that resonates at the second frequency f ₂ (element length: L ₁ -L ₂ ).

Further, as shown in FIG. 3, the length L ₁ of the feed element 1 is changed to an equivalent impedance 7 composed of two parallel short-circuited wires composed of the feed element 1 and the folded element 2. an intermediate loading the portion of the element length (L ₁ -L ₂₎ of the synthesized impedance is to resonate at a first frequency, sets the length L _1.

With this configuration, the antenna device operates as a two-resonance antenna that resonates at both the first frequency and the second frequency, and the radio uses the first frequency and the second frequency. It is possible to share the bandwidth with the system.

Currently, digital mobile communication services for the public operated in Japan are 800 MHz band, 1.5 G
Hz band and 1.9 GHz band. For example, 80
In the case of configuring an antenna of a shared device in the 0 MHz band and the 1.9 GHz band, the length L ₂ of the folded element ₂ is:
L ₁ −L ₂ is set to a substantially equivalent electric length so that resonance occurs in the 1.9 GHz band, and the length L ₁ of the feed element ₁ is
The length of the element 1 is determined so as to resonate in the 800 MHz band by taking into account the intermediate loading of the impedance obtained in the 800 MHz band by the two parallel lines of the tip short-circuit consisting of the element 1 and the folded element 2.

In the same manner, a shared device for the 800 MHz band and the 1.5 GHz band, and a 1.5 GHz band and the 1.5 GHz band.
A 9 GHz band shared device can be realized.

(Second Embodiment) In the antenna device of the second embodiment, the antenna is formed in a helical shape.

As shown in FIG. 4A, this antenna device comprises a feeding helical antenna 9 and a folded helical antenna 10, and the distance between the feeding helical antenna 9 and the folded helical antenna 10 is the first frequency ( <Second
(Frequency) is set to be sufficiently smaller than the substantially equivalent electrical length of one wavelength. The feeding helical antenna 9 and the folded helical antenna 10 form two parallel short-circuited ends.

These two helical antennas 9 and 10
May be integrally molded with a resin such as ABS or elastomer. At this time, the feeding helical antenna 9 and the folded helical antenna 10 are wound concentrically with different diameters as shown in FIG. 5 or alternately wound on circles having the same diameter as shown in FIG. Configure. In the latter case, the helical antenna can be manufactured by plating, and the manufacture is easy.

The two integrated helical antennas are:
A wireless circuit 5 operating at the first frequency and the second frequency is connected through a matching circuit 4 housed in a wireless device housing 6.

The two parallel lines composed of the feeding helical antenna 9 and the folded helical antenna 10 operate in the same manner as the feeding element 1 and the folded element 2 in the first embodiment (FIG. 1). Therefore, by setting the element length L ₂ of the folded helical antenna 10 substantially equivalent electrical length of the first optional higher than the frequency a quarter wavelength of the frequency _{f 3 (λ 3/4)} , impedance (Equation 1) Zin becomes Zin → ∞, and as shown in FIG. 4C, the portions of the folded helical antenna 10 and the feeding helical antenna 9 parallel to the folded helical antenna 10 are equivalently eliminated, and the second frequency f ₂ (element length:
(L ₁ −L ₂ ).

The length L ₁ of the feeding helical antenna 9
Is a feeding helical antenna 9 as shown in FIG.
And a folded helical antenna 10 and an equivalent impedance 7 composed of two short-circuited parallel wires at the element length (L ₁ -L ₂ ) of the feeding helical antenna 9, and the combined impedance is the first impedance. to resonate at a frequency, it sets the length L _1.

With this configuration, the antenna device operates as a two-resonance helical antenna that resonates at both the first frequency and the second frequency.

In this helical antenna, the length L ₂ of the folded helical antenna 10 is defined as L ₁ -L _{2, which} is 1.9 GHz.
Set substantially equivalent electrical length as to resonate at the band, also obtained at 800MHz band the length L ₁ of the feeding helical antenna 9, by two parallel lines of the tip shorting consisting helical antenna 10 Metropolitan folded helical antenna 9 By taking the intermediate loading of impedance into consideration and determining the length of the helical antenna 9 so as to resonate in the 800 MHz band, it is possible to configure a helical antenna of a shared machine for the 800 MHz band and the 1.9 GHz band. Similarly, 800
A shared device for the MHz band and 1.5 GHz band, and 1.5 GHz
It is also possible to realize a shared device for the band and the 1.9 GHz band.

Since the helical antenna has a narrow original band, the current 800 MHz band (transmission band: 940 to 9
58 MHz, reception band: 810-828 MHz),
1.5 GHz band (transmission band: 1429-1453MH)
z, reception band: 1477 to 1501 MHz)
In a system in which multiple separation (transmission and reception bands are separated), sufficient communication quality can be ensured only in either the transmission band or the reception band. However, in the antenna of this embodiment, the length L ₂ of the folded helical antenna 10 is L ₁ -L ₂ is set to a substantially equivalent electrical length such that it resonates in a high frequency band, and the length L ₁ of the feeding helical antenna 9 is set in consideration of the intermediate loading of the impedance due to the two parallel lines with the short-circuited end. By determining such that resonance occurs in a low frequency band, a helical antenna that can ensure good communication quality in both the transmission band and the reception band can be realized.

[0040]

As is clear from the above description, the antenna device of the present invention can resonate in a plurality of frequency bands and can be used as an antenna in a shared radio of a plurality of systems.

Further, the narrow band of the helical antenna can be improved, and the application range of the helical antenna can be expanded.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an antenna device according to a first embodiment of the present invention;

FIG. 2 is a view for explaining an operation principle at the time of receiving a second frequency in the antenna device according to the first embodiment;

FIG. 3 is a diagram illustrating an operation principle at the time of receiving a first frequency in the antenna device according to the first embodiment;

FIGS. 4A and 4B are explanatory diagrams illustrating the configuration of an antenna device according to a second embodiment of the present invention, FIG. 4B illustrating an operation principle at the time of receiving a first frequency, and FIG. Figure (c) to be explained,

FIG. 5 is a configuration diagram of an antenna device according to a second embodiment;

FIG. 6 is another configuration diagram of the antenna device according to the second embodiment;

FIG. 7 is a configuration diagram showing a conventional antenna device when it is extended,

FIG. 8 is a configuration diagram showing a state where a conventional antenna device is stored.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Feeding element 2 Folded element 3 Whip antenna 4 Matching circuit 5 Radio circuit 6 Radio case 7 Equivalent impedance 8 Equivalent element 9 Helical antenna 10 Folded helical antenna 11 Ground plate 12 Sleeve 13 Insulator 14 Monopole antenna 15 Connection spring

Claims (5)

[Claims] 1. An antenna device that resonates at a plurality of frequencies, comprising: a linear feed element having a length L ₁ , a length L disposed in close proximity to the feed element, and short-circuited at one end with the feed element. and a linear folded element having _2, the length L ₂ of the folded element, are set so as to resonate to the higher frequency in the L ₁ -L _2, the length L ₁ of the feeding element The antenna device is set to have such a length as to act together with the folded element and resonate with the frequency at the lower frequency. 2. The antenna according to claim 1, wherein the length of the folded element is set to a substantially equivalent electrical length of 波長 wavelength of an arbitrary frequency higher than the lower frequency. apparatus. 3. The antenna device according to claim 1, wherein the feed element and the folded element are formed of a helical antenna. 4. The antenna device according to claim 3, wherein the feed element and the folded element are formed of concentrically arranged helical antennas having different diameters. 5. The antenna device according to claim 3, wherein the feed element and the folded element are formed of helical antennas having the same diameter and wound alternately.