JPH07106994A - Antenna for portable radio - Google Patents

Abstract

(57) [Summary] [Purpose] To extract radio waves efficiently by causing a part of the extraction antenna to be applied to a portable wireless terminal whose size is 1/2 or less of the used wavelength to protrude outside the housing when the antenna is housed. [Structure] A linear first antenna 2 having an electrical contact 4 at one end, and another end having a contact of a second antenna 1 having an electrical contact 3 at one end and having a shorter wavelength than a working wavelength, at the other end.
The first antenna includes a composite antenna that is joined without making electrical contact, and a matching circuit that has two contact points and is formed by transmission lines 8 and 9 connecting each of the two contact points and the feeding point 11. When using a second antenna, it is electrically coupled to feed only one contact of the matching circuit, and when using a second antenna, the same power is fed by two contacts of the matching circuit. [Effect] With a single power feeding part, impedance matching with the power feeding part can be achieved with good performance both when the antenna is pulled out and when it is stored, and it is effective in reducing the volume and cost of the portable wireless terminal by simplifying the power feeding circuit. is there.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna applied to a portable mobile radio terminal.

[0002]

2. Description of the Related Art Conventionally, an antenna applied to a portable mobile radio terminal is housed inside a housing when the terminal is normally carried and the antenna is removed from the housing when the terminal is used for the convenience of the user. The form of pulling out and using is widely used, but in order to compensate for the deterioration of the sensitivity of the wireless terminal when the antenna is housed in the housing, part of the antenna is left outside when the antenna is housed in the housing In order to radiate radio waves more efficiently, there is proposed a method (Patent Laid-Open No. 3-245603) of supplying power to the power feeding portion when the antenna is pulled out, in that it is different from the portion inside the housing that feeds the antenna when the antenna is pulled out. . In addition, according to the above method, it is necessary to provide electric contacts at different locations in the housing, which increases the volume of the housing and raises the cost. Therefore, the portion that remains outside the housing when the antenna is pulled out is called an electrical antenna part. Keep it separate,
In addition, a method of arranging electrical contacts for exciting only the portion of the antenna remaining outside the housing on the antenna side so that the two contacts provided in the housing are at the same location (EP0467).
822A2) has also been proposed, but when applied to a mobile terminal with a dimension that is excellent in portability and is smaller than a quarter of the operating wavelength, in order to efficiently radiate radio waves from the antenna, the antenna can be stored and pulled out. 1 /
Limited to 4-wavelength monopole.

[0003]

In the first prior art described above, since the part of the antenna that is housed inside the housing when the antenna is housed operates as a transmission line, the antenna side is open when the antenna is pulled out and when the antenna is housed. The antenna is excited in the same operating mode because the power supply part of is not changed. Therefore, in both the first and second conventional techniques, there is a problem that the operating state cannot be changed when the antenna is pulled out from the housing and when the antenna is partially housed in the housing. When these antennas are applied to a wireless terminal whose housing size is less than 1/4 of the used wavelength, in the 1/4 wavelength monopole mode, the characteristics of the antenna change significantly due to the change in the current induced in the housing. Since the human body is close to the housing during use, the antenna gain is greatly deteriorated and the sensitivity of the wireless terminal is significantly deteriorated. On the other hand, in the 1/2 wavelength monopole mode or the 3/8 wavelength monopole mode, the input impedance becomes extremely higher than the feeding impedance, and it is generally difficult to realize a good impedance matching state in a wide frequency band, and it is effective. When the radiation volume of a typical radio wave is small, that is, when the antenna is radiated from the outside of the housing when the antenna is housed, the frequency band satisfying the good impedance matching state is extremely narrow, and the entire frequency range for communication is There is a problem that it is not possible to radiate radio waves efficiently from the antenna in the band.

It was

Means for Solving the Problems The above problem is solved by a second antenna having an electrical contact at one end and a second antenna having an electrical contact at one end and having a shorter wavelength than a working wavelength. A composite antenna that joins one end with a contact without making electrical contact; and a matching circuit that has two contacts and is formed by a transmission line that connects each of the two contacts to a feeding point, This can be solved by electrically coupling and feeding only one contact of the matching circuit when using one antenna, and feeding the same power by two contacts of the matching circuit when using the second antenna.

[0005]

[Operation] This antenna is mechanically integrated,
It is characterized in that two electrically separated antennas are fed by different methods at two adjacent points. The first antenna part having a large radio wave radiation volume is fed by only one of the two contacts of the matching circuit. The size of the second antenna part is much smaller than the wavelength used, and because it is much smaller than that of the first antenna part, the operating state that efficiently radiates radio waves is strongly influenced by the case, and almost no current is induced in the case. Determined by appearance. In a small wireless mobile terminal, the size of the housing is about 1/4 of the wavelength used or less, and the antenna and the housing resonate as a unit, and the basic resonance state in which efficient radio wave emission is obtained is a 1/4 wavelength monopole. It is a state (or a 1/2 wavelength dipole state). For this reason, the transmission line connected to the first contact of the matching circuit and the transmission line connected to it as well as the second contact that excites the second antenna has an extremely high input impedance in the 1/4 wavelength monopole state. Since it is close to the impedance, it is physically short and electrically short-circuited. For this reason,
Despite the fact that the first antenna and the second antenna are excited by the second antenna, the operation of the first contact and the transmission line connected to it is almost the same because of the parallel connection relationship between the low-impedance line and the high-impedance line. It is treated as an open circuit and practically has no effect on the feeding state of the second antenna.
In addition, when feeding the first antenna, the second contact and the transmission line connected to the second contact are connected to the feeding point as an extremely short open transmission line, so that the feeding point is connected to the first contact. It has almost no effect on the coupled transmission line. Therefore, by using the present invention, in a small portable terminal, at two points close to each other, which can be regarded as the same power feeding place,
Since it is possible to excite two antennas with different impedance states in a good impedance matching state, it is possible to efficiently radiate radio waves both when the antenna is pulled out and when it is stored. It is possible to provide an antenna that satisfies both portability.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a configuration diagram of an embodiment of an antenna for a portable wireless device according to the present invention, and FIGS. 1a and 1b are connection diagrams showing an actual use state of the antenna. A first linear antenna having an electrical contact 4 and one end of the second linear antenna 1 having an electrical contact 3 via an insulator 5 without an electrical contact of the first antenna; The electrical contacts of the two antennas are connected to form a composite antenna. A first transmission line 8 coupled to a first contact 6 is coupled to one input of a two-synthesis circuit 10 for feeding the composite antenna,
The second transmission line 9 coupled to the second contact 7 is coupled to the other input of the synthesis circuit, and the output of the synthesis circuit is the power supply unit 11.
Bind to. The first linear antenna 2 is fed by electrically coupling the electrical contact 4 and the first contact 6 as shown in FIG. 1a, and the second linear antenna 2 as shown in FIG. 1b. 1 is supplied with electricity by electrically connecting the electrical contact 3, the first contact 6 and the second contact 7.
In order to maintain a good matching state of the input impedance between the feeding antenna 11 and the extremely short linear antenna 1 which is less than or equal to ¼ of the wavelength used by the wireless terminal to which the antenna is applied, the convenient size is half the wavelength used. In the case of the following cases, transmission line 9
Has a very short value (1/6 or less of the used wavelength) electrically. Therefore, when power is fed to the first linear antenna 2 via the first transmission line 8 at the first contact 6, the second contact 7 serving as an open end and the power feeding unit 11 are connected to the synthesizing circuit 10. The electrical effect exerted on the power supply portion of the second transmission line 9 that is connected by way of is small. In addition, when the second linear antenna 2 is fed by the first contact 6 via the first transmission line 8 and the second contact 7 via the second transmission line 9, the electrical contact 3 Since the transmission line having an extremely short electrical length and the line having a long electrical length are coupled between the and the combining circuit 10 at the same time, the electrical effect of the electrically long transmission line hardly appears. Therefore, the length of the first transmission line and the characteristic impedance can be freely selected so that the first antenna and the power feeding section achieve a good impedance matching state. According to this embodiment, a mechanism for exciting an extremely short linear antenna having a wavelength of ¼ or less of the used wavelength and another linear antenna having an arbitrary size while maintaining a good impedance matching state with the power feeding portion. With two adjacent contacts and two different transmission lines
Since it can be realized with a simple structure by a synthetic circuit, it is possible to realize a small and inexpensive antenna structure that uses a pull-out antenna and causes a part of the pull-out antenna to protrude from the housing when the pull-out antenna is housed to efficiently radiate radio waves. There is.

Another embodiment of the present invention will be described with reference to FIGS. 2a and 2b. 2a and 2b are diagrams showing a method of applying the antenna for a portable wireless device according to the present invention to a housing of a wireless device whose size is 1/2 or less of a used wavelength. The first transmission line, the second transmission line, and the combined circuit are formed on one matching circuit board 12, and the first contact is the first linear antenna 2 having the electric contact 4 and the electric contact. The second linear antenna 1 having 3 has a composite antenna in which one end without electrical contact of the first antenna and the electrical contact of the second antenna are connected through the insulator 5 to and from the composite antenna. The composite antenna is set at a position close to the surface of the housing, and is installed close to a position far from the surface of the housing where the composite antenna is taken in and out in the moving axis direction of the composite antenna. According to the present embodiment, when the extraction antenna, which is the composite antenna, is housed, the first antenna does not come into contact with any contact of the matching circuit and is not positioned so close as to cause electromagnetic induction. When the antenna is pulled out, it is possible to avoid that the second contact is located so close as to cause electromagnetic induction with the first antenna, so that the portable wireless device antenna of the present invention is used as a housing of a wireless terminal, and the electrical characteristics are impaired. There is an effect that can be easily applied without any. FIG. 3 is a configuration diagram of another embodiment of the antenna for portable radio device according to the present invention. The difference from FIG. 1 is that the second antenna is formed of the helical conductor 14. By using the helical conductor, it is possible to realize a good impedance matching state between the second antenna and the feeding portion due to the shorter dimension of the antenna in the longitudinal direction. According to this embodiment, the dimension of the second antenna in the longitudinal direction is reduced, and when the antenna for a mobile radio device of this embodiment is applied to an actual small mobile terminal, the first linear shape having the electrical contact 4 is formed. The antenna 2 and the second helical antenna 1 having the electrical contact 3 are connected via the insulator 5 to one end of the first antenna having no electrical contact and the electrical contact of the second antenna. When only one composite antenna is stored, the length of the portion protruding from the housing of the small mobile terminal is reduced, which is effective in improving the portability of the terminal. FIG. 4 is a configuration diagram of another embodiment of the antenna for portable radio device according to the present invention. The difference from FIG. 1 is that the second antenna is formed of the meander conductor 15. By using a meander conductor, due to the shorter antenna longitudinal dimension,
A good impedance matching state between the second antenna and the power feeding section can be realized. According to this embodiment, FIG.
Similar to the embodiment of the above, the length of the portion protruding from the housing of the small portable terminal is reduced, which is effective in improving the portability of the terminal, and the meander structure is a flat structure, which makes it easy to introduce print patterns and the like. It also has the effect of reducing manufacturing costs.

FIG. 5 is a block diagram of another embodiment of the antenna for portable radio equipment according to the present invention. The difference from FIG. 3 is that the second antenna is formed of a helical conductor 16 that internally includes a meander conductor. According to the present embodiment, by forming the meander conductor inside the helical conductor, different resonance phenomena corresponding to the electrical dimensions of each conductor are induced, and a good impedance between the second antenna and the feeding part is obtained. This has the effect of widening the frequency band that realizes the matching state.

FIG. 6 is a block diagram of another embodiment of the antenna for portable radio equipment according to the present invention. 4 is different from that of FIG. 4 in that the second antenna is formed by the first meander conductor 17 formed in the dielectric 19 and the second meander conductor 18 arranged in proximity to the meander conductor 17 without electrically contacting the meander conductor 17. It is a composed point. According to the present embodiment, the operating state of the first helical conductor 18 that is fed and the second meander conductor 19 that is not fed are different from the monopole state in the former and the dipole state in the latter. A different resonance phenomenon corresponding to the dynamic dimension is induced, and there is an effect of widening the frequency band for realizing a good impedance matching state between the second antenna and the feeding portion. In addition, this structure can be realized by stacking two-dimensional structures, and has the effect of being excellent in mass productivity.

FIG. 7 is a block diagram of another embodiment of the antenna for portable radio equipment according to the present invention. The difference from FIG. 4 is that the first transmission line 20 and the second transmission line 21 have a characteristic impedance higher than the characteristic impedance of the power feeding unit 11. When the size of the first linear antenna 2 is much larger than 1/4 of the operating frequency of the radio device, and particularly close to 1/2, the impedance of the first antenna seen from the electrical contact 4 is the impedance of the power feeding portion. Since it is larger than 50 ohms, the matching state can be more easily inspected by using a transmission line having a characteristic impedance larger than the characteristic impedance of the power feeding section. Therefore, according to this embodiment, the matching circuit is simplified, and the size of the matching circuit is reduced, which has the effect of reducing the volume of the mobile terminal.

FIG. 8 is a block diagram of another embodiment of the antenna for portable radio equipment according to the present invention. The difference from FIG. 1 is that the first transmission line 22 and the second transmission line 23 are formed by coaxial lines. When the transmission line is realized by a strip line, if the characteristic impedance is increased, the amount of electromagnetic waves radiated in the bent portion of the transmission line increases accordingly. Since this radiation does not contribute to communication, the antenna loss equivalently increases. Since the radiation phenomenon from the borrowing section does not appear in the coaxial line, according to this embodiment, the antenna loss can be reduced by the unnecessary radiation from the transmission line,
This is effective in improving the sensitivity of the wireless terminal by improving the antenna gain.

[0012]

According to the present invention, a pull-out antenna is used, which is suitable for a portable small radio terminal having a size equal to or less than 1/2 of the used frequency, and a part of the pull-out antenna is partially accommodated when the pull-out antenna is housed. In the method of projecting to the outside of the casing and efficiently radiating radio waves from this part, it is possible to achieve good impedance matching with the power feeding part with one power feeding part both when pulling out the antenna and when storing. Therefore, the simplification of the power feeding circuit is effective in reducing the volume and cost of the portable wireless terminal.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an antenna for a portable wireless device according to the present invention.

FIG. 2 is a configuration diagram when the antenna for a mobile wireless device according to the present invention is mounted on a small mobile terminal.

FIG. 3 is a configuration diagram of another portable wireless device antenna according to the present invention.

FIG. 4 is a configuration diagram of another portable radio antenna according to the present invention.

FIG. 5 is a configuration diagram of another portable radio antenna according to the present invention.

FIG. 6 is a configuration diagram of another portable wireless device antenna according to the present invention.

FIG. 7 is a configuration diagram of another portable radio antenna according to the present invention.

FIG. 8 is a configuration diagram of another portable wireless device antenna according to the present invention.

FIG. 9 is a configuration diagram of an antenna for a portable wireless device according to the present invention.

[Explanation of symbols]

1: Second linear antenna 2: First linear antenna 3: Electrical contact 4: Electrical contact 5: Insulator 6: First contact 7: Second contact 8: First transmission line 9 : Second transmission line 10: 2 composite circuit 11: Feeding part 12: Matching circuit board 13: Radio equipment housing 14: Helical conductor 15: Meander conductor 16: Meanda / helical antenna 17: Feeding meander antenna 18: Non-feeding meander Antenna 19: Dielectric 20: First transmission line 21: Second transmission line 22: First coaxial line 23: Second coaxial line

Claims (10)

[Claims] 1. A linear first antenna having an electrical contact at one end thereof is electrically connected to the other end of a second antenna having an electrical contact at one end, the second antenna having the contact being shorter than a working wavelength. In the case of using the first antenna, a composite antenna that is joined without contact with the antenna and a matching circuit that has two contact points and is formed by a transmission line that connects each of the two contact points to the feeding point are used. An antenna for a portable wireless device, which is characterized in that only one contact of a matching circuit is electrically coupled to feed power, and when a second antenna is used, the same power is fed by two contacts of the matching circuit. 2. The antenna according to claim 1, wherein the matching circuit is arranged inside the radio device, and the composite antenna has a second antenna portion of the composite antenna protruding outside the radio device housing when housed in the radio device. When extracting from the radio, only the electrical contact of the first antenna of the composite antenna and its surroundings remain inside the wireless housing, and the other parts of the composite antenna project outside the housing. An antenna for a portable wireless device, wherein only the second antenna of the composite antenna is fed and operates as an antenna, and when the composite antenna is pulled out, only the first antenna of the composite antenna is fed and operates as an antenna. 3. The antenna according to claim 1, wherein the second antenna is formed of a helical conductor. 4. The antenna according to claim 1 or 2, wherein the second antenna is formed of a meandering conductor. 5. The antenna according to claim 1, wherein the second antenna is formed of a meandering conductor and a helical conductor. 6. The antenna according to claim 2, wherein the two contacts of the matching circuit are juxtaposed in a direction in which they move when the composite antenna is pulled out and stored, and the electrical contact of the first antenna of the composite antenna is An antenna for a portable wireless device, which is electrically connected only to a contact located in a direction in which a housed composite antenna is pulled out of the contacts arranged side by side. 7. The antenna according to claim 1, wherein the characteristic impedance of the transmission line of the matching circuit is higher than the feeding impedance. 8. The antenna according to any one of claims 2 to 5 or claim 7, wherein a contact point of a matching circuit for feeding the first antenna of the composite antenna when the composite antenna is pulled out from the housing. An antenna for a portable wireless device, wherein the length of the transmission line connected to the matching circuit is longer than the length of the transmission line connected to the other contact of the matching circuit. 9. The antenna according to claim 7 or 8, wherein the matching circuit is formed by a strip line. 10. The antenna according to any one of claims 2 to 5 or claim 7 or 8, wherein the first antenna of the composite antenna is formed as a ½ wavelength or 3/8 wavelength monopole antenna. And a second antenna of the composite antenna has an operation mode of a quarter-wave monopole antenna.