JP2004040154A - Antenna for portable radio apparatus and portable radio apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna for a portable radio apparatus that is not susceptible to the effect of the enclosure of the portable radio apparatus, has a high gain within a horizontal plane, and has a broad band characteristic suitable for large capacity transmission and to provide the radio apparatus. <P>SOLUTION: A first antenna element 18 whose electric length is 1/4 wavelength with respect to the operating frequency or over is placed at a side of the enclosure 12 equivalent to the lid body of the radio apparatus and an L-shaped second antenna element 19 is placed closely to its lower end 18b. The end 18a of the first antenna element 18 is connected to a radio section 15 via an impedance matching circuit 16. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement of a portable wireless device antenna and a portable wireless device mounted on a portable wireless device for communicating voice, data, and the like.
[0002]
[Prior art]
In recent years, various types of mobile communication using the quasi-microwave band such as mobile phones have been in the spotlight, and the need for not only voice but also data and image communication has been increasing. There is a need for a wide antenna. Also, in a fading environment, the radio waves arriving from the base station arrive on the mobile station side in a concentrated manner in a substantially horizontal plane, so that the antenna attached to the mobile terminal side has a high gain in the horizontal direction when using data communication or the like. Things are needed.
[0003]
2. Description of the Related Art Conventionally, as an antenna mounted on this kind of portable wireless device, an antenna that is pulled out when used and stored when carried is used. FIG. 7 shows an example of a conventional antenna for a portable wireless device. FIG. 7 is drawn to show the operation principle of the antenna unit. In FIG. 1, the portable wireless device antenna has a first housing 10 and a second housing 12 provided on the first housing 10 so as to be opened and closed by a hinge 11. The first housing 10 includes a key unit 13 mounted on the surface, a data processing unit (not shown) including a CPU, a memory, and the like, and a battery (not shown) inside. The second housing 12 has a liquid crystal screen 14 mounted on the surface thereof, a radio unit 15 inside, and an antenna unit 23 which can be pulled out and stored at the upper end.
[0004]
The antenna unit 23 has a first antenna 24 having conductivity, and a second antenna 26 including a coil and the like disposed at an upper end of the first antenna via an insulator 25. The lower end of the first antenna 24 is provided with a contact portion 24a at the time of pull-out, and the lower end of the second antenna 26 is provided with a contact portion 24a at the time of pull-out and a connection portion 26a at the time of storage connected to an antenna holder 27 fixed to the housing at the time of storage. Has been.
[0005]
The antenna holder 27 is connected to the radio unit 15 by a power supply terminal 28 formed of a spring or the like, and is connected to the matching circuit 16 in the radio unit. At the time of drawing out the antenna, the connecting end 24a at the time of drawing out is coupled to the antenna holder 27, and the rod-shaped first antenna 24 is supplied with power via the matching circuit 16 and operates as an antenna. At this time, the second antenna 26 is not supplied with power by the insulator 25 and does not operate as an antenna. On the other hand, at the time of storage, the connection end 26a at the time of storage is connected to the antenna holder 27, and the coiled second antenna 26 is supplied with power via the matching circuit 16 and protrudes from the housing to operate as an antenna. At this time, the stored first antenna 24 is not supplied with power by the insulator 25 and does not operate as an antenna.
[0006]
At the time of pulling out the antenna, the first antenna 24 is set to be approximately 波長 wavelength longer than 使用 wavelength of the used frequency in order to make it less susceptible to the influence of the housing, and has a directivity close to the figure 8 having the maximum value in the horizontal plane. Is shown. When the antenna is housed, the second antenna 26 is set to have an electrical length slightly shorter than the first antenna 24 to secure a band, and the directivity is slightly deteriorated as compared to when the antenna is pulled out, but the coil is small. The second antenna 26 operates.
[0007]
[Problems to be solved by the invention]
2. Description of the Related Art In recent years, portable wireless devices are strongly required to communicate not only voice but also data, images, and the like, and portable wireless devices having diversified housing shapes suitable for them are required. On the other hand, broadband communication is desired to increase transmission speed and subscriber capacity. As an antenna suitable for them, a built-in antenna suitable for various housing shapes, having a high gain in a horizontal plane without being affected by the housing at the time of use, and having a broadband characteristic is desired. I have.
[0008]
Generally, when the electrical length of the antenna is more than 1/4 wavelength and about 1/2 wavelength of the used frequency, the antenna is hardly affected by the housing and has a high gain in a horizontal plane. However, the bandwidth becomes narrower as the wavelength approaches １ ／ wavelength to 波長 wavelength. On the other hand, when the antenna is built-in, compared to the case where the antenna is not built-in, a metal object such as a wireless unit is closer to the antenna, so that the antenna volume cannot be secured and the band is narrow.
[0009]
In the case of the portable wireless device shown in FIG. 6, when the antenna is pulled out, the first antenna having approximately one-half wavelength of the operating frequency protrudes from the housing and operates. The degree of freedom is low due to poor design. In addition, when the antenna is housed, the electrical length of the antenna is shortened, so that the gain in the horizontal plane is deteriorated, and the portability is impaired because the second antenna projects from the housing. Inverted-F antennas widely used as built-in antennas are configured with １ ／ wavelength of the used frequency in order to secure a band, and are greatly affected by the housing, and the horizontal gain is significantly deteriorated.
[0010]
The present invention has been made in view of the above problems, and is a portable wireless device that is suitable for diversifying housing shapes, has a high gain in a horizontal plane that is hardly affected by the housing, and has a wideband characteristic suitable for large-capacity transmission. An object of the present invention is to provide an antenna and a wireless device.
[0011]
[Means for Solving the Problems]
In the antenna for a portable wireless device of the present invention, the upper end of the second antenna element is disposed close to the lower end of the first antenna element having a wavelength of, for example, 1/4 or more. Therefore, the first and second antenna elements are capacitively coupled and integrally operate as an antenna, so that the antenna volume is increased, and the antenna is hardly affected by the housing, and a wide-band characteristic is ensured despite high horizontal gain. It becomes possible.
[0012]
The portable wireless device antenna is built in or fixed to a portable wireless device housing including a wireless unit, for example, and has a first antenna element whose electrical length is １ ／ wavelength or more of a used frequency, A matching circuit connected to a first end of the first antenna element for performing impedance matching with the radio unit, and a second end facing the first end of the first antenna element Is configured to have a second antenna element whose upper end is disposed close to the second antenna element.
[0013]
In this case, it is preferable that the second antenna element is formed of a conductive member whose both ends are open at both ends and whose electrical length is approximately 波長 wavelength of the used frequency. In this case, resonance occurs in the vicinity of the operating frequency, and double resonance occurs with the first antenna element, so that the frequency band becomes much wider.
[0014]
Further, the second antenna element is constituted by a one-end short-circuited conductive member whose electrical length is approximately 1/4 of the operating frequency, and the open end side of the one-end short-circuited conductive member is the first antenna. It may be arranged in non-contact proximity to the second end of the element. In this case, the second antenna element is a quarter-wave antenna with one end short-circuited, resonates near the used frequency, and double resonates together with the first antenna element, so that the frequency band becomes much wider.
[0015]
When a conductive member is provided at the lower end of the second antenna element and the conductive member is arranged close to the shield of the radio unit, a predetermined capacitance is exhibited between the shield and the shield. The second antenna element resonates in the vicinity of the operating frequency and double-resonates with the first antenna element, so that the frequency band becomes much wider.
[0016]
An additional conductor may be integrally formed with the first end of the first antenna element, or the additional conductor may be connected to the first antenna element. In this case, since the additional conductor operates as an open stub in terms of impedance, the inductance component of the impedance viewed from the first end of the first antenna element can be canceled, thereby improving the impedance characteristics. Also, an antenna current flows through the additional conductor, assisting the antenna current flowing through the first antenna element and improving the gain in the horizontal plane.
[0017]
The portable wireless device includes a first housing and a second housing movable so as to overlap the first housing, and the first and second antenna elements are provided at side ends of the second housing. When the second housing is provided on the first housing and the second housing overlaps the first housing, the first and second antenna elements may be arranged at positions protruding from the first housing. In this case, even when the first housing and the second housing overlap, the antenna volume does not decrease because the first and second antenna elements protrude from the first housing.
[0018]
By providing the above-mentioned antenna for a portable wireless device, the wireless device can obtain a broadband antenna with a small gain and a high gain in a horizontal plane despite the built-in antenna having no protrusion from the housing. Thus, the degree of freedom in housing design is improved.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A and 1B are diagrams showing a portable wireless device and an antenna according to a first embodiment of the present invention. FIG. 1A is a perspective view showing the wireless device when the housing is opened, and FIG. It is.
[0020]
The portable wireless device of FIG. 1 has a second housing 12 provided on a first housing 10 so as to be opened and closed by a hinge 11. The first housing 10 has a key unit 13 mounted on the surface, a data processing unit (not shown) including a CPU, a memory, and the like, and a battery (not shown) inside.
[0021]
The second housing 12 has a liquid crystal screen 14 on its surface, a wireless unit (wireless circuit unit) 15 therein, a matching circuit 16 for performing impedance matching with the wireless unit 15, and a second housing 12. A first antenna element 18 disposed on the side projection 17 and having a first end 18 a connected to the matching circuit 16; and a lower portion of the projection 17 below the first antenna element 18. It has a second antenna element 19. The projecting portion 17 does not overlap with the first housing 10 when the housing is closed as shown in FIG. 1B so that the antenna characteristics do not deteriorate even when the first and second housings 10 and 12 are closed. It has become.
[0022]
The first element 18 is hardly affected by the housing, and has an electrical length of approximately 波長 wavelength longer than ４ wavelength with respect to the operating frequency in order to obtain a large gain in a horizontal plane. The second antenna element 19 is formed of an L-shaped conductive member whose electrical length is １ ／ wavelength with respect to the operating frequency and is open at both ends. , And the upper end is disposed close to the second end 18b opposite to the first end 18a of the first antenna element 18, and is electrically connected to the second end 18b by capacitance. To form an antenna system integrally with the first antenna element 18 and operate.
[0023]
Therefore, the substantial antenna volume increases and the second antenna element 19 also resonates at the used frequency, so that double resonance can be realized, and the band characteristics are improved. More preferably, the electrical length of the second antenna element 19 is slightly shifted from λ / 2, and the resonance frequency of the first antenna element 18 is appropriately changed to obtain good characteristics in a desired band. Can be Here, λ represents the wavelength of the electric signal.
[0024]
FIG. 2 shows an input return loss characteristic indicating a matching state of the high-frequency circuit. The horizontal axis indicates frequency, and the vertical axis indicates input return loss. Fo on the horizontal axis indicates the center of the used frequency, and BW indicates the bandwidth of the used frequency. In the figure, a solid line 20 indicates the characteristic when the second antenna element 19 exists, and a broken line 21 indicates the characteristic when the second antenna element 19 does not exist.
[0025]
When the second antenna element 19 is not provided, since the first antenna element 18 is close to the radio unit 15, the volume occupied by the antenna is reduced, and the frequency characteristic becomes narrower as indicated by a broken line 21 in FIG. As a result, the input impedance decreases, and the input return loss characteristics deteriorate. However, when the second antenna element 19 exists, the first antenna element 18 and the second antenna element 19 integrally form an antenna system, and double resonance occurs as shown by a solid line 20 in FIG. 2 shows two dips in the input return loss characteristic, showing a very wide band characteristic.
[0026]
According to the present embodiment, there is a case where a half-wavelength antenna longer than a quarter-wavelength is used for a working frequency which has a narrow frequency band but is hardly affected by the housing and has a large gain in a horizontal plane. Also, by combining with the second antenna element 19 disposed in the housing, a sufficient antenna occupation volume is ensured, and excellent characteristics can be obtained in a very wide band due to double resonance.
[0027]
In the present embodiment, the second antenna element 19 is L-shaped along the protrusion 17 and the lower surface 30 of the second housing 12, but the electrical length may be approximately λ / 2. For example, a shape such as zigzag or coil shape may be adopted. Further, if the second antenna element 19 having a long housing length A and an electrical length of λ / 2 can be stored only on the side surface of the housing, it is not particularly necessary to make the second antenna element 19 L-shaped, but may be a straight shape. In addition, the protruding portion 17 is provided at a position where the first and second housings 10 and 11 do not overlap when the housing is closed. However, when the characteristics at the time of closing may be sacrificed to some extent, the protruding portion 17 does not need to be particularly protruded. . Therefore, in that case, the first and second housings 10 and 11 entirely overlap each other at the time of closing.
[0028]
Next, FIG. 3 is an enlarged view of an antenna part showing a second embodiment of the present invention. The antenna for a portable wireless device according to the second embodiment further improves the antenna characteristics of the first embodiment described above. The first end 18a is connected to the matching circuit 16 and the electrical length is reduced. The first antenna element 18 having a wavelength approximately half of the operating frequency, and the electrical length disposed close to the lower second end 18b of the first antenna element 18 is １ ／ of the operating frequency. The second antenna element 19 having the wavelength is connected to the upper portion of the first end 18 a of the first antenna element 18, and is formed in an L shape along the side surface 31 and the upper surface 32 of the second housing 12. It has an additional conductor 22 arranged.
[0029]
The additional conductor 22 operates as an open stub in terms of impedance, cancels out the inductance component of the impedance seen from the first end 18a of the first antenna element 18, which is a feeding terminal, and improves the impedance characteristic, Further, there is an effect of obtaining broadband characteristics and an effect that the antenna current flowing through the additional conductor 22 assists the antenna current flowing through the first antenna element 18 to improve the gain in the horizontal plane.
[0030]
According to the present embodiment, it is possible to improve both the impedance characteristics and the gain characteristics in the waterfront surface. In the present embodiment, the additional conductor 22 is L-shaped. However, the additional conductor 22 may be a simple rectangle, or may have a zigzag or coil shape.
[0031]
Next, FIG. 4 is an enlarged view of an antenna part according to a third embodiment of the present invention. 4 is an example in which the second antenna element 19 shown in the above-described second embodiment is reduced in size. As the second antenna element 19, a λ / 4 antenna with a short-circuit on one end is used as a housing. It is arranged in. The upper end of the second antenna element 19 is open, and the lower end is connected to the ground potential point of the radio unit 15. The second end 18b of the first antenna element 18 and the upper end of the second antenna element 19 are close to each other and are coupled via a capacitance, so that the first antenna element 18 and the second antenna element 19 double-resonates, and a very wide band characteristic is obtained.
[0032]
According to this embodiment, the size of the second antenna element 19 can be reduced, and even when the length A of the second housing 12 is short, the antenna element can be arranged only on the side surface of the housing. Further, since the lower end of the second antenna element 19 is connected to the ground point of the radio unit 15, a high-frequency current of the antenna can flow through the ground of the radio unit 15, and although there is a slight disturbance in directivity, Thus, a wider band characteristic than that of the first embodiment can be obtained.
[0033]
FIG. 5 is an enlarged view of an antenna part according to the fourth embodiment of the present invention. The antenna for a portable wireless device in FIG. 5 includes a wireless unit 15 disposed in a second housing 12, a matching circuit 16 for performing impedance matching with the wireless unit 15, and a first end 18 a serving as a matching circuit 16. A first antenna element 18 that is connected and has an electrical length of approximately half the wavelength of the working frequency, and a second antenna element 18 that is disposed close to a second end 18b below the first antenna element 18. Antenna element 19. The above-described additional conductor 22 for improving characteristics is connected to an upper portion of the first end 18a of the first antenna element 18.
[0034]
The second antenna element 19 is divided into a radiating portion 19a and a capacitance portion 19b, and the radiating portion 19 is set to an arbitrary electrical length that is larger than １ ／ wavelength and smaller than 波長 wavelength of the used frequency, and the upper end thereof is provided. The first antenna element 18 is arranged close to the second terminal 18b, and the lower end is connected to the capacitor 19b. The capacitance portion 19 b is formed of a conductive plate disposed in proximity to the ground portion of the wireless portion 15 in a non-contact manner, and serves to ground the lower end of the radiation portion 19 a of the second antenna element 19 via the capacitance 40. . The capacitance value determined by the area of the capacitance section 19b is set so as to resonate at the operating frequency together with the electrical length of the radiation section 19a. Therefore, similarly to the above-described embodiment, the first antenna element 18 and the second antenna element 19 double-resonate in the vicinity of the operating frequency, and exhibit broadband characteristics.
[0035]
According to the present embodiment, the second antenna element 19 can be set to any electrical length other than １ ／ and 波長 wavelength of the used frequency, and the degree of freedom in design is improved. Also, the distortion of directivity, the band characteristics, and the occupied volume of the antenna are reduced by changing the length of the radiating portion 19a and the area of the capacitive portion 19b under the condition that the first antenna element 18 and the second antenna element 19 are subjected to double resonance. By adjusting, it is possible to make a trade-off, so that the degree of freedom of design is remarkably improved. Further, since the capacitance section 19b is connected to the ground of the wireless section 15 via the capacitance and is in a non-contact state, stable characteristics can be obtained without variation during production.
[0036]
In the present embodiment, the capacitance portion 19b is formed of a rectangular conductive plate, but may have any shape as long as a predetermined capacitance can be obtained, and may be a lumped constant component such as a capacitor. In addition, although the capacitance portion 19b forms the capacitance 40 in proximity to the ground of the wireless portion 15, the capacitance 40 may be formed in proximity to a shield formed by plating or the like in the housing.
[0037]
In each of the above embodiments, when disposing (incorporating) the antenna elements 18 and 19 in the second housing 12, the antenna elements are screwed to the inner surface of the housing 12, or a recess is provided in the inner surface of the housing 12 in advance. And may be embedded there. Further, it may be mounted on a printed circuit board that forms a part of the radio unit 15, or may be printed on the printed circuit board. In these cases, all of them are built in the housing 12, but they may be arranged outside the housing 12 as shown in FIG. In FIG. 6, the housing 12 is formed with a step so that a box portion 12a for storing a wireless unit and the like and a non-box portion 12b are present. Then, the first and second antenna elements 18 and 19 are arranged on the non-box 12b. In this case, it is convenient to close the housing 12 by applying an insulating resin to the stepped portion 12b provided with the antenna element and making the surface of the housing 12 a uniform height.
[0038]
【The invention's effect】
As described above, the antenna for a portable wireless device according to the present invention has the upper end of the second antenna element disposed close to the lower end of the first antenna element having a quarter wavelength or more with respect to the frequency used. Since the antennas are capacitively coupled and operate integrally as an antenna, the antenna volume increases, and it is difficult to be affected by the housing, and a wide-band characteristic can be secured despite high horizontal gain. More preferably, by forming the second antenna element to resonate with the operating frequency, it is possible to double-resonate with the first antenna element to secure an extremely wide band characteristic.
[0039]
Further, by connecting an additional conductor to the first end of the first antenna element, the inductance component of the first antenna element is canceled, the impedance characteristic is improved, and the antenna current flowing through the first antenna element is improved. And the gain in the horizontal plane can be further improved.
[0040]
In addition, the portable wireless device equipped with the antenna for a portable wireless device according to the present invention can obtain a broadband antenna while having a high gain in a horizontal plane with little influence of the housing, so that the radiation performance from the antenna is maintained. It is very easy to handle without protrusions and can be adapted to various housing shapes.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of an antenna for a portable wireless device according to the present invention.
FIG. 2 is an input characteristic diagram of the antenna for a portable wireless device of the present invention.
FIG. 3 is a view showing a second embodiment of the antenna for a portable wireless device of the present invention.
FIG. 4 is a diagram illustrating a third embodiment of the antenna for a portable wireless device according to the present invention.
FIG. 5 is a view showing a fourth embodiment of the antenna for a portable wireless device of the present invention.
FIG. 6 is a view showing a fifth embodiment of the antenna for a portable wireless device of the present invention.
FIG. 7 is a diagram showing a conventional portable wireless device antenna.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 First housing 11 Hinge part 12 Second housing 13 Key part 14 Liquid crystal screen 15 Wireless part 16 Matching circuit 17 Projecting part 18 First antenna element 18a First end 18b of first antenna First antenna The second end 19 of the second antenna element 20, 21 The return loss characteristic curve 22 The additional conductor 23 The antenna section 24 The first antenna 24a The connection part 25 at the time of drawing out The insulator 26 The second antenna 26a The contact part 27 at the time of storage The antenna Holder 28 Power supply terminal

Claims (9)

A first antenna element having an electrical length equal to or longer than a quarter wavelength of the operating frequency and a first end of which is connected to the radio unit via an impedance matching circuit; A second antenna element whose upper end is arranged close to a second end opposite to the first end, and which is built in or arranged in a portable wireless housing incorporating the wireless section. An antenna for a portable wireless device. 2. The portable wireless device antenna according to claim 1, wherein the second antenna element is formed of a conductive member having an electrical length substantially equal to a half wavelength of a used frequency and open at both ends. The second antenna element is formed of a one-sided short-circuited conductive member having an electrical length of approximately 波長 wavelength of the operating frequency, and the open end side of the one-sided short-circuited conductive member is the first end of the first antenna element The antenna for a portable wireless device according to claim 1, wherein the antenna is arranged close to an end of the portable wireless device. A conductive member that is arranged close to the shield member of the wireless unit and forms a predetermined capacitance with the shield member; and a lower end of the second antenna element is connected to the conductive member. The antenna for a portable wireless device according to claim 1, wherein: The antenna for a portable wireless device according to claim 1, further comprising an additional conductor built in or disposed in the portable wireless device and connected to a first end of the first antenna element. . The antenna according to claim 5, wherein the additional conductor is formed integrally with the first antenna element. The portable wireless device includes a first housing and a second housing movable so as to overlap the first housing, and the first and second antenna elements are provided in the second housing. And when the second housing is overlaid on the first housing, the first and second antenna elements are arranged at positions protruding from the first housing. The antenna for a portable wireless device according to claim 1, wherein: The portable wireless housing incorporating the wireless section has a step portion that does not form a box on a side portion, and the first and second antenna elements are provided in the step portion. Item 7. An antenna for a portable wireless device according to any one of Items 1 to 7. A portable wireless device comprising the portable wireless device antenna according to any one of claims 1 to 6.

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