JP3590307B2 - Portable radio - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a portable wireless device such as a portable telephone or a portable information terminal having an integrated antenna, and more particularly to a technique for reducing the influence of an object around the antenna on antenna characteristics.
[0002]
[Prior art]
2. Description of the Related Art Portable wireless devices such as mobile phones and personal digital assistants have been reduced in size and thickness. Since a portable wireless device must be excellent in portability, it is very important to be small and thin.
[0003]
In addition, since the portable wireless device is placed close to the user during a call, the influence of the human body on the antenna poses a problem. The human body not only absorbs and scatters radio frequency radio waves, but also has the effect of varying the operating impedance of an adjacent antenna. This is because the human body works as a dielectric having a very high relative dielectric constant of 50 or more in terms of high frequency. As a result, the radiation characteristics of the antenna deteriorate due to the proximity of the human body. Further, as the size and thickness of the portable wireless device are reduced, the ear tends to be closer to the antenna, which further deteriorates the antenna characteristics due to the human body.
[0004]
FIG. 15 and FIG. 16 show the results of an investigation by the present inventors on such a problem of deterioration of antenna characteristics due to a human body. As shown in FIG. 15, a portable wireless device model in which the antenna 110 is attached to the wireless device housing 100 is prepared, and the thickness (terminal thickness) of the housing 100 is 20 mm or more in (a) and less than 20 mm in (b). And
[0005]
FIG. 16 shows the result of measuring the amount of gain deterioration due to the change in the impedance of the antenna 110 using the thickness of the wireless device housing 100 as a parameter in the state of a call using the wireless device model at a transmission / reception frequency of 2 GHz. is there. From this result, it can be seen that when the thickness of the wireless device housing 100 is thinner than 20 mm, the ear comes into contact with the antenna 110 and the gain of the antenna 110 is greatly deteriorated.
[0006]
As described above, the cause of the deterioration of the antenna characteristics is that the impedance of the antenna fluctuates due to the influence from the human body. The human body is an object having a very high dielectric constant, and when the antenna approaches such an object, the electrical length of the antenna appears equivalently longer. In this case, the resonance frequency of the antenna deviates from a desired value, and the impedance of the antenna changes accordingly. As described above, even when the impedance of the antenna is adjusted to be optimal in the terminal of the portable wireless device, the impedance value deviates from the optimal value due to the proximity of the human body to the antenna.
[0007]
Further, the transmission output of the portable wireless device may deteriorate due to a change in the impedance of the antenna. This phenomenon will be described. In order to radiate radio waves from the antenna, required power must be input to the antenna. The optimum condition for inputting power to the antenna is that the impedance of the antenna is an optimum value, that is, a value equal to the impedance of the feed line.
[0008]
If the impedance of the antenna fluctuates from the optimal value, the power transmitted through the feed line is partially reflected at the input end of the antenna and returns to the transmission amplifier, and the power output from the transmission amplifier is not sufficiently input to the antenna. become. The reflection of power at the antenna input terminal degrades performance such as efficiency and gain of the transmission amplifier, and consequently causes deterioration of transmission performance of the portable wireless device.
[0009]
As a method of solving such a problem, Japanese Patent Application Laid-Open No. H10-256930 proposes a method of correcting the antenna impedance changed by the influence of the human body by changing the electrical length of the antenna. However, this method can correct the antenna impedance, but cannot solve the problem of a change in the radiation pattern due to the influence from the human body near the antenna. Even if power can be supplied to the antenna by adjusting the electrical length of the antenna, if the radiation pattern changes due to a nearby human body, the communication characteristics will be significantly degraded.
[0010]
The change in the radiation pattern of the antenna due to the proximity of the human body is caused by the fact that the human body is a dielectric material having a high dielectric constant, like the change in the impedance. The characteristic deterioration due to the change of the radiation pattern cannot be largely improved by slightly separating the antenna from the human body as disclosed in Japanese Patent Application Laid-Open No. 10-256930.
[0011]
For example, when the antenna is in contact with the ear as in a normal call, the gain of the antenna is reduced by about 8 dB compared to when the portable wireless device is held only by the hand away from the head. When the antenna is separated from the ear by about 3 mm, the antenna gain is greatly improved to about 4 dB, but the deterioration of the antenna gain is still large compared to when the antenna is sufficiently separated from the head.
[0012]
[Problems to be solved by the invention]
As described above, in the related art, there is a problem that deterioration of antenna characteristics due to the proximity of a human body, particularly deterioration of radiation characteristics, which is a problem in a portable wireless device, cannot be sufficiently improved.
[0013]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a portable wireless device that can perform favorable communication by improving deterioration of antenna characteristics due to proximity of a human body.
[0014]
[Means for Solving the Problems]
In order to solve the above problem, a portable wireless device according to the present invention includes a plurality of antennas, an antenna selecting unit for selecting an arbitrary one from the plurality of antennas, and transmitting to an antenna selected by the antenna selecting unit. Transmitting means for supplying a signal; power supply means for supplying power to the transmitting means; current detecting means for detecting a current value flowing from the power supplying means to the transmitting means for each antenna selected by the antenna selecting means; Control means for deciding an optimum antenna based on the detected current value of each antenna by the current value detecting means, and controlling the antenna selecting means so as to select the optimum antenna.
[0015]
In the control means, specifically, a correlation value (for example, a difference between the absolute values of the current values) between the current value detected by the current value detection means and a reference current value set in advance for each antenna is obtained. The optimum antenna is determined by comparing the correlation values.
[0016]
With such a configuration, good communication can be performed by selecting an antenna with less characteristic deterioration due to the proximity of a human body and using it for transmission and reception.
Another portable wireless device according to the present invention includes a plurality of antennas, and a variable gain amplifier provided corresponding to each of the plurality of antennas, and supplies a transmission signal to each antenna via the variable gain amplifier. Means, power supply means for supplying power to the transmission means, current detection means for individually detecting a current value flowing into each of the variable gain amplifiers from the power supply means, and each variable gain amplifier by the current detection means. Control means for deciding the gain distribution to each variable gain amplifier based on the detected current value, and controlling the gain of each variable gain amplifier based on this gain distribution.
[0017]
More specifically, the control unit obtains a correlation value (for example, a difference between absolute values of the current values) between the current value detected by the current value detection unit and a reference current value set in advance corresponding to each antenna. The optimal gain distribution is determined by comparing the correlation values of.
[0018]
With this configuration, it is possible to relatively increase the power distribution to the antenna with less characteristic degradation due to the proximity of the human body, and to perform good communication.
[0019]
In a configuration having an isolator inserted between a plurality of antennas and a transmitting means during communication, it is desirable to short-circuit this isolator when determining an optimum antenna or an optimum gain distribution.
[0020]
According to one aspect, the plurality of antennas are arranged on the top of the radio housing side by side in the longitudinal direction of the top. According to another aspect, the plurality of antennas includes an omni-directional antenna and a directional antenna. In another aspect, at least one of the plurality of antennas is located on a top of the radio housing, and at least one other is built into the radio housing.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(1st Embodiment)
FIG. 1 is a block diagram showing a configuration of the portable wireless device according to the first embodiment of the present invention. The portable wireless device includes a plurality of antennas 11 and 12, an antenna selection switch 13 for selecting one of the antennas 11 and 12, a transmission circuit 14 including a transmission signal source 15 and a transmission amplifier 16, and a portable wireless device. A power supply circuit 17 for supplying power to each part of the machine; a current detector 18 for detecting a current value flowing from the power supply circuit 17 to the transmission amplifier 15; an antenna selection switch 13 for receiving the current value detected by the current detector 18; It comprises a controller 20 for controlling the signal source 15 and a memory 19.
[0022]
At the time of transmission, a transmission signal modulated according to the information signal by the transmission signal source 15 and mixed at a predetermined transmission frequency is generated and sent to the transmission amplifier 16. The transmission amplifier 16 is a power amplifier, amplifies the transmitted transmission signal to a required transmission power, and supplies the signal to one of the antennas 11 and 12 selected by the antenna selection switch 13.
[0023]
The antennas 11 and 12 radiate radio waves into the air upon receiving the power-amplified transmission signal, and a part of the radiated radio waves becomes reflected waves via the antennas 11 and 12 and the antenna selection switch 13 so that the transmission amplifier 16 is transmitted. Come back to. The returned signal varies the gain and efficiency of the transmission amplifier 16. The fluctuation of the gain and the efficiency causes the fluctuation of the current consumption of the transmission amplifier 16.
[0024]
The fluctuation of the consumption current, that is, the value of the power supply current supplied from the power supply circuit 17 to the transmission amplifier 16 is detected by the current detector 18, and the obtained information on the detected current value is sent to the controller 20. The controller 20 determines an optimum antenna based on the detected current value and controls the antenna selection switch 13 to select the antenna, as described later.
[0025]
Here, before describing the operation of the present embodiment, an experiment performed to explain the above-described phenomenon will be described.
First, a wireless device model shown in FIG. 2 was prepared for an experiment. This wireless device model has a receiver 101 and a transmitter 13 attached to a wireless device housing 100, a transmission circuit 103 including a transmission amplifier is mounted inside the receiver, and an antenna 110. Power is supplied to the transmission circuit 103 from the outside using a constant voltage power supply 121 via a power supply line, and from the reading of the ammeter 122 provided in the constant voltage power supply 121, the power consumption including the current consumption of the transmission amplifier in the transmission circuit 103 is included. The current consumption of the wireless device circuit can be measured.
[0026]
The operating frequency (transmission frequency) of this wireless device model is around 2 GHz, and the size of the housing 100 is about λ in length, about λ / 4 in width, and about λ in thickness, where λ is the wavelength at this operating frequency. Is about λ / 20. Further, as the antenna 110, an antenna having a built-in helical antenna 111 having a height of about λ / 10 in a cap 112 was used.
[0027]
FIGS. 3 and 4 are graphs showing the results of measurement using the wireless device model shown in FIG. 2, and FIG. 3 shows the relationship between the distance between the antenna and the human body and the current consumption. It can be seen from FIG. 3 that the current consumption of the transmission amplifier increases as the antenna approaches the human head.
FIG. 4 shows the relationship between the average of the radiated power in the horizontal plane and the distance between the antenna and a human body, as shown in FIG. As is clear from the comparison of these results, it can be seen that there is a strong correlation between the increase in the current consumption of the transmission amplifier and the radiated power.
[0028]
This phenomenon is due to the fact that when considering the antenna as the load of the transmission amplifier, the load fluctuation due to the change in the distance between the antenna and the human body causes the efficiency of the transmission amplifier to deteriorate, resulting in an increase in current consumption. Conceivable. Also, the load fluctuation at this time is clearly caused by the human body. In this experiment, the current consumption of the entire wireless device circuit was measured, and the change in the current consumption of the transmission amplifier alone was larger.
[0029]
As described above, the fluctuation of the current consumption of the transmission amplifier changes depending on the distance between the antenna and the human body. Therefore, by selecting one of the antennas 11 and 12 having a smaller change in current consumption by the antenna selection switch 13, an antenna less affected by the human body can be used for communication. Communication performance can be improved.
[0030]
Hereinafter, processing of the controller 20 that determines an optimal antenna based on the current consumption of the transmission amplifier 16 and controls the selection of the antenna will be described.
The controller 20 determines the most suitable antenna for communication among the antennas 11 and 12 based on the current value detected by the current detector 18 at the start of communication and at an appropriate timing during communication, and the antenna is selected. The antenna selection switch 13 is controlled as described above.
[0031]
First, at the start of communication, a request to output a known signal is made to the transmission signal source 15 (step S101). In this state, the antenna selection switch 13 is connected to the antenna 11 (step S102), and the detected current of the current detector 18 is detected. The value is read (step S103). The detected current value at this time is defined as I11. Next, the detected current value I11 and the reference current value Iref11 are compared (step S105), and a correlation value between them, in this example, a difference | I11−Iref11 | of the absolute value is obtained, and this value is written in the memory 19 ( Step S106).
[0032]
Next, the antenna selection switch 13 is connected to the antenna 12 (step S106), and the detected current value of the current detector 18 is read (step S107). The detected current value at this time is defined as I12. Thereafter, a request to stop outputting the known signal is made to the transmission signal source 15 (step S108), the detected current value I12 is compared with the reference current value Iref12 (step S109), and the correlation value between the two is determined in the same manner as described above. The difference | I12−Iref12 | of the absolute value of the user is obtained, and this value is written in the memory 19 (step S110).
[0033]
Next, the two types of correlation values written in the memory 19, ie, | I11−Iref11 | and | I12−Iref12 | are compared (step S111). If | I11−Iref11 | <| I12−Iref12 | The antenna selection switch 13 is connected to the antenna 11 (step S112), and unless | I11−Iref11 | <| I12−Iref12 |, the antenna selection switch 13 is connected to the antenna 12 (step S113).
[0034]
That is, the correlation values between the detected current values I11 and I12 and the reference current values Iref11 and Iref12 when each of the antennas 11 and 12 are selected, in this example, the detected current values I11 and I12 with respect to the reference current values Iref11 and Iref12. The antenna having the smaller absolute value difference is selected by the antenna selection switch 13 as the antenna most suitable for communication, and communication (transmission and reception) is performed in this state (step S114).
[0035]
During this communication, a sleep mode is started by a timer in the controller 20, the device wakes up at a desired time interval until the communication is interrupted, and returns to the first step S101 to repeat the same processing. That is, until it is determined in step S115 that the communication has been completed, it is determined in step S116 whether the communication operation has elapsed for a certain period of time. When the predetermined time has elapsed, the process returns to step S101.
[0036]
As the reference current values Iref11 and Iref12, for example, in the final stage of the manufacture of the portable wireless device, the portable wireless device outputs a known signal in the radio wave anechoic chamber, and the antenna selection switch 13 is set to the antennas 11 and 12, respectively. What is necessary is just to obtain the value of the current detector 18 (ammeter) measured in the connected state. The values of the reference current values Iref11 and Iref12 thus determined are stored in the memory 19.
[0037]
As described above, according to the present embodiment, the controller 20 determines the optimum antenna among the plurality of antennas 11 and 12, selects the antenna by the antenna selection switch 13, and uses the selected antenna for communication. The communication performance of the portable wireless device can be improved.
[0038]
(Second embodiment)
FIG. 7 is a block diagram illustrating a configuration of a portable wireless device according to the second embodiment of the present invention. The difference between the first embodiment and the first embodiment will be described by assigning the same reference numerals to the same parts as those in FIG. 1. The present embodiment has a feature in the configuration when the isolator 21 is used.
[0039]
The isolator is an element having a property that the output impedance is constant even if the input impedance fluctuates, and an element manufactured using ferrite is commercially available. When the isolator 21 is inserted between the antennas 11 and 12 and the transmission amplifier 16 as shown in FIG. 7, when the reflected waves from the antennas 11 and 12 are used as input waves, reflection of the antennas 11 and 12 causes Even if a change occurs in the input impedance, the effect does not reach the transmission amplifier 16, so that the performance of the transmission amplifier 16 does not change.
[0040]
As described above, the isolator 21 works very effectively with respect to the stabilization of the performance of the transmission amplifier 16, but on the other hand, as in the first embodiment, the current consumption of the transmission amplifier 16 (the current detector 18 When trying to determine which one of the antennas 11 and 12 is most suitable for communication based on the detected current value, the presence of the isolator 21 is very inconvenient.
[0041]
In consideration of such points, in the present embodiment, the isolator 21 is connected between the transmission amplifier 16 and the antenna selection switch 13 via two isolator control switches 22 and 23. Two paths are formed between the isolator control switches 22 and 23, a line with the isolator 21 interposed therebetween and a direct line without the isolator 21. These paths are controlled by the controller 20 by the switches 22 and 23. It can be selected.
[0042]
More specifically, when checking the optimum one of the antennas 11 and 12 in the same manner as in the first embodiment, the controller 20 selects the switches 22 and 23 by selecting the path of the direct line where the isolator 21 is not inserted. To control. On the other hand, during communication, the controller 20 controls the switches 22 and 23 so as to select the path in which the isolator 21 is inserted.
[0043]
As described above, according to the present embodiment, when the optimum antenna is determined based on the present invention, the power consumption from the current detected by the current detector 18 when the antennas 11 and 12 are connected is accurately determined without the influence of the isolator 21. The current can be checked correctly, and the effect of suppressing the gain fluctuation of the transmission amplifier 16 by the isolator 21 can be obtained even if the characteristics of the antennas 11 and 12 change in a normal communication state.
[0044]
(Third embodiment)
FIG. 8 is a block diagram illustrating a configuration of a portable wireless device according to the third embodiment of the present invention. The present embodiment relates to optimization of gain distribution of an amplifier in a transmission circuit system when not operating one of a plurality of antennas 11 and 12 but operating both at the same time.
[0045]
The variable gain amplifiers 31 and 32 are individually connected to the antennas 11 and 12 as transmission amplifiers. Further, switches 33 and 34 are inserted into power supply lines for supplying power to the variable gain amplifiers 31 and 32, respectively.
[0046]
With reference to the flowchart shown in FIG. 9, the processing of the controller 20 in the present embodiment will be described.
The controller 20 determines the gain distribution to the variable gain amplifiers 31 and 32 based on the detected current values of the variable gain amplifiers 31 and 32 obtained by the current detector 18 at the start of communication and at an appropriate timing during communication. Then, gain control of the variable gain amplifiers 31 and 32 is performed based on this gain distribution.
[0047]
First, a request to output a known signal is made to the transmission signal source 15 by starting communication (step S201), and the switch 33 is turned on and the switch 34 is turned off (step S202). Then, the gain of the variable gain amplifier 31 is set to a predetermined reference value (step S203), and the detected current value of the current detector 18 is read (step S204). The detected current value at this time is defined as I11. Next, the detected current value I11 is compared with the reference current value Iref11 (step S205), and a correlation value between them, for example, a difference | I11−Iref11 |
[0048]
Next, the switch 34 is turned on and the switch 33 is turned off (step S207), so that the power supply current is supplied only to the variable gain amplifier 32, and the gain of the variable gain amplifier 31 is set to a predetermined reference value. After setting (Step S208), the current value detected by the current detector 18 is read (Step S209). The detected current value at this time is defined as I12.
[0049]
Thereafter, a request to stop outputting the known signal is made to the transmission signal source 15 (step S210), the detected current value I12 is compared with the reference current value Iref12 (step S211), and the correlation value between the two is determined in the same manner as described above. The difference | I12−Iref12 | of the absolute value of the user is obtained and written in the memory 19 (step S212).
[0050]
Next, the two types of correlation values written in the memory 19, that is, the ratio between | I11−Iref11 | and | I12−Iref12 |, are calculated (step S213), and this ratio | I11−Iref11 | / | I12−Iref12 | , The gain distribution of the variable gain amplifiers 31 and 32 is determined, and each gain is set based on this distribution (step S214).
[0051]
Then, in this state, the switches 33 and 34 are both turned on, and communication is performed in this state (step S215).
[0052]
During this communication, the sleep mode is started by the timer in the controller 20, the device wakes up at a desired time interval until the communication is interrupted, and returns to the first step S201 to repeat the same processing. That is, until it is determined in step S217 that the communication has been completed, it is determined in step S218 whether the communication operation has elapsed for a predetermined period of time. When the predetermined time has elapsed, the process returns to step S201.
[0053]
As the reference current values Iref11 and Iref12, for example, in the final stage of the manufacture of the portable wireless device, the portable wireless device outputs a known signal in the radio wave anechoic chamber, and the antenna selection switch 13 is set to the antennas 11 and 12, respectively. What is necessary is just to obtain the value of the current detector 18 (ammeter) measured in the connected state. The values of the reference current values Iref11 and Iref12 thus determined are stored in the memory 19.
[0054]
On the other hand, regarding the gain distribution to the variable gain amplifiers 31 and 32, the ratio | I11−Iref11 | / | I12−Iref12 | of the two correlation values obtained in step S213 is represented by β as shown in the following equation.
β = | I11−Iref11 | / | I12−Iref12 |
α = (β + 1) / β
Substitute for
[0055]
The value obtained by multiplying the obtained value α by the maximum gain of the variable gain amplifiers 31 and 32 is defined as the gain value of the amplifier 31, and (1−α) is also multiplied by the maximum gain of the variable gain amplifiers 31 and 32. The obtained value is used as the gain value of the amplifier 32.
[0056]
In this manner, the gain can be appropriately distributed to the amplifiers 31 and 32 in accordance with the characteristic deterioration of the variable gain amplifiers 31 and 32 due to the reflection at the antennas 11 and 12 due to the proximity of the human body. By keeping the total gain of the amplifiers 31 and 32 constant, the transmission power can always be kept constant.
[0057]
As described above, according to the present embodiment, the gain distribution to the variable gain amplifiers 41 and 42 used as transmission amplifiers individually provided corresponding to the antennas 11 and 12 is determined by the current detector 18 for each amplifier 41 and 42. By optimizing based on the detected current value in the above, the transmission power from the antenna with less deterioration due to the influence of the human body among the antennas 11 and 12 is increased, and the transmission power from the antenna with more deterioration is reduced. This makes it possible to transmit radio waves efficiently.
[0058]
(Fourth embodiment)
FIG. 10 is a block diagram illustrating a configuration of a portable wireless device according to the fourth embodiment of the present invention. In the present embodiment, the transmission amplifiers 41 and 42 connected to the antennas 11 and 12, respectively, are fixed gain amplifiers.
[0059]
An up-converter 40 for frequency-converting (up-converting) the transmission signal from the intermediate frequency to a required high frequency is inserted between the transmission amplifiers 41 and 42 and the transmission signal source 15. There is provided a variable gain amplifier which is controlled so that the same gain distribution as in the third embodiment is performed.
[0060]
FIG. 11 shows an internal configuration of the up-converter 40. Mixers 43 and 44 for frequency conversion are inserted between the transmission signal source 15 and the transmission amplifiers 41 and 42.
[0061]
On the other hand, a reference signal source 45 for generating a high-frequency reference signal corresponding to a local signal is provided. The reference signal output from the reference signal source 45 is divided into two and input to the variable gain amplifiers 46 and 47. . Here, assuming that the fixed gain transmission amplifiers 41 and 42 in FIG. 10 are main amplifiers, the variable gain amplifiers 46 and 47 serve as preamplifiers. The reference signals amplified by the variable gain amplifiers 46 and 47 are multiplied by the intermediate frequency transmission signal output from the transmission signal source 45 by the mixers 43 and 44, and are multiplied as high frequency transmission signals. 42 respectively.
[0062]
In the present embodiment, the gain distribution of the variable gain amplifiers 46 and 47 is controlled by the controller 30. In this case, the processing of the controller 30 replaces the variable gain amplifiers 41 and 42, which are transmission amplifiers for gain control based on the determination of the gain distribution, with the variable gain amplifiers 46 and 47 for amplifying the reference signal in the up-converter 40. Except for this point, the procedure is the same as that of the flowchart shown in FIG.
[0063]
(Fifth embodiment)
Next, as a fifth embodiment of the present invention, a description will be given of a preferred antenna configuration method as the antennas 11 and 12 used in the portable wireless devices of the first to fourth embodiments described above.
[0064]
First, the background of this embodiment will be described with reference to FIG. FIGS. 12A and 12B show the relationship with the earlobe when the antenna 110 is arranged above and below the top of the housing 100, respectively.
[0065]
The portable wireless device is held pressed against the ear. As shown in FIG. 12, the upper end portion of the earlobe is generally protruded, so that it is easy to approach and contact the antenna 110 as shown in FIG. On the other hand, the portion from the middle to the lower part of the earlobe has a recessed structure as compared with the upper end, so that it is easier to separate from the antenna 110 than the upper end.
[0066]
Therefore, as shown in FIG. 12B, by allowing the antenna 110 to always be disposed below the center of the earlobe, the influence of the human body can be reduced or eliminated. However, with the recent miniaturization of portable wireless devices, it is actually difficult to arrange the antenna 110 in this way.
[0067]
For example, when holding the portable wireless device with the right hand and the left hand respectively, if the antenna is located at a position away from the upper end of the earlobe when held by one hand, the upper end will be held when held by the other hand Will be in a position close to. There is also a method of arranging the antenna at the center of the top of the radio housing. However, in a miniaturized terminal, it is difficult to sufficiently improve the performance with such a central arrangement because the antenna cannot be far away from the upper end of the earlobe. become.
[0068]
In the present embodiment, the antenna is configured and arranged as shown in FIG. 13 in consideration of such points. The antenna configuration of the present embodiment has an effect of reducing the influence of the upper end of the earlobe close to the antenna. 13A schematically illustrates the antenna, and FIG. 13B illustrates the antenna more specifically.
[0069]
13A and 13B, reference numeral 100 denotes a wireless device housing, 101 denotes a receiver, and 102 denotes a transmitter. As shown in FIG. 13A, the antennas 11 and 12 are arranged on the top of the wireless device casing 100 so as to be separated from each other as much as possible in the longitudinal direction of the top (the width direction of the wireless device casing 100). By arranging the antennas 11 and 12 in this manner, even if the portable wireless device is held by either the left or right hand, it is possible to always separate the antenna from any of the upper ends of the earlobe.
[0070]
Therefore, by selecting the antenna farther from the earlobe according to the first and second embodiments, or by increasing the gain distribution to the antenna farther from the earlobe according to the third and fourth embodiments. By increasing the size, it is possible to reduce the influence of the upper end of the earlobe. The antenna farther from the earlobe can be recognized based on the current value detected by the current detector 18 as described in the first to fourth embodiments.
The antennas 11 and 12 in FIG. 13A can be specifically realized by helical antennas 11A and 12A which are small monopole antennas as shown in FIG. 13B, for example. Note that caps are actually mounted on the helical antennas 11A and 12A as shown by broken lines.
[0071]
(Sixth embodiment)
FIGS. 14A and 14B show the configuration and arrangement of an antenna according to a sixth embodiment of the present invention. In the present embodiment, one antenna 11 is disposed on the top of the radio device housing 100, and the other antenna 12 is disposed on the rear surface of the radio device housing 100, that is, the surface (front surface portion) on which the receiver 101 and the transmitter 102 are disposed. ) And on the opposite side.
[0072]
In the present invention, as described above, it is fundamental to improve the communication performance by selecting an antenna with little influence of the human body and by relatively increasing the power distribution to the antenna. There are two methods to realize such a configuration more efficiently.
[0073]
One is a method according to the fifth embodiment shown in FIG. 13, in which the arrangement positions of the antennas 11 and 12 are changed so that the distance between the antennas 11 and 12 from the human body is different. Another method is a method in which the influence from the human body is changed by changing the types (radiation characteristics) of the antennas 11 and 12 as in the present embodiment.
[0074]
In the present embodiment, as shown in FIG. 14A, since the antenna 11 is disposed on the top of the wireless device housing 100, the antenna 11 is omnidirectional. It is already known that an antenna disposed on the top of a conductive housing or a housing having a large number of conductive components therein becomes omnidirectional.
[0075]
On the other hand, the antenna 12 is disposed on or close to the surface of the wireless device housing 100. When the antenna 12 is arranged in this manner, the radiation from the surface on which the antenna 12 is arranged becomes strong, and the radiation characteristics of the antenna 12 have strong directivity in the normal direction to the surface on which the antenna 12 is arranged. In particular, in FIG. 14A, since the antenna 12 is installed on the opposite side (back side) of the surface on which the human head is in close contact, the effect of the human head can be expected to be reduced during a call.
[0076]
However, for example, in a standby state, another object may approach the surface on which the antenna 12 is mounted. For example, there is a case where a portable wireless device is placed in a breast pocket, a case where a portable wireless device is arranged on a desk, and the like. In such a case, the influence of an object closer to the antenna 11 is smaller.
[0077]
Therefore, the antennas 11 and 12 are arranged as shown in FIG. 14 (a), and the antenna 12 is selected during the call and the antenna 11 is selected during the standby, or the antenna 11 is selected during the call and the antenna 11 during the standby. By distributing a large amount of power, high communication performance can be obtained in both states during a call and during a standby state.
[0078]
FIG. 14B shows a specific example of the antennas 11 and 12 in FIG. The antenna 11 which is an omnidirectional antenna is realized by a helical antenna 11B which is a small monopole antenna as in FIG. On the other hand, the antenna 12 which is a directional antenna is realized by an inverted-F type antenna 12B built in the wireless device housing 100.
[0079]
In the above embodiment, the case where the number of antennas is two has been described, but the present invention can be similarly applied to the case where the number of antennas is three or more.
[0080]
【The invention's effect】
As described above, according to the portable wireless device of the present invention, by selecting an antenna or performing appropriate power distribution based on the power supply current value corresponding to each antenna, the deterioration of antenna characteristics due to the proximity of a human body is effected. It is possible to improve the communication and perform good communication.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a portable wireless device according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of a wireless device model used for an experiment in the present invention.
FIG. 3 is a diagram showing a relationship between a distance between a human body and an antenna and a current consumption of a wireless device.
FIG. 4 is a diagram showing a relationship between a distance between a human body and an antenna and a radiated power of a wireless device.
FIG. 5 is a diagram showing measurement conditions of FIG. 4;
FIG. 6 is a flowchart showing a control procedure for selecting an optimum antenna according to the first embodiment;
FIG. 7 is a block diagram showing a configuration of a portable wireless device according to a second embodiment of the present invention.
FIG. 8 is a block diagram showing a configuration of a portable wireless device according to a third embodiment of the present invention.
FIG. 9 is a flowchart showing a control procedure for determining an optimum gain distribution of the variable gain amplifier according to the third embodiment;
FIG. 10 is a block diagram showing a configuration of a portable wireless device according to a fourth embodiment of the present invention.
11 is a block diagram showing the relationship between the internal configuration of the up-converter and the controller in FIG.
FIG. 12 is a diagram illustrating a positional relationship between an antenna of a portable wireless device and an earlobe when the human head is worn to explain the present invention;
FIG. 13 is a diagram showing an example of an arrangement and a shape of an antenna in a portable wireless device according to a fifth embodiment of the present invention.
FIG. 14 is a diagram showing another example of the arrangement and shape of the antenna in the portable wireless device according to the fifth embodiment of the present invention.
FIG. 15 is a diagram showing a change in a positional relationship between an antenna and an earlobe when the head of a human body is worn due to a change in terminal thickness of the portable wireless device.
FIG. 16 is a diagram showing deterioration of antenna gain in the horizontal direction caused by the proximity of the antenna to the head when the portable wireless device is worn on the human head;
[Explanation of symbols]
11,12 ... antenna
13. Antenna selection switch
14 ... Transmission circuit
15 ... Transmission signal source
16 ... Transmission amplifier
17 Power supply circuit
18 Current detector
19… Memory
20 ... Controller
21 ... Isolator
22, 23 ... isolator control switch
30 ... Controller
31, 32 ... variable gain amplifier
33, 34 ... power supply current control switch
40 ... Up converter
41, 42 ... transmission amplifier (fixed gain amplifier)
43,44 ... Mixer
45 ... Reference signal source
46, 47 ... variable gain amplifier

Claims (6)

Multiple antennas,
Antenna selection means for selecting any one from the plurality of antennas,
A transmission unit that includes a transmission amplifier that amplifies a transmission signal, and supplies a transmission signal amplified by the transmission amplifier to an antenna selected by the antenna selection unit,
Power supply means for supplying power to the transmission amplifier ,
Current detection means for detecting a current value flowing into the transmission amplifier from the power supply means for each antenna,
The difference between the detected current value for each antenna by the current value detection means and a reference current value set in advance for each antenna is determined, and the optimum antenna having the smallest difference is determined. Control means for controlling the antenna selection means to be selected. Multiple antennas,
A transmitting unit that includes a variable gain amplifier provided corresponding to each of the plurality of antennas, and supplies a transmission signal to each antenna via the variable gain amplifier,
Power supply means for supplying power to the variable gain amplifier ,
Current detection means for individually detecting a current value flowing into each of the variable gain amplifiers from the power supply means,
A correlation value between a detected current value for each variable gain amplifier by the current value output means and a reference current value set in advance corresponding to each antenna is obtained, and these correlation values are compared to each variable gain amplifier. And a control means for determining the gain distribution of the variable gain amplifier and controlling the gain of each variable gain amplifier based on the gain distribution. An isolator, a direct line, and, during communication, the isolator is connected between the antenna selecting means and the transmitting means, and when the control means determines the optimum antenna, the antenna selecting means and the transmitting means 2. The portable wireless device according to claim 1, further comprising: means for connecting the direct line between the portable wireless devices. The portable wireless device according to claim 1, wherein the plurality of antennas are arranged on a top of the wireless device housing in a longitudinal direction of the top. The portable wireless device according to claim 1, wherein the plurality of antennas include an omnidirectional antenna and a directional antenna. The portable wireless device according to claim 1, wherein at least one of the plurality of antennas is disposed at a top of a wireless device housing, and at least one of the other antennas is built in the wireless device housing.

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