Patent Grant
8462065
The present invention relates to an ideal antenna apparatus applied for use in a communication apparatus that uses a comparatively high frequency for wireless communication, such as a communication apparatus for a wireless LAN system, for example, and also to a communication apparatus provided with such an antenna apparatus.
In recent years, various types of wireless transmission systems that use comparatively high frequencies such as from several hundred MHz to several GHz for wireless transmission have proliferated. For example, technologies that use the 2 GHz band, the 5 GHz band, etc. have been developed as wireless LAN systems. Technologies of various methods are being developed and implemented as antenna apparatus provided in wireless communication apparatus that use such bands.
In PTL 1, there is a description of an exemplary antenna for this type of communication apparatus. The technology described in PTL 1 is disposed with a plurality of antenna elements and is configured to have what is called diversity.
PTL 1: Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2009-514292
Meanwhile, technologies that use a comparatively wide band as the band used for wireless transmission in a wireless transmission system are increasing, and wide band technologies are desired as antennas for use with comparatively high frequency bands such as from several MHz to several GHz.
Also, even for antennas having diversity, antennas having a simple and compact configuration with better diversity characteristics are desired.
The present invention takes as an object to provide an antenna apparatus having wide band characteristics.
Also, the present invention takes as an object to provide an antenna apparatus having favorable diversity characteristics.
The present invention is an antenna apparatus that includes a first antenna element, a second antenna element, and a branch circuit to which the first antenna element and the second antenna element are coupled via respectively separate transmission lines.
Additionally, a delay process is conducted on one of the transmission lines by modifying the lengths of the transmission line coupling the first antenna element to the branch circuit and the transmission line coupling the second antenna element to the branch circuit.
By conducting this delay adjustment, the input impedance and/or phase of the first and second antenna elements are adjusted, and wider band characteristics than the antenna characteristics of the first and second antenna elements individually are configured.
According to the present invention, an antenna apparatus provided with two antenna elements is given wider band characteristics than the antenna characteristics of a single antenna element individually, and a favorable antenna apparatus having wide band characteristics with a comparatively simple configuration is obtained. Also, the wireless communication characteristics of a communication apparatus provided with such an antenna apparatus can be made favorable.
Embodiments of the present invention will be explained in the following order.
1. First embodiment
1.1 Configuration of antenna apparatus (
1.2 Exemplary disposition of antenna elements (Ex. 1:
1.3 Exemplary disposition of antenna elements (Ex. 2:
1.4 Exemplary characteristics (
1.5 Exemplary disposition of Ex. 2 antenna (
1.6 Exemplary disposition of Ex. 2 antenna (
1.7 Exemplary characteristics of
2. Second embodiment
2.1 Configuration of antenna apparatus (
2.2 Exemplary characteristics (
3. Third embodiment
3.1 Configuration of antenna apparatus (
3.2 Exemplary characteristics (
4. Modifications
Hereinafter, an exemplary first embodiment of the present invention will be explained with reference to
To summarize the configuration of the antenna apparatus illustrated in
Next, a specific configuration of the antenna apparatus illustrated in
A communication apparatus 10 is a wireless communication apparatus that conducts wireless communication in a frequency band from several hundred MHz to several GHz, for example, and the first antenna element 11 and the second antenna element 12 are provided as an antenna apparatus attached to the communication apparatus 10.
In the case of the present embodiment, the respective antenna elements 11 and 12 are configured as what is called an inverted F monopole antenna, with the respective antenna elements 11 and 12 taken to be elements of equal length. The details of exemplary dispositions of the two antenna elements 11 and 12 are discussed later, but herein the two rod-shaped antenna elements 11 and 12 are spaced a given interval apart and are disposed so as to line up in a nearly straight line. In the example in
In the first antenna element 11, a feed point 11a of the first antenna element 11 is coupled to the divider circuit (branch circuit) 13 via the transmission line 15, while in the second antenna element 12, a feed point 12a of the antenna element 12 is coupled to the divider circuit 13 via the transmission line 16. The divider circuit 13 internally couples the two transmission lines 15 and 16, combines obtained signals received by the two antenna elements 11 and 12, and supplies them to a feed port 14. Also, a signal obtained from the feed port 14 when transmitting is divided (split) between the two antenna elements 11 and 12.
Herein, between the two transmission lines 15 and 16, the length of one transmission line 16 is made longer than the other transmission line 15, and is configured to function as a delay line. For example, in the case of configuring as an antenna for sending and receiving in the 2 GHz band, the length L1 of the transmission line 15 is taken to be 100 mm, while the length L2 of the transmission line 16 that functions as a delay line is taken to be 160 mm. The values for these lengths L1 and L2 are an example.
As illustrated in
Additionally, the feed point 11a of the first antenna element 11 is coupled to the transmission line 15. The feed point 11a is made to couple with the GND plane 17 via a bonding conductor 11b.
Also, the feed point 12a of the second antenna element 12 is coupled to the transmission line 16. The feed point 12a is made to couple with the GND plane 17 via a bonding conductor 12b.
In the case of the example in
In the case of the example in
In other words, as illustrated in
In the example in
In the case of configuring an antenna apparatus, either the disposition illustrated in
In
In
Consequently, according to an antenna apparatus with a configuration of the present embodiment, the antenna characteristics can be spread over an extremely wide band. This band widening is due to lengthening one transmission line 16 from between the transmission lines 15 and 16 and configuring it as a delay line. In other words, by having a delay line, the input impedance or phase of the respective antenna elements 11 and 12 are adjusted, and the comprehensive characteristics S2 can be widened more than the characteristics S1 of just a single antenna element. As discussed earlier for example, a length of 60 mm is given by taking one transmission line 15 to be 100 mm and the other transmission line 16 to be 160 mm, and by providing an approximately 70° phase differential with respect to the 2 GHz frequency, band widening can be designed by combination of signals with that phase differential.
Next, a more specific exemplary configuration of the antenna apparatus in the example in
To summarize the configuration of the antenna apparatus illustrated in
A specific example will now be explained with reference to
Also, L2−L1=D2 is taken to hold, where L1 is taken to be the length of the transmission line 15 coupling the first antenna element 11′ to the divider circuit 13, and L2 is taken to be the length of the transmission line 16 coupling the second antenna element 12′ to the divider circuit 13. In other words, the length differential between the transmission line 15 and the transmission line 16 is taken to be D2. This distance D2 is equivalent to the length of a delay line comprised by the transmission lines.
The configuration of the antenna apparatus illustrated in
|D1−D2|=m·λ0
D1+D2=n·λ0
Herein, m is an integer equal to or greater than 0, and n is an integer equal to or greater than 1. λ0 is the wavelength of the center frequency at which transmitting or receiving is conducted in the antenna apparatus.
As a preferable example, a configuration taking m=0∩n=1 is conceivable, for example. By configuring in this way, coupling from the first antenna element 11 to the second antenna element 12 and coupling from the second antenna element 12 to the first antenna element 11 both become in-phase. For this reason, the individual antennas are coupled to operate as a single large antenna, thus enlarging the antenna volume and enlarging the radiant efficiency. Also, delay line loss produced by the difference in the length of the transmission lines becomes smaller.
Another example of D1 and D2 in
D1=(¼+m′)λ0
D2=(¼+n′)λ0
Herein, m′ is an integer equal to or greater than 1, and n′ is an integer equal to or greater than 0. λ0 is the wavelength of the center frequency at which transmitting or receiving is conducted in the antenna apparatus.
In the case of this example, m′=n′=0 is most desirable.
In the case of setting D1 and D2 as in this example, coupling from the first antenna element 11 to the second antenna element 12 becomes in-phase, while coupling from the second antenna element 12 to the first antenna element 11 becomes anti-phase. Consequently, radiant directionality heading from the first antenna element 11 to the second antenna element 12 becomes stronger.
Yet another example of D1 and D2 in
D1=(¾+m′)λ0
D2=(¼+n′)λ0
Herein, m′ is an integer equal to or greater than 1, and n′ is an integer equal to or greater than 0. λ0 is the wavelength of the center frequency at which transmitting or receiving is conducted in the antenna apparatus.
In the case of this example, m′=n′=0 is most desirable.
In the case of setting D1 and D2 as in this example, coupling from the first antenna element 11 to the second antenna element 12 becomes anti-phase, while coupling from the second antenna element 12 to the first antenna element 11 becomes anti-phase. Consequently, radiant directionality heading from the first antenna element 11 to the second antenna element 12 becomes stronger.
As these respective examples demonstrate, it becomes possible to adjust to a desired directionality and radiant efficiency by arbitrarily controlling a distance D1 between two antenna elements and a distance D2 of a delay line.
To summarize the configuration of the antenna apparatus illustrated in
A specific exemplary configuration will be explained with reference to
As illustrated in
Additionally, as illustrated in
The height direction separating the respective antenna elements 11′ and 12′ from the edge 17a is taken to be parallel to the direction in which the GND plane 17 extends as a plane. This height Ha separating the antenna elements 11′ and 12′ from the edge 17a (
As illustrated by enlargement in
Furthermore, the length Da of the respective antenna elements 11′ and 12′ including the bonding conductors 11b and 12b (
Herein, a length, height, thickness, and width are illustrated for one of the antenna elements 11′ and 12′ in
Regarding the configuration of the transmission lines and divider circuit coupled to the respective antenna elements 11′ and 12′, the configuration explained with
Next, exemplary radiant characteristics of an antenna apparatus with the configuration in
As the radiant efficiency characteristics in
Hereinafter, an exemplary second embodiment of the present invention will be explained with reference to
The second embodiment is an example of coupling a hybrid circuit which is a 90° phase shifter instead of the divider circuit 13 illustrated in
To summarize the configuration of the antenna apparatus, it is provided with a first antenna element 11 and a second antenna element 12. The first antenna element 11 and the second antenna element 12 are coupled to a 90° hybrid circuit 23 by respectively separate transmission lines 15 and 16. It is configured such that a delay process is conducted on one of the transmission lines by modifying the lengths of the transmission line 15 coupling the first antenna element 11 to the 90° hybrid circuit 23 and the transmission line 16 coupling the second antenna element 12 to the 90° hybrid circuit 23. The 90° hybrid circuit 23 sets the input impedance and/or phase of two ports to which the respective antenna elements 11 and 12 are coupled to a given state.
Next, a specific configuration will be explained with reference to
A communication apparatus 20 is a wireless communication apparatus that conducts wireless communication in a frequency band from several hundred MHz to several GHz, for example, and a first antenna element 11 and a second antenna element 12 are provided as an antenna apparatus attached to the communication apparatus 20. Regarding exemplary dispositions of the respective antenna elements 11 and 12, herein the configuration explained in
Additionally, in the first antenna element 11, a feed point 11a of the first antenna element 11 is coupled to the 90° hybrid circuit 23 via a transmission line 15. In the second antenna element 12, a feed point 12a of the antenna element 12 is coupled to the 90° hybrid circuit 23 via a transmission line 16. The lengths of the transmission line 15 and the transmission line 16 are modified and the transmission line 16 is configured to function as a delay line, similarly to the first embodiment. However, the length of the delay line is not limited to being the same as the length described in the first embodiment.
The 90° hybrid circuit 23 is configured coupled to two feed ports 21 and 22, and may for example couple the respective feed ports 21 and 22 to respectively separate communication circuits.
The first through fourth ports 23a to 23d are coupled to adjacent ports by a conductor pattern 24 coupled in a square shape. For example, the first port 23a is coupled to a first antenna element 11 via a transmission line 15, while the second port 23b is coupled to a second antenna element 12 via a transmission line 16. Also, the third port 23c is coupled to a feed port 21, while the fourth port 23d is coupled to a feed port 22.
By preparing such a 90° hybrid circuit 23 in which four ports 23a to 23d are coupled by a conductor pattern 24, signals from two antenna elements 11 and 12 are given a 90° phase differential at a given frequency and combined. Furthermore, the combined signal is obtained at the third port 23c and the fourth port 23d with the 90° phase differential.
Furthermore, by using elements that operate at two given frequencies (800 MHz and 2 GHz, for example) as the antenna elements, signals are given a 90° phase differential at the two frequencies and combined, while also being retrieved with the 90° phase differential.
In the case where the 90° hybrid circuit 23 is a 90° phase shifter, the signals at the four ports 23a to 23d of that 90° hybrid circuit 23 can be represented by an S-matrix as follows.
As the characteristics S12 illustrated in
Also, a signal obtained at the third port 23c and a signal obtained at the fourth port 23d have diversity. Namely,
Consequently, spatial diversity is achieved between a signal received by supplying a signal obtained at the third port 23c to a communication circuit from a feed port 21, and a signal received by supplying a signal obtained at the fourth port 23d to a communication circuit from a feed port 22.
Furthermore, the 90° hybrid circuit 23 may also be configured to impart an approximately 90° phase differential with respect to a plurality of frequencies, such as two frequencies.
Hereinafter, an exemplary third embodiment of the present invention will be explained with reference to
The third embodiment is an example of coupling a hybrid circuit which is a 180° phase shifter instead of the 90° hybrid circuit 23 illustrated in
To summarize the configuration of the antenna apparatus, it is provided with a first antenna element 11 and a second antenna element 12. The first antenna element 11 and the second antenna element 12 are coupled to a 180° hybrid circuit 33 by respectively separate transmission lines 15 and 16. It is configured such that a delay process is conducted on one of the transmission lines by modifying the lengths of the transmission line 15 coupling the first antenna element 11 to the 180° hybrid circuit 33 and the transmission line 16 coupling the second antenna element 12 to the 180° hybrid circuit 33.
Next, a specific configuration will be explained with reference to
A communication apparatus 30 is a wireless communication apparatus that conducts wireless communication in a frequency band from several hundred MHz to several GHz, for example, and a first antenna element 11 and a second antenna element 12 are provided as an antenna apparatus attached to the communication apparatus 30. Regarding exemplary dispositions of the respective antenna elements 11 and 12, herein the configuration explained in
Additionally, in the first antenna element 11, a feed point 11a of the first antenna element 11 is coupled to the 180° hybrid circuit 33 via a transmission line 15. In the second antenna element 12, a feed point 12a of the antenna element 12 is coupled to the 180° hybrid circuit 33 via a transmission line 16. The lengths of the transmission line 15 and the transmission line 16 are modified and the transmission line 16 is configured to function as a delay line, similarly to the first embodiment. However, the length of the delay line is not limited to being the same as the length described in the first embodiment.
The 180° hybrid circuit 33 is configured coupled to two feed ports 31 and 32, and may for example couple the respective feed ports 31 and 32 to respectively separate communication circuits.
The first through fourth ports 33a to 33d are coupled to adjacent ports by a conductor pattern 34 coupled in a square shape, but a meander part 34a is provided between the third port 33c and the fourth port 33d. The shape of this conductor pattern 34 is exemplary, and may also taken to be another pattern shape.
The first port 33a is coupled to a first antenna element 11 via a transmission line 15, while the second port 33b is coupled to a second antenna element 12 via a transmission line 16. Also, the third port 33c is coupled to a feed port 31, while the fourth port 33d is coupled to a feed port 32.
By preparing such a 180° hybrid circuit 33 in which four ports 33a to 33d are coupled by a conductor pattern 34, signals from two antenna elements 11 and 12 are given a 180° phase differential at a given frequency and combined. Furthermore, the combined signal is obtained at the third port 33c and the fourth port 33d with the 180° phase differential.
Furthermore, by using elements that operate at two given frequencies (800 MHz and 2 GHz, for example) as the antenna elements, signals are given a 180° phase differential at the two frequencies and combined, while also being retrieved with the 180° phase differential.
In the case where the 180° hybrid circuit 33 is a 180° phase shifter, the signals at the four ports 33a to 33d of that 180° hybrid circuit 33 can be represented by an S-matrix as follows.
As the characteristics S32 illustrated in
Also, a signal obtained at the third port 33c and a signal obtained at the fourth port 33d have diversity. However, since there is a 180° phase differential, the radiant pattern differs from the example of a 90° phase differential in
Furthermore, the 180° hybrid circuit 33 may also be configured to impart an approximately 180° phase differential with respect to a plurality of frequencies, such as two frequencies.
In the second and third embodiments discussed above, a 90° hybrid circuit 23 or a 180° hybrid circuit 33 is coupled after having made one among transmission lines 15 and 16 a delay line, but the transmission lines 15 and 16 may also be taken to have the same length. In other words, it may also be configured such that band widening and diversity are obtained by adjusting just the 90° hybrid circuit 23 or the 180° hybrid circuit 33. Also, in the second and third embodiments, it was configured such that two feed ports are provided and diversity reception could be received, but merely providing a single feed port is acceptable in cases where diversity reception is not required.
Also, in the foregoing explanation, it is explained that phase is adjusted by a delay line and hybrid circuit in the respective embodiments, but it may also be configured such that the input impedance of antenna elements is adjusted. In other words, it may be configured to design band widening by adjusting one or both of input impedance and phase with a delay line. Alternatively, it may also be configured to design band widening by adjusting one or both of input impedance and phase with a 90° hybrid circuit 23 or a 180° hybrid circuit 33.
Also, although the first and second antenna elements are described as inverted F antennas by way of example, antenna elements of another format may also be applied. In this case, besides the case of using elements wherein the impedances of the first and second antenna elements have the same frequency characteristics, it may also be configured such that the impedances of the first and second antenna elements have different frequency characteristics.
Also, the center frequency used to calculate the characteristics described in the respective exemplary embodiments may be other than the frequency at the exact center of the frequency band used by an antenna apparatus, and may be a frequency nearly at the center. Alternatively, it may also be a representative frequency at which transmission and reception is conducted in an antenna apparatus, for example.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-000739 | Jan 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/073550 | 12/27/2010 | WO | 00 | 10/27/2011 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2011/083712 | 7/14/2011 | WO | A |
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| 6184839 | Butscher et al. | Feb 2001 | B1 |
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| 7142164 | Legay et al. | Nov 2006 | B2 |
| 7782261 | An et al. | Aug 2010 | B2 |
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| Entry |
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| International Search Report issued Apr. 5, 2011 in PCT/JP10/073550 filed Dec. 27, 2010. |
| Number | Date | Country | |
|---|---|---|---|
| 20120280885 A1 | Nov 2012 | US |
