JP3606005B2 - Antenna device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antenna device used in a mobile communication device such as a mobile phone.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an antenna device for mobile communication devices such as mobile phones, a configuration of a diversity antenna using both a linear antenna and a surface mount antenna has been adopted.
[0003]
[Problems to be solved by the invention]
In general, linear antennas have the advantage of having a simple structure and high gain over a relatively wide band, and surface-mounted antennas are extremely small and can be surface-mounted with other electronic components on a circuit board. It has the advantage that the overall size can be reduced. Therefore, if this linear antenna and the surface mount antenna are made to have a diversity configuration, an antenna device having both advantages should be obtained.
[0004]
However, the conventional antenna device using both the linear antenna and the surface mount antenna does not necessarily exhibit the synergistic effect.
[0005]
The inventors have clarified through experiments that the cause of failure to obtain the expected characteristics is the mutual interference between the linear antenna and the surface mount antenna. An object of the present invention is to provide an antenna device that makes use of the characteristics of the surface-mounted antenna and also makes use of the characteristics of a linear antenna such as a whip antenna or a helical antenna.
[0006]
[Means for Solving the Problems]
The present invention relates to an antenna diversity circuit that synthesizes or switches received signals from a linear antenna and a surface-mounted antenna and supplies them to a receiving unit, or distributes or switches transmission signals from a transmitting unit to a linear antenna An antenna device used in a communication device including an antenna diversity circuit for supplying to a surface-mounted antenna, wherein the antenna device eliminates a problem caused by mutual interference between the linear antenna and the surface-mounted antenna. As described above, the surface mount antenna is a surface mount antenna in which a radiation electrode is provided on a dielectric or dielectric magnetic substrate, and a feed electrode for supplying power to the radiation electrode. The surface mount antenna is arranged in such a direction that the open end of the radiation electrode of the antenna is away from the linear antenna.
[0007]
With this configuration, since the open end of the radiation electrode of the surface mount antenna is disposed in a direction away from the linear antenna, mutual interference between both antennas is prevented, and a high overall antenna gain can be maintained. Even when the above linear antenna is a whip antenna and the whip antenna is housed, a surface mount antenna should be arranged so that mutual interference between the whip antenna and the surface mount antenna is prevented. Therefore, the reception sensitivity can always be kept high.
[0008]
In general, a linear antenna has a wide band characteristic, whereas a surface mount antenna has a narrow band characteristic. For example, a so-called PDC 800 MHz winding method (corresponding to both 810 to 818 MHz band and 870 to 885 MHz band) is portable. In the telephone system, the areas actually used are only the 810 to 818 MHz band and the 870 to 885 MHz band. Therefore, the sensitivity in the band actually used can be increased by using the surface mount antenna as an auxiliary. .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The configuration of the antenna device according to the first embodiment of the present invention will be described with reference to FIGS.
[0010]
FIG. 1 is a perspective view showing a configuration of a surface mount antenna used in an antenna device. In the figure, reference numeral 11 denotes a dielectric substrate made of a dielectric ceramic or a synthetic resin having a relatively high relative dielectric constant. Radiation electrodes indicated by 1a, 1b, and 1c are formed again on the upper surface of the dielectric substrate 11 through the left rear end surface from the upper surface in the drawing. Further, feed electrodes indicated by 2a and 2b are formed from the lower surface in the figure of the dielectric substrate 11 to the end surface on the right front side. Further, ground electrodes indicated by 3a, 3b, 3c are formed from the lower surface of the dielectric substrate 11 to the upper surface via the right front end surface.
[0011]
In the surface mount antenna shown in FIG. 1, capacitances are generated between the gap portion between the open end o of the radiation electrode 1c and the ground electrode 3c, and between the vicinity of the open end o and the feed electrodes 2a and 2b, These capacitances and the inductance component of the radiation electrode constitute a resonance circuit. Further, the feed electrode and the radiation electrode are capacitively coupled by electrostatic capacitance generated between the feed electrodes 2a and 2b and the radiation electrode 1c.
[0012]
FIG. 2 is an equivalent circuit of the surface mount antenna shown in FIG. In the figure, C23 is an electrostatic capacity generated between the feeding electrodes 2a, 2b and the ground electrodes 3a, 3b, 3c, C21 is an electrostatic capacity generated between the feeding electrodes 2a, 2b and the radiation electrode 1c, and C13 is The electrostatic capacitance L generated between the vicinity of the open end o of the radiation electrode 1c and the ground electrode 3c is an inductance component of the radiation electrode. Among these, C13, C21, and L mainly constitute a resonance circuit. R is the radiation resistance of the antenna.
[0013]
FIGS. 3A and 3B are diagrams showing two configuration examples of the antenna device provided with the surface mount antenna and the whip antenna shown in FIG. In the figure, reference numeral 21 denotes a circuit board on which the surface-mounted antenna 10 is surface-mounted. In the figure, reference numeral 20 denotes a whip antenna. In the example shown in (A), the open end o is moved away from the whip antenna 20 by mounting the surface-mounted antenna 10 with the position of the open end o of the radiation electrode facing downward in the drawing. Further, in the example shown in FIG. 5B, the open end o of the surface mount antenna 10 is moved away from the whip antenna 20 by mounting the open end of the radiation electrode of the surface mount antenna 10 facing the outside of the communication device. . In both cases (A) and (B), mutual interference between the surface-mounted antenna 10 and the whip antenna 20 is prevented, and a high overall antenna gain is maintained.
[0014]
Although detailed electrode patterns on the circuit board 21 side corresponding to the respective electrodes of the surface mount antenna 10 are omitted, a ground electrode 22 is provided in a region excluding these electrode patterns. On this circuit board 21, as will be described later, a reception filter for using the surface-mounted antenna 10 as a reception antenna, a transmission filter and reception filter for the whip antenna 20, and synthesis for switching or switching received signals with the whip antenna / Switching circuit etc. are provided.
[0015]
When the mutual interference between the surface mount antenna 10 and the whip antenna 20 in the arrangement structure shown in FIG. 3A was measured, the following results were obtained.
[0016]
That is, the maximum gain [dBd] of the zx-plane dipole comparison is
-0.7 for whip antenna only
When both whip antenna and surface mount antenna are used -0.5
It became.
[0017]
Here, the z-axis and the x-axis are as shown in FIG. That is, in FIG. 4, the circuit board 21 on which the surface-mounted antenna 10 is mounted is housed in a housing 23 of a communication device such as a mobile phone, and the longitudinal direction of the circuit board 21 is the z axis and the circuit board 21 surface. With the vertical direction as the x-axis, the maximum gain in the in-plane direction including the z-axis and the x-axis was obtained.
[0018]
Thus, the total antenna gain is improved by using both antennas. Similar characteristics can be obtained with the arrangement structure shown in FIG.
[0019]
16 (A) and 16 (B) are shown as comparative examples for FIGS. 3 (A) and 3 (B). As shown in FIG. 16A, the open end o of the radiation electrode of the surface-mounted antenna 10 ′ is arranged so as to face the direction in which the whip antenna 20 extends (upper part of the communication device), or in FIG. As described above, when the open end o of the radiation electrode of the surface mount antenna 10 ′ is arranged so as to approach the whip antenna 20, the total antenna gain decreases due to mutual interference between the surface mount antenna 10 ′ and the whip antenna 20.
[0020]
FIG. 5 is a block diagram showing a configuration of an antenna input / output portion of an antenna apparatus using the whip antenna and the surface mount antenna. Here, ANTm is an antenna terminal for a whip antenna, ANTs is an antenna terminal for a surface mount antenna, TX is an input terminal for a transmission signal from the transmission circuit, and RX is an output terminal for a reception signal to the reception circuit. In this manner, the reception signals of the whip antenna and the surface mount antenna are respectively combined or switched by the combining / switching circuit through the RX filter and output to the receiving circuit. That is, in this combining / switching circuit, the received signal level of the whip antenna and the surface mount antenna is detected, and depending on both received signal levels, the signal having the higher received signal level is selectively output to the RX terminal, Both signals are combined and output to the RX terminal. In this example, a whip antenna is used for both transmission and reception, a surface mount antenna is used only for reception, and an antenna diversity circuit is configured together with the whip antenna.
[0021]
In the example shown in FIG. 5, the antenna diversity circuit is configured for the received signal. However, the antenna diversity circuit is configured for the transmitted signal by distributing the transmitted signal and supplying the signal to the whip antenna and the surface mount antenna, respectively. Also good.
[0022]
Next, the configuration of the antenna device according to the second embodiment is shown in FIGS. FIG. 6 is a perspective view showing the configuration of the surface mount antenna. In FIG. 6, reference numeral 11 denotes a dielectric substrate made of dielectric ceramics or a synthetic resin having a relatively high relative dielectric constant. Radiation electrodes indicated by 1a, 1b, 1c, 1d, and 1e are formed on the upper surface again from the lower surface in the drawing of the dielectric substrate 11 through the end surface on the right front, the upper surface, and the left rear end surface. Further, feed electrodes indicated by 2a, 2b, and 2c are formed from the lower surface of the dielectric substrate 11 to the upper surface via the right front end surface. Further, ground electrodes indicated by 3a, 3b, 3c are formed from the lower surface of the dielectric substrate 11 to the upper surface via the right front end surface.
[0023]
In the case of the surface mount antenna shown in FIG. 6, capacitances are generated between the gap between the open end o of the radiation electrode 1e and the ground electrode 3c, and between the vicinity of the open end o and the feed electrodes 2a and 2b. These capacitances and the inductance component of the radiation electrode constitute a resonance circuit. Further, the feed electrode and the radiation electrode are capacitively coupled by electrostatic capacitance generated between the feed electrodes 2b and 2c and the radiation electrodes 1b and 1c. Therefore, the equivalent circuit is the same as that shown in FIG.
[0024]
FIG. 7 is a diagram showing a configuration of an antenna device using the surface mount antenna shown in FIG. 6 together with the whip antenna. Also in this case, as in the case of the first embodiment, the surface-mounted antenna 10 is arranged in such a direction that the open end o of the radiation electrode is away from the whip antenna 20, thereby preventing mutual interference between the two antennas. The overall antenna gain has been improved.
[0025]
FIG. 8 is a perspective view of a surface mount antenna used in the antenna device according to the third embodiment. In the figure, reference numeral 11 denotes a dielectric substrate made of dielectric ceramics or a synthetic resin having a relatively high relative dielectric constant. Radiation electrodes indicated by 1a, 1b and 1c are formed on the upper surface of the dielectric substrate 11 from the lower surface in the drawing to the right front end surface. Further, a feeding electrode indicated by 2a is formed on the lower surface of the dielectric substrate 11 in the figure. Further, ground electrodes indicated by 3a, 3b, 3c are formed from the lower surface of the dielectric substrate 11 to the upper surface via the right front end surface.
[0026]
In the case of the surface mount antenna shown in FIG. 8, the equivalent circuit is the same as that shown in FIG. That is, electrostatic capacitance is generated between the gap between the open end o of the radiation electrode 1c and the ground electrode 3c, and between the vicinity of the open end o and the power supply electrode 2a. A resonant circuit is configured. Further, the power supply electrode and the radiation electrode are capacitively coupled by an electrostatic capacitance generated between the power supply electrode 2a and the radiation electrode 1b.
[0027]
FIG. 9 is a diagram showing a configuration of an antenna device using the surface mount antenna shown in FIG. 8 together with the whip antenna. Also in this case, the surface-mounted antenna 10 is arranged in such a direction that the open end o of the radiation electrode is away from the whip antenna 20, thereby preventing mutual interference between the two antennas and improving the overall antenna gain.
[0028]
FIG. 10 is a perspective view of a surface mount antenna used in the antenna device according to the fourth embodiment. As shown in the figure, radiation electrodes indicated by 1a, 1b, and 1c are formed on the upper surface of the dielectric substrate 11 via the end surface on the right side from the lower surface in the drawing. Further, feed electrodes indicated by 2a, 2b, and 2c are formed from the lower surface of the dielectric substrate 11 to the upper surface via the right front end surface. Further, ground electrodes indicated by 3a, 3b, 3c are formed from the lower surface of the dielectric substrate 11 to the upper surface via the right front end surface.
[0029]
In the case of the surface mount antenna shown in FIG. 10, the equivalent circuit is the same as that shown in FIG. 2, the gap between the open end o of the radiation electrode 1c and the ground electrode 3c, and the vicinity of the open end o and the feed electrode. Capacitances are respectively generated between 2a, 2b, and 2c, and these capacitances and the inductance component of the radiation electrode constitute a resonance circuit. Further, the feed electrode and the radiation electrode are capacitively coupled by electrostatic capacitance generated between the feed electrodes 2b and 2c and the radiation electrodes 1b and 1c.
[0030]
FIG. 11 is a diagram showing a configuration of an antenna device using the surface mount antenna shown in FIG. 10 together with the whip antenna. In this example, the surface-mounted antenna 10 is disposed so as to be inclined in the direction of about 45 ° with respect to the whip antenna 20 so that the open end o of the radiation electrode is away from the whip antenna 20. Also in this case, mutual interference between the surface mount antenna 10 and the whip antenna 20 is prevented, and the overall antenna gain is improved.
[0031]
FIG. 12 is a perspective view of a surface mount antenna used in the antenna device according to the fifth embodiment. In the figure, reference numeral 11 denotes a dielectric substrate, and ground electrodes indicated by 3a and 3b are formed from the lower surface to the right front end surface in the drawing, and this ground electrode is followed by the right rear end surface of the dielectric substrate 11. Then, radiation electrodes indicated by 1a, 1b, 1c are formed on the left rear end face, and the end of the radiation electrode 1c is an open end o. Further, feed electrodes indicated by 2a, 2b, and 2c are formed from the lower surface of the dielectric substrate 11 to the upper surface via the left front end surface. Further, control electrodes 4a and 4b connected to the radiation electrodes are formed from the lower surface of the dielectric substrate 11 to the front right end surface in the drawing. A frequency switching circuit including a diode D, capacitors C1 and C2, and a choke coil L is connected to the control electrode 4a. When no control signal is input to the control signal input terminal IN, the diode D is in an open state. However, when the control signal is input, the diode D becomes conductive and the control electrodes 4a and 4b are connected via the diode D and the capacitor C1. Grounded. That is, the on / off state of the diode D changes the inductance of the radiation electrode from the ground end to the open end, and the resonance frequency is switched. In the case of the PDC mobile phone system, the two resonance frequencies by this switching are the center frequencies of the 810 to 818 MHz band and the 870 to 885 MHz band, respectively. As a result, both of the two bands can be handled by switching.
[0032]
FIG. 13 is an overall equivalent circuit diagram including the surface mount antenna shown in FIG. 12 and a frequency switching circuit connected thereto. In the figure, L11 is a main inductance component due to the radiation electrodes 1a, 1b and 1c, and L12 is an inductance component between the control electrodes 4a and 4b and the ground electrodes 3a and 3b. D, C1, L, and C2 constitute a frequency switching circuit. Other configurations of the C23, C21, C13, and R portions are the same as those shown in FIG. In a state where no control voltage is applied to the control terminal IN, resonance occurs at a resonance frequency determined by a resonance circuit including C13, C21, L11, and L12. However, when a positive control voltage is applied to the control terminal IN, the diode D becomes conductive. The connection point of the inductance components L11 and L12 is grounded via the frequency switching circuit, and the inductance component of the resonance circuit is composed of only L11 (the length of the radiation electrode from the ground end to the open end is equivalent) Therefore, the resonance frequency is increased. That is, the resonance frequency of the antenna is increased.
[0033]
14 is a diagram showing a configuration of an antenna apparatus using the surface mount antenna shown in FIG. 12 together with the whip antenna. As shown in both figures, since the surface-mounted antenna 10 is arranged in a direction in which the open end o of the radiation electrode is away from the whip antenna 20, mutual interference between both antennas is prevented and the overall antenna gain is improved. .
[0034]
In each of the embodiments described above, a whip antenna that is a monopole antenna is used as a linear antenna. However, for example, a helical antenna may be used. FIG. 15 is a diagram showing a configuration of an antenna device according to the sixth embodiment showing an example thereof. The configuration of the surface mount antenna 10 in the figure is the same as that of the surface mount antenna shown in FIG. In addition, any of those shown in FIGS. 6, 8, 10, and 12 may be used. Also in this case, the surface-mounted antenna 10 is arranged in such a direction that the open end o of the radiation electrode is away from the helical antenna 24, thereby preventing mutual interference between both antennas and preventing a decrease in the overall antenna gain. be able to.
[0035]
Further, in each of the embodiments described above, a surface mount antenna having various electrodes formed on a dielectric substrate is used. However, a surface mount antenna having various electrodes similarly formed on a dielectric magnetic substrate is used. Also good.
[0036]
【The invention's effect】
According to the present invention, the reception signals of the linear antenna such as the whip antenna and the helical antenna and the surface mount antenna are synthesized by the antenna diversity circuit or switched to be supplied to the reception unit or from the transmission unit. Since the transmission signal is distributed or switched and supplied to at least two antennas, and the open end of the radiation electrode of the surface mount antenna is arranged in a direction away from the linear antenna, When both the antenna and the surface mount antenna are used, mutual interference between both antennas is prevented, and a high overall antenna gain can be maintained.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a surface mount antenna used in an antenna device according to a first embodiment.
FIG. 2 is an equivalent circuit diagram of the surface mount antenna shown in FIG.
FIG. 3 is a diagram illustrating a configuration of an antenna device according to the first embodiment.
FIG. 4 is a diagram showing coordinate axes of the antenna device.
FIG. 5 is a block diagram showing a configuration of an antenna input / output portion of the antenna apparatus.
FIG. 6 is a perspective view showing a configuration of a surface mount antenna used in an antenna device according to a second embodiment.
FIG. 7 is a diagram illustrating a configuration of an antenna device according to a second embodiment.
FIG. 8 is a perspective view showing a configuration of a surface mount antenna used in an antenna device according to a third embodiment.
FIG. 9 is a diagram illustrating a configuration of an antenna device according to a third embodiment.
FIG. 10 is a perspective view showing a configuration of a surface mount antenna used in an antenna device according to a fourth embodiment.
FIG. 11 is a diagram illustrating a configuration of an antenna device according to a fourth embodiment.
FIG. 12 is a perspective view showing a configuration of a surface mount antenna used in an antenna device according to a fifth embodiment.
FIG. 13 is an equivalent circuit diagram of the entire surface mount antenna including a resonance frequency switching circuit.
FIG. 14 is a diagram illustrating a configuration of an antenna device according to a fifth embodiment.
FIG. 15 is a diagram illustrating a configuration of an antenna device according to a sixth embodiment.
16 is a diagram showing a comparative example of the antenna device of FIG. 3;
[Explanation of symbols]
1-Radiation electrode 2-Feed electrode 3-Ground electrode 4-Control electrode 10-Surface mount antenna 11-Dielectric substrate 20-Whip antenna 21-Circuit board 22-Ground electrode 23-Housing 24-Helical antenna

Claims (1)

An antenna diversity circuit that synthesizes or switches received signals from a linear antenna and a surface mount antenna and supplies them to the receiver, or distributes or switches a transmit signal from the transmitter to switch the linear antenna and the surface mount antenna An antenna device used in a communication device equipped with an antenna diversity circuit to be supplied to
The surface mount antenna is a surface mount antenna in which a radiating electrode and a feeding electrode for feeding power to the radiating electrode are provided on a dielectric or dielectric magnetic substrate. An antenna device, wherein the surface-mounted antenna is disposed in a direction in which an open end of a radiation electrode moves away from the linear antenna.

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