JP2009273084A - Dual band antenna apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a dual band antenna apparatus which, in wireless communication equipment incorporating a dual band radio system and another radio system, does not incur interference caused by antenna current, when a high band of the dual band radio system is close to a band of the other radio system, and which can be made compact. <P>SOLUTION: A first switch 5 blocks passing of a high-band (first frequency) signal and allows a low-band (second frequency) signal to pass. A second switch 6 blocks passage of the low-band (second frequency) signal and allows the high-band (first frequency) signal to pass. Thus, a dual band antenna apparatus operates as a dipole antenna, in which antenna current does not flows to a feeder, at the first frequency and operates as a monopole antenna, in which a radiation element constituting the dipole antenna and the feeder which is to serve as a radiation element, in the second frequency that is lower than the first frequency. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a dual-band antenna device, and more particularly to a dual-band antenna device used in a dual-band radio system in a radio communication device incorporating a dual-band radio system and another radio system.

  In recent years, as represented by mobile phones, there are an increasing number of wireless communication devices that can handle a dual-band wireless system using two frequency bands, a high band and a low band. In addition, among these wireless communication devices, wireless communication devices incorporating another wireless system such as a wireless LAN have appeared to improve convenience.

  An example of this is a wireless communication device that combines a dual-band GSM mobile phone using the 900 MHz band and 1800 MHz band and a DECT cordless telephone. If the access line of the DECT cordless telephone is a GSM mobile phone, the DECT cordless telephone can be used even in a place without a telephone line, and convenience is improved.

  However, when a dual-band wireless system and another wireless system are built in one wireless communication device, depending on the combination, coupling due to the antenna current flowing through the substrate occurs, and it is stabilized by interference. It becomes impossible to communicate.

  In the above example, because the GSM 1800 MHz band (1710 to 1880 MHz) is adjacent to the DECT band (1880 to 1900 MHz), when the antenna is a monopole antenna, interference occurs due to the antenna current flowing through the substrate, Stable communication is not possible.

  In the case of combining wireless systems with close frequencies, a dipole antenna that does not allow the antenna current to flow through the substrate is effective in order to avoid interference due to the antenna current flowing through the substrate.

  Therefore, when a dipole antenna is used as a dual band antenna of a wireless communication device that enables a DECT cordless phone incorporating the above-described GSM mobile phone, the configuration shown in FIG.

  FIG. 10 is a diagram illustrating a configuration example of a wireless communication device using a conventional dual-band antenna. In FIG. 10, reference numeral 40 denotes a substrate. The direction parallel to the plate surface of the substrate 40 and perpendicular to the left and right side edges is the direction of the horizontal line. That is, the horizontal plane is a plane that is perpendicular to the plate surface of the substrate 40 and parallel to the upper and lower side edges of the substrate 40. The direction parallel to the plate surface of the substrate 40 and perpendicular to the upper and lower side edges is a so-called vertical line direction. That is, the vertical plane is a plane that is perpendicular to the plate surface of the substrate 40 and is parallel to the left and right side edges of the substrate 40.

  Now, on the board surface of the substrate 40, the radio circuit of the GSM mobile phone is arranged on the left side, and the radio circuit of the DECT cordless phone is arranged on the right side. In these arrangement regions, a ground conductor 39 is provided and necessary connection is made.

  The radio circuit of the GSM mobile phone has a configuration in which a dual-band dipole antenna 33 provided so as to penetrate the plate surface of the substrate 40 and a GSM module 35 that transmits and receives GSM signals are connected by a power supply line 34 of a microstrip line. It is. The dipole antenna 33 has a configuration in which a trap 32 including a parallel resonance circuit of a capacitor and a coil is inserted in the middle of the radiating element 31. In the dipole antenna, dual banding by inserting a trap in a radiating element is a generally adopted technique.

  The radio circuit of the DECT cordless telephone has a configuration in which a single-band dipole antenna 36 provided so as to penetrate the plate surface of the substrate 40 and a DECT module 38 that transmits and receives a DECT signal are connected by a power supply line 37 of a microstrip line. It is.

  The dipole antenna 33 and the dipole antenna 36 are arranged with a radiating element inclined at 45 degrees with respect to the vertical plane and orthogonal to each other in consideration of directivity in a horizontal plane and avoiding coupling by a radiated wave. is doing.

It is known that in a dipole antenna, current flows only through a radiating element, whereas in a monopole antenna, a current that is paired with a current flowing through the radiating element also flows through a ground conductor. Therefore, according to the configuration shown in FIG. 10, the dipole antenna is used for both the antenna connected to the GSM module and the antenna connected to the DECT module. It is possible to perform stable communication without causing it.
Hideyuki Negiya (Author), Maki Ogawa (Author) “Antenna Design in the Ubiquitous Era”, Tokyo Denki University Press, September 30, 2005 (P133-134)

  By the way, in the dipole antenna, the symmetry of the current distribution is important for obtaining good directivity. Therefore, when a high-band antenna is a dipole antenna, in order to make a dual band using a trap, a trap is connected to both radiating elements, the radiating elements are added, and a low-band antenna is also a symmetrical structure. It is better to do.

  However, such wireless communication devices, particularly wireless communication devices that are often used indoors, are required to be downsized. If a dual-band antenna is used as a dipole antenna, the low band has a long radiating element length. It is disadvantageous in terms of conversion.

  The present invention has been made in view of the above, and in a wireless communication device incorporating a dual-band wireless system and another wireless system, the high-band of the dual-band wireless system is different from the band of the other wireless system. An object of the present invention is to obtain a dual-band antenna device that can be miniaturized without causing interference due to an antenna current when close to each other.

  In order to achieve the above-described object, a dual-band antenna device according to the present invention includes a dipole antenna including first and second radiating elements, a high-frequency circuit that transmits, receives, or transmits and receives a high-frequency signal, A feed line having a signal conductor connecting the dipole antenna and the high-frequency circuit, and the signal conductor of the feed line and the corresponding ground conductor are connected to prevent passage of a signal of the first frequency. A first switch that passes a signal having a second frequency lower than the first frequency, and the signal conductor of the feeder line on the high-frequency circuit side in the vicinity of the arrangement position of the first switch. Connected between the ground conductor of the high frequency circuit and the ground conductor of the high frequency circuit, allowing the signal of the first frequency to pass through, and passing the signal of the second frequency of A second switch for preventing excess, and the lengths of the first and second radiating elements are each ¼ wavelength of the first frequency, and the first and second radiating elements And the corresponding conductor of the feeder line are each ¼ wavelength of the second frequency.

  According to the present invention, a switch is inserted in a feed line connecting a dipole antenna and a high-frequency circuit, and operates as a dipole antenna in which no antenna current flows through the feed line at the first frequency, which is lower than the first frequency. At the second frequency, the radiating element and the feed line constituting the dipole antenna operate as a monopole antenna that becomes the radiating element.

  As a result, a dual-band radio system and another radio system are built-in, and the antenna current that flows through the ground conductor of the board is high even if the high-band of the dual-band radio system is close to the frequency of the other radio system. There is an effect that a small dual-band antenna device can be obtained without interference.

  Exemplary embodiments of a dual-band antenna device according to the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a perspective view showing a configuration of a dual-band antenna device according to Embodiment 1 of the present invention. In FIG. 1, 24 is a substrate. The direction parallel to the plate surface of the substrate 24 and orthogonal to the left and right side edges is the direction of the horizontal line. That is, the horizontal plane is a plane that is perpendicular to the plate surface of the substrate 24 and parallel to the upper and lower side edges of the substrate 24. The direction parallel to the plate surface of the substrate 24 and perpendicular to the upper and lower side edges is the so-called vertical line direction. That is, the vertical plane is a plane that is perpendicular to the plate surface of the substrate 24 and parallel to the left and right side edges of the substrate 24.

(Configuration of dual-band antenna device A)
As shown in FIG. 1, the dual-band antenna device A according to Embodiment 1 includes a dipole antenna 1 disposed on one end (upper end in FIG. 1) side of a substrate 24 and the other side (in FIG. 1). A high-frequency module 3 which is a high-frequency circuit disposed on the lower side, a feed line 2 having a microstrip line (signal conductor) connecting them, and a first disposed on the high-frequency module 3 side of the feed line 2 The switch 5 and the second switch 6 are provided.

  A ground conductor 4a is provided on the back surface of the substrate 24 corresponding to the arrangement region of the feeder line (signal conductor) 2 and the first switch 5, and the back surface of the substrate 24 corresponding to the arrangement region of the high-frequency module 3 is A ground conductor 4b is provided.

The dipole antenna 1 includes first and second radiating elements 1a and 1b that are symmetrically disposed through the front and back surfaces of the substrate 24 in a vertical plane. Each of the first and second radiating elements 1a and 1b has a length of λ / 4 (λ is a wavelength) of a high-band frequency f _H that is a first frequency.

  The feed line (signal conductor) 2 is arranged linearly along the vertical line. The upper end of the feeder (signal conductor) 2 is connected to the first radiating element 1 a at the feeding point of the dipole antenna 1, and the lower end is connected to the high-frequency module 3.

  A ground conductor corresponding to the feeder line (signal conductor) 2 is a ground conductor 4a. The upper end of the ground conductor 4a is connected to the second radiating element 1b at the feeding point of the dipole antenna 1, and the lower end is in a position close enough not to contact the upper end of the ground conductor 4b.

The total length of the feeder line (signal conductor) 2 and the first radiating element 1a combined, and the total length of the ground conductor (ground conductor 4a) corresponding to the feeder line (signal conductor) 2 and the second radiating element 1b Respectively have a length of λ / 4 of the low-band frequency f _L (f _H > f _L ) as the second frequency.

The first switch 5 is connected in parallel between the feeder line (signal conductor) 2 and the corresponding ground conductor (ground conductor 4a) at the end of the feeder line (signal conductor) 2 on the high frequency module 3 side. Chip capacitor 5a and chip coil 5b. A parallel circuit of the chip capacitors 5a and the chip coil 5b constitute a parallel resonance circuit with a resonance frequency is set to a frequency f _H of the high band.

The second switch 6 includes a chip capacitor 6a connected in parallel between the lower end of the ground conductor (ground conductor 4a) of the feeder line 2 and the upper end of the ground conductor (ground conductor 4b) of the high-frequency module 3. It is comprised with the chip coil 6b. Parallel circuit also constitutes a parallel resonance circuit with a resonance frequency of the chip capacitor 6a and the chip coil 6b is set to a frequency f _L of the low band.

(Operation of the first switch 5 and the second switch 6)
FIG. 2 is a diagram illustrating frequency characteristics of the parallel resonant circuit. 2A shows the frequency characteristics when the resonance frequency is the frequency f _H , and FIG. 2B shows the frequency characteristics when the resonance frequency is the frequency f _L.

Since the resonant frequency of the parallel resonant circuit constituting the first switch 5 is the frequency f _H , the frequency characteristic is as shown in FIG. In FIG. 2A, the absolute value of the impedance is maximum at the frequency f _H and minimum at the frequency f _L.

Accordingly, the first switch 5 is open at the frequency f _H to prevent passage of a high-band (first frequency) signal, and short-circuited at the frequency f _L to become a low-band (second frequency) signal. It becomes what is called a low-pass filter that passes through.

In addition, since the resonance frequency of the parallel resonance circuit constituting the second switch 6 is the frequency f _L , the frequency characteristic is as shown in FIG. In FIG. 2B, the absolute value of the impedance is maximum at the frequency f _L and minimum at the frequency f _H.

Accordingly, the second switch 6 is open at the frequency f _L to prevent passage of a low-band (second frequency) signal, and short-circuited at the frequency f _H to be a high-band (first frequency) signal. Is a so-called high pass filter.

(Operation of Dual Band Antenna Device A)
This will be described with reference to FIGS. 3 shows an equivalent circuit (a) for the dual band of the dual-band antenna device shown in FIG. 1, an equivalent circuit (b) for the high band at the frequency f _H , and an equivalent circuit (c) for the low band at the frequency f _L. FIG. FIG. 4 is a diagram showing the relationship between the current flowing in the microslip line and the corresponding ground conductor and the magnetic field.

  As shown in FIG. 3A, in the dual band antenna device A, for the dual band, the first switch 5 is connected to the feed line (signal conductor) 2 on the connection side of the feed line (signal conductor) 2 to the high frequency module 3. The signal conductor 2 is provided between the corresponding ground conductor (ground conductor 4a), and the second switch 6 is provided between the ground conductor 4a and the ground conductor 4b.

In the high band of the frequency f _H , the first switch 5 is opened and the second switch 6 is short-circuited. As shown in FIG. 3, the first radiating element 1a is supplied with the excitation current of the high-frequency module 3 from the feeder (signal conductor) 2, while the second radiating element 1b is connected to the ground conductor 4b via the ground conductor 4a. It becomes the composition connected to.

Since each of the first and second radiating elements 1a and 1b has a length of λ / 4 of the frequency f _H , the current distribution 7 of the standing wave is fed at the center as shown in FIG. It becomes maximum at the point and becomes zero at both ends of the first and second radiating elements 1a and 1b. Therefore, the dipole antenna 1 operates as a half-wave dipole antenna. That is, the dual-band antenna device A operates as an antenna device in which the feed line is connected to the dipole antenna 1 for the high band of the frequency f _H.

On the other hand, in the low band of the frequency f _L , the first switch 5 is short-circuited, and the second switch 6 is open. Therefore, the dual-band antenna device A is configured as shown in FIG. As shown in FIG. 3, the ground conductor 4a to which the second radiating element 1b is connected is connected to the high-frequency module 3 together with the power supply line (signal conductor) 2 to which the first radiating element 1a is connected. In this case, the length of the feed line (signal conductor) 2 is equal to the length of the corresponding ground conductor (ground conductor 4a).

  In the configuration shown in FIG. 3 (c), the excitation current 9 of the high-frequency module 3 is applied to the current 10a on the power supply line (signal conductor) 2 side and the corresponding ground conductor (signal conductor) in the first switch 5 in the short-circuit state. The current is distributed to the current 10b on the ground conductor 4a) side. The current 10a becomes the current 11a flowing through the first radiating element 1a, and the current 10b becomes the current 11b flowing through the second radiating element 1b.

  However, since the first radiating element 1a and the second radiating element 1b are opposite to each other by 180 degrees, the electromagnetic waves generated by the currents 11a and 11b cancel each other. That is, electromagnetic waves are not radiated from the first and second radiating elements 1a and 1b.

  Further, since the current 10a and the current 10b are in phase, as shown in FIG. 4, the magnetic field 12 generated by each current is generated between the feed line (signal conductor) 2 and the corresponding ground conductor (ground conductor 4a). Electromagnetic waves are radiated from the ground conductor (ground conductor 4a) corresponding to the feeder line (signal conductor) 2 because they cancel each other and strengthen each other outside the two conductors. In this case, the electromagnetic wave generated in the ground conductor (ground conductor 4a) corresponding to the feeder line (signal conductor) 2 is equal to the electromagnetic wave radiated from the monopole antenna.

The length of the first radiating element 1a and the feeder line (signal conductor) 2 is combined, and the second radiating element 1b and the ground conductor (4a) corresponding to the feeder line (signal conductor) 2 are combined. Since the lengths are both λ / 4 of the low band frequency f _L , as shown in FIG. 3C, the current distributions 8a and 8b of the standing waves generated in both are first and second, respectively. The radiating elements 1a and 1b are zero at both ends, and are maximized at the lower ends of the feeder line (signal conductor) 2 and the corresponding ground conductor (4a). That is, the first and second radiating elements 1a and 1b, the feeder line (signal conductor) 2 and the corresponding ground conductor (4a) as a whole operate as a monopole antenna. That is, a dual band antenna device A, for the low-band frequency f _L, the feeder line (signal conductor) 2 and the corresponding current flowing through the ground conductor (4a) 10a, a monopole antenna that performs transmission and reception of electromagnetic waves by 10b It operates as an antenna device having.

As described above, according to the first embodiment, a dual-band antenna device that operates as a dipole antenna for the high band of frequency f _H and operates as a monopole antenna for the low band of frequency f _L is obtained. It is done.

As shown in FIG. 3B, the dual-band antenna device A flows through the feed line (signal conductor) 2 and the corresponding ground conductor (ground conductor 4a) in the high band of the frequency f _{H that} operates as a dipole antenna. The currents are out of phase with each other.

  Therefore, even when the high band of the dual-band radio system to which the dual-band antenna device A is applied is close to the frequency of another built-in radio system, coupling due to the antenna current flowing through the ground conductor can be prevented.

  In addition, since the antenna current is a monopole antenna in the low band where the antenna current is not related to interference, the dual band antenna device A can be reduced in size.

Since the first and second switches 5 and 6 are arranged on the high-frequency module 3 side of the feeder line (signal conductor) 2 and the corresponding ground conductor (ground conductor 4a), there is no portion that becomes a parasitic element, Interference of parasitic elements can be eliminated. In this measure, the frequency at which the length of the feeder line (signal conductor) 2 and the corresponding ground conductor (ground conductor 4a) is λ / 4 is far away from the low-band frequency f _L , and the bandwidth is increased by the parasitic element. It is effective when it is not possible.

Also, as shown in FIG. 1, since the feeder line (signal conductor) 2 is arranged in a straight line, transmission / reception efficiency can be increased in a monopole antenna that operates at a low-band frequency f _L.

  In addition, if the signal conductor of the feeder line is configured by a microslip line, the ground conductor 4a on which the first and second switches 5 and 6 are mounted can be formed integrally with the microslip line. The switches 5 and 6 can be constituted by inexpensive chip capacitors and chip coils, so that the cost can be reduced and the mounting of the first and second switches 5 and 6 can be facilitated.

  In the first embodiment, the case where the microslip line is used as the power supply line has been described. However, the power supply line can be configured by a coaxial line. FIG. 5 is a diagram showing the relationship between the current flowing in the coaxial line and the magnetic field.

When the feeder line is a coaxial cable, as shown in FIG. 5, at a low-band frequency f _L , a magnetic field 15a generated by a current 14a flowing through the center conductor 13a of the coaxial cable 13 and a current flowing through the outer conductor 13b of the coaxial cable. Since the magnetic field 15b generated by 14b spreads concentrically, the directivity of the electromagnetic wave radiated from the coaxial cable 13 is equivalent to that of a monopole antenna having one radiating element, and a directivity closer to a perfect circle can be obtained. it can.

(Embodiment 2)
FIG. 6 is a perspective view showing a configuration of a dual-band antenna device according to Embodiment 2 of the present invention. In FIG. 6, components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1) are assigned the same reference numerals. Here, the description will be focused on the portion related to the second embodiment.

(Configuration characteristic of dual-band antenna device B according to Embodiment 2)
As shown in FIG. 6, the dual-band antenna device B according to the second embodiment has a first configuration in place of the first and second switches 5 and 6 in the configuration shown in FIG. 1 (the first embodiment). The second switches 20 and 21 are disposed on the dipole antenna 1 side.

  Accordingly, the ground conductors 4a and 4b formed on the back surface of the substrate 24 are also changed. That is, the ground conductor 4 a is formed around the connection end of the feeder line (signal conductor) 2 with the dipole antenna 1, and the ground conductor 4 a is connected to most of the feeder line (signal conductor) 2 and the high-frequency module 3. It is formed in the corresponding area.

The first switch 20 is connected in parallel between the feed line (signal conductor) 2 and the corresponding ground conductor (ground conductor 4a) at the connection end of the feed line (signal conductor) 2 to the dipole antenna 1. Chip capacitor 20a and chip coil 20b. A parallel circuit of the chip capacitor 20a and the chip coil 20b constitute a parallel resonance circuit with a resonance frequency is set to a frequency f _H of the high band.

The second switch 21 includes a chip capacitor 6a connected in parallel between the lower end of the ground conductor (ground conductor 4a) of the feeder line 2 and the upper end of the ground conductor (ground conductor 4b) of the high-frequency module 3. It is comprised with the chip coil 6b. Parallel circuit also constitutes a parallel resonance circuit with a resonance frequency of the chip capacitor 6a and the chip coil 6b is set to a frequency f _L.

Since the parallel resonant circuit constituting the first switch 20 has a resonant frequency set to a high-band frequency f _H , the absolute value of the impedance is large at the frequency f _H and small at the frequency f _L. Accordingly, as in the first embodiment, the first switch 20 is open at the frequency f _H and short-circuited at the frequency f _L , thereby preventing the passage of a high-band (first frequency) signal. _{In L} , it becomes a short circuit and becomes a so-called low-pass filter that passes a low-band (second frequency) signal.

Further, since the resonance frequency of the parallel resonance circuit constituting the second switch 21 is set to the low band frequency f _L , the absolute value of the impedance is large at the frequency f _L and small at the frequency f _H. Therefore, as in the first embodiment, the second switch 21 becomes open at the frequency f _L, and blocks the passage of the signal low-band (second frequency) in a short circuit at the frequency f _H, the frequency f _H Then, a so-called high-pass filter that short-circuits and passes a high-band (first frequency) signal is obtained.

(Operation of Dual Band Antenna Device B)
This will be described with reference to FIG. FIG. 7 is a diagram showing an equivalent circuit (a) for the dual band of the dual band antenna device shown in FIG. 6, an equivalent circuit (b) for the high band of frequency f _H , and an equivalent circuit (c) for the low band of frequency f _L. is there.

  As shown in FIG. 7A, in the dual-band antenna device B, for the dual band, the first switch 20 is connected to the feed line (signal conductor) 2 on the side where the feed line (signal conductor) 2 is connected to the feed line ( The signal conductor 2 is provided between the corresponding ground conductor (ground conductor 4a), and the second switch 21 is provided between the ground conductor 4a and the ground conductor 4b.

In the high band of the frequency f _H , the first switch 20 is open and the second switch 21 is short-circuited. Therefore, the dual band antenna device B is shown in FIG. As shown, the first radiating element 1a is supplied with the excitation current of the high-frequency module 3 from a feeder (signal conductor) 2, while the second radiating element 1b is connected to the ground conductor 4b. Become.

Since each of the first and second radiating elements 1a and 1b has a length of λ / 4 of the frequency f _H , the dual-band antenna device B has a high-band frequency as described in the first embodiment. For f _H , the antenna device operates as an antenna device in which a feed line is connected to the dipole antenna 1.

On the other hand, in the low band of the frequency f _L , the first switch 20 is short-circuited and the second switch 21 is open. Therefore, the dual-band antenna device B is configured as shown in FIG. As shown in FIG. 2, since the second radiating element 1b is connected to the first radiating element 1a in the vicinity of the feeding point, the second radiating element 1b is connected to the feeding line (signal conductor) 2 together with the first radiating element 1a. And the high frequency module 3 is connected. In this case, the length of the feed line (signal conductor) 2 is equal to the length of the corresponding ground conductor (ground conductor 4b).

  In the configuration shown in FIG. 7C, the excitation current 22 of the high-frequency module 3 passes through the feed line (signal conductor) 2 and reaches the vicinity of the feed point of the dipole antenna 1, where the first switch 5 is short-circuited. Thus, the current is divided into the first radiating element 1a side and the second radiating element 1b side, so that a current 23a flows in the first radiating element 1a, and a current 23b flows in the second radiating element 1b.

  However, since the first radiating element 1a and the second radiating element 1b are opposite to each other by 180 degrees, the electromagnetic waves generated by the currents 23a and 23b cancel each other. That is, electromagnetic waves are not radiated from the first and second radiating elements 1a and 1b.

The combined length of the first radiating element 1a and the feeder line (signal conductor) 2 and the combined length of the second radiating element 1b and the ground conductor (4b) corresponding to the feeder line (signal conductor) 2 Since both are λ / 4 of the low band frequency f _L , they operate as λ / 4 monopole antennas.

  The ground conductor (4b) corresponding to the feeder line (signal conductor) 2 is a parasitic element that resonates at a frequency at which the length of the feeder line (signal conductor) 2 is λ / 4. The frequency band is expanded to the high frequency side by coupling to a monopole antenna composed of the radiating elements 1a and 1b and the feed line (signal conductor) 2.

  Therefore, the dual-band antenna device B shown in FIG. 6 can be operated as a monopole antenna in which linearly polarized waves are radiated in the direction of the feed line (signal conductor) 2.

As described above, according to the second embodiment, a high frequency band f _H operates as a dipole antenna, a low frequency f _L band operates as a monopole antenna, and the monopole antenna A dual-band antenna device that can widen the band to the high frequency side is obtained.

  By applying this dual-band antenna device B to a dual-band radio system, even when the high band of the dual-band radio system is close in frequency to another built-in radio system, coupling due to antenna current flowing through the substrate is prevented. be able to.

  Moreover, since the antenna current is a monopole antenna in the low band where the antenna current is not related to interference, the dual band antenna device can be downsized.

  Since the ground conductor from the second switch 21 of the feeder line to the high frequency module 3 functions as a parasitic element, it is possible to widen the frequency characteristic of the monopole antenna operating in the low band.

  In the dual-band antenna device B according to the second embodiment, a coaxial line can be used as the feeder line as in the first embodiment.

(Embodiment 3)
FIG. 8 is a perspective view showing a configuration of a dual-band antenna device according to Embodiment 3 of the present invention. In FIG. 8, components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1) are given the same reference numerals. Here, the description will be focused on the portion related to the third embodiment.

(Configuration characteristic of dual-band antenna device C according to Embodiment 3)
As shown in FIG. 8, in the dual-band antenna device C according to the third embodiment, in the configuration shown in FIG. 1 (first embodiment), the feed line 25 bent at a right angle instead of the straight feed line 2. Is provided.

According to this configuration, the dual-band antenna device can be reduced in height because it operates as an inverted L antenna at the low-band frequency f _L.

  In addition, although the application example to Embodiment 1 was shown, it can apply similarly to Embodiment 2. Further, the feeder line 25 bent at a right angle may be constituted by a coaxial line. Hereinafter, an application example of the dual band antenna device A according to the first embodiment will be shown as a specific example.

(Embodiment 4)
FIG. 9 is a perspective view showing an application example of the dual-band antenna device according to Embodiment 1 as Embodiment 4 of the present invention. In FIG. 9, the same reference numerals are given to the same or equivalent components as those shown in FIG. 1 (Embodiment 1). Here, the description regarding the housing is omitted, and the description will be focused on the portion related to the fourth embodiment.

(Configuration of wireless communication apparatus having two wireless systems)
In FIG. 9, in addition to the dual band antenna device A according to the first embodiment, another antenna device D is juxtaposed on the substrate 26. In the dual-band antenna device A, 27 provided at the position of the high-frequency module 3 is a GSM module that realizes a dual-band radio system. The GSM module 27 uses GSM 900 MHz band and 1800 MHz band (1710 to 1880 MHz). The feeder line 2 is connected to the antenna terminal of the GSM module 27.

  In another antenna device D, 28 is a DECT module. The DECT module 28 is another wireless system that uses a frequency band (1880 to 1900 MHz) close to the high-band frequency (1800 MHz band) in the GSM module 27. A dipole antenna 30 is connected to the antenna terminal of the DECT module 28 through a feeder line 29.

  The dipole antenna 1 and the dipole antenna 30 are arranged such that their radiating elements are orthogonal to each other in the vertical plane and inclined by 45 degrees with respect to the vertical line. This is a measure aimed at avoiding the null point from coming to the horizontal plane because the GSM base station and the DECT slave unit are likely to be almost on the horizontal plane in actual usage.

(Operation of wireless communication apparatus having two wireless systems)
In FIG. 9, when the GSM module 27 uses the 1800 MHz band, transmission / reception is performed using the dipole antenna 1 including the first and second radiating elements 1 a and 1 b, and the DECT module 28 transmits and receives using the dipole antenna 30. I do. Since both antennas are dipole antennas, coupling due to antenna current flowing through the ground conductor 4b does not occur.

  Moreover, coupled with the orthogonality of the radiating elements, a large isolation can be obtained. Further, when the GSM module 27 uses the 900 Mz band, the GSM module 27 is radiated from the monopole antenna including the feeder line 2 and the first and second radiating elements 1a and 1b.

  As described above, when the dual-band antenna device A according to the first embodiment is applied, the antenna connected to the GSM module 27 has a dual-band configuration, but the length of the radiating element is matched to the 1800 MHz band of the GSM module 27. What is necessary is that the size can be reduced as compared with the conventional technique in which a trap is placed in the radiating element to form a dual band.

  In the fourth embodiment, the application example of the antenna device A according to the first embodiment has been described. However, the dual band antenna devices B and C according to the second and third embodiments can also be used in the same manner.

  As described above, the dual-band antenna device according to the present invention is a wireless communication device including a dual-band wireless system and another wireless system, and the high-band of the dual-band wireless system has the bandwidth of the other wireless system. When the antennas are close to each other, it is useful as a dual-band antenna device that can be reduced in size without causing interference due to antenna current.

The perspective view which shows the structure of the dual band antenna apparatus by Embodiment 1 of this invention. The figure which shows the frequency characteristic of the parallel resonant circuit in Embodiment 1 of this invention. The figure which shows the equivalent circuit of the dual band antenna apparatus in Embodiment 1 of this invention The figure which shows the relationship between the electric current and magnetic field which flow into a micro slip line and a corresponding ground conductor Diagram showing the relationship between the current flowing in the coaxial line and the magnetic field The perspective view which shows the structure of the dual band antenna apparatus by Embodiment 2 of this invention. The figure which shows the equivalent circuit of the dual band antenna apparatus in Embodiment 2 of this invention The perspective view which shows the structure of the dual band antenna apparatus by Embodiment 3 of this invention. As a fourth embodiment of the present invention, a perspective view showing an application example of the dual-band antenna device according to the first embodiment. The figure which shows the structure of the radio | wireless communication apparatus using the conventional dual band antenna

Explanation of symbols

A, B, C Dual-band antenna device 1 Dipole antenna 1a First radiating element 1b Second radiating element 2 Feed line (micro slip line)
2a Signal conductor of feeder line 2b Ground conductor of feeder line 3 High-frequency module (high-frequency circuit)
4a, 4b Ground conductor 5 First switch 5a Chip capacitor 5b Chip coil 6 Second switch 6a Chip capacitor 6b Chip coil 20 First switch 20a Chip capacitor 20b Chip coil 21 Second switch 21a Chip capacitor 21b Chip coil 24 Board 25 Feed line bent at right angle 26 Board 27 GSM module 28 DECT module 29 Feed line (micro slip line)
30 Dipole antenna D Another antenna device

Claims (8)

A dipole antenna including first and second radiating elements; a high-frequency circuit that transmits, receives, or transmits / receives a high-frequency signal; and a feed line that includes a signal conductor that connects the dipole antenna and the high-frequency circuit; , Connected between the signal conductor of the feeder line and the corresponding ground conductor to prevent passage of a signal of a first frequency and pass a signal of a second frequency lower than the first frequency. The first switch and the high frequency circuit side in the vicinity of the position where the first switch is disposed are connected between a ground conductor corresponding to the signal conductor of the feeder line and a ground conductor of the high frequency circuit, A second switch for passing a signal of one frequency and blocking the passage of the signal of the second frequency, and the first and second radiating elements Each of the lengths is ¼ wavelength of the first frequency, and the total length of the first and second radiating elements and the corresponding conductor of the feeder line is respectively the second frequency. A dual-band antenna device characterized by having a quarter wavelength. A dipole antenna including first and second radiating elements; a high-frequency circuit that transmits, receives, or transmits / receives a high-frequency signal; and a feed line that includes a signal conductor that connects the dipole antenna and the high-frequency circuit; The feed line is connected between the signal conductor of the feed line and the corresponding ground conductor in the vicinity of the connection end of the feed line with the dipole antenna, and blocks the passage of a signal having a first frequency. A first switch that passes a signal having a second frequency lower than the first frequency; a ground conductor corresponding to the signal conductor of the feeder line on the high-frequency circuit side in the vicinity of the arrangement position of the first switch; A first conductor connected to a ground conductor of the high-frequency circuit for passing the signal of the first frequency and blocking the passage of the signal of the second frequency; The lengths of the first and second radiating elements are each ¼ wavelength of the first frequency, and the correspondence between the first and second radiating elements and the feeder line The total length of the combined conductors is ¼ wavelength of the second frequency, respectively. 3. The dual-band antenna device according to claim 1, wherein the first switch is configured by a parallel resonance circuit in which a resonance frequency is set to the first frequency. 3. The dual-band antenna device according to claim 1, wherein the second switch is configured by a parallel resonance circuit in which a resonance frequency is set to the second frequency. The dual-band antenna device according to claim 1, wherein the feed line is arranged in a straight line shape. The dual-band antenna device according to claim 1 or 2, wherein the feeder is arranged in a shape bent at a right angle. The dual-band antenna device according to claim 1, wherein the feed line is a strip line. The dual-band antenna device according to claim 1, wherein the feeder line is a coaxial line.

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