JP2011015329A - Integrated antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an integrated antenna having high isolation between a transceiver antenna and a receiver antenna constituting diversity.SOLUTION: In a telephone substrate 120, two antenna element forming parts 121 and 122 disposed in parallel proximately to two end sides, which face each other, of a first ground plate 102 are formed in both right and left ends of a substrate principal part 123. A telephone antenna 110 includes the transceiver antenna 111 formed in the antenna element forming part 121 and the receiver antenna 112 formed in the antenna element forming part 122. Furthermore, in the substrate principal part 123, a second ground plate 124 is formed without contact with the first ground plate 102.

Description

  The present invention relates to an integrated antenna mounted on a vehicle, and more particularly to an in-vehicle integrated antenna in which a telephone antenna is further integrated with an antenna such as ETC or VICS.

  Conventionally, an integrated antenna has been developed in which the antennas used for ETC (Electronic Toll Collection System), VICS (Vehicle Information and Communication System), GPS (Global Positioning System), etc. are integrated on a common ground. Has been. For example, in Patent Document 1, the VICS antenna and the GPS antenna are arranged on one composite substrate, and the ETC antennas having different directivities are arranged on another substrate, and these two substrates are shared by one. Located near the center of the ground. A substrate ground is formed on almost the entire surface of the substrate opposite to the surface on which each antenna is mounted.

  On the other hand, in recent years, there has been a growing need to mount a telephone antenna for use in a mobile phone or the like in a vehicle, and it is difficult to secure a space for installing a telephone antenna. It is highly desired. The telephone antenna uses a frequency band of 800 MHz. Further, in order to obtain suitable reception characteristics, it is desired that the telephone antenna has a diversity configuration. As an in-vehicle integrated antenna provided with a telephone antenna having a diversity configuration, for example, an antenna described in Patent Document 2 is known.

  FIG. 13 shows an example of an integrated antenna including a telephone antenna having a diversity configuration. In the integrated antenna 900 shown in the figure, a GPS antenna 902 is disposed substantially at the center of the ground plane 901, and the ground plane 901 acts as a ground for the GPS antenna 902. Further, telephone antennas 903 and 904 are arranged on the left and right sides of the GPS antenna 902, respectively. Telephone antennas 903 and 904 are formed on substrates 905 and 906, respectively.

  The telephone antennas 903 and 904 are antennas that operate in the same frequency band. By using this antenna to configure diversity, high reception characteristics can be obtained. Here, the telephone antenna 903 is a transmission / reception antenna (hereinafter referred to as a TRx antenna), and the telephone antenna 904 is a reception-only antenna (referred to as an Rx antenna).

  As the telephone antennas 903 and 904, inverted F-type antennas as shown in FIG. 14 can be used. FIG. 14 is an explanatory diagram schematically showing the telephone antennas 903 and 904 with the illustration of the substrates 905 and 906 omitted. Each of the telephone antennas 903 and 904 has a feeding point connected to the feeding cables 907 and 908 and a grounding point connected to the ground plane 901.

JP 2004-056773 A JP 2007-124016 A

  However, when the diversity antenna is configured by incorporating the TRx antenna and the Rx antenna into the integrated antenna, there is a problem that a transmission wave from the TRx antenna leaks into the Rx antenna. That is, there is a problem that it is difficult to ensure sufficient isolation between the TRx antenna and the Rx antenna.

  Accordingly, the present invention has been made to solve the above problem, and an object thereof is to provide an integrated antenna having high isolation between the TRx antenna and the Rx antenna constituting the diversity.

  The first aspect of the integrated antenna of the present invention is an integrated antenna in which a telephone antenna is integrated with a first antenna that uses at least the first ground plane as a ground, and the telephone antenna is the first ground plane. A telephone board disposed on the telephone board; a transmission / reception antenna formed on the upper surface of the telephone board in parallel and adjacent to one of two opposing edges of the first ground plane; and the telephone board The reception antenna formed in parallel with the other of the two opposing edges on the top surface of the telephone and the first ground plane are formed on the top surface and the bottom surface of the telephone board in a non-contact manner. And a second ground plane to which the respective grounding points of the receiving antenna and the receiving antenna are connected. The second ground plane electrically connects the grounding point of the transmitting / receiving antenna and the grounding point of the receiving antenna. Separation Characterized in that it has a Tsu bets.

  In another aspect of the integrated antenna of the present invention, the second ground plane is at least directly below the first antenna between the transmitting / receiving antenna and the receiving antenna, of the top and bottom surfaces of the telephone board. And a bottom surface portion in the vicinity of a feeding point and a grounding point of each of the transmitting / receiving antenna and the receiving antenna.

  Another aspect of the integrated antenna of the present invention is characterized in that the second ground plane is further formed on a bottom surface portion directly below the transmitting / receiving antenna and the receiving antenna of the telephone board.

  Another aspect of the integrated antenna of the present invention is characterized in that the first ground plane has one or more current interrupting portions in which a part of a conductor is cut out immediately below the transmitting / receiving antenna.

  Another aspect of the integrated antenna of the present invention is characterized in that the first ground plane further includes one or more other current interrupting portions in which a part of a conductor is notched directly below the receiving antenna. To do.

  Another aspect of the integrated antenna of the present invention is characterized in that the telephone board is separated into two parts, the transmitting / receiving antenna side and the receiving antenna side.

  In another aspect of the integrated antenna of the present invention, the transmission / reception antenna and the reception antenna are inverted F-type antennas.

  As described above, according to the present invention, it is possible to provide an integrated antenna having high isolation between the TRx antenna and the Rx antenna constituting the diversity.

It is the top view, side view, and bottom view of the integrated antenna which concerns on 1st Embodiment of this invention. It is the top view of the telephone board | substrate of 1st Embodiment, a bottom view, and the top view of a 1st ground plane. It is a graph which shows the VSWR characteristic, gain characteristic, and isolation characteristic of the integrated antenna of 1st Embodiment. It is the top view of the board | substrate for telephones which shows the structure of a prior art example, the top view of a 1st ground plane, and sectional drawing of a 1st ground plane and a 2nd ground plane. It is a graph which shows the VSWR characteristic, gain characteristic, and isolation characteristic of a prior art example. It is the top view, side view, and bottom view of the integrated antenna which concerns on 2nd Embodiment of this invention. It is the top view of the telephone board | substrate of 2nd Embodiment, a bottom view, and the top view of a 1st ground plane. It is a top view which shows typically the state through which an electric current flows into the edge which opposes an antenna. It is a graph which shows the VSWR characteristic, gain characteristic, and isolation characteristic of the integrated antenna of 2nd Embodiment. It is the top view of the integrated antenna which concerns on 3rd Embodiment of this invention, a side view, and a bottom view. It is the top view of the telephone board | substrate of 3rd Embodiment, a bottom view, and the top view of a 1st ground plane. It is a graph which shows the VSWR characteristic, gain characteristic, and isolation characteristic of the integrated antenna of 3rd Embodiment. It is the top view and side view of an integrated antenna provided with the antenna for telephones of the conventional diversity structure. It is a perspective view of the telephone antenna using an inverted F antenna.

  An integrated antenna according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. Each component having the same function is denoted by the same reference numeral for simplification of illustration and description. The integrated antenna of the present invention is an integrated antenna for a vehicle equipped with an antenna such as ETC or VICS, and further integrated with a telephone antenna.

  An integrated antenna according to a first embodiment of the present invention will be described with reference to FIG. 1A is a plan view of the integrated antenna 100 of the present embodiment, FIG. 1B is a side view, and FIG. 1C is a bottom view. The integrated antenna 100 of the present embodiment is configured by integrating the telephone antenna 110 with the one on which the first antenna is mounted. FIG. 1 shows an embodiment in which a GPS antenna 101 is mounted as an example of the first antenna. However, the present invention is not limited to this, and an ETC antenna can be further mounted adjacent to the GPS antenna 101. The ETC antenna is placed at a predetermined angle with respect to the first ground plane 102.

  The GPS antenna 101 is disposed substantially at the center of the first ground plane 102, and the first ground plane 102 acts as the ground of the GPS antenna 101. The telephone antenna 110 has a diversity configuration including a TRx antenna 111 that transmits and receives in a predetermined frequency band and an Rx antenna 112 that performs only reception, and both antennas 111 and 112 are GPS antennas 101. Between the left and right ends of the telephone board 120. Hereinafter, the frequency band of the TRx antenna 111 is referred to as a transmission / reception frequency band F1, and the frequency band of the Rx antenna 112 is referred to as a reception frequency band F2. As an example, the respective frequency bands are set to F1 = 824 to 925 MHz and F2 = 843 to 875 MHz, and characteristics when adjusted to the respective frequency bands will be described below.

  The TRx antenna 111 and the Rx antenna 112 are formed on the telephone substrate 120 as inverted F-type antennas. The telephone board 120 has antenna element forming portions 121 and 122 on which the TRx antenna 111 and the Rx antenna 112 are respectively arranged at both left and right ends of the board main portion 123. In addition, a second main plate 124 used as a ground for the TRx antenna 111 and the Rx antenna 112 is formed on the substrate main portion 123. The second ground plane 124 is formed on the front and back sides of the telephone board 120 except at least directly below the GPS antenna 101. The feeding point 111 a of the TRx antenna 111 and the feeding point 112 a of the Rx antenna 112 are connected to a predetermined cable to be fed, and the ground points 111 b and 112 b are connected to the second ground plane 124.

  The integrated antenna 100 of the present embodiment achieves high isolation by suitably forming the first ground plane 102 and the second ground plane 124. Below, the characteristic of the 1st ground plane 102 and the 2nd ground plane 124 of this embodiment is demonstrated.

  The features of the first ground plane 102 and the second ground plane 124 will be described with reference to FIG. In the same figure, (a) and (b) show a plan view and a bottom view, respectively, of the telephone board 120, and (c) shows a plan view of the first ground plane 102. 2A and 2B, only the second ground plane 124 is illustrated with the illustration of the TRx antenna 111 and the Rx antenna 112 formed on the telephone substrate 120 omitted.

  As a first feature of the present embodiment, as shown in FIG. 1B, the first ground plane 102 and the second ground plane 124 are not brought into contact with each other so as not to be electrically connected. As a second feature, the second ground plane 124 is separated into the TRx antenna 111 side and the Rx antenna 112 side by forming a separation slit 125 in the second ground plane 124. The second ground plane 124 is formed on the front side of the telephone board 120 in a region directly below the GPS antenna 101 and on the area excluding the antenna element forming portions 121 and 122, and on the back side of the telephone board 120, directly below the GPS antenna 101. It is formed in the area except. In the present embodiment, the substrate main part 123 is also separated to the left and right in accordance with the separation slit 125 separating the second ground plane 124 to the left and right. However, the present invention is not limited to this.

  The isolation between the TRx antenna 111 and the Rx antenna 112 can be increased by reducing the wraparound in the space or by reducing the wraparound from the substrate. Among these, in the method of reducing the wraparound in the space, it is necessary to increase the spatial distance between the TRx antenna 111 and the Rx antenna 112, and the installation space of the telephone antenna 110 is increased. Therefore, in the integrated antenna 100 of the present embodiment, the first ground plane 102 and the second ground plane 124 are preferably formed to reduce the wraparound from the substrate as much as possible.

  In order to reduce the wraparound via the first ground plane 102 and the second ground plane 124 as much as possible, first, a separation slit 125 is formed to separate the second ground plane 124 into the TRx antenna 111 side and the Rx antenna 112 side. is doing. As a result, wraparound via the second ground plane 124 is prevented. Further, by electrically insulating the first ground plane 102 and the second ground plane 124, it is possible to prevent the second ground plane 124 from going around via the first ground plane 102.

  The characteristics of the integrated antenna 100 of the present embodiment configured as described above are shown in FIG. In the same figure, (a) and (b) are the VSWR (Voltage Standing Wave Ratio) characteristics of the TRx antenna 111 and the Rx antenna 112, respectively, and (c) and (d) are the TRx antenna 111 and the Rx antenna 112, respectively. (E) shows the isolation characteristic (S21) between the TRx antenna 111 and the Rx antenna 112, respectively.

  The VSWR characteristic of the TRx antenna 111 is adjusted to be sufficiently low in the transmission / reception frequency band F1, as shown in FIG. Further, the VSWR characteristic of the Rx antenna 112 is adjusted to be sufficiently low in the reception frequency band F2, as shown in FIG. 3B. Similarly, the gain characteristic is adjusted so that the gain characteristic of the TRx antenna 111 is sufficiently high in the transmission / reception frequency band F1 (FIG. 3C), and the gain characteristic of the Rx antenna 112 is sufficiently high in the reception frequency band F2. (FIG. 3D). Further, with respect to the isolation characteristics between the TRx antenna 111 and the Rx antenna 112, as shown in FIG. 3E, the TRx antenna is used in a wide frequency band including the transmission / reception frequency band F1 and the reception frequency band F2. S21 is reduced to such an extent that interference between the antenna and the Rx antenna does not become a problem, and high isolation can be realized.

  In the present embodiment, the first ground plane 102 and the second ground plane 124 are not brought into contact with each other so as not to be electrically connected, and a separation slit 125 is formed in the second ground plane 124 to form the TRx antenna 111 side. FIG. 4 shows a configuration of a conventional integrated antenna that does not have such a feature. In the same figure, (a) and (b) are a plan view and a bottom view, respectively, of a conventional telephone board 820, (c) is a plan view of a first ground plane 802, and (d) is a telephone board 820. Sectional drawing of the 2nd ground plane 824 and 1st ground plane 802 which were formed in 1 is shown, respectively. Also here, the TRx antenna 111 and the Rx antenna 112 are not shown on the telephone board 820, and only the second ground plane 824 is displayed. As shown in FIG. 4D, in the conventional example, the first ground plane 802 and the second ground plane 824 are brought into contact with each other and are electrically connected.

  FIG. 5 shows VSWR characteristics, gain characteristics, and isolation characteristics of the conventional example. Here, as in FIG. 3, (a) and (b) show the VSWR characteristics of the TRx antenna 111 and the Rx antenna 112, respectively, and (c) and (d) show the TRx antenna 111 and the Rx antenna 112, respectively. The gain characteristics and (e) show the isolation characteristics between the TRx antenna 111 and the Rx antenna 112, respectively. As shown in FIG. 5 (e), when the first ground plane 802 and the second ground plane 824 are electrically connected, S21 increases in the 800 MHz band, and the space between the TRx antenna 111 and the Rx antenna 112 is increased. Lowers the isolation. In contrast, in the integrated antenna 100 of the present embodiment, it can be seen that the isolation characteristics shown in FIG. 3E are significantly improved as compared with the conventional integrated antenna.

  An integrated antenna according to a second embodiment of the present invention will be described with reference to FIGS. 6A is a plan view of the integrated antenna 200 of the present embodiment, FIG. 6B is a side view, and FIG. 6C is a bottom view. 7A and 7B are a plan view and a bottom view of the telephone board 120, respectively, and FIG. 7C is a plan view of the first ground plane 202. In FIGS. 7A and 7B, illustration of the TRx antenna 111 and the Rx antenna 112 formed on the telephone substrate 120 is omitted, and only the second ground plane 124 is illustrated.

  As a feature of the present embodiment, a total of four current interrupting portions 202a are formed on the left and right edges of the first ground plate 202, two each. Each current cut-off portion 202a is longer than the length from the vicinity of each end side to directly below each antenna in the direction orthogonal to the TRx antenna 111 and the Rx antenna 112, and the center line of the first ground plane 202 A part of the conductor is cut out with a length shorter than the length up to. In addition, the electric current interruption part 202a is not limited to the slit shape as shown in FIG.6, 7, For example, you may form in a wider rectangle or square.

  In the integrated antenna 200 of the present embodiment, since the TRx antenna 111 and the Rx antenna 112 are arranged close to the two opposite sides of the first ground plane 202, each antenna is arranged. A strong current flows in the adjacent edge and the opposite edge, and a wraparound occurs that the current affects the other antenna. FIG. 8 schematically shows a state in which current flows along two end sides on the antenna side and the opposite side. In the same figure, when the antenna 10 arranged close to the end side 11a of the ground plane 11 transmits and receives, a strong current 12a flows along the end side 11a immediately below the antenna 10, and the opposite end side 11b is also weaker than the current 12a. It shows that the current 12b flows.

  When the currents 12a and 12b as described above flow along the end sides 11a and 11b, when another antenna is arranged on the end side 11b side, the characteristics of the antenna are affected. Therefore, in order to reduce the currents 12a and 12b flowing along the two opposing edges as much as possible, it is preferable to form the current interrupting portion 13 in the ground plane 11. As a result, the currents 12a and 12b flowing along the respective edges can be reduced.

  Similarly to the above, in the present embodiment, the first ground plane 202 is orthogonal to each antenna on each of the adjacent edge on which the TRx antenna 111 is disposed and the adjacent edge on which the Rx antenna 112 is disposed. The current interrupting part 202a is formed in the direction (that is, the direction orthogonal to each edge). Each current interrupting portion 202a is formed up to a position reaching the end side, thereby reducing current flow along each end side. In addition, each current cutoff unit 202a is formed to have a length longer than that immediately below the TRx antenna 111 and the Rx antenna 112. However, each current cutoff unit 202a is made shorter so that the TRx antenna 111 and If it does not reach the position immediately below the Rx antenna 112, the effect of reducing the current flowing along the above-mentioned end side cannot be obtained. Further, in the above description, the current interrupting portion 202a has a slit shape, a rectangular shape, or a square shape, and two current blocking portions 202a are provided on each of the left and right edges of the first ground plane 202. However, the shape and number of the current interrupting portions 202a are as follows. It is not limited to this. It has been confirmed that the formation of the current interrupting section 202a as described above on the first ground plane 202 does not affect the characteristics of the GPS antenna 101.

  In the present embodiment, the number of current interrupting portions 202a formed on the first ground plane 202 is two each. It is preferable to form at least one current cut-off portion 202a on each of two opposing sides of the first ground plane 202 directly below the TRx antenna 111 and the Rx antenna 112.

  FIG. 9 shows VSWR characteristics, gain characteristics, and isolation characteristics of the integrated antenna 200 of this embodiment. In the integrated antenna 200, S21 shown in FIG. 9 (e) is slightly smaller than that of the integrated antenna 100 of the first embodiment shown in FIG. 3 (e), and a higher isolation characteristic than that of the integrated antenna 100 is obtained. Yes. Further, in the gain characteristics shown in FIGS. 9C and 9D, characteristics comparable to those of the integrated antenna 100 of the first embodiment shown in FIGS. 3C and 3D are obtained. As described above, in the integrated antenna 200 of this embodiment, the isolation between the TRx antenna 111 and the Rx antenna 112 is further increased by providing two current blocking portions 202a on the first ground plane 202. It becomes possible.

  An integrated antenna according to a third embodiment of the present invention will be described with reference to FIGS. 10A is a plan view of the integrated antenna 300 of the present embodiment, FIG. 10B is a side view, and FIG. 10C is a bottom view. 11A and 11B are a plan view and a bottom view of the telephone board 320, respectively, and FIG. 11C is a plan view of the first ground plane 202. In FIGS. 11A and 11B, illustration of the TRx antenna 111 and the Rx antenna 112 formed on the telephone substrate 120 is omitted, and only the second ground plane 324 is illustrated.

  In the present embodiment, the second ground plane 324 is formed on the bottom surface side of the telephone board 320 at positions other than directly below the GPS antenna 101 and directly below the radiation portions of the TRx antenna 111 and Rx antenna 112. ing. Here, the radiating portions of the TRx antenna 111 and the Rx antenna 112 are antenna element portions excluding the vicinity of the feeding points 111a and 112a and the grounding points 111b and 112b of the antennas 111 and 112, respectively. When the second ground plane is also formed directly below the TRx antenna 111 and the Rx antenna 112, a current similar to the current generated in the first ground plane described with reference to FIG. 8 is applied to the second ground plane. May also occur. Therefore, in the present embodiment, in order to prevent the above-described current from flowing through the second ground plane, the second ground plane 324 is not formed immediately below the TRx antenna 111 and the Rx antenna 112. Yes.

  FIG. 12 shows VSWR characteristics, gain characteristics, and isolation characteristics of the integrated antenna 300 of this embodiment. In the integrated antenna 300, S21 shown in FIG. 12 (e) is smaller than the integrated antenna 100 of the first embodiment shown in FIG. 3 (e) and the integrated antenna 200 of the second embodiment shown in FIG. 9 (e). It can be seen that high isolation characteristics can be obtained. In addition, even in the gain characteristics shown in FIGS. 12C and 12D, the integrated antenna 100 of the first and second embodiments shown in FIGS. 4C and 4D and FIGS. 9C and 9D is used. , Characteristics better than 200 are obtained. In the integrated antenna 300 of the present embodiment, the second ground plane 324 is not formed immediately below the TRx antenna 111 and the Rx antenna 112, thereby isolating between the TRx antenna 111 and the Rx antenna 112. Can be further increased.

  Note that the description in the present embodiment shows an example of the integrated antenna according to the present invention, and the present invention is not limited to this. The detailed configuration, detailed operation, and the like of the integrated antenna in this embodiment can be changed as appropriate without departing from the spirit of the present invention.

100, 200, 300, 900 Integrated antenna
101, 902 GPS antennas 102, 202, 802, 901 First ground plate 202a Current blocking unit 110, 903, 904 Telephone antenna 111 TRx antenna 111a, 112a Feed point 111b, 112b Ground point 112 Rx antenna 120, 320 Telephone substrate 121, 122 Antenna element forming portion 123 Substrate main portion 124, 324 Second ground plate 125 Separation slit

Claims (7)

An integrated antenna in which a telephone antenna is integrated with a first antenna using at least a first ground plane as a ground,
The telephone antenna is
A telephone substrate disposed on the first ground plane;
A transmitting / receiving antenna formed in parallel on the top surface of the telephone substrate in the vicinity of one of the two opposing edges of the first ground plane;
A receiving antenna formed in parallel on the upper surface of the telephone substrate in proximity to the other of the two opposite sides;
A second ground plane formed on the top and bottom surfaces of the telephone board in contact with the first ground plane and connected to the respective grounding points of the transmitting / receiving antenna and the receiving antenna;
The second ground plane has a separation slit for electrically separating a ground point of the transmitting / receiving antenna and a ground point of the receiving antenna. The second ground plane includes a double-sided portion of the top and bottom surfaces of the telephone board except for at least a portion directly below the first antenna between the transmission / reception antenna and the reception antenna, the transmission / reception antenna, 2. The integrated antenna according to claim 1, wherein the antenna is formed on a bottom portion in the vicinity of each feeding point and grounding point of the receiving antenna. 3. The integrated antenna according to claim 2, wherein the second ground plane is formed on a bottom surface portion directly below the transmitting / receiving antenna and the receiving antenna of the telephone board. The integration according to any one of claims 1 to 3, wherein the first ground plane has one or more current interrupting portions in which a part of a conductor is cut out immediately below the transmitting / receiving antenna. antenna. 5. The integrated antenna according to claim 4, wherein the first ground plane further includes one or more other current interrupting portions in which a part of a conductor is notched directly below the receiving antenna. The integrated antenna according to any one of claims 1 to 5, wherein the telephone board is separated into two parts, the transmitting / receiving antenna side and the receiving antenna side. The integrated antenna according to any one of claims 1 to 6, wherein the transmitting / receiving antenna and the receiving antenna are inverted F-type antennas.

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