KR20050016942A - Antenna with built-in filter - Google Patents

Abstract

A dielectric sheet 31 having a conductor film formed on one surface thereof is laminated to form at least one filter 2, and a laminated dielectric block 3 is formed, and fixed to the laminated dielectric block 3 to radiate the radiation element 1 Is provided, and one electrode of the filter 2 is electrically connected to the radiating element 1. The other electrode of the filter 2 is not exposed on the side surface, so that the via contact 33 and the wiring 34 are not exposed. ) Is led to the mounting surface Ｂ (surface facing the mounted circuit board) of the laminated dielectric block 3 and connected to the feed terminal electrode 4 provided on the mounting surface. Even if it is mounted directly on the circuit board, it is possible to obtain an antenna with a filter, which is capable of improving isolation characteristics and improving transmission and reception characteristics without interfering with each other between the electronic circuit on the circuit board and the feed terminal electrode of the antenna. ．

Description

Antenna with filter {ANTENNA WITH BUILT-IN FILTER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna with built-in filter, which is small in size suitable for mounting in a mobile phone or a portable terminal, and at the same time does not interfere with an electronic circuit on a circuit board when mounted on a circuit board. In addition, in detail, for example, when used in a plurality of frequency bands such as for cellular and GPS or Bluetooth, the signal of the other party rotates to the receiving circuit side via the feed terminal electrode. The present invention relates to an antenna for built-in filters, which is a structure in which no mutual interference occurs.

Conventionally, signals transmitted and received by an antenna can transmit and receive only signals of a desired frequency band through a filter such as a band pass filter. The filter is conventionally manufactured separately and externally connected to an antenna. In recent years, filter-integrated antennas incorporating antennas and filters have been developed based on elimination of the inconvenience of matching antennas and filters, miniaturization of electronic devices, and the like.

Such a filter built-in antenna 85 is a capacitor constituting a filter, as shown in some perspective explanatory diagrams and cross-sectional explanatory diagrams of an example of the state mounted on the circuit board 86 in FIGS. 7A and 7B, for example. The radiation element 81 is formed on the surface side of the laminated dielectric block 83 in which a dielectric sheet on which a conductive pattern is formed is laminated to form an inductor, and is fired. It is electrically connected to the element 81, and the other electrode is connected to a feed terminal electrode 84 provided on the outer surface of the laminated dielectric block 83 so as to be connected to a transceiver circuit of an external circuit and the like. As an antenna, as shown in the cross-sectional explanatory diagram of FIG. 7A in FIG. 7B, the wiring film 834 is removed from the other electrode of the filter 82 formed of a conductor pattern in which an inductor or a capacitor is formed. After extending to the end as it is, the laminated dielectric block 83 is formed, and then connected to the wiring film 834 exposed on the side surface of the feed terminal electrode 84 from the side surface (circuit board 86). Surface of the circuit board). The power supply terminal electrode 84 is directly connected to the power supply line 862 of the circuit board 86 by soldering or the like.

As described above, the conventional filter built-in antenna has a mounting surface from the side of the dielectric block 83 such that the other electrode of the filter is led to the side of the dielectric block 83 and connected to the derived wiring film 834. The feed terminal electrode 84 is provided over the surface (surface and back surface facing the antenna board). Therefore, the feed terminal electrode 84 on the side of the dielectric block transmits and receives radio waves transmitted and received by the radiating element 81 or the like. In addition, in recent years, a cellular phone transmits and receives a cellular signal and receives a GPS (Global Positioning System) signal or wireless LAN. An antenna is configured to transmit and receive signals of two or more frequency bands, such as an antenna for a blue toe, and the power supply terminal electrode 84 easily feeds signals of two or more frequency bands.

On the other hand, an electronic circuit such as a receiving circuit, a transmitting circuit, or the like including a receiving side low noise amplifier (not shown) is formed in the circuit board 86 on which the filter-embedded antenna 85 is mounted. In the case of transmitting and receiving in two or more frequency bands, these electronic circuits are formed in respective frequency bands, and the feed terminal electrodes and these electronic circuits are electromagnetically coupled so that the noise or other frequency signals detected by the feed terminal electrodes are directly Interfering with the circuit on the circuit board, there is a problem that the isolation characteristics (small mutual coupling) is reduced (noise increase), or the transmission and reception characteristics are degraded.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and while minimizing by integrating a filter and a radiating element by a stack of dielectric sheets, the electronic terminal on the circuit board and the power supply terminal electrode of the antenna can be mounted directly on the circuit board. It is an object of the present invention to provide an antenna with a filter, which is a structure capable of improving isolation characteristics and improving transmission / reception characteristics without interfering with each other.

Another object of the present invention is to provide a mounting structure of a built-in filter antenna mounted on a circuit board so as to be particularly suitable for preventing mutual interference between electronic circuits when the built-in filter antenna is mounted on a circuit board.

1A to 1C are explanatory diagrams showing an embodiment of an antenna with a filter according to the present invention.

2A to 2B are diagrams showing an example of the configuration of a filter in the multilayer dielectric block shown in FIG.

3 is a diagram showing an example of the configuration of an example of the via contact shown in FIG.

4 is a cross-sectional explanatory diagram of an example in which the filter-embedded antenna shown in FIG. 1 is mounted on a circuit board.

5 is a diagram showing an outline of a device for examining the characteristics of FIG.

6A is an antenna gain frequency characteristic diagram according to the present invention, and FIG. 6B is an antenna gain frequency characteristic diagram according to a conventional structure.

7A to 7B are explanatory views of a state in which a conventional built-in filter antenna is mounted on a circuit board.

In the antenna with a filter according to the present invention, a dielectric sheet having a conductive film formed on one surface thereof is laminated to form at least one filter, and is laminated and fixed to the multilayer dielectric block. An electrically connected radiating element and a feed terminal electrode electrically connected to the other electrode of the filter, the feed terminal electrode provided on an outer surface of the laminated dielectric block, the feed terminal electrode, and the laminated dielectric block being an external circuit board It is provided on the opposing mounting surface, which is an opposing surface when it is mounted on, and is formed so that the connection wiring connecting the other electrode of the filter and the feeding terminal electrode is not exposed to the outer surface other than the mounting surface of the laminated dielectric block.

Here, the "radiation element" means that a radio wave of a radiation electrode or a planar radiation electrode pattern in which a radiation pattern is formed on one surface of the dielectric block with a conductive film can be radiated. In addition, "electrically connected" means a conductor. In addition to the direct connection by means of the connection, it is meant to include the case where the connection is made via other electronic components or when the connection is made by an electromagnetic field without being directly connected by a conductor. It means the surface exposed to, and a "mounting surface" means the surface facing the mounted circuit board.

With the above structure, the power supply terminal electrode faces only a circuit board on which a filter-embedded antenna is mounted, and since the multilayer board or the like in which the shield plate is embedded can be used for the circuit board, the circuit board is completely shielded while the power supply terminal electrode is completely shielded. As a result, external noise does not directly interfere with the feed terminal electrode, and even if a signal of a different frequency band appears on the feed terminal electrode, it is not combined with a receiving circuit of another frequency band. As a result, the isolation characteristics between the feed terminal electrode and the electronic circuit on the circuit board are considerably improved, and there is no fear of degrading the characteristics of the desired transmission / reception signal, etc., and it functions as a highly efficient antenna with a filter.

The electrical connection between the other electrode of the filter and the feed terminal electrode is performed via, for example, a via contact made of a conductor embedded in a contact hole provided in the dielectric sheet.

The mounting structure of the antenna with a filter according to the present invention is mounted on a circuit board having a laminated structure in which the antenna with a filter according to claim 1 has at least a shield layer and a wiring layer, and the feed terminal electrode is electrically connected to internal wiring provided in the circuit board. And the electronic component provided on the circuit board surface and the feed terminal electrode are electrically connected through the internal wiring. By the above configuration, the internal wiring can be used for the feed line connected to the feed terminal electrode. Since it can be connected to the components which comprise an electronic circuit in the state shielded by the shielding plate, without exposing it to the outside at all, the transceiver of a very high characteristic can be obtained.

<Example>

Next, a filter built-in antenna of the present invention will be described with reference to the drawings. As shown in FIGS. 1A to 1C, the antenna with built-in filter has a conductor film formed on one surface thereof. The dielectric sheet 31 is laminated so as to form at least one filter 2, and a laminated dielectric block 3 is formed. The radiating element 1 is fixed to the laminated dielectric block 3 and installed. One electrode (not shown) is electrically connected to the radiating element 1. The other electrode 22 of the filter 2 is connected to the via contact 33 and the wiring 34. Is connected to the feed terminal electrode 4 provided on the outer surface of the laminated dielectric block 3. In the present invention, the feed terminal electrode 4 is laminated as shown in the rear view in FIG. 1C. Dielectric block 3 not shown As when it is mounted on a substrate is provided with the circuit side - surface opposed to the substrate only to B, the side exposed to the outside of the laminated dielectric block (3) is characterized in that is formed so as not to expose.

In the example shown in FIG. 1, only one radiating element 1 and a filter 2 corresponding to a signal of one frequency band are shown. For example, cellular AMPS / PCS, satellite positioning system (PSPS), or blue A plurality of radiating elements 1 (some radiating elements may be used for a plurality of frequency bands) or a plurality of frequency band signal filters 2 to transmit and receive signals of a plurality of frequency bands, such as a tow (BT), etc. It is also possible to be mounted on, or made of, one multilayer dielectric block 3. In addition, when a filter for two or more frequency bands is made in one multilayer dielectric block 3, for each block of each frequency band filter 2, the longitudinal direction is used. It is desirable to form a shield wall in the laminated dielectric block 3 so as not to interfere with each other. The shield wall can be formed in the same manner as the strip-shaped via contact described later. .

In the example shown in FIG. 1, the radiating element 1 is an example formed of a patch-shaped radiation electrode provided on a ground conductor 35 with a dielectric layer interposed therebetween, and is patterned by a band-shaped conductor or a band-shaped conductor. Other configurations, such as a ceramic antenna which capacitively couples an electrode etc. with a feed electrode, may be sufficient, and the structure provided in the side of the dielectric block 3 may be sufficient.

As described later, the filter 2 forms an inductor L, a capacitor C, and a resonator in the multilayer dielectric block 3, and is connected to each other so as to be shown in FIG. 2A, for example, to form a single filter or a low pass. The filter LPF, the high pass filter HPF, and the resonator together with a filter group combining at least two of the band pass filter GPF and the band elimination filter can be configured to pass only a desired frequency band. One electrode 21 of 2 is electrically connected to the radiating element 1, and the other electrode 22 is electrically connected to the feed terminal electrode 4. Moreover, radiating elements and filters for two or more frequency bands are provided. In the case of incorporation of a wire into the filter, for example, the AMPS (0.8HZ) / PCS (1.8GHz) cellular and the GPS (1.5HZ) are installed. As shown in Fig. 2B, a high pass filter LP is cut in a frequency band lower than 1.4 kHz, and a low pass filter LP cut in a frequency band higher than 1.6 kHz is connected, and a 1.8 kHz band close to 1.5 kHz is reliably cut. Therefore, by inserting the 1.8 kHz band elimination filter VE, it is possible to reliably prevent the other party's signal from interfering. Even in other frequency bands, it is possible to change the size and connection of L and C only. can do.

As the cross-sectional explanatory drawing of the multilayer dielectric block 3 is shown in Fig. 1B, for example, a conductive film is formed on one surface of the ceramic sheet (green sheet) 31 by a printing or the like, and the filter described above. (2) A via line connecting the inductor L and the capacitor C so that a capacitor C or the like is formed by forming a conductor film by interposing a strip line L constituting an inductor or the like for forming the dielectric sheet 31. Each dielectric sheet 31 is formed such that a via contact 33 or a wiring 34 for connecting the contact 32 or the other electrode 22 of the filter 2 to be described later with the feed terminal electrode 4 is formed. The conductive film is formed in a desired pattern on the surface, or the conductive film 35 is formed on the entire surface of the shield, and the ceramic sheets 31 are cut and sintered in a state where they are pressed to each other. For example, ~30mm) × (2~30mm) the size of a, is formed to a thickness of about 0.5~7mm.

The via contact 33 and the wiring 34 for connecting the other electrode 22 of the filter 2 with the power supply terminal electrode 4 connect the electrode 22 via the side surface of the laminated dielectric block 3. It is formed to lead directly to the bottom surface (mounting surface Ｂ) of the dielectric block 3 via the inside of the laminated dielectric block 3, without deriving it from the bottom surface side. The via contact 33 is connected via the wiring 34, but this may be the case where the filter electrode 22 and the feed terminal electrode 4 are deflected on a flat surface, or the bottom of the electrode 22 and the dielectric block 3 are connected. In the case where the distance from the surface is large, when the via contact is formed in several dielectric sheets at the same place, only the part becomes thicker, so that the via contact 33 needs to be moved to a position different from the plane area. ， Formed to move the position of the via contact 33 C. However, if there is no need to do, and may directly connect to the other electrode 22 and the feeding terminal electrode 4 of the filter in one via-contact 33.

In the case of connecting the upper and lower conductive films by sandwiching the ceramic sheet 31, the contact holes (through holes) formed in the ceramic sheet 31 are connected by via contacts 32 and 33 for embedding and connecting the conductors. As shown in the cross-sectional explanatory diagram of the via contact portions 32 and 33 in the perpendicular direction of the via contact portion 32 shown in Fig. 3 and Fig. 1B, the via contacts 32 and 33 are formed in a band shape so that the connection cross-sectional area is increased to provide high frequency resistance It is possible to prevent the increase, and to form a filter in a laminated structure, and to form a high-performance filter. To form the strip-shaped via contacts 32 and 33, the contact holes provided in the ceramic sheet 31 have elongated grooves. It can form by forming in a shape.

In order to manufacture such a laminated dielectric block 3, for example, a via contact hole or an elongated groove is formed in a ceramic sheet 31 having a thickness of about 100 μm with a molding die, and the inside of the groove and necessary strip lines are electrically conductive. It is formed by printing a sieve paste or the like. Then, as described above, dozens of sheets are pressed and hardened so as to form filter circuits or via contacts 32 and 33, and cut into respective stacked dielectric block sizes, or After forming the cutting groove, it is formed by sintering. In addition, when the radiating element 1 or the grounding conductor 36 is formed on the surface, the side surface or the bottom surface of the multilayer dielectric block 3, a conductor such as silver paste is formed on the side surface by printing or the like. can do.

As in the case of forming the radiating element 1 or the ground conductor 36 described above, the feed terminal electrode 4 is provided so as to be connected to the via contact 33 by a conductive material such as silver paste or the like, It is formed by baking.

Such a filter built-in antenna is usually mounted directly on a circuit board on which a signal processing circuit and the like are formed and incorporated into a case of a mobile phone or the like. The feed terminal electrode 4 of the present invention is exposed to the side surface of the laminated dielectric block 3. The filter-embedded antenna 5, which is a structure that does not have a structure, is a circuit board having a laminated structure in which at least one layer of wiring layers such as the shield layer 63 and the feed line 62 are formed on the insulating sheet 61 as shown in FIG. By using the circuit board 6 (in the example shown in FIG. 4, the shield layer 63 is provided on the upper and lower outer surfaces, only one side may be provided or may be provided inside). For example, the low noise amplifier 65 of the received signal processing circuit can be connected in a completely shielded state, and the coupling between the feed terminal electrode 4 and the electronic circuit can be almost completely eliminated. Even if the feed terminal electrode is directly connected to the feed line on the surface of the circuit board, the conventional installation structure shown in Fig. 7, since the feed terminal electrode is completely located only on the back side of the laminated dielectric block, the mutual connection between the feed terminal electrode and the electronic circuit on the circuit board Coupling is significantly suppressed, and mutual isolation characteristics are improved.

Investigating the frequency characteristics of the antenna, which is a gain relation with respect to the frequency, by connecting an antenna with a filter according to the present invention to a feed line provided on the circuit board surface, compared with an antenna with a filter having a structure in which a feed terminal electrode is provided over the side wall of a conventional laminated dielectric block. As shown in Fig. 5, in the characteristic test, for example, a test antenna 72 is installed in a case 71, such as a mobile phone, and a filter built-in antenna 5 is mounted in the case 71. When one circuit board 6 is provided and a 0.8 to 4 kHz frequency signal is emitted from the test antenna 72, the gain frequency characteristics of the received signal are examined. In other words, the filter built-in antenna 5 was used as a 2.4 kHz band antenna for a blue tow. FIG. 6A is a diagram in which the antenna according to the present invention is directly connected to a feed line provided on a circuit board surface. The antenna characteristic of the structure in which the feed electrode terminal is provided also in the same side shown.

As can be seen from Fig. 6, according to the present invention, attenuation is considerably attenuated in a frequency band of 1.76 HzHz or less and 3.04 HzHz 'or more (preferably attenuation in a frequency band other than the desired 2.4 HzHz' band). Also, the attenuation is small in the frequency band, and it is easy to be mixed as noise. This means that the filter is incorporated so as to attenuate signals in the frequency band other than the 2.4 kHz band in the built-in filter. Although it is attenuated in the frequency band away from it, in the conventional structure, it is considered that there is a radio wave directly detected by the feed terminal electrode, and that the radio wave does not pass through the filter and thus is not removed. If exposed, considerably zero of external noise It is easy to receive the fragrance, and the interaction between the power supply terminal electrode and the receiving circuit is also likely to occur. This tendency is not limited to the antenna for Bluetooth, but also for the antenna for GPS and the antenna for cellular. I can get it.

According to the present invention, the feed terminal electrode of the antenna with built-in filter is provided only on the mounting surface facing the mounted circuit board, and not on the sidewall exposed to the outside. On the other hand, in the laminated dielectric block, a suitable conductive film is wide. It can be installed in a range to function as a shield plate, a ground conductor can be provided around the feed terminal electrode, and a circuit board can also be provided to the circuit board, so that interference with the outside can be suppressed reliably. For this reason, the received signal does not enter the feed terminal electrode directly without passing through the filter, and the feed terminal electrode and the electronic circuit on the circuit board do not interact with each other by electromagnetic field coupling. Isolation characteristics (small coupling degree between the feed terminal electrode and the nearby electronic circuit) are improved and The influence of external noise can be greatly suppressed and improving the antenna characteristics.

Further, according to the present invention, since the feed terminal electrode is not formed on the side of the laminated dielectric block 3, the electronic circuit formed on the circuit board and the antenna with a filter can be arranged in close proximity, and the circuit board can be miniaturized. In addition, by using a circuit board of a laminated structure having wiring therein as a circuit board, it is possible to connect the electrical connection between the power supply terminal electrode and the electronic circuit component in a completely shielded state, and to improve new isolation characteristics. At the same time, having a complete shield function, there is no problem even when connecting to a remote electronic component, thereby increasing the degree of freedom of component placement on the circuit board.

According to the present invention, since the feed terminal electrode of the antenna with a filter integrated with the antenna and the filter is formed in a structure that is hard to interfere with the outside, the interaction with the circuit board on which the antenna with a filter is mounted can be significantly suppressed. In addition, it is possible to obtain an antenna with a filter that greatly improves the transmission and reception characteristics. In addition to the integration of the filter and the antenna, the antenna with a filter and an electronic circuit on the circuit board can be arranged so that a mobile telephone or the like can be provided. Even if the miniaturization is particularly required in a mobile device, it can contribute to the miniaturization.

In addition, in the case of using the antenna with a filter according to the present invention, the isolation characteristics can be further improved by using a laminated structure substrate as the circuit board and connecting the electronic circuit via a shielded internal wiring.

According to the present invention, the feed terminal electrode can be connected to the feed line of the circuit board while completely shielding the feed terminal electrode, and external noise does not directly interfere with the feed terminal electrode, and even if a signal of another frequency band appears on the feed terminal electrode, It is not combined with a reception circuit of a frequency band. As a result, it can be used as a compact high performance antenna suitable for mounting on a cellular phone or a mobile terminal used in a plurality of frequency bands, such as cellular, GPS, and Bluetooth.

Claims (10)

A dielectric sheet having a conductive film formed on one surface thereof, the multilayer dielectric block formed by stacking at least one filter; and a radiating element fixed to the multilayer dielectric block and electrically connected to one electrode of the filter; It is electrically connected to the other electrode of the filter, and has a feed terminal electrode provided on an outer surface of the laminated dielectric block, and the feed terminal electrode is provided on a mounting surface that is a surface facing when the laminated dielectric block is mounted on an external circuit board. And a connection wiring connecting the other electrode of the filter and the feed terminal electrode to be not exposed to an outer surface other than the mounting surface of the multilayer dielectric block. The method of claim 1, An antenna with built-in filter in which electrical connection between the other electrode of the filter and the feed terminal electrode is performed via a via contact made of a conductor embedded in a contact hole provided in the dielectric sheet. The method of claim 2, An antenna with built-in filter, wherein at least two via contacts are provided at different positions from a planar position of the dielectric block, and the at least two via contacts are connected via wirings provided on dielectric sheets constituting the dielectric block. The method of claim 2, And the via contact is formed in a band shape by embedding a conductor in an elongated groove-like contact hole provided in the dielectric sheet, and is formed such that the cross-sectional area of the via contact is increased. The method of claim 1, And a filter built-in antenna, wherein the filter comprises a filter group including at least two of a low pass filter, a high pass filter, and a band cancellation filter. The method of claim 1, And the radiating element is formed so as to transmit and receive two or more frequency bands, and wherein the filter is formed in two or more so that the filter can transmit and receive signals of the two or more frequency bands. The method of claim 6, The at least two filters include an internal filter filter including a band cancellation filter for removing a frequency band of a signal transmitted and received by another filter. The method of claim 6, 2. An antenna with built-in filter, in which at least two frequency bands transmitted and received by said radiating element comprise at least two kinds of cellular, GPS, and blue toes. The method of claim 6, And said at least two filters are structured so as not to interfere with each other by a shield wall formed in a direction perpendicular to the dielectric sheet of said laminated dielectric block via a strip-shaped via contact formed in said dielectric sheet. The antenna with a filter according to claim 1 is mounted on a circuit board having a laminated structure having at least a shield layer and a wiring layer, and the feed terminal electrode is electrically connected to an internal wiring provided in the circuit board, and interposes the internal wiring. A mounting structure of an antenna with a filter formed by electrically connecting an electronic component provided on the circuit board surface and the feed terminal electrode.