JP2023142207A - board antenna - Google Patents

Abstract

To provide a new board antenna with excellent reception efficiency and radiation efficiency.SOLUTION: In a board antenna, a communication circuit for transmitting, receiving, or transmitting and receiving radio waves, a power supply line connected to the communication circuit, and a GND line connected to the communication circuit are provided on a printed board. The communication circuit is separated from the power supply line and the GND line in terms of high frequency. In addition, an input, output, or input/output unit of the communication circuit is connected to a portion of the power supply line or the GND line that is separated from the communication circuit in terms of high frequency, in a state where the unit can receive, transmit, or transmit/receive a high frequency signal. Furthermore, the portions of the power supply line and the GND line that are separated from the communication circuit in terms of high frequency are connected through a capacitor.SELECTED DRAWING: Figure 1

Description

The technology disclosed herein relates to a substrate antenna.

Patent Document 1 discloses a wireless device including a transmitting/receiving circuit. In Patent Document 1, a transmitting/receiving circuit and a power supply line are formed on a circuit board. One end of a part of the power supply line is grounded at high frequency, and the other end is floating at high frequency from the ground. The antenna connection point for the transmitter/receiver circuit is then connected within a portion of the power supply line. Patent Document 1 uses a part of the power supply line as an antenna and omits a structure in which it functions solely as an antenna. As a result, the size of the circuit board has become smaller, realizing a compact wireless device.

Japanese Patent Application Publication No. 2005-323249

If the power line on the circuit board is used as an antenna as in Patent Document 1, the size of the circuit board can be reduced. However, there is a demand for further miniaturization of circuit boards, and simply using a power supply line as an antenna does not provide sufficient radio wave reception efficiency or radiation efficiency. Therefore, further improvements are needed in the technology of forming antennas on circuit boards. The purpose of this specification is to provide a novel substrate antenna with excellent reception efficiency and radiation efficiency.

The substrate antenna disclosed in this specification includes, on a printed circuit board, a communication circuit for transmitting, receiving, or transmitting and receiving radio waves, a power line connected to the communication circuit, and a GND line connected to the communication circuit. It is being The communication circuit is separated from the power supply line and the GND line in terms of high frequency. Further, the input, output, or input/output section of the communication circuit is connected to a portion of the power supply line or the GND line that separates the communication circuit in terms of high frequency in a state where it can receive, transmit, or transmit/receive a high frequency signal. Further, portions of the power supply line and the GND line that separate the communication circuits in terms of high frequency are connected by a capacitor.

In the substrate antenna, both a portion of the power line that is separated from the communication circuit in terms of high frequency and a portion of the GND line that is separated in terms of high frequency from the communication circuit can be used as antennas. Typically, a power supply line and a GND line occupy a large proportion (area) of a pattern formed on a printed circuit board (circuit board). Therefore, by using both the power supply line and the GND line as an antenna, the antenna area can be secured even if the size of the printed circuit board is reduced. Therefore, the above-mentioned substrate antenna can realize a printed circuit board with high antenna reception efficiency or radiation efficiency although it is small.

The substrate antenna includes a first inductor for high-frequency isolation between a power source that supplies power to the communication circuit and the power line, and a first inductor for high-frequency isolation between the GND of the communication circuit and the GND line. 2 inductors may be provided. By providing the first inductor, the portion of the power supply line that isolates the communication circuit in terms of high frequency can be isolated in terms of high frequency from the power supply. Thereby, the high frequency of the power source can be superimposed on the portion of the power line that is isolated from the communication circuit in terms of high frequency. Furthermore, by providing the second inductor, the portion of the GND line that separates the communication circuit in terms of high frequency can be separated from GND in terms of high frequency. Thereby, the GND high frequency can be superimposed on the portion of the GND line that is separated from the communication circuit in terms of high frequency.

In the substrate antenna described above, the GND of the communication circuit may be connected to the casing in which the printed circuit board is mounted. The casing itself functions as a GND, and radio waves can be emitted/received through the opening of the casing.

Further, in the above-mentioned substrate antenna, the portion that separates the communication circuit of the GND line in terms of high frequency may be connected to the casing in which the printed circuit board is mounted. As a result, the casing itself functions as an antenna, and radio waves can be emitted/received from the casing as well.

A circuit diagram of a substrate antenna according to a first embodiment is shown. The circuit diagram of the board|substrate antenna of 2nd Example is shown. The circuit diagram of the board|substrate antenna of 3rd Example is shown. The circuit diagram of the board|substrate antenna of 4th Example is shown. The circuit diagram of the board|substrate antenna of 5th Example is shown. A printed circuit board on which the substrate antenna of the first embodiment is formed is shown (fifth embodiment). A modification of the fifth embodiment is shown (sixth embodiment).

(First example)
The substrate antenna 50 will be described with reference to FIG. 1. The substrate antenna 50 is formed on a printed circuit board (not shown). The substrate antenna 50 includes a communication circuit 12 that transmits and receives radio waves to and from an external device, and a plurality of circuits 26 and 32. Each circuit 12, 26, 32 is connected to a power line 2 and a GND line 30. The power line 2 is connected to a power source 6 external to the substrate antenna (printed circuit board) 50 via a first inductor 8 . The first inductor 8 isolates the power source 6 and the power line 2 from each other in terms of high frequency. Further, the GND line 30 is connected to GND outside the substrate antenna 50 via the second inductor 16. The second inductor 16 isolates GND and the GND line 30 in terms of high frequency. Note that the total length of the power supply line 2 and the GND line 30 is adjusted to be 1/10 to 1/4 of the wavelength of the frequency of radio waves used in the communication circuit 12.

The communication circuit 12 is connected to the power supply line 2 via the third inductor 10. The third inductor 10 isolates the communication circuit 12 and the power line 2 in terms of high frequency. A first inductor 8 and a third inductor 10 are connected in series on a wiring 12a leading from a power source 6 to a communication circuit 12, and a power line 2 is connected to an intermediate point 9 thereof. Further, the input and output of the communication circuit 12 are connected to the power supply line 2 via the capacitor 4. The capacitor 4 is adjusted to have a capacity that allows electric field coupling between the input/output of the communication circuit 12 and the power supply line 2 . Therefore, it can be said that the input and output of the communication circuit 12 are connected to the power supply line 2 by electric field coupling. Since the power supply line 2 is separated from the communication circuit 12 (wiring 12a) in terms of high frequency, a high frequency signal is superimposed thereon.

Further, the communication circuit 12 is connected to the GND line 30 via the fourth inductor 14. The fourth inductor 14 isolates the communication circuit 12 and the GND line 30 in terms of high frequency. A fourth inductor 14 and a second inductor 16 are connected in series on a wiring 12b leading from the communication circuit 12 to GND, and a GND line 30 is connected to an intermediate point 15 thereof. A bypass capacitor 20 is connected between the power supply line 2 and the GND line 30. Bypass capacitor 20 is provided between communication circuit 12 and circuit 26. Typically, bypass capacitor 20 passes high frequency signals used in radio waves. Therefore, a high frequency signal is also superimposed on the GND line 30.

As described above, the circuits 26 and 32 are connected to the power supply line 2 and the GND line 30. The input of circuit 26 is connected to input terminal 22 via inductor 24 . Further, the output section of the circuit 32 is connected to an output terminal 34 via an inductor 36. Note that a bypass capacitor 28 is provided between the circuits 26 and 32, and the bypass capacitor 28 is also connected to the power supply line 2 and the GND line 30. The bypass capacitor 28 also passes high frequency signals used in radio waves. Note that the bypass capacitors 20 and 28 are provided near each circuit 12, 26, and 32 to remove noise in the circuits 12, 26, and 32.

As described above, in the substrate antenna 50, both the power supply line 2 and the GND line 30 are separated from the communication circuit 12 in terms of high frequency. Therefore, both the power line 2 and the GND line 30 function as antennas for the communication circuit 12. Typically, the power line 2 and the GND line 30 occupy a relatively large area on the circuit board. Therefore, the substrate antenna 50 uses both the power supply line 2 and the GND line 30 as antennas for the communication circuit 12, and is not provided with a structure for exclusively functioning as an antenna. Therefore, the substrate antenna 50 can reduce the size of the printed circuit board while having the antenna function. Moreover, since the board antenna 50 uses both the power supply line 2 and the GND line 30 as antennas, the antenna reception efficiency and radiation Efficiency can be improved.

Further, as described above, circuits other than the communication circuit 12 (circuits 26 and 32) are also connected to the power line 2 and the GND line 30, which are separated in terms of high frequency. Since the circuits 26 and 32 change the amplitude of the superimposed high-frequency signals, the high-frequency signals are also superimposed on the signal lines and the like that constitute the circuits 26 and 32. As a result, in the substrate antenna 50, the components of the circuits 26 and 32 also function as an antenna for the communication circuit 12.

Note that in the above embodiment, the communication circuit 12 that transmits and receives radio waves to and from an external device has been described. However, the communication circuit 12 may be a transmitting circuit that emits radio waves to an external device, or a receiving circuit that receives radio waves from the external device. Furthermore, in the above embodiments, an example has been described in which the input and output of the communication circuit 12 are connected to the power supply line 2 via the capacitor 4. Modifications regarding the type of communication circuit 12 and the portion of communication circuit 12 connected to the capacitor are common to the second to seventh embodiments described below.

The second to seventh embodiments will be described below. The second to fifth embodiments show modifications of the substrate antenna 50, and the sixth and seventh embodiments show specific forms of the substrate antenna. Therefore, in the following description, features common to the substrate antenna 50 may be given the same reference numerals as those of the substrate antenna 50, and repeated explanations may be omitted.

(Second example)
FIG. 2 shows substrate antenna 150. FIG. In the substrate antenna 150, the input and output of the communication circuit 12 are connected to the GND line 30 via the capacitor 4. In the substrate antenna 150, the GND line 30 is separated from the communication circuit 12 (wiring 12b) in terms of high frequency, so a high frequency signal is superimposed thereon. Then, the high frequency signal passes through the bypass capacitors 20 and 28, and the high frequency signal is also superimposed on the power supply line 2. In the substrate antenna 150, both the power line 2 and the GND line 30 function as antennas for the communication circuit 12.

(Third example)
FIG. 3 shows a substrate antenna 250. FIG. In the substrate antenna 250, the input and output of the communication circuit 12 are coupled to the power supply line 2 via the transformer 204. In the transformer 204, the number of turns of the primary coil and the secondary coil are adjusted so that the input/output of the communication circuit 12 and the power line 2 are magnetically coupled. Therefore, it can be said that the input and output of the communication circuit 12 are connected to the power supply line 2 by magnetic coupling. In the substrate antenna 250, a high frequency signal is fed to the power line 2 by the transformer 204, and the high frequency signal is superimposed on the power line 2. In the substrate antenna 250, both the power line 2 and the GND line 30 function as antennas for the communication circuit 12.

(Fourth example)
FIG. 4 shows a substrate antenna 350. In the substrate antenna 350, the wiring 12b (communication circuit 12 GND line) is connected. In the substrate antenna 350, the casing 40 functions as a stable GND for the communication circuit 12, and radio waves can be transmitted and received from an opening (not shown) of the casing 40 with this GND as a reference. Note that, in the substrate antenna 350, transmission and reception of radio waves outward from the outer edge of the housing 40 is suppressed.

(Fifth example)
FIG. 5 shows a substrate antenna 450. In the substrate antenna 450, the GND wire 30 is connected to the casing 40 in which the substrate antenna 50 (see FIG. 1) is mounted. The total length of the power line 2, the GND line 30, and the outer edge of the housing 40 is adjusted to be 1/10 to 1/4 of the wavelength of the radio wave frequency used in the communication circuit 12. Therefore, a relatively small housing 40 is selected so that the outer edge length does not become too long. In the substrate antenna 450, the housing 40 can also be used as an antenna for the communication circuit 12.

In the fourth and fifth embodiments described above, an example in which the board antenna 50 is mounted on the housing 40 has been described, but instead of the board antenna 50, the board antenna 150 (see FIG. 2) or the board antenna 250 may be mounted on the housing 40.

(6th example)
FIG. 6 schematically shows a substrate antenna 50 formed on a printed circuit board 60. The total length of the length L21 of the power supply line 21 and the length L31 of the GND line 31 formed on the printed circuit board 60 is longer than 1/4 of the wavelength of the radio wave frequency used in the communication circuit 12. Therefore, in the substrate antenna 50, a part of the power line 21 is made thinner, and a portion with large inductance is formed in the middle of the power line 21. A portion with a large inductance formed in the middle of the power supply line 21 becomes the first inductor 8 (see also FIG. 1). By forming the first inductor 8, the portion of the power line 2 connected to the communication circuit 12 can be separated from the portion of the power line 3 connected to the power source 6 in terms of high frequency.

Similarly, a portion of the GND line 31 is also thinned to form a portion with large inductance in the middle of the GND line 31. A portion with large inductance formed in the middle of the GND line 31 becomes the second inductor 16. By forming the second inductor 16, the portion of the GND line 30 connected to the communication circuit 12 can be separated from the portion of the GND line 33 connected to GND in terms of high frequency.

The positions where the first inductor 8 and the second inductor 16 are formed are such that the total length of the power line 2 length L2 and the GND line 30 length L30 is approximately the wavelength of the radio wave frequency used in the communication circuit 12. It is adjusted to be 1/4. This allows the power line 2 and the GND line 30 to function as an antenna for the communication circuit 12.

(Seventh Example)
FIG. 7 schematically shows a substrate antenna 550 formed on the printed circuit board 60. The substrate antenna 550 is different from the substrate antenna 50 in the connection positions of connected components (see comparison in FIG. 6). The circuit 26 is connected in parallel with the communication circuit 12 between the third inductor 10 and the fourth inductor 14, and is isolated from the power line 2 and the GND line 30 in terms of high frequency. Further, the circuit 32 is connected to a portion of the power line 21 that is separated from the power line 2 in terms of high frequency (power line 3), and is also connected to the GND line 30 via an inductor 46. Therefore, the circuit 32 is also separated from the power supply line 2 and the GND line 30 in terms of high frequency. In the substrate antenna 550, no high frequency signal is superimposed on the voltage applied to the circuits 26 and 32, and the voltage is constant.

Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The techniques described in the claims include various modifications and changes to the specific examples illustrated above. Further, the technical elements described in this specification or the drawings exhibit technical usefulness singly or in various combinations, and are not limited to the combinations described in the claims as filed. Furthermore, the techniques illustrated in this specification or the drawings can achieve multiple objectives simultaneously, and achieving one of the objectives has technical utility in itself.

12: Communication circuit 2: Power line GND: GND line 20: Capacitor 50: Board antenna

Claims (4)

A communication circuit for transmitting, receiving, or transmitting and receiving radio waves, a power line connected to the communication circuit, and a GND line connected to the communication circuit are provided on the printed circuit board,
The communication circuit is separated from the power line and GND line in terms of high frequency.
The input, output, or input/output part of the communication circuit is connected to a part of the power supply line or GND line that separates the communication circuit in terms of high frequency in a state where it can receive, transmit, or transmit/receive a high frequency signal,
A substrate antenna in which the part that separates the communication circuit of the power line and GND line in terms of high frequency is connected by a capacitor. a first inductor for high-frequency isolation between a power source that supplies power to the communication circuit and the power line;
a second inductor for high frequency isolation between GND and GND lines of the communication circuit;
The substrate antenna according to claim 1, comprising: 3. The substrate antenna according to claim 1, wherein GND of the communication circuit is connected to a casing in which the printed circuit board is mounted. 4. The substrate antenna according to claim 1, wherein the portion of the GND line that separates the communication circuit in terms of high frequency is connected to a casing in which a printed circuit board is mounted.

Images