JP2006121633A - Radio communication module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic circuit module which receives little effect of a size of a substrate and existence of a surrounding conductor to an antenna, makes limitation of flexibility to the cabinet or substrate design small, and makes an adjustment of a high frequency circuit unnecessary; and moreover, to provide the electronic circuit module which can realize a radio communication function without requiring advanced knowledge of an antenna or a high frequency circuit to a circuit designer. <P>SOLUTION: The electronic circuit module is constituted such that the antenna, an impedance matching circuit, and a high frequency transceiver circuit are mounted on the same printed wiring board; the antenna is a Brown antenna which is configured on the printed circuit board as a conductor pattern, and has a loop in which a line length configured by the conductor pattern on the printed circuit board is nearly the same length of a 1/2 wave length of the operating frequency; and the conductor pattern is made in a meander shape. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic circuit module having a specific low-power radio station and a radio communication function using weak radio waves.

  In recent years, various devices have been made wireless. In particular, short-distance wireless data communication devices such as a wireless LAN and a remote keyless entry system have a wide application range and are expected to be further popularized in the future.

  Approved in Japan as a frequency band that can be used for such short-range wireless data communications are the 400 MHz band, 1200 MHz band, and 2400 MHz band of specific low-power radio stations, and mainly weak radio waves in the 300 MHz band. In particular, specific low-power radio stations in the 400 MHz band and weak radio waves in the 300 MHz band have a wide range of uses because low-power-consumption radio communication equipment can be realized with a relatively simple circuit configuration. Moreover, the fact that ICs and circuit modules in which this frequency band wireless communication circuit is made into one chip is on the market indicates that there is a great demand for short-range wireless data communication devices.

  However, since the IC and circuit module mainly include only the baseband circuit and the high-frequency transmission / reception circuit, even if the circuit design related to transmission / reception can be simplified, only the antenna is separately designed or an existing product is purchased or purchased. Must be custom-ordered. Furthermore, it is necessary to consider impedance matching between the antenna and the high-frequency transmission / reception circuit.

  When the frequency is 300 MHz to 400 MHz, a general quarter-wave monopole antenna is unsuitable for downsizing the device because the shape of the antenna itself is large and the efficiency is reduced when the housing (ground plate) is small. In recent years, dielectric antennas that have been miniaturized in this frequency band have been developed. However, it is necessary to individually adjust the characteristics according to the size of the printed wiring board to be mounted, which limits the board design. A loop antenna is typically used as a relatively small and efficient antenna. However, as the antenna is reduced in size, the bandwidth becomes narrower, and an adjustment for absorbing variations in the impedance matching circuit corresponding to this is required.

  The design of the antenna and the impedance matching circuit of the antenna requires knowledge about radio wave propagation and a high-frequency circuit and expensive dedicated measurement equipment, and is an area where general electronic circuit design engineers cannot easily enter. Thus, even if the demand for wireless communication increases and ICs and circuit modules corresponding to the demand are on the market, the design of the wireless device requires a special technology such as antenna and high-frequency circuit design. This is an obstacle to the expansion of communication applications.

  The present invention provides an electronic circuit module that is less affected by the size of the substrate and the presence of surrounding conductors with respect to the antenna, reduces the restriction on the degree of freedom of housing and substrate design, and does not require adjustment of a high-frequency circuit. . It is another object of the present invention to provide an electronic circuit module that allows a circuit designer to realize a wireless communication function without requiring advanced knowledge of an antenna or a high-frequency circuit.

  The present invention is a wireless communication module used in a 400 MHz band specific low-power radio station or a 300 MHz band weak radio wave, wherein an antenna, an impedance matching circuit, and a high-frequency transmission / reception circuit are mounted on the same printed wiring board, A brown antenna having a loop formed of a conductor pattern on a wiring board and having a loop whose length is substantially equal to a half wavelength of the used frequency, and having the conductor pattern in a meander shape It solves the problem.

  In addition, the pair of feeding points of the antenna is the wireless communication module characterized in that the antenna is disposed at a certain distance on the printed wiring board.

  The present invention provides a wireless communication module in which an antenna, an impedance matching circuit, and a high-frequency transmission / reception circuit are integrated, so that an electronic circuit designer develops a wireless communication device without requiring a lot of specialized knowledge about the high-frequency circuit and the antenna. it can. In addition, the antenna built in this module is less affected by the surroundings, so there are few restrictions on the degree of freedom in housing design. With these features, it is possible to accelerate the development speed of short-range wireless communication devices using specific low-power radio stations and weak radio waves, and further expand the application range.

  Details of the present invention will be described below with specific examples. FIG. 1 shows an example of the configuration of a wireless communication module according to the present invention. Reference numeral 1 denotes an antenna, 2 denotes an impedance matching circuit, 3 denotes a high-frequency receiving circuit, 4 denotes a high-frequency transmitting circuit, 5 denotes a transmission / reception baseband circuit, and 6 denotes a wireless communication module body. The wireless communication module according to the present invention is characterized by including not only a high-frequency circuit but also an antenna and an impedance matching circuit therein. Note that the configuration shown here is merely an example, and it is also possible to include a transmission only or reception only configuration, a control circuit such as a CPU, an interface circuit, and the like.

  Next, FIG. 2 and FIG. 3 schematically show an antenna built in the wireless communication module of the present invention. 2 and 3, 1 is an antenna, 7 is a pair of feeding points of the antenna, 8 is a ground plane (ground plane), and 9 is a printed wiring board. One antenna and eight ground planes are part of an electric circuit formed of a conductor on a nine printed wiring board. According to the test results of the present inventor, good characteristics are obtained when the outer shape of the printed wiring board is about 45 mm × 25 mm at 315 MHz and 426 MHz by the antenna pattern of FIGS.

  The wiring pattern of the antenna will be described in detail. The basic configuration of this antenna is a brown antenna whose line length is ½ wavelength shown in FIG. If the antenna of 300 MHz band is configured as it is, the total length will be about 25 cm. Therefore, as shown in FIG. 5, a fold is provided to suppress the height, and the entire line is made into a meander shape as shown in FIGS. 3 pattern.

  Since this antenna has a line length of about ½ wavelength, the frequency bandwidth is wide, and there is a margin in the frequency bandwidth with respect to variations in the impedance matching circuit, so that the impedance matching circuit can be unadjusted.

  Although this antenna is basically an electric field antenna, as shown in FIGS. 2 and 3, a pattern of this antenna is obtained by arranging a pair of feeding points in the vicinity of two opposite sides of the printed wiring board and grounding one of them. Since it forms a closed loop through the ground plane, it also has the characteristics of a magnetic field antenna. Since the electric field component tends to attenuate and the magnetic field component tends to increase near the human body or conductor, this antenna has little deterioration in efficiency due to such surrounding conditions.

  Since the characteristic impedance of the antenna itself is not a standard 50Ω in a high frequency circuit, an impedance matching circuit is essential. This module provides the antenna, impedance matching circuit, and high-frequency transmission / reception circuit, which are the main parts of the wireless communication circuit.

  Configuration of wireless communication module according to the present invention   Antenna pattern 1 built into this module   Antenna pattern 2 built into this module   Basic antenna example   Example of bent brown antenna

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 Impedance matching circuit 3 High frequency receiving circuit 4 High frequency transmitting circuit 5 Transmission / reception baseband circuit 6 Radio communication module main body 7 Antenna feeding point 8 Ground plane (ground plane)
9 Printed wiring board

Claims (2)

  A wireless communication module used in a 400 MHz band specific low power radio station or a 300 MHz band weak radio wave, wherein an antenna, an impedance matching circuit, and a high frequency transmission / reception circuit are mounted on the same printed wiring board, and the antenna is mounted on the printed wiring board. A radio communication module, characterized in that it is a brown antenna formed of a conductor pattern and having a loop whose line length is substantially equal to a half wavelength of a used frequency, and the conductor pattern is formed in a meander shape.   2. The wireless communication module according to claim 1, wherein the pair of feeding points of the antenna are respectively arranged in the vicinity of two opposite sides of the printed wiring board, and one feeding point is grounded.

Images