JP2008167365A - Antenna connection structure for wireless communication card - Google Patents

Abstract

When an information processing apparatus is provided with a wireless function by inserting a wireless communication card, a high gain antenna can be designed by incorporating the antenna in the information processing apparatus side in advance. However, in the conventional configuration, when the radio circuit in the card and the antenna are connected via a coaxial line, the ground of the coaxial cable and the ground on the card side are not stabilized due to the contact condition of the terminals, and the characteristics as an antenna are improved. It had a problem that it could not be held.
An RF connector for inputting and outputting a radio signal from a card includes a balanced line for connecting two spring terminals and a loop antenna, and the two spring terminals and the surface of the radio communication card are provided. The two pad terminals 22 are electrically connected.
[Selection] Figure 2

Description

  The present invention relates to a method for connecting a wireless communication card and an external antenna.

  Nowadays, devices using wireless technology such as wireless LAN and Bluetooth compatible devices compliant with the IEEE802.11a / b / g standard have become widespread, and wireless functions can be implemented by installing wireless communication functions in card-type terminals and inserting them into devices. Increasing number of cases that can be retrofitted.

  On the device side, an interface for connecting a wireless communication card is provided, and the wireless communication card is sold separately, so that a product that does not require a wireless function can be provided at a low price.

  A wireless communication card requires an antenna for efficiently radiating or receiving a wireless signal into space. The antenna is generally installed at the end of the board in the card so as to protrude from the device. However, as the size of the card is reduced, the antenna is also required to be reduced. Yes. Furthermore, it is also required to install the antenna without projecting to the outside of the card slot from the viewpoint of storage property, durability, and design when being carried. However, in general, when the antenna is downsized, the gain and directivity are sacrificed. In addition, the closer the distance between the device and the antenna, the lower the performance of the antenna.

  Therefore, a method is considered in which an antenna is incorporated in a device in advance without providing an antenna in the communication card. By doing so, the space that can be used for antenna installation is greatly expanded, and it becomes possible to design a high-gain antenna having desired antenna directivity. Further, since it is not necessary to consider the area for the antenna on the card side, further miniaturization and improvement in storage, durability, and design are facilitated.

  At this time, the problem is how to connect the card and the antenna. The card needs to be provided with a connector connected to a radio circuit inside the card in addition to the normal interface terminal. When a coaxial connector is mounted on a card substrate, there are problems in terms of the strength of the substrate that can withstand the pressure at the time of insertion / removal and the signal loss at the connection portion due to aging of the connector.

  As a prior art for solving this problem, for example, the invention described in Patent Document 1 provides a method of connecting a wireless communication card and an antenna using a pad terminal and converting the same into a coaxial connector. FIG. 11 shows a connection structure of a conventional wireless communication card described in Patent Document 1.

As shown in FIG. 11A, the wireless communication card is provided with a GND pad terminal 5a and a signal pad terminal 5b that reach the wireless communication circuit. Further, as shown in FIG. 11B, an antenna (not shown) installed inside the housing is provided inside the card slot 1 via the coaxial cable 3, the coaxial connector 8, the GND 7a, and the signal line 7b. The spring terminals 2a and 2b are connected. 11B, when the wireless communication card 4 is inserted into the card slot 1, as shown in FIG. 11C, the GND pad terminal 5a, signal pad terminal 5b, and spring terminal 2a on the card surface. The spring terminals 2b are respectively connected to perform transmission / reception processing.
JP 2002-108497 A

  The card connection structure described in Patent Document 1 eliminates the need for a coaxial connector on the board, thereby eliminating problems such as physical restrictions such as the card outer shape and connector mounting area, and board damage due to pressure during insertion and removal. There is an effect.

  However, in the conventional configuration, since the ground line of the coaxial cable and the card-side ground are connected only by the spring terminal, the ground potential fluctuates due to a slight change in the contact state, and the antenna characteristics are not stable. It had the problem that. In addition, the unbalanced antenna used by connecting to a coaxial cable needs to secure a sufficient area as a ground, and has a problem in terms of miniaturization.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide a connection means between a card and an in-casing antenna so that radio waves can be efficiently radiated from the antenna.

  In order to solve the above-described conventional problems, the wireless communication card connection structure of the present invention includes a balanced line and a balanced antenna connected to the balanced line inside a connector adjacent to the card slot. The balanced line inside the connector and the wireless card are connected by a spring terminal provided on the connector and a pad terminal provided on the wireless card.

  With this configuration, it is possible to input and output balanced wireless signals along the path from the wireless communication circuit in the card to the antenna.

  By connecting the wireless communication card and the built-in antenna using the connection method of the present invention, balanced signals are input and output, so the problem that the ground potential becomes unstable is solved and caused by the contact state of the terminals It is possible to prevent the antenna characteristics from changing.

  Further, since it is not necessary to provide a ground region for the antenna, the area required for antenna installation can be minimized.

  Furthermore, loop antennas and folded dipole antennas, which are a type of balanced feed antenna, are not easily affected by the human body and can be used in a wide range of frequencies, but they are good because they can be connected without a balun. Communication characteristics can be expected.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
In the present embodiment, a connection structure in the case where pad terminals formed on an SD card type wireless communication card are formed on the upper surface of the card will be described.

  FIG. 1 is a perspective view showing a wireless communication card connection structure according to Embodiment 1 of the present invention. FIG. 2 (a) is an enlarged front view of the card slot, and FIG. 1 (b) is an enlarged view of the card slot. It is a side view.

  In FIG. 1, the information processing apparatus 11 has a card slot 13 for storing a wireless communication card 12. An SD card connector 14 is provided inside the card slot 13 and is connected to the information processing apparatus 11 through an interface 15. Further, two pad terminals 22 are formed on the upper surface of the wireless communication card 12 and connected to an internal high-frequency signal processing unit (not shown). In addition, a spring terminal, a pin terminal, etc. are used as a pad terminal.

  FIG. 2 shows a state where the wireless communication card 12 is inserted into the card slot 13. As shown in FIG. 2A, the RF connector 18 for inputting / outputting a radio signal from the card includes a balanced line 20 for connecting two spring terminals 19 and a loop antenna 21. 19 and two pad terminals 22 on the surface of the wireless communication card are electrically connected. In addition, a metal plate, a pin terminal, etc. are used as a spring terminal.

  Further, as shown in FIG. 2B, a card insertion passage 16 is formed in the SD card connector 14, and the wireless communication card 12 is inserted in a state where the wireless communication card 12 is inserted into the card insertion passage 16. It is formed so as to be connected to the connector pin 17. An RF connector 18 and a spring terminal 19 are installed on the upper surface of the SD card connector 14 and are electrically connected to the pad terminal 22 on the surface of the wireless communication card. The spring terminal 19 and the loop antenna 21 are electrically connected via a balanced line 20 (not shown) provided on the RF connector 18.

  According to this configuration, the high-frequency signal processing unit inside the wireless communication card 12 is connected to the loop antenna via the two pad terminals 22, the two spring terminals 19, and the balanced line 20. From the antenna to the antenna, everything is processed with a balanced signal, and the problem that the ground potential becomes unstable is solved, and the antenna characteristic change due to the contact state of the terminal can be prevented.

  In addition, a balanced power supply antenna using a loop antenna as a representative example does not need to be provided with a ground region, so that the area required for antenna installation can be minimized.

  Furthermore, as long as the wireless communication card uses the same frequency band, it is possible to cope with various wireless communication systems by simply replacing the SD card. For example, an 802.11b / g-compliant wireless LAN using the 2.4 GHz band and Bluetooth can be considered.

  As an example, FIG. 3A shows a perspective view of an electromagnetic field simulation model in the present embodiment, and FIG. 3B shows a side view of the simulation model. In this case, 2.5 mm x 3 mm pad terminals are provided at a spacing of 1.6 mm on the surface of an SD card (width 24 mm x length 32 mm x thickness 2.1 mm) via a 3 mm x 7 mm x 11 mm connector. Then, power is supplied to the loop antenna 21 having a height of 24 mm and a width of 44 mm. It is assumed that the loop antenna 21 is installed so as to surround the wireless communication card 12.

  The electromagnetic field simulation results in this configuration are shown in FIGS. 4 is an antenna radiation characteristic diagram of the simulation model of FIG. 3, and FIG. 5 is a VSWR (Voltage Standing Wave Ratio) characteristic diagram of the simulation model of FIG.

  FIG. 4 shows a radiation directivity characteristic in a horizontal plane at 2.45 GHz, and the radiation directivity characteristic has a maximum gain of 2.9 dBi. Further, as shown in FIG. 5, the VSWR is 2 or less from 2.4 GHz to 2.5 GHz, and shows good characteristics suitable for use in an 802.11b / g-compliant wireless LAN and Bluetooth.

  In general, the radiation efficiency Pr of an antenna is proportional to the square of l, where l (> 0) is the antenna length. When trying to incorporate an antenna in a small card, it is difficult to radiate efficiently. Since the connection method according to the present invention is not limited by the size of the card, it is very effective in constructing a highly efficient antenna.

(Embodiment 2)
In this embodiment, a case will be described in which a pad terminal formed on a wireless communication card is connected to a wireless communication card formed on both sides so that the card is sandwiched.

  FIG. 6 is a perspective view of an information processing apparatus into which a wireless communication card according to Embodiment 2 of the present invention can be inserted as seen from the front. FIG. 7A is an enlarged front view of the card slot, and FIG. ) Is an enlarged side view of the card slot. 6 and 7, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIGS. 7A and 7B, in the wireless communication card 12 according to the present embodiment, pad terminals 22 are formed on the upper and lower surfaces of the card so as to be paired, and an internal high-frequency signal is formed. It is connected to the processing unit.

  Further, as shown in the figure, a portion adjacent to the SD card connector 14 is installed in a pair so as to sandwich a card with two RF connectors 18 inserted therebetween, and the loop antenna 21 is supplied with two power supplies. It is arranged to be connected to the point. Two spring terminals 19 and a balanced line 20 are incorporated in the two RF connectors 18. With this configuration, when the card is inserted, the two pad terminals 22 and the two spring terminals 19 provided on the upper and lower surfaces on the card side are electrically connected to each other. In addition, a spring terminal, a pin terminal, etc. are used as a pad terminal, and a metal plate, a pin terminal, etc. are used as a spring terminal.

  According to this configuration, the radio frequency signal processing unit of the radio communication card is connected to the antenna via the upper and lower two pad terminals, the upper and lower spring terminals, and the balanced line. Are all processed with balanced signals. Therefore, the problem that the ground potential becomes unstable is solved, and the antenna characteristic change due to the contact state of the terminal can be prevented.

  FIG. 8 shows a simulation model diagram in the present embodiment as an example. In this case, a 2.5 mm x 3 mm pad terminal is provided on the front and back surfaces of a wireless communication card having an SD card shape (width 24 mm x length 32 mm x thickness 2.1 mm) via a 3.5 mm x 12 mm x 10 mm connector. Power is supplied to the loop antenna 21 having a height of 24 mm and a width of 44 mm.

  The electromagnetic field simulation results in this configuration are shown in FIGS. 9 is an antenna radiation characteristic diagram of the simulation model of FIG. 8, and FIG. 10 is a VSWR characteristic diagram of the simulation model of FIG.

  FIG. 9 shows radiation directivity characteristics in the xy plane at 2.45 GHz, and the average gain is 2.2 dBi. Further, the radiation directivity characteristic shows non-directivity on the same plane, and a characteristic suitable for use in a device at home or the like can be obtained. Further, as shown in FIG. 10, VSWR is 2 or less from 2.4 GHz to 2.5 GHz, and shows good characteristics suitable for use in an 802.11b / g-compliant wireless LAN and Bluetooth.

  In the present invention, an SD card type wireless communication card is exemplified as the wireless communication card. However, the present invention can also be applied to PCMCIA (Personal Computer Memory Card International Association) standard cards and other cards. Similarly, other card connectors may be used instead of the SD card connector.

  In the present invention, the radio communication card mainly has a radio frequency of 2.4 GHz in mind, but the present invention is not limited by the radio frequency.

  In addition, the information processing apparatus is described as an example of a device for inserting a wireless communication card, but the device is not limited to this as long as the device can be attached with a card slot.

  Further, the shape and the location of the pad terminal and the spring terminal are not limited as long as they can input and output a balanced signal. For example, the present invention can be applied even if a pin type terminal is provided on the side of the card.

  Further, the balanced line is configured only in the RF connector, but the line length is not limited, and it is only necessary to connect the RF connector and the antenna. Therefore, the present invention can be applied even when there is no balanced line.

  In addition, the antenna to be connected is a loop antenna as a representative of the balanced feed antenna, but is not limited to this as long as it is a balanced feed antenna.

  The antenna to be connected may be formed on a printed board or a flexible board and connected to the spring terminal.

  Since the wireless communication card connection structure according to the present invention can prevent deterioration of characteristics due to the contact state of the terminals, it is useful as a method for connecting the wireless communication card and the external antenna with high efficiency.

The perspective view which shows the connection structure of the radio | wireless communication card in Embodiment 1 of this invention (A) Front view with enlarged card slot, (b) Side view with enlarged card slot (A) Perspective view of the simulation model, (b) Side view of the simulation model Antenna radiation characteristics diagram of the simulation model of FIG. VSWR characteristic diagram of simulation model of FIG. The perspective view which shows the connection structure of the radio | wireless communication card in Embodiment 2 of this invention (A) Front view with enlarged card slot, (b) Side view with enlarged card slot (A) Perspective view of the simulation model, (b) Side view of the simulation model Antenna radiation characteristics diagram of the simulation model of FIG. VSWR characteristic diagram of simulation model of FIG. (A) Perspective view showing a wireless communication card, (b) A view showing a connection structure of a conventional wireless communication card, (c) A side view showing a connection structure of a conventional wireless communication card

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Information processing apparatus 12 Wireless communication card 13 Card slot 14 SD card connector 15 Interface 16 Insertion path 17 Connector pin 18 RF connector 19 Spring terminal 20 Balance line 21 Loop antenna 22 Pad terminal

Claims (4)

A wireless card connection structure in a device capable of wireless communication by inserting a wireless communication card provided with a pad terminal into a slot,
A spring terminal electrically connected to the pad terminal;
A balanced feed antenna for transmitting and receiving radio signals;
A wireless card connection structure comprising: a balanced line for electrically connecting the balanced power supply antenna and the spring terminal. 2. The wireless card connection structure according to claim 1, wherein the antenna structure is formed on a printed circuit board or a flexible substrate. 2. The wireless card connection structure according to claim 1, wherein when the pad terminal is disposed on both surfaces of the wireless communication card, the spring terminal is disposed so as to sandwich the card. The wireless card connection structure according to claim 1, wherein the spring terminal is a metal plate or a pin terminal.