JPS63318826A - Radio equipment - Google Patents

Abstract

PURPOSE:To decrease the null points caused by the reflection, diffraction, absorption, etc., produced by the indoor construction, by radiating or receiving the polarized wave after switching the angles of said wave via two antennas. CONSTITUTION:An earth plate 2 serving as a conductor plate and an antenna element 3 are laminated with an insulator set between them and the single end face of the element 3 is connected to the plate 2 via a short circuit plate 4. Then a proper position of the element 3 is defined as a feeding point. Thus the radiation or reception characteristics approximate to the non-directivity can be obtained. Then plural antennas 1 are set in different directions and each antenna 1 is switched by a switch means 6 in terms of time division and connected to a transmitting or receiving circuit. Thus different polarized waves can be radiated or received at one time and therefore the null points caused by the reflection, diffraction, absorption, etc., produced by the indoor construction can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to a wireless device that transmits and receives radio waves between a transmitter and a receiver.

[Background Art 1 Recently, wireless devices using radio waves have been used indoors, and examples of such wireless IF include wireless chimes and wireless display boards.

By the way, since there are many objects that reflect radio waves indoors, interference diffraction, absorption, etc. occur frequently. For this reason, the propagation characteristics of indoor radio waves have become complicated. In general, the range of radio waves is narrower than the range of radio waves in free space due to reflection, absorption, and transmission from construction surfaces such as walls, and furthermore, within this range, radio waves are extremely weakened by interference of reflected waves. There are many null points. Furthermore, the range of radio waves and the shape and position of the null point vary greatly depending on the environment. This null
If such a point exists, an area where radio waves cannot propagate occurs, which poses a problem in that the installation location of the wireless device is restricted.

One way to alleviate this drawback is the space diversity method. 'When this method is applied to the receiving side, multiple antennas are spaced apart so that the correlation coefficients are small, and the signals received separately are combined, or the antennas are switched to receive the signals. It is used as When two receiving antennas are used, in order to achieve a spatial arrangement that reduces the correlation coefficient, an interval of at least a fraction of a wavelength is required, for example, 4
If it is separated by one-tenth of a wavelength, at 300MHz it is 25
It is necessary to separate them by about cm, which makes it difficult to miniaturize the device. Furthermore, even when this method is used on the transmitting side, miniaturization is difficult due to similar restrictions on antenna placement.

Another method is a frequency diversity method. However, in this method, communication is carried out by transmitting the same signal on two or more frequencies, so multiple antennas and transmitting/receiving circuit systems are required, or a wide frequency band is required, resulting in an expensive problem.

Further, as yet another method, there is a polarization diversity method. In this method, signals are received separately using receiving antennas with polarizations different by 90°, or transmitted using transmitting antennas with polarizations different by 90°. As this antenna, an antenna in the form of an earthen loop or a guiball was used.The directivity of these antennas is omnidirectional in a plane parallel to a specific plane, but only generates linearly polarized waves in a certain direction. However, if antennas of the same type are installed to utilize polarized waves that differ by 90 degrees, the directivity on the same plane will be 8-fold, not omnidirectional. The shape of the radio wave range differs depending on the wave direction, and the range in which polarization diversity is effective becomes narrower.Also, when one of the transmitting or receiving antennas is fixed, and the other transmits (receives) polarized waves that are 90 degrees different , the antenna on the fixed side can only transmit (receive) polarized waves in a specific direction, so for polarized waves that differ by 90 degrees, the transmit (receive) level will be extremely low, and the polarization ubiquity effect will be Don't expect much. By the way, indoors, the slope of polarized waves changes due to the reflection of radio waves, so even if you can only transmit (receive) polarized waves in a specific direction, there will be a slight improvement indoors, but there will still be a level difference. However, in many cases, the polarization variability effect cannot be expected.

In other words, the above-described conventional method of reducing the presence of null points due to indoor radio wave propagation characteristics is not sufficient for wireless devices used indoors.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and its purpose is to reduce the null points and the area where radio waves cannot propagate, and to achieve miniaturization and cost reduction. The object of the present invention is to provide an M-free device that can be reduced.

[Disclosure 1 of the Invention (Configuration) The present invention provides a wireless communication system that performs transmission and reception using radio waves between a transmitter and a receiver. The antenna is constructed by laminating a ground plate, which is a conductive plate, and an antenna element with an insulator in between, and connecting one end face of the antenna element to the ground plate with a shorting plate, and using a suitable position of the antenna element as a feeding point. It is equipped with a plurality of antennas, and is equipped with a switching means for arranging each of the above antennas in different directions, switching each antenna on a time-sharing basis, and connecting it to a transmitting circuit or a receiving circuit, with an insulator in between. By stacking the ground plane, which is a conductive plate, and the antenna element, and connecting one end face of the antenna element to the ground plane with a shorting plate, and using an antenna with the feeding point at an appropriate position of the antenna element, it is possible to achieve near omnidirectionality. A plurality of these antennas are provided so that the radiation or reception characteristics can be obtained, and each antenna is arranged in a different direction, and each antenna is switched in a time division manner by a switching means to connect the transmitting circuit or the receiving circuit. By connecting to a circuit, different polarized waves can be emitted or received at the same time, and although it is nearly omnidirectional, each polarized wave has directivity, and the angle of that polarized wave can be changed to multiple antennas. The signal is switched to radiate or receive, and then reflected by indoor construction surfaces.

This device is designed to reduce null points caused by diffraction, absorption, etc., and is relatively small and inexpensive compared to other conventional devices that take measures against null points.

(Example) An example of the present invention will be described based on FIGS. 1 to 8. In this embodiment, a wireless device equipped with two antennas will be described. This antenna 1 consists of a ground plate 2, which is a conductive plate, and an antenna element 3, with an insulator (air in this example) in between.
are arranged opposite to each other, one end of the antenna element 3 is connected to the ground plane 2 by a shorting plate 4, and an appropriate position of the antenna element 3 is used as a feeding point.As shown in FIG.
The directions of the two are changed by 90 degrees. In this embodiment, the ground plate 2 of each antenna 1 is integrated.

As shown in FIG. 2, the antenna 1 has a switch J=f
fi 6 is used to time-divisionally switch the signal to the transmitting circuit 5 (or receiving circuit) alternately. This switching means 6
A specific circuit is shown in Fig. 3. This switching means 6 connects diodes D, , D2 to respective branch paths branching the transmitter 5 output.
is inserted, and the diodes [ ) +1D2 are alternately forward biased to control conduction, and the transmitter 5 and each antenna 1 are alternately connected. An antenna switching signal S1 is applied directly to the diode D, and an output obtained by inverting this antenna switching signal S1 by an inverter 1 is applied to the diode D2. In addition, Chitark foil L, -L
.

is inserted to reduce leakage of high frequency signal components from this line, and capacitors C8 to C1 are DC cut capacitors. The outputs of the switching means 6 are connected to the feed points of the antenna element 3 through feed lines 7, respectively.

The radiation pattern of the antenna 1 alone is as follows.

Taking the XYZ axes as shown in Figure 4(a),
As shown in (a) of b) to (d), the antenna 1 is connected to the ground 8.
When the radiated electric field intensity in a plane parallel to the earth 8 was measured for both vertical and horizontal polarization, the results were as shown in (b) of Figures 4 (b) to (d), respectively. . Note that the solid line in the figure indicates the electric field strength of vertically polarized waves, and the broken line indicates the electric field strength of horizontally polarized waves. As shown in (b) of Figure 4 (b) to (d), either the vertical or horizontal polarization is approximately circular in each plane, or they complement each other as in the X-Y plane. As a result, it has an almost circular shape. In other words, it can be seen that this antenna 1 is close to an omnidirectional antenna. Conventional Goupole and loop antennas are omnidirectional only in the horizontal plane relative to a certain plane, so propagation to the upper floors is generally disadvantageous when used indoors.
The antenna 1 of this embodiment can be expected to have a relatively good propagation effect. Furthermore, when a Gouyball antenna is installed on a conductive wall, if it is installed within approximately 1/8 wavelength from the wall, the antenna gain will decrease. 300M
In the case of a frequency of about Hz, it is about 10-odd am, so
It is difficult to make wireless devices thinner. On the other hand, when the antenna 1 of this embodiment is installed at a similar distance, as long as the ground plate 2 is parallel to the wall surface, there is no decrease in antenna gain and it is possible to fit closely to the wall.

Next, FIG. 5 shows the results of observing the received voltage distribution by the antenna 1 of this embodiment in a straight line direction indoors in a certain building. 5(a) to 5(d), (a) shows the installed state of the antenna 1, and (b) shows the measurement results.

The vertical axis in (b) of FIGS. 5(a) to (d) is the voltage (unit: dBμV) that can be received by the receiving antenna (fixed), and the horizontal axis is the sweep distance. In addition, (
The arrow in b) indicates the line-of-sight direction of the receiving antenna 1. Further, the receiving antenna 1 is fixedly set as shown in FIG. 5(e), and the direction indicated by the arrow in the figure is the direction of the transmitting antenna 1.
This is the line-of-sight direction. In addition, FIGS. 5(a) to (cl
), the origin and direction of the sweep.

The distances are the same and the output power of the transmitter is also constant. In this case, assuming that the minimum receiving input voltage of the receiver is -15 dBμV, (
b) It can be seen that reception is impossible in the shaded area. Here, FIG. 5(a).

Let us consider the combination of (b) or the combinations of FIGS. 5(c) and (d). If FIGS. 5(a) and 5(b), and FIGS. 5(C) and 5(d) are simply superimposed, the result will be as shown in FIG. 6. In the transmission of the transmitter 5, the same data is switched by the switching means 6, as shown in FIG. 5(&), (b) or FIG. 5(C).

If the combination of antenna 1 in (d) is used to repeatedly transmit in time division, the intensity distribution in the above line direction will be as shown in Fig. 5(a).
(b) or as shown in Fig. 5(e) and (d), and if reception is possible in either of these states, data transmission is possible, so the effective reception strength is as shown in Fig. 6(d). a
)? It becomes as shown by the thick line (1+). Therefore, in this case, there is no unreceivable area on this line, and a great improvement effect can be obtained. Although this example is not representative of all cases, it is generally thought that similar effects can be found indoors. Note that this effect can be considered as a type of polarization guipasina.

However, the radiation pattern of antenna 1 used here simultaneously radiates polarized waves that differ by 90 degrees as described above, and although it is nearly omnidirectional in terms of energy, it has directivity for each polarized wave. It is different from the conventional simple polarized wave because the angle of the polarized wave is switched and radiated by two 7-antennas 1. Moreover, in this example, +i,
Compared to the case where no null point countermeasure is taken, an additional switching means 6 and an additional antenna 1 are required, and a circuit for creating an antenna switching signal for the switching means 6 is also required. Compared to a device that takes point measures, it is relatively small and can be realized at low cost. Furthermore, in terms of dimensions, since two antennas are physically arranged, the size of the antenna 1 itself becomes an issue, but by loading a passive element into the antenna element 3, the antenna size ratio with respect to the wavelength can be sufficiently increased. It is possible to make it small (1/10 wavelength or less). For example, as shown in FIG. 7(a),
By narrowing the width of the shorting plate 4, inductance is loaded on the same side, and the antenna element 3 can be made smaller, as shown in FIG.
Even if a capacitor 9 is loaded between the end portion and the ground plane 2, the antenna element can be made smaller.

By the way, in the above embodiment, it is simply physically possible to
Although the number of antennas 1 is simply arranged, #II8 figure (a
), near-linear shorting plates 41=42 are provided on both of the two orthogonal sides of the antenna cable 3, and as shown in FIG.

42 are alternately connected to the ground plate 2 in a time-sharing manner by the switching means 10, and although it appears to be one antenna, it operates as two antennas that are substantially perpendicular to each other.
In terms of space, it will be less than 1/2 the size. Therefore, miniaturization is possible.

Above, we have explained the case where two antennas are provided on the transmitting side, but the relative relationship of the orientations of the antennas to be combined may be other than the combinations described here, and the number is not limited to two but may be multiple. Also good. Furthermore, the same effect can be expected by using a similar configuration on the receiving side.

[Effect of the Invention J As described above, the present invention is a wireless communication device that performs transmission and reception using radio waves between a transmitter and a receiver! ! An antenna in which a ground plate, which is a conductive plate, and an antenna element are stacked with an insulator in between, one end surface of the antenna element is connected to the ground plate by a shorting plate, and a suitable position of the antenna element is used as a feeding point. A plurality of antennas are provided, and each of the above antennas is arranged in a different direction,
It is equipped with a switching means that connects each antenna to a transmitting circuit or a receiving circuit by time-divisionally switching the respective antennas, and a base plate, which is a conductive plate, and an antenna element are laminated with an insulator in between, and one of the antenna elements is By using an antenna whose end face is connected to the ground plane with a short-circuit plate and whose feeding point is at an appropriate position of the antenna element, it is possible to obtain nearly omnidirectional radiation or reception characteristics. By arranging each antenna in a different direction and using a switching means to time-divisionally switch each antenna and connecting it to the transmitting circuit or receiving circuit, different polarized waves can be emitted or received simultaneously, resulting in omnidirectional Each polarized wave has its own directivity, and the angle of the polarized wave can be switched between multiple antennas to radiate or receive.
Reflections from indoor construction surfaces.

Null points caused by diffraction, absorption, etc. can be reduced,
Moreover, it can be made smaller by making the shorting plate linear or loading a capacitor, and compared to other conventional devices that take measures against null points, it only requires switching and connecting multiple antennas. This has the effect of simplifying the circuit configuration and making it relatively inexpensive.

[Brief explanation of drawings]

Fig. 1 is an external perspective view of an embodiment of the present invention, Fig. 2 is a schematic configuration diagram of the same, Fig. 3 is a specific circuit diagram of the switching means of the above,
Figures 4 to 6 are explanatory diagrams of the characteristics of the above antenna, and Figure 7
Figures (a) and (b) are explanatory diagrams of miniaturization of the antenna shape,
FIGS. 8(a) and 8(b) are an external perspective view and a schematic configuration diagram of another embodiment of the present invention. 1 is an antenna, 2 is a ground plane, 3 is an antenna element, 4 is a shorting plate, 5 is a transmitting circuit, and 6 is a switching means. Agent Patent Attorney Ishi 1) Chief 7Q Figure 5 Figure 6 (b) Figure 7 (a) (b) Figure 8 (a) Medium (b) Procedural Techniques: (Voluntary) July 31, 1988 Patent N! 4 No. 154822 2, Name of the invention Wireless device 3, Relationship with the case of the person making the amendment Address of the patent author 1048 Kadoma, Kadoma City, Osaka Prefecture Name (58
3) Matsushita Electric Works Co., Ltd. Representative Sadao Fujii 4 Agent postal code 530 Address 1-12-17 Umeda, Kita-ku, Osaka 5.3 Date of original order Vol. 6 Number of inventions increased by amendment None 7. Subject of correction Drawings Figure 5 (a) (B) (b) (0> (0) (B) Figure 5 (d) (0) (e)

Claims (2)

[Claims] (1) A wireless device that transmits and receives radio waves between a transmitter and a receiver, in which a ground plate, which is a conductive plate, and an antenna element are stacked with an insulator in between, and one end surface of the antenna element is connected to a short-circuit plate. It is equipped with a plurality of antennas that are connected to the ground plane at A wireless device comprising a switching means connected to a receiving circuit. (2) The wireless device according to claim 1, wherein either a transmitter or a receiver is provided with the antenna and switching means.