JP2011030196A - Multi-band loop antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the functions of a multi-band loop antenna. <P>SOLUTION: The multi-band loop antenna comprises: a ground board; a radiating element constituted of a plate-like conductor which is connected with the ground board at one terminal to form a first loop via the ground board and to form a second loop of a resonant frequency lower than that of the first loop on the first loop; and a power feed point connected to the ground board and the radiating element, respectively. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a loop antenna that operates effectively in a plurality of bands.

  In recent years, many characteristics are required for an antenna. Among them, research on a multiband antenna that operates effectively for a plurality of frequency bands is being conducted every day. The multiband antenna can support a plurality of communication standards, and is expected to become more important in the future.

  The multiband antenna is used for information communication devices such as indoor base stations, repeaters, and wireless LAN devices of mobile phone systems, for example.

  The cellular phone system is required to be able to connect and talk in almost all places, and has a problem in connection and talking on a higher floor of a building or an underground shopping center where radio waves from an outdoor base station do not reach. In such a place, an antenna is generally installed on the ceiling or wall surface, and a small base station is added to make it possible to use a mobile phone.

  The above antennas installed on the higher floors and underground malls of buildings are installed on the ceiling and wall surface to be as inconspicuous as possible. In this case, these antennas are not conspicuous, that is, they are thin (low profile) ) Is strongly desired.

  Further, it is desired that an antenna used in a recent base station is an antenna that can cover a plurality of bands such as an 800 MHz band and a 2 GHz band. Considering future development, it is required to support a plurality of radio systems having different frequencies and communication methods, such as cognitive radio and software radio.

  If these things are dug down from the side of the antenna, it is preferable to support a 2.4 GHz band wireless LAN system and a 2.6 GHz band WiMAX system in addition to the current 800 MHz band and 2 GHz band. . It is also desirable to support the bandwidth of the 3.9G (LTE) system.

JP 2007-174158 A

Koichi Sakaguchi Koji Nagasawa Nozomu Hasebe, “UWB Curved Plate Antenna” paper 2005 Society of Electronics, Information and Communication Engineers Society Conference B-156

As described above, as an antenna band, an antenna that can cover a communication band assigned to communications represented by the 800 MHz band and the 2 GHz band is required.
In addition, it is required to be thin and have a low profile, and to be simple and inexpensive. In addition, it is required that the interference is low for a frequency band that is not used or a frequency band that cannot be used.

  However, if the ceiling-mounted antenna of the mobile phone base station installed indoors is taken as an example, there is currently no antenna that satisfies the characteristics of the above requirements. Further, even if the use examples other than the mobile phone base station are seen, there is no satisfactory antenna having good characteristics in a plurality of frequency bands in addition to being thin (low profile) and inexpensive.

Here, techniques related to the present invention will be listed.
An example of a low-profile antenna is a ceiling-embedded antenna for a mobile phone base station described in Patent Document 1. However, as shown in FIG. 6 of the publication [0034] and the publication, this antenna has a specific bandwidth of only about 10%. Further, as described in the publication [0006] [0047], a height of about 0.1 wavelength of the use frequency is required, and a complicated structure is used as shown in FIG. 9 of the publication. There is a problem that. An example of an antenna having multiband characteristics is “curved plate antenna for UWB” described in Non-Patent Document 1. The appearance of the antenna is shown in FIG. 25 as an antenna example of the related technology. In the UWB curved plate antenna shown in FIG. 25, a curved plate element 501 made of a conductor is disposed on a conductor ground plate 500, and the wider side that is the bottom side of the curved plate element 501 is connected to the ground plate 500. The structure is such that the sharp edge, which is the tip of the curved plate-like element 501, is electrically connected to the ground plate 500. According to Non-Patent Document 1, the antenna has a return loss of −10 dB or less over 3 GHz to 12 GHz and has a wide band characteristic, but requires a height of 12 mm and a minimum use frequency of 3 GHz. When converted in terms of wavelength, it becomes 0.12 wavelength. For example, when the height of 0.12 wavelength is calculated at a wavelength of 810 MHz, which is the assumed minimum use frequency in the current 800 MHz band, the loop height is 44 mm, and there is a problem that the posture is not lowered. Furthermore, the curved plate-like element has a complicated shape and is difficult to manufacture with high accuracy at low cost.

In view of the above problems, an object of the present invention is to provide a multiband loop antenna that is thin, low in profile, and inexpensive.
Another object of the present invention is to provide a multiband loop antenna that is thin, low profile, inexpensive, and ensures non-interference in a predetermined frequency band.

  The multiband loop antenna according to the present invention is connected to a ground plate and the ground plate at one end, and forms a first loop via the ground plate, and the first loop on the first loop. It has a radiating element comprising a plate-like conductor forming a second loop having a resonance frequency lower than that of the loop, and a ground point and a feeding point respectively connected to the radiating element.

The present invention can provide a multiband loop antenna that is thin, low in profile, and inexpensive.
In addition, the present invention can provide a multiband loop antenna that is thin, low in profile, inexpensive, and ensures non-interference in a predetermined frequency band.

It is a block diagram of the 1st Example of the multiband loop antenna of this invention. It is explanatory drawing of the radiation element 2 of this invention. It is a block diagram (1) of the 2nd Example of the multiband loop antenna of this invention. It is a block diagram (2) of the 2nd Example of the multiband loop antenna of this invention. It is explanatory drawing of another Example (1) of the radiation element 2. FIG. It is explanatory drawing of another Example (2) of the radiation element 2. FIG. It is explanatory drawing of another Example (3) of the radiation element 2. FIG. It is explanatory drawing of another Example (4) of the radiation element 2. FIG. It is explanatory drawing of another Example (5) of the radiation element 2. FIG. It is explanatory drawing of another Example (6) of the radiation element 2. FIG. It is a block diagram (1) of the 3rd Example of the multiband loop antenna of this invention. It is a block diagram (2) of the 3rd Example of the multiband loop antenna of this invention. It is a block diagram (1) of the 4th Example of the multiband loop antenna of this invention. It is a block diagram (2) of the 4th Example of the multiband loop antenna of this invention. It is explanatory drawing of the Example of another radiation element. It is explanatory drawing of Example (2) of another radiation element. It is a block diagram of the 5th Example of the multiband loop antenna of this invention. It is a block diagram of the Example which has arrange | positioned the multiband loop antenna of this invention inside the lighting fixture of wall surface installation. It is a block diagram of the Example which has arrange | positioned multiple multiband loop antennas of this invention inside the lighting fixture of a wall surface installation. It is a block diagram of the Example which has arrange | positioned multiple multiband loop antennas of this invention inside the emergency cage. It is a block diagram of the Example which has arrange | positioned multiple multiband loop antennas of this invention inside the straight tube | pipe type fluorescent lamp. It is a block diagram of the Example which has multiply arranged the multiband loop antenna of this invention in the embedded type lighting fixture. It is explanatory drawing of the configuration requirement of the multiband loop antenna of this invention. It is a graph of an example of the return loss characteristic of the multiband loop antenna of this invention. It is a block diagram which shows the antenna described in the nonpatent literature 1.

Hereinafter, the present invention will be described using examples of the present invention.
FIG. 1 is a perspective view of a first embodiment of a multiband loop antenna according to the present invention. The multiband loop antenna of the present invention includes a ground plate 1 made of a conductor, a radiating element 2 made of a conductor and radiating microwaves, and a coaxial cable 3. One end of the radiating element 2 is connected / conductive to the ground plate 1, and the other end is connected / conductive to the coaxial central conductor 4 of the coaxial cable 3. The coaxial outer conductor 5 of the coaxial cable 3 is connected / conductive to the ground plate 1. Power feeding to the multiband loop antenna is performed by the coaxial cable 3. The transmitter and receiver connected to the coaxial cable 3 are not closely related to the present embodiment, and thus detailed description thereof is omitted.

  FIG. 2 shows a detailed view of the radiating element 2. The radiating element 2 includes a rectangular upper plate 23 disposed substantially parallel to the ground plate 1, two rectangular wall plates 21 and 22 disposed substantially perpendicular to the ground plate at both ends thereof, and the ground plate 1 It is composed of three rectangular upper additional plates 24, 25, 26 made of conductors and a stub 27 made of conductors, which are arranged substantially parallel and at the same height as the upper plate.

  One end of the wall plates 21, 22 is connected to both ends of the upper plate 23, and a U-shape is formed with the open side of the wall plates 21, 22 facing downward (ground plate side) at both ends of the upper plate 23. It is configured as follows. At this time, since the coaxial central conductor 4 is connected to the lower side of the wall plate 21, the lower end of the wall surface 21 is not electrically connected to the ground plate 1. Therefore, the length of the wall surface 21 in the height direction is shorter than the wall surface 22.

  On the other hand, the upper additional plates 24, 25 and 26 are all arranged in the same plane, and the upper additional plate 24 and 26 are connected so that the upper additional plate 24 and 26 have a U-shape at both ends. The open side is connected to the side surface on the same plane as the upper plate 23.

  A stub 27 made of a conductor is disposed on the side of the upper plate 23. The stub 27 is added in order to obtain matching of the electrical input impedance as an antenna, and therefore does not necessarily have to be in a fixed place. For example, in FIG. 2, it is added to the right side edge of the upper plate 23, but it does not matter if it is the optimum point for impedance matching even at the right side center or near end. Similarly, from the viewpoint, it is not necessary to be connected to the upper plate 23, and any of the wall plates 21, 22 and the upper additional plates 24, 25, 26 may be used.

Next, a second embodiment of the multiband loop antenna of the present invention will be described.
FIG. 3 is a perspective view of a second embodiment of the multiband loop antenna of the present invention. In this embodiment, the coaxial connector 6 is used for power feeding.

  That is, in the multiband loop antenna of the second embodiment, the portion of the coaxial connector 6 that is electrically connected to the outer conductor of the coaxial cable is installed and connected to the back surface of the ground plate 1, and the coaxial connector center conductor 7 is connected to the ground plate 1. The ground plate 1 is penetrated in a non-contact manner, and is connected to and fed to the lower end of the wall surface 21 that is the lower end of the radiating element 2.

  FIG. 4 is an explanatory diagram illustrating the second embodiment of the multiband loop antenna of the present invention by trigonometry. The radiating element 2 is connected to the ground plate 1 on the wall plate 22 side, and is connected to the coaxial connector center conductor 7 without being connected to the ground plate 1 on the wall plate 21 side.

  FIG. 5 shows another form of the radiating element 2. The radiating element 20 in FIG. 5A shows a case where the stub 27 is not present as compared with the radiating element 2 in FIG. The stub 27 is not necessary if the dimensions of the upper plate 23, the wall plates 21 and 22, and the upper additional plates 24, 25, and 26 can be adjusted to obtain electrical input impedance matching.

The radiating element 30 in FIG. 5B is characterized in that the wall plates 31 and 32 are trapezoidal (tapered) extending downward in the figure as compared to the radiating element 2 in FIG. Similarly, the radiating element 40 in FIG. 5C is characterized in that the wall plates 41 and 42 are trapezoids (reverse taper shape) narrowing downward in the figure as compared to the radiating element 2 in FIG. In the figure, both wall plates have the same taper shape or reverse taper shape, but it is not always necessary to align the dimensions, and only one of them may have a shape in which the lengths of the upper side and the lower side are different.
In this feature, the capacitance value between the ground plates differs depending on the length of the lower ends of the wall plates 31 and 41 to which power is fed. Therefore, the impedance can be adjusted by adjusting this length. Become.

FIG. 6 shows another form of the radiating element 2. The radiating element 50 in FIG. 6A is characterized in that the upper additional plate 55 is used in place of the upper additional plates 24, 25, and 26, as compared with the radiating element 2 in FIG. The upper addition plate 55 has a shape (elliptical arc shape) obtained by cutting a circular ring or an elliptical ring. The radiating element 60 in FIG. 6B has a substantially triangular outer shape using two upper additional plates 65 instead of the additional plates 24, 25, and 26, as compared with the radiating element 2 in FIG. It has a special feature.
Since the antenna installed indoors has a high probability of communication by radio waves reflected on the wall surface indoors, it is more stable to radiate slanted and oblique polarized waves than to emit pure vertical and horizontal polarized waves. Sometimes continue. In FIG. 6B, the oblique side portion of the radiating element 60 radiates oblique polarization, and in FIG. 6A, the curved surface portion of the radiating element 50 radiates oblique polarization. With such a shape, various polarized waves are radiated, and an antenna with better communication performance may be realized.

FIG. 7 shows another form of the radiating element 2. 7A is arranged such that the wall plates 71 and 72 are not perpendicular to the ground plate 1 and the distance between the two wall plates is widened compared to the radiating element 2 of FIG. It is characterized by being inclined. Similarly, the radiating element 80 in FIG. 7B is characterized in that the wall plates 81 and 82 are not perpendicular to the ground plate 1 but are arranged (tilted) so that the interval between the two wall plates is narrowed. Have The radiating element 90 of FIG. 7C is characterized in that the wall plates 91 and 92 are formed in a step shape as compared with the radiating element 2 of FIG.
In each antenna shown in FIG. 7, since the distribution of the high-frequency current becomes antinode (maximum value) in the area near the ground plate of the wall surfaces 71, 72, 81, 82, 91, 92, a large current is distributed in that portion. To do. That is, since the shape of the ground part greatly affects the impedance matching, impedance matching can often be performed by adjusting the shape of this part. For example, the wall surfaces 72 and 82 can be provided with capacitive impedance between the wall surface 72 and the ground plate by inclining the surfaces thereof obliquely to the ground plate. In addition, since the stepped portion in the middle of the wall surface 92 has a capacitance with the ground plate, an effect equivalent to a matching circuit in which a capacitance is added in parallel in the middle of the loop is obtained. is there. In addition, you may perform adjustment by a connection part with the ground board 1 only with respect to one wall board. Moreover, you may adjust combining an inclined wall board and a step-like wall board.

  FIG. 8 shows another form of the radiating element 2. The radiating element 100 of FIG. 8A has wall plates 101 and 102 that are substantially perpendicular to the ground plate 1 as compared with the radiating element 2 of FIG. Is arranged. In the manufacturing process, the radiating element 2 needs to be bent (processed) twice (two lines), whereas this configuration is advantageous in that only one (one line) bending process (process) is required. Similarly, in the radiating element 110 in FIG. 8B, the wall plates 111, 112, and 113 are arranged on the right side surface of the upper plate 23. This configuration can be understood as a structure in which the bending processing position is not the base of the wall plates 101 and 102 but rather a part of the upper plate 23 in the configuration of FIG. Further, the radiating element 120 of FIG. 8C includes all the upper plate 23 in the configuration of FIG. 8A and includes the upper plate 23 instead of the bases of the wall plates 101 and 102 in the bending position. The wall plate 121 is formed by being bent at the base of 26.

FIG. 9 shows another form of the radiating element 2. Since the radiating element 130 in FIG. 9A forms a folded portion on the second loop as compared with the radiating element 100 in FIG. 8A, the upper additional plate 25 of the radiating element 100 is bent halfway. 9 and has a feature formed as an upper addition plate 135 in FIG. On the other hand, in the radiating element 140 in FIG. 9B, the upper additional plate 25 of the radiating element 100 in FIG. 8A is bent at the boundary with the upper additional plates 24 and 26, and the radiating element 140 in FIG. It is characterized by being formed as an upper addition plate 145. Similarly, in the radiating element 150 of FIG. 9C, the upper addition plate 25 of the radiating element 100 of FIG. 8A and a part of the upper addition plates 24 and 26 are bent together, and FIG. It is characterized by being formed as an upper addition plate 155.
Bending the upper additional plates 135, 145, and 155 to the lower side, that is, the ground plate side, has an effect of providing a capacitance between the upper additional plates 135, 145 and 155. That is, by bending the upper additional plates 135, 145, and 155, which are a part of the loop antenna, to the lower side, there is an effect that the capacitance is placed in parallel with the ground plate. It is effective as On the other hand, if the capacitive reactances in the upper additional plates 135, 145, and 155 are too large, the capacitive reactance is reduced by bending these parts upward, and in some cases, inductive reactance is obtained. be able to. Bending upward is also effective as a means of impedance matching.

FIG. 10 shows another form of the radiating element 2. Compared with the radiating element 2 of FIG. 2, the radiating element 160 of FIG. 10A has the upper addition plate 25 of the radiating element 2 and a part of the upper addition plates 24 and 26 bent upward together, It is characterized by being bent in the direction of warping and formed as an upper addition plate 165 in FIG. This configuration is effective when the lateral width of the radiating element 160 is desired to be reduced.
Further, the radiating element 170 of FIG. 10B is a curved surface obtained by removing the stub 27 and combining the upper plate 23 and the upper additional plates 24, 25, and 26 of the radiating element 2 as compared with the radiating element 2 of FIG. It is characterized by having a curved shape, and an upper plate 173 and upper additional plates 174, 175, and 176, respectively. In this case, although the height is slightly increased, it is effective when it is desired to reduce the length of the radiating element 170 in the front-rear direction. Further, in the form of FIG. 10B, in addition to the upper plate 173 and the upper additional plates 174, 175, and 176, the wall plates 21 and 22 are also integrated and work effectively as a form in which the whole is curved with a curved surface. Similarly, a configuration method is possible in which a curved surface is formed in a pseudo manner by a plurality of bent portions instead of a curved surface.

Next, a third embodiment of the multiband loop antenna of the present invention will be described.
11 and 12 are configuration diagrams (1) and (2) of the third embodiment of the multiband loop antenna. In the present embodiment, unlike FIGS. 1 and 2, the upper plate 183 is not parallel to the ground plate 1. Similarly to FIG. 2, the radiating element 180 includes wall plates 181 and 182 that are substantially perpendicular to the ground plate 1, an upper plate 183, upper additional plates 184, 185, and 186, and a stub 187. At this time, in the multiband loop antenna of the present embodiment, the upper plate 183, the upper additional plates 184, 185, 186, and the stub 187 are configured on the same plane, and the plane including these (the plane configuring the second loop), In addition, the upper plate 183 is configured to be inclined with respect to the ground plate 1. That is, the second loop is connected obliquely with respect to the ground plate. Further, the current path of the first loop is provided obliquely with respect to the ground plate 1.
11 and 12 show the feature that the upper plate 183 is inclined with respect to the ground plate 1, and the upper additional plates 184, 185, 186 and the stub 187 are not necessarily on the same plane. Absent. In other words, the upper additional plates 184, 185, 186, and the stub 187 may be adjusted by bending or the like as necessary for adjusting input impedance or obtaining electric performance and radiation characteristics. In particular, the input impedance can be finely adjusted by bending these portions upward or downward from the base or the like.

Next, a fourth embodiment of the multiband loop antenna of the present invention will be described.
FIGS. 13 and 14 are configuration diagrams (1) and (2) of the fourth embodiment of the multiband loop antenna of the present invention. In the present embodiment, in the configuration of FIG. 8C, the upper side and the lower side of the wall plate 121 are not parallel to the ground plate 1, but are oblique sides like the wall plate 191 of FIGS. As a result, the upper additional plates 194, 195, and 196 constituting the radiating element 190 connected to the upper side of the wall plate 191 are also in the same plane, and thus are configured in an inclined positional relationship with respect to the ground plate 1. .
FIG. 15 is an example of another radiating element. The radiation element 200 in FIG. 15A has a structure in which the side addition plates 204 and 206 are arranged substantially perpendicular to the wall plate 201 and the wall plate 201 and the side addition plate 205 are arranged substantially in parallel. . Further, the stub 207 is substantially parallel to the ground plate 1, but may be at an arbitrary angle and may be flush with the wall plate 201.

  The radiation element 210 in FIG. 15B has a configuration in which the wall plate 201 and the side addition plates 204, 205, 206 of the radiation element 200 in FIG. The side addition plates 214, 215, and 216 do not need to be rectangular as shown in FIG. 15A and do not need to be square. These need only be connected to the wall plate 211 in a band shape and have an annular shape. Further, the upper side and the lower side of the wall plate 211 do not need to be parallel to the ground 1 and can be inclined sides.

  FIG. 16 shows an embodiment (2) of another radiating element. The radiating element 220 in FIG. 16A may be considered as a shape in which the radiating element 100 in FIG. That is, the upper plate 23 and the upper additional plates 24, 25, and 26 are arranged on the same plane as the wall plates 101 and 102 in FIG. The wall plates 221 and 222 in FIG. 16A correspond to the walls 101 and 102, and the side addition plates 224, 225 and 226 correspond to the upper addition plates 24, 25 and 26. The stub 227 appropriately adjusts the input impedance at an arbitrary position.

  The radiation element 230 of FIG. 16B is configured by an arbitrary straight line, curve, or figure, whereas each part of FIG. 16A is configured by a rectangle. You can think of it as a shape. Also in this example, the stub 237 appropriately adjusts the input impedance at an arbitrary position.

  FIG. 17 is a perspective view of a fifth embodiment of the multiband loop antenna of the present invention. In this embodiment, a configuration using a printed circuit board 300 is shown. The printed circuit board 300 is generally composed of a dielectric 301 made of Teflon (registered trademark), Gatus epoxy material, or the like, and a layer (ground plate 302) formed of a metal such as copper foil. A power supply microstrip line 303 and a land 304 are provided on the opposite surface (upper surface) of the ground plate 302 surface of the printed circuit board 300. The land 304 is provided with a plurality of through holes 305 and is electrically connected to the ground 302.

  The radiating element 310 disposed on the printed board 300 is fixed and connected by soldering at the left end of the microstrip line 303 and the land 304. The difference between the radiating element 310 and the radiating element 2 is that an electrode 320 is provided at the lower end portion of the wall plate 311. The electrode 320 has a structure in which the tip of the wall plate 311 is bent, and is configured to be soldered to the left end of the microstrip line 303 to supply power. Since the land 304 is connected to the ground 302 and the lower end of the wall plate 312 is also soldered to the land 304, the radiating element 310 is electrically the same as that shown in FIG. Note that the microstrip line 303 and the land 304 may be formed using a double-sided printed board, or the conductive layer may be formed by another method.

  The various shapes of the multiband loop antenna of the present invention have been described above, but an embodiment built in a lighting fixture will be described as an effective housing method of the antenna.

  Since this antenna has a low posture and can be configured by a simple sheet metal, it can be easily incorporated in a lighting fixture provided on a wall surface or a ceiling.

  FIG. 18 shows an embodiment in which the present antenna is arranged inside a wall-mounted lighting fixture. This antenna (multiband loop antenna) 400 is arranged with a lighting fixture 401 having a fluorescent lamp 404 as a base plate 402. The fluorescent lamp 404 is held by the holder 405 on the base plate 402. A cover 403 is disposed on the front surface. Thus, by embedding the antenna in the lighting fixture, there is an advantage that it is not necessary to arrange individual antenna devices in the room and the design of the room is not impaired.

  FIG. 19 shows an embodiment in which two sets of antennas are arranged inside a wall-mounted lighting fixture. FIG. 19A shows an example in which two are arranged so as to have the same polarization. In FIG. 19B, the right antenna is rotated 90 degrees so as to have orthogonal polarization. When the distance between the two antennas cannot be secured, the correlation between the two antennas can be reduced by orthogonalizing the polarizations, which is effective when using a technique such as MIMO.

  FIG. 20 shows an embodiment in which two sets of the antennas are arranged inside lighting such as an emergency pole. The lighting fixture 411 has a structure in which a fluorescent lamp 414 is disposed on a base plate 412 and a cover 413 is placed thereon. The antenna 400 is disposed on the base plate 412. In this example, the polarizations are arranged so as to have the same polarization. However, as shown in FIG. 20B, the right antenna may be rotated 90 degrees so as to obtain orthogonal polarizations. By incorporating an antenna in the emergency room, it is not necessary to install an individual antenna. In addition, since the emergency station is in a place where it can be easily seen, incorporating an antenna therein makes it easier to establish a communication connection in that area.

  FIG. 21 is an example of a lighting fixture 421 having a long fluorescent lamp 424 that is generally installed on a ceiling or a wall surface. The fluorescent lamp 424 and the antenna 400 are arranged on the base plate 422, and the cover 423 covers the top. The number, interval, and installation direction of the antenna 400 are arbitrary.

  FIG. 22 is an example of a lighting fixture 431 having a long fluorescent lamp 433 generally installed on the ceiling. The fluorescent lamp 433 is held by a plug provided on the surface of the side plate 435. On the other hand, there is a method in which the radiating element of the antenna 400 is arranged on the base plate 432 or the side plate 434. There is also a method of installing on the side plate 435 if space permits. The number, interval, and installation direction of the antenna 400 are arbitrary.

  18 to 22, in the lighting apparatus described in any one of the above, when the lighting switch and the switch of the wireless device connected to the multi-band dope antenna are interlocked, the power of the wireless device is turned off when the illumination is turned off. Leads to. In general, on the floor, communication equipment such as a wireless LAN is used for the time when the lighting is on. Therefore, a power saving effect can be obtained by interlocking with the power source of the lighting.

  In addition, if a normal wireless device takes time when restarting by turning off the power, and there is a demerit that the wireless device does not operate at the same time as the lighting is turned on, the lighting power supply and a part of the wireless device By linking the power supply, power saving is possible. In this case, a part of the power source linked to the wireless device is effective in a portion where the power consumption during idling is large, such as a transmission power amplifying unit of the wireless device, and the device can operate immediately after the power is turned on.

  The configuration and configuration of the multiband loop antenna of the present invention have been described above. The requirements and principles of the configuration of the present invention will be described below.

The requirements for the configuration of the multiband loop antenna of the present invention are as follows.
(1) It has a conductor ground plate.
(2) A conductor loop structure (first loop: antenna element) is formed with the conductor ground plate, one end of which is released, and power is fed from that portion.
(3) Another conductor loop (second loop: antenna element) connected to the conductor loop of (2) is formed, and the feed current also passes through the loop.

The elements will be described with reference to FIG. The current to be described means a high frequency current.
The above (1) corresponds to the ground plate in FIGS. 23 (a) and 23 (b).
The above (2) is the configuration of FIG. 23A, and i2 flows through the current route as indicated by the arrow of the current path L2.
The above (3) has the configuration of FIG. 23 (b), and a U-shaped metal is connected to the structure side surface of (a) to form a current path L1 that is a route of the current i1.

In general, in the structure of FIG. 23A, it is known that the current path L2 resonates at half the wavelength used. From this, it can be estimated that the configuration of FIG. 23B can be used by resonating at a frequency of 1/2 wavelength of L1 and L2. In the figure, since L1> L2 is clear, it can be seen that the frequency of the current i1 passing through the route of L1 is lower.
In the current path L2, wide band characteristics can be obtained by increasing the conductor width of the path, that is, the loop width. This is because, by widening, frequencies with long wavelengths are distributed obliquely, and frequencies with short wavelengths are distributed over the shortest distance.

FIG. 23C shows an example of the frequency characteristic of the return loss in the antenna having the configuration shown in FIG. Assuming that the lowest usable frequency in the low frequency band is F1 (wavelength is λ1) and the lowest usable frequency in the high frequency band is F2 (wavelength is λ2), when L1 = λ1 / 2 and L2 = λ2 / 2, Considering this, the characteristic shown by the dotted line in FIG. 23C is obtained, and a good return loss should be obtained in a low frequency band with F1 as a lower limit and a high frequency band with F2 as a lower limit, and it should be usable.
However, in reality, the current paths L1 and L2 do not operate completely independently. In this case, although the influence of the current path of L2 is low on the current path of L1, the current path of L1 influences the current path of L2 to some extent.
The reason why the current path of L2 does not affect the current path of L1 is that the frequency of the current i1 resonating at L1 is low and the wavelength is long. ).

  On the other hand, the current path of L1 has a considerable influence on the current path of L2, because the current i2 having a frequency resonating in the current path of L2 is longer than the resonance length of L2 because the current path of L1 is longer than the resonance length of L2. And the impedance matching state is deteriorated as a whole. This is because i2 does not flow only into the current path (upper plate) of L2.

  From the above, if the length of the current path of L1 is greatly different from the wavelength of the resonance frequency of the current path of L2, the impedance of the path becomes large, so the influence can be reduced. In general, if the frequency F1 of the current path L1 and the frequency F2 of the current path L2 are more than twice, the impedance of the current path L1 is sufficiently high for the frequency of the current path L2, and the inflowing current is also Extremely decreases. Therefore, if the frequency F2 of i2 becomes approximately twice or more than the frequency F1 of i1, it is possible to reduce the flow of i2 into the current path of L1, and it is considered that the antenna element operates in the good manner as an antenna element in the current path of L2. Good. If this characteristic is taken into consideration and a lower frequency band having a lower limit frequency F1 is taken into consideration, assuming that a frequency twice as high as the upper limit frequency F1 ′ of this band is F3, the actual return loss characteristic is as shown in FIG. It becomes like the solid line of 23 (c).

  By using the above characteristics, it is possible to set a dead zone (non-interference band) for a frequency band sandwiched between two frequency bands while giving good characteristics in two frequency bands that are desired to be used as an antenna. That is, if it demonstrates using FIG.23 (c), the current path L1 length which operate | moves as an antenna element of a lower frequency band (F1-F1 '), and an antenna of a higher frequency band (F3-F3') Considering the length of the current path L2 that operates as an element, the antenna is a good antenna for both frequency bands, and a dead zone is provided for the intermediate frequency band (F2 to F3).

Next, the return loss characteristics of an actual prototype multiband loop antenna will be described. FIG. 24 shows an example of the return loss characteristic of the multiband loop antenna of the present invention. In this example, the following conditions are used.
Antenna configuration: Configuration of FIG.
Antenna size: in FIG. 3, H = 30 mm, S1 = 60 mm, S2 = 27 mm.
At this time, the following is applied to the above description.
(Current path L1)
Approximate path length of current path L1 = 30 mm + 27 mm + 60 mm + 27 mm + 30 mm = 174 mm
Wavelength λ1 = 174mm × 2 = 348mm
Frequency F1 = 300 × 10 ⁸ [m / s] / 348 mm = 862 MHz
Compare this calculation result with the actual measurement result of FIG. In FIG. 24, when VSWR <2.1, that is, a return loss of −9 dB or less is set as a use band, a band of 800 MHz to 1 GHz is obtained. From this, it can be judged from the measurement results that F1 = 800 MHz and F1 ′ = 1 GHz. The calculated value F1 is slightly different from the actually measured 800 MHz, but it can be said that this is changed by the current path passing through the outer peripheral portion due to the width of the radiating element.

(Current path L2)
Approximate path length of current path L2 = 30 mm + 60 mm + 30 mm = 120 mm
Wavelength λ2 = 120 mm × 2 = 240 mm
Frequency F2 = 300 × 10 ⁸ [m / s] / 240 mm = 1.25 GHz
According to this calculation result, F2 is in the vicinity of 1.25 GHz. However, due to the above characteristics, a band should actually be obtained from a frequency about twice F1 ′ (= 1 GHz). From the measurement result, since F1 ′ = 1 GHz, F3 = 1 GHz × 2 = 2 GHz. In the actual measurement result of FIG. 24, good values are obtained at 1.85 GHz to 3 GHz in the high frequency band. As a result, the value is approximately the same as F3 = 2 GHz.

  In FIG. 24, when viewing a band of VSWR 2.1, that is, a return loss of −9 dB, in the low frequency band, about 22% (800 MHz to 1 GHz) is obtained as a specific band. Similarly, in the high frequency band, about 47% (1.85 GHz to 3 GHz) is obtained in the specific band. Thus, it can be seen that it can be used in two bands, and a wide band characteristic can be obtained in a high frequency band.

As described above, typical effects obtained by configuring the antenna as described above are shown below.
(1) A thin and low-profile antenna can be realized.
(2) Multiband characteristics.
(3) The structure is simple and can be constructed at low cost.
(4) A non-resonant region (insensitive region: non-interference band) is provided on the low frequency side of the frequency band having high multiband characteristics.
Supplementing the above,
In (1), an antenna can be realized at a wavelength of the lowest use frequency of the use band and at a height of about 0.08 wavelength.
From the viewpoint of (2), this antenna can cover a low frequency band and a high frequency band. In the low frequency band, a band of about 22% is obtained, and in the high frequency band, a band of about 47% is obtained. Specifically, the 800 MHz band of the mobile phone can be covered as the low band, and the 2 GHz band of the mobile phone, the 2.4 GHz band of the wireless LAN, and the 2.6 GHz band of WiMAX can be covered as the high band.
From the viewpoint of (3), since it can be generally configured by bending one sheet metal, it can be manufactured at low cost.
From the viewpoint of (4), an intermediate frequency band (1) located between the low frequency band (800 MHz band) and the high frequency band (2 GHz band, 2.4 GHz, band 2.6 GHz band) used in the same space. Insensitive area for .5 GHz band, etc.). This can ensure non-interference with respect to other communication standards arranged adjacent to each other and base station devices and repeater devices used by other companies.

  More specifically, when installing communication equipment in a closed space such as an underground shopping mall, it is necessary to support many communication standards for many communication frequency bands, but it is a pioneer when installing later. In the future, it is required to consider interference with devices installed in the network, or interference with later installed communication devices (in the above example, 1.5 GHz band, 1.7 GHz band). That is, like the antenna of the present invention, an antenna provided with a non-resonant region functions effectively so as not to interfere with other than the corresponding communication frequency band. In addition, even if it is an existing base station apparatus or repeater, it can enjoy the characteristic of the said antenna, without changing especially a transmitter, a receiver, an amplifier circuit, a control part, etc. by replacing | exchanging from an existing antenna.

As described above, according to the present invention, it is possible to provide a multiband loop antenna that is thin, low in profile, and inexpensive.
Further, according to the present invention, it is possible to provide a multiband loop antenna that is thin, low in profile, inexpensive, and that ensures no interference with a predetermined frequency band.

  It should be noted that the specific configuration of the present invention is not limited to the above-described embodiment, and changes within a range not departing from the gist of the present invention are included in the present invention.

In addition, a part or all of the above-described embodiments can be described as follows. Note that the following supplementary notes do not limit the present invention.
[Appendix 1]
A ground plate,
Connected to the ground plate at one end to form a first loop through the ground plate, and a second loop having a resonance frequency lower than that of the first loop is formed on the first loop. A radiating element comprising a plate-shaped conductor;
A multiband loop antenna comprising the ground plate and a feeding point connected to each of the radiating elements.

[Appendix 2]
A ground plate,
A direction of current generated in the antenna element of the first loop from the end of the first loop, connected to the ground plate at one end, forming a first loop using the ground plate and serving as an antenna element A radiating element that forms a second loop having an outflow path and an inflow path of current in a substantially vertical direction with respect to the plate-shaped conductor serving as an antenna element;
A multiband loop antenna comprising a feeding point connected to each of the ground plate and the radiating element.

[Appendix 3]
A ground plate made of a conductor;
A rectangular upper plate disposed substantially parallel to the ground plate and two rectangular wall plates disposed substantially perpendicular to the ground plate at both ends of the upper plate form a part of the first loop. Three substantially rectangular conductors, which are arranged on the ground plate so as to form a letter, connect one end on the open side of the U-shape, and are substantially parallel to the ground plate and the same plane as the upper plate. A radiating element connected to the side of the upper plate so that the open side of the U-shape forms part of the second loop,
A multiband loop antenna having a feeding point between any one of the wall plates and the ground plate.

[Appendix 4]
The multiband loop antenna as set forth in the above supplementary note, wherein a coaxial connector is used at the feeding point.

[Appendix 5]
The multiband loop antenna according to the above supplementary note, wherein the second loop is connected obliquely with respect to the ground plate.

[Appendix 6]
The multiband loop antenna according to the above supplementary note, wherein the current path of the first loop is provided obliquely with respect to the ground plate.

[Appendix 7]
The connecting portion between the ground plate and the feeding point constituting the first loop of the radiating element, or one of the portions is tapered or inversely tapered. Multiband loop antenna.

[Appendix 8]
The connection part of the ground plate and the feeding point constituting the first loop of the radiating element, or any one of the parts has a trapezoidal shape. Multiband loop antenna.

[Appendix 9]
The multiband loop antenna according to the above supplementary note, wherein the second loop has a substantially arc shape or a substantially triangular shape.

[Appendix 10]
The multiband loop antenna according to the above supplementary note, wherein a connection portion between the ground plate and the feeding point constituting the first loop is inclined or stepped.

[Appendix 11]
A portion of the first loop that is substantially perpendicular to the ground plate is formed by bending the radiating element from a single plate-shaped conductor once. The multiband loop antenna according to the above supplementary note, wherein the multiband loop antenna is formed so as to be perpendicular to a connection end portion of the antenna.

[Appendix 12]
The multiband loop antenna according to the above supplementary note, wherein a folded portion is formed on the second loop.

[Appendix 13]
The multiband loop antenna according to the above supplementary note, wherein the plate-like conductors forming the first loop and the second loop are curved in a curved shape.

[Appendix 14]
The multiband loop antenna according to the above supplementary note, wherein stubs are provided in the first loop and / or the second loop.

[Appendix 15]
The multiband loop antenna according to the above-mentioned supplementary note, wherein the radiating element is formed by bending a single plate-like conductor.

[Appendix 16]
The multiband loop antenna according to the above supplementary note, wherein the ground plate is formed on a printed circuit board, and the radiating element is disposed on a surface opposite to the ground plate surface of the printed circuit board.

[Appendix 17]
An indoor base station of a mobile communication system having a frequency band having incoherence between two frequency bands using the multiband loop antenna described in the above supplementary note.

[Appendix 18]
A repeater for a mobile communication system, using the multiband loop antenna described in the above supplementary note, having a frequency band having incoherence between two frequency bands.

[Appendix 19]
A lighting fixture incorporating the multiband loop antenna described in the above supplementary note.

[Appendix 20]
A lighting fixture incorporating two or more multiband loop antennas as described in the above supplementary notes.

[Appendix 21]
A luminaire in which two or more multiband loop antennas described in the above supplementary notes are installed and installed so that there are two or more installation rotation angles.

[Appendix 22]
About the lighting fixture of the said supplementary note, the lighting fixture and the power switch of the radio | wireless apparatus to which this multiband dope antenna is connected, or the supply of the one part power supply of a radio | wireless apparatus interlock | cooperates.

  The present invention can be used as an antenna of a small base station compatible with a plurality of systems such as a mobile phone and a wireless LAN. More specifically, an 800 MHz band mobile phone, a 2 GHz band mobile phone, a 2.4 GHz band wireless LAN, and a 2.6 GHz band WiMAX system can be used together. In addition, it is possible to provide a multiband loop antenna that ensures non-interference and reduces interference with the subsequent technology with respect to the 1.5 GHz band and the 1.7 GHz band.

  It can also be used as a repeater device for a mobile phone system, an antenna for a wireless LAN device, or the like.

  Since the installation environment can be realized with a low attitude, it is suitable as an antenna attached to a ceiling or a wall.

  Also, it can be applied to cognitive radio systems and software radio systems adapted to various communication methods.

1 Ground plate 2, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 310 Radiation element 3 Coaxial cable 4 Coaxial center conductor 5 Coaxial outer conductor 6 Coaxial connector 7 Coaxial connector center conductor 21, 22, 31, 32, 41, 42, 71, 72, 81, 82, 91, 92, 101, 102, 111 112, 113, 121, 181, 182, 191
201, 211, 221, 222 Wall plate 23, 173, 183 Upper plate 24, 25, 26 Upper additional plate 27, 187, 207, 227, 237 Stub 55, 65, 135, 145, 155, 165, 174, 175, 176, 184, 185, 186, 194, 195, 196 Upper additional plate 204, 205, 206, 214, 215, 216, 224, 225, 226 Side additional plate 300 Printed circuit board 301 Dielectric 302 Ground plate 303 Microstrip line 304 Land 305 Through hole 311, 312 Wall plate 320 Electrode 400 Multiband loop antenna 401, 411, 431 Lighting fixture 402, 412, 422, 432 Base plate 403, 413, 423 Cover 404, 414, 424, 433 Fluorescent lamp 405 Holder 434 435 side plate

Claims (14)

A ground plate,
Connected to the ground plate at one end to form a first loop via the ground plate, and a second loop having a resonance frequency lower than that of the first loop is formed on the first loop. A radiating element comprising a plate-shaped conductor;
A multiband loop antenna comprising the ground plate and a feeding point connected to each of the radiating elements. A ground plate,
A direction of current generated in the antenna element of the first loop from the end of the first loop, connected to the ground plate at one end, forming a first loop using the ground plate and serving as an antenna element A radiating element that forms a second loop having an outflow path and an inflow path of current in a substantially vertical direction with respect to the plate-shaped conductor serving as an antenna element;
A multiband loop antenna comprising a feeding point connected to each of the ground plate and the radiating element. A ground plate made of a conductor;
A rectangular upper plate disposed substantially parallel to the ground plate and two rectangular wall plates disposed substantially perpendicular to the ground plate at both ends of the upper plate form a part of the first loop. Three substantially rectangular conductors, which are arranged on the ground plate so as to form a letter, connect one end on the open side of the U-shape, and are substantially parallel to the ground plate and the same plane as the upper plate. A radiating element connected to the side of the upper plate so that the open side of the U-shape forms part of the second loop,
A multiband loop antenna having a feeding point between any one of the wall plates and the ground plate. 4. The connecting portion between the ground plate and the feeding point, or any one of the portions constituting the first loop of the radiating element, has a tapered shape or a reverse tapered shape. The multiband loop antenna according to any one of the above. 5. The connection part of the ground plate and the feeding point constituting the first loop of the radiating element, or one of the parts is trapezoidal. The multiband loop antenna according to item. The multiband loop antenna according to any one of claims 1 to 5, wherein the second loop is connected obliquely with respect to the ground plate. The multiband loop antenna according to any one of claims 1 to 6, wherein the current path of the first loop is provided obliquely with respect to the ground plate. A portion of the first loop that is substantially perpendicular to the ground plate is formed by bending the radiating element from a single plate-shaped conductor once. The multiband loop antenna according to any one of claims 1 to 7, wherein the multiband loop antenna is formed so as to be perpendicular to a connection end portion. The multiplicity according to any one of claims 1 to 8, wherein the ground plate is formed on a printed circuit board, and the radiating element is disposed on a surface opposite to the ground plate surface of the printed circuit board. Band loop antenna.   An indoor base station of a mobile communication system using the multiband loop antenna according to any one of claims 1 to 9 and having a frequency band having incoherence between two frequency bands.   A repeater for a mobile communication system using the multiband loop antenna according to any one of claims 1 to 9 and having a frequency band having incoherence between two frequency bands.   A lighting fixture incorporating the multiband loop antenna according to any one of claims 1 to 9.   A lighting fixture in which two or more of the multiband loop antennas according to any one of claims 1 to 9 are built in and installed so as to have two or more installation rotation angles.   14. The lighting apparatus according to claim 12, wherein the lighting switch and a power switch of a wireless device to which the multi-band dope antenna is connected, or supply of a part of the power of the wireless device are interlocked. lighting equipment.

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