KR20170062354A - Manhole cover type omni directional antenna - Google Patents

Abstract

The present invention relates to a manhole cover type omnidirectional antenna capable of long distance communication because an angle between a main radiation direction and an earth surface is relatively small and can exhibit an omnidirectional characteristic. A main body installed in the groove of the upper surface of the manhole cover and adapted to convert an electrical signal into an electromagnetic wave to wirelessly communicate with a gateway remote from the manhole cover; A radome fitted in the groove to cover the main body and maintaining the same level as the upper surface of the manhole cover; And a connector connected to a cable that electrically connects the body and the wireless transmission device to each other, wherein the body has a short monopole shape and impedance matching to the shorting strip so that the surface and the kitchen yarn directions exhibit small antenna performance , And the slots are arranged symmetrically along the direction orthogonal to the arrangement direction of the shorting strips, and exhibit omnidirectional characteristics in the horizontal plane.

Description

[0001] The present invention relates to a manhole cover type omni directional antenna,

The present invention relates to a manhole cover type omnidirectional antenna, and more particularly to a manhole cover type omnidirectional antenna which is installed inside a manhole cover for a manhole arranged horizontally in correspondence with an earth surface in order to remotely collect and manage various sensing information underground, To a manhole cover type omnidirectional antenna that can be configured as a wireless sensor network or a wide area wireless communication network.

Generally, it is common that the manhole cover installed on the surface of the earth is made of metal such as iron and zinc. When the antenna is mounted on the manhole cover, it is not protruded to the ground surface in order to prevent damage or performance degradation due to the external environment It should be a non-structure.

Types of antennas applicable to manhole covers include planar patch antennas or small-sized dielectric antennas.

As a technique for constructing the system by applying such a general antenna, there is a technology of an underground information communication system and a manhole cover of the same, for example, as disclosed in US2001 / 0011009.

However, since a plurality of manhole cover antennas installed in an arbitrary position must be capable of wireless communication with a gateway on the ground, omni directional characteristics should be displayed on a horizontal plane. At this time, as the angle formed between the main beam direction and the ground surface in the vertical plane is smaller, longer distance communication is possible.

In the case where the antenna main body is mounted on the manhole structure without the protruding portion on the upper surface of the manhole, the manhole structure made of metal affects the designed radiation property and radiation gain of the antenna main body, It is very difficult to implement a small, high-performance antenna.

FIG. 1 shows whether or not communication is possible according to the difference of the main radiation direction according to the related art.

Referring to FIG. 1, the first sensor node 10 and the second sensor node 20 are located in the underground space U based on the ground surface S, respectively. Which are respectively electrically connected to internal antennas 13 and 23 provided inside the manhole covers 11 and 21, respectively.

The gateway 30 and the gateway antenna 31 for wireless communication with the first sensor node 10 or the second sensor node 20 are installed at predetermined positions in the area where the plurality of the manhole covers 11 and 21 are located . Particularly, the gateway antenna 31 is positioned on the ground surface S at a predetermined height h.

On the other hand, when the internal antennas 13 and 23 for the first sensor node 10 or the second sensor node 20 are mounted inside the manhole covers 11 and 21, they are placed on the ground surface S, 30 or the height h of the gateway antenna 31, the omnidirectional characteristic can not be obtained.

The radiation 22 from the inner antenna 23 of the manhole cover 21 connected to the second sensor node 20 is made along a direction perpendicular to the ground surface S (e.g., a right angle).

As a comparative example, the radiation 12 of the inner antenna 13 of the manhole cover 11 connected to the first sensor node 10 is made along a direction corresponding to a relatively small inclination angle with respect to the ground surface S .

At this time, the distances g between the first sensor node 10 and the gateway 30 or between the second sensor node 20 and the gateway 30 are equal to each other, The actual communicable distances L1 and L2 may be different.

However, as a conventional art, a monopole antenna is the most typical antenna of an omnidirectional antenna. Since the monopole antenna is generally installed perpendicular to the ground surface, it is difficult to mount the antenna in a manhole cover made of metal.

In addition, when a planar antenna or a small-sized dielectric antenna such as a patch antenna that is easily mounted on a manhole cover is mounted inside a manhole cover or a manhole, it is difficult to have omnidirectional characteristics, It is necessary to develop an antenna having a structure that is easy to apply to the antenna.

SUMMARY OF THE INVENTION An object of the present invention is to provide a planar multi-plate structure which can be mounted horizontally in the inside of a manhole cover in parallel with an earth surface, wherein an angle between the main radiation direction and the earth surface is relatively small So that it is possible to perform long-range communication in accordance with the omni-directional characteristic.

It is another object of the present invention to provide a radio communication apparatus and a radio communication method which can realize a relatively small radiation angle with the ground surface when the radio wave is buried in a manhole through a main body which is an antenna of a structure described later, And it is an object of the present invention to provide an omnidirectional manhole cover type omni-directional antenna.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a manhole cover type omni-directional antenna comprising: a manhole cover provided on a manhole of an earth surface; A main body installed in the groove of the upper surface of the manhole cover and adapted to convert an electrical signal into an electromagnetic wave to wirelessly communicate with a gateway remote from the manhole cover; A radome fitted in the groove to cover the main body and maintaining the same level as the upper surface of the manhole cover; And a connector connected to a cable that electrically connects the body and the wireless transmission device to each other, wherein the body has a short monopole shape and impedance matching to the shorting strip so that the surface and the kitchen yarn directions exhibit small antenna performance , And the slots are arranged symmetrically along the direction orthogonal to the arrangement direction of the shorting strips, and exhibit omnidirectional characteristics in the horizontal plane.

The wireless transmission device is connected to a plurality of sensors disposed inside the manhole and provides the electrical signal corresponding to the sensing information input from the sensor to the main body through the cable and the connector.

Wherein the groove has a circular side which is disposed on the manhole cover and is smaller than the manhole cover but has a groove diameter larger than that of the main body, a bottom surface horizontally connected to the side surface at a depth smaller than the thickness of the manhole cover, And a cable hole through which the connector is inserted or through which the cable passes.

The body has a body diameter smaller than the groove diameter.

The main body includes a lower plate disposed on a bottom surface of a groove of the manhole cover with respect to a cable hole of the manhole cover into which the connector is inserted and serving as a ground plane, A metal pole extending in a vertical direction up to a height corresponding to an interval between the metal pawl and the metal pole; a metal pole connected to the upper end of the metal pole and kept parallel to the lower plate, A shorting strip for connecting the top plate and the bottom plate to each other at a position spaced from the metal poles and a shorting strip formed on the top plate so as to be spaced apart from the metal pole, Lt; / RTI >

The upper plate uses a point where the upper end of the upper plate and the upper end of the metal pole are connected to each other as a feeding point.

The upper plate is short-circuited to the lower plate through the shorting strip.

The main body comprises a planar multi-plate structure by the upper plate and the lower plate parallel to each other with the metal pole and the shorting strip interposed therebetween.

The main body converts the electrical signal received through the connector into electromagnetic waves corresponding to the shape of the planar multi-plate structure, and the angle between the main radiation direction and the ground surface of the electromagnetic wave is small and omnidirectional.

The main body forms a large area information network in the network.

In the shorting strip, an upper end of the shorting strip is fitted into an upper connecting hole of the upper plate, a lower end of the shorting strip is fitted into a lower connecting hole of the lower plate, and is fixed by welding.

According to another aspect of the present invention, there is provided a manhole cover type omni-directional antenna comprising: a lower plate provided in a groove on an upper surface of a manhole cover; A connector disposed on the lower plate and connected to a cable for a wireless transmission device; A metal pole connected to the lower end of the connector and extending vertically through the lower plate to a height corresponding to a distance between the plates; An upper plate connected to the upper end and being parallel to the lower plate and serving as a radiator; A shorting strip connecting the top plate and the bottom plate to each other at a position spaced from the metal pole; And a radome fitted in the groove to cover the main body and maintaining the same level as the upper surface of the manhole cover.

The radome has a diameter and a thickness corresponding to the groove, and further includes a coupling groove formed in the radome to receive the top plate, the bottom plate, the metal pole, and the shorting strip.

The top plate includes a slot formed in the top plate so as to be spaced from the metal pole with respect to a position not overlapping the shorting strip.

Wherein the shorting strip includes: a shorting portion for shorting the upper plate and the lower plate to each other; And a column portion that contacts the bottom or top surface of the top plate and the bottom or top surface of the bottom plate and supports the top plate with respect to the bottom plate.

The upper plate includes a first substrate supported by the shorting strip and formed in a circular shape and serving as a dielectric, a second substrate attached to the upper surface of the first substrate, and a feed pattern connected to the metal pole, And a circular patch portion having a radiation pattern which is connected and converts an electric signal into an electromagnetic wave.

Wherein the lower plate comprises a second substrate spaced apart from the lower plate by the shorting strip and a grounding member attached to the bottom or upper surface of the second substrate and electrically connected to the shorting portion of the shorting strip, It is made of cotton.

The manhole cover type omnidirectional antenna according to the present invention is applied to a manhole cover as a planar multi-plate structure having an upper plate and a lower plate parallel to each other with a metal pole and a shorting strip interposed therebetween, Wireless communication is possible up to the ground position and it can help collecting and managing the wireless sensor network or the wide area wireless communication network related to the sensing information collected by the plurality of sensors inside the manhole at a long distance.

Since the manhole cover type omnidirectional antenna according to the present invention has small omnidirectional characteristics between the main radiation direction and the ground surface, it is possible to relatively increase the actual communicable distance with respect to the distance between the main body and the gateway, It is possible to form a large area information network in a network including a wireless sensor network or a wide area wireless communication network operated with a small power.

INDUSTRIAL APPLICABILITY The manhole cover type omnidirectional antenna according to the present invention can securely acquire information wirelessly without being close to a manhole at a location where it is not easy to approach such as on a road in an urban area.

The manhole cover type omnidirectional antenna according to the present invention has a manhole cover type omnidirectional antenna which is installed inside a manhole cover at a level equal to that of the ground surface and has a frequency and bandwidth capable of smooth communication and has a radiation angle relative to the ground surface Since the electric signals can be stably converted into electromagnetic waves between the wireless transmission device connected to the sensor of the small space and the ground, the underground space and the ground space can be configured as a wireless sensor network or a wide area wireless communication network There is a good advantage.

The manhole cover type omnidirectional antenna according to the present invention is horizontally placed in the cavity of the manhole cover and is protected by a radome having the same level as the upper surface of the manhole cover, It is advantageous that the antenna can be used as a product having a relatively long communication distance or a large antenna gain because it operates smoothly inside the manhole cover.

The manhole cover type omnidirectional antenna according to the present invention is mounted and assembled in the groove of the manhole cover and has an omnidirectional characteristic so that the installation height of the gateway installed at a spaced position from the manhole cover installed at an arbitrary position is almost the same as the surface height The angle formed between the main radiation direction and the surface of the ground is relatively small as compared with the conventional product and the main body diameter and thickness are relatively small compared to the diameter of a typical manhole cover. have.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the communication availability according to the difference in the main radiation direction according to the prior art. FIG.
2 is a block diagram of a wireless sensor network using a manhole cover type omni-directional antenna according to a first embodiment of the present invention.
3 is a perspective view of the main body of the manhole cover type omni-directional antenna shown in Fig.
4 is a cross-sectional view taken along the line AA shown in Fig. 3; Fig.
5 is a cross-sectional view taken along the line BB shown in Fig. 3; Fig.
FIG. 6 is an exploded perspective view for explaining a coupling relationship between the main body shown in FIG. 2, the manhole cover, and the radome.
7 is a sectional view taken along the line CC shown in Fig. 6 in a state where the main body, the manhole cover and the radome are assembled together.
FIG. 8 is an exploded perspective view of a main body of a manhole cover type omni-directional antenna according to a second embodiment of the present invention. FIG.
9 is a sectional view of the body shown in Fig.
FIG. 10 is a graph showing frequency characteristics of an antenna when the body shown in FIG. 8 is applied to a manhole cover.
11 to 14 are graphs showing radiation characteristics related to antenna gain and radiation pattern of a manhole cover type omnidirectional antenna for each manhole diameter.
15 is a graph for explaining a formation pattern of a radiation pattern of a conventional antenna according to a comparative example of the present invention.
FIG. 16 is a graph for explaining a formation pattern of a radiation pattern of a manhole cover type omnidirectional antenna. FIG.
FIG. 17 is a three-dimensional graph showing the radiation characteristics of a manhole cover type omni-directional antenna mounted on a manhole cover.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below, but may be implemented in various other forms, and only the first embodiments are intended to be illustrative of the present invention, To fully disclose the scope of the invention to those skilled in the art, and the invention is defined by the claims.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. &Quot; comprises " and / or "comprising" when used in this specification is taken to specify the presence or absence of one or more other components, steps, operations and / Or add-ons. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1st Example

2 is a block diagram of a wireless sensor network using a manhole cover type omni-directional antenna according to a first embodiment of the present invention. 2 shows a wireless sensor network configuration in which a main body 200, which is an antenna, is installed in a manhole cover 100 provided on an earth surface S, Here, the wireless sensor network may include a wide area wireless communication network.

Referring to FIG. 2, the first embodiment includes a manhole cover 100, a main body 200, a radome 300, and a connector 400.

The manhole cover 100 is installed in the manhole 40 of the ground surface S and can be disposed at the edge of the upper opening hole edge of the manhole 40 so as to cover or open the upper opening hole of the manhole 40 have.

The main body 200 refers to the manhole cover type omni-directional antenna according to the first embodiment.

In other words, the main body 200 exhibits a short monopole shape and an antenna performance in which the surface of the main surface 200 and the direction of the main surface are small.

The main body 200 is mounted or installed in the groove 110 on the upper surface of the manhole cover 100. The main body 200 plays a role of converting electrical signals into electromagnetic waves so as to wirelessly communicate with the gateway 500 remote from the manhole cover 100. Here, the gateway antenna 510 may be installed on the ground above or around the gateway 500.

The main body 200 has a structure in which the angle Q between the main radiation direction F and the ground surface S (for example, the radiation angle) is relatively higher than that of the conventional antenna product It can exhibit small omni-directional characteristics.

Such a main body 200 makes it possible to smoothly communicate with the main body 200 even if the gateway 500 is installed at a relatively low height such as the ground surface S or the like.

The radome 300 may be fitted or filled in the groove 110 to cover the main body 200 and may maintain the same level as the upper surface of the manhole cover 100. Here, the main body 200 serving as an antenna is covered with the radome 300.

The radome 300 may be made of a rigid dielectric of a non-metallic material. The dielectric material is a non-conductive material having a dielectric constant higher than that of air. The higher the dielectric constant, the better the polarization to RF (Radio Frequency) signals occurs. Examples of such dielectric materials include polycarbonate, acrylic, ceramic, PWB Printed Writing Board) or Teflon may be used.

The connector 400 is not only disposed at the lower center position of the main body 200 according to the design but also at a position other than the lower center position or the lower side in consideration of the direction that can be connected to the main body 200, May also be connected to the main body 200.

The wireless transmission device 600 is located in an underground space 41 inside a manhole 40, such as a hollow structure.

The wireless transmission device 600 may be connected to a plurality of sensors 700 disposed in the manhole 40 or in the underground space 41. [ The wireless transmission apparatus 600 may provide an electrical signal corresponding to the sensing information input from the sensor 700 to the main body through the cable 800 and the connector 400. Here, the connector 400 may be inserted into the cable hole 120 of the manhole cover 100, connected to the cable 800, and then fixed with an adhesive or a molding agent.

The sensor 700 refers to a plurality of sensor nodes and may be provided in a sensing object (not shown) installed in the underground space 41, respectively. The sensor 700 is connected to the wireless transmission device 600 by wire or wireless, and collects sensing information about the sensing object and transmits the sensing information to the wireless transmission device 600.

The wireless transmission apparatus 600 is connected to the connector 400 of the main body 200 through a cable 800 which is an RF line. Here, the connector 400 is connected to the main body 200 mounted on the groove 110 of the manhole cover 100. For example, the connector 400 is disposed at the bottom of the main body 200 and protrudes downward to connect the main body 200 with the cable 800 that electrically connects the radio transmission device 600 to each other.

The wireless transmission device 600 can wirelessly transmit sensing information to the gateway 500 on the ground or receive signals from the gateway 500 through the cable 800, the connector 400 and the main body 200 .

Thus, for the exemplary wireless sensor network or wide area wireless communication network as shown in FIG. 2, the main body 200 can be easily mounted on the manhole cover 100 of the planar metal structure.

In addition, compared to the exemplary radiation 22 shown in FIG. 1, the angle Q with the ground surface S along the main radiation direction F is similar to that of the exemplary radiation 12 shown in FIG. 1 Or relatively small, omni-directional antenna characteristics.

FIG. 3 is a perspective view of the main body of the manhole cover type omnidirectional antenna shown in FIG. 2, FIG. 4 is a sectional view taken along the line AA shown in FIG. 3, Fig.

3 to 4, the main body 200 may include a lower plate 210, a metal pole 220, a top plate 230, and a shorting strip 240.

The lower plate 210, the metal pole 220, the upper plate 230, and the shorting strip 240 may correspond to a metal portion through which a surface current flows, as components of the main body 200.

The lower plate 210 or the upper plate 230 may be formed in a circular shape, but may be formed in any shape, such as a square shape, a hexagonal shape, a polygonal shape, and the like, depending on the design, .

The shorting strips 240 may be formed as a pair as shown in FIG.

The height p of the shorting strip 240 or the spacing distance between the bottom plate 210 and the top plate 230 may be determined to correspond to the impedance matching.

The top plate 230 has a pair of radiators or one or more slots 231 symmetrically or non-symmetrically positioned with a feeding point 221 disposed on the top plate 230. Although the slot 231 is not shown in FIG. 3, the shape, the shape, and the number may vary according to the design. In FIG. 3, for example, a pair of the slots 231 is used. However, Structure.

The shorting strips 240 are also disposed symmetrically or asymmetrically between the top plate 230 and the bottom plate 210, which are emitters. The power supply to the top plate 230 can be performed through the metal pole 220, which is the core of the connector 400.

The lower plate 210 is disposed on the bottom surface of the groove 110 of the manhole cover 100 and functions as a ground plane with reference to the cable hole 120 of the manhole cover 100 shown in FIG.

The metal pole 220 may be a core of the connector 400 as described above, and may be a feeding probe. The lower end of the metal pole 220 extends from the connector 400. The connector 400 may include an insulator 410 provided inside the body of the connector 400 and a metal pole 220 disposed inside the insulator 410.

The position of the metal pawl 220 is not necessarily the center position of the lower plate 210 and the upper plate 230 as long as the lower plate 210 and the upper plate 230 can be connected to each other, It is possible to perform the feeding function of the pawl 220.

The core 410 can physically support the metal pole 220 and electrically conduct the metal pole 220. The threaded portion formed on the outer side of the core portion 410 of the connector 400 may be coupled to the cable connection portion so as to be electrically conductive.

The metal pole 220 penetrates through the lower plate 210 and extends in the vertical direction to the upper end of the height corresponding to the interval between the plates.

The upper plate 230 is connected to the upper end of the metal pole 220, and is parallel to the lower plate 210, and serves as a radiator.

The upper plate 230 may have the same body diameter D as the lower plate 210 or may have different sizes as compared with the lower plate 210.

A point where the upper end of the upper plate 230 and the upper end of the metal pole 220 are connected to each other is used as a feed point 221.

Illustratively, the main body diameter D means the diameter of the main body 200 or the diameter of the top plate 230 and is smaller than the groove diameter of the groove 110 of the manhole cover 100 shown in FIG. 6 have. For example, the body diameter D may correspond to any one size selected within a numerical range of 6 to 30 cm.

However, numerical values such as body diameter (D) or size may not be limited to specific numerical values. That is, it can be set in consideration of the wavelength of the frequency using the antenna. In addition, the minimum diameter size of the numerical range may not be set to 6 cm. That is, since the frequency and the wavelength are in inverse proportion to each other, for example, when the applied frequency band rises to the 2.4 GHz band, the body 200 can be manufactured in a smaller size.

Also, the maximum diameter size in the numerical range should be smaller than or equal to the diameter of the manhole, so it may not be limited to 30 cm.

The shorting strip 240 is disposed between the top plate 230 and the bottom plate 210 and connects the top plate 230 and the bottom plate 210 to each other at a position spaced apart from the metal pole 220.

The shorting strip 240 is made of a conductive material or a material and is connected to the top plate 230 and the bottom plate 210 so as to be electrically conductive through soldering or the like.

3, the antenna according to the first embodiment includes a metal pole 220 positioned at the center of a circular patch (not shown) or the top plate 230, And a shorting strip 240 is provided for impedance matching.

Conventional planar antennas typically use one or more shorting strips (or shorting pins) simply for the purpose of matching impedances without separate arrangement rules, and when a radio wave is applied by a pole of a conventional planar antenna, A surface current is formed in the upper radiation portion of the disk of the planar antenna of the technology, and the radiation pattern is determined according to the distribution of the surface current.

The shorting strip 240 connecting the upper plate 230, which is a radiation part, and the lower plate 210, which is a ground plane, is connected to the metal pole 220 or Are spaced apart symmetrically with respect to the feed point 221.

Impedance matching is performed according to the distance k1 of the shorting strip 240 and the separation distance n1 from the metal pole 220 or the feeding point 221 to the shorting strip 240. That is, the impedance matching is realized while adjusting the length k1 of the symmetrically arranged shorting strip 240 and the separation distance n1 between the feeding end 211 and the shorting strip 240.

Thus, the first embodiment realizes impedance matching such as the characteristics of the short-type monopole antenna, so that the angle between the radiation direction and the ground surface (for example, the radiation angle) can become very small.

However, only the structure up to this point does not show the omnidirectional characteristic as an eight-letter shape like the radiation pattern of the horizontal plane (for example, X-Y plane) as shown in Fig. That is, the main emission 54 is formed along both directions whose main emission direction is orthogonal to the arrangement direction of the shorting strip 53 of the prior art, and this prior art main emission 54 has omni- I can not show.

In order to compensate for this, as described later in the first embodiment, the slots 231 are symmetrically arranged in a direction orthogonal to the arrangement direction of the shorting strips 240.

Adjusting the distance n2 between the metal pole 220 or the feed point 221 to the slot 231 and the length k2 of the slot 231 corresponding to the central portion of the top plate 230, The ground surface or the XY plane).

3 or 4, the upper end of the shorting strip 240 is fitted or connected to the upper connection hole 232 of the upper plate 230. As shown in FIG. The lower end of the shorting strip 240 is fitted or connected to the lower connection hole 212 of the lower plate 210. Here, the connection can be fixed by a connection method that can be physically connected while maintaining welding or other electrical energization, resulting in an electrically energizable state.

The arrangement direction of the upper connection hole 232 and the lower connection hole 212 may be orthogonal to the arrangement direction of the slot 231. [

The upper plate 230 is short-circuited to the lower plate 210 through the shorting strip 240.

The slots 231 are also spaced apart from the metal pawls 220 with respect to a direction perpendicular to the direction in which the shorting strips 240 are disposed or not overlapping with the shorting strips 240. [ As shown in Fig.

Each slot 231 is formed in the top plate 230.

Each slot 231 has a relatively narrow width of the slot 231 and a length of the slot 231 of 25 to 30 times the width of the slot 231.

At this time, the main body 200 is formed of a planar multi-plate structure by the upper plate 230 and the lower plate 210 which are parallel to each other with the metal pole 220 and the shorting strip 240 interposed therebetween.

The main body 200 having the multi-plate structure and the slot 231 in the direction or shape has an electrical signal supplied through the connector 400, which is converted into an electromagnetic wave corresponding to the shape of the planar multi- The angle between the main radiation direction and the ground surface is small and omnidirectional characteristics are exhibited.

Accordingly, the main body 200 can form a large area information network in a wireless sensor network or a wide area wireless communication network operating with a small power.

Fig. 6 is an exploded perspective view for explaining the coupling relation between the main body, the manhole cover and the radome shown in Fig. 2, Fig. 7 is a perspective view of the main body, the manhole cover and the radome along the line CC shown in Fig. Fig.

Referring to FIG. 6 or 7, the main body 200 may be mounted on the manhole cover 100. At this time, the main body 200 is fitted into the coupling groove 310 of the bottom of the radome 300, which is a dielectric. The radome 300 having the main body 200 is fitted into the cavity 110 of the manhole cover 100 so that the level of the top surface between the radome 300 and the manhole cover 100 can be kept horizontal have. Further, the ground portion of the main body 200 may be connected to the metal portion of the manhole cover 100 to be short-circuited.

The grooves 110 of the manhole cover 100 are disposed in the manhole cover 100. Here, the groove 110 may not be the center of the manhole cover 100, or may be formed at any one of the upper planes of the manhole cover 100.

The groove 110 of the manhole cover 100 has a circular side surface 111 having a manhole diameter or a groove diameter smaller than that of the manhole cover 100 but larger than that of the main body 200, And a bottom surface 112 connected horizontally to the side surface 111 at a small depth. The groove 110 of the manhole cover 100 may include a cable hole 120 into which the connector 400 described above is inserted or the cable 800 described above is inserted.

The radome 300 has a diameter and a thickness corresponding to the grooves 110 and is formed in the coupling groove portion 310 formed in the radome 300 to accommodate the upper plate, the lower plate, the metal pole, ).

The main body 200 and the radome 300 of the manhole cover 100 are formed so as not to protrude from the upper surface of the manhole cover 100 and can also transmit the underground space and the ground space to a wireless sensor network or a wide area wireless As a component of a communication network, it is possible to wirelessly acquire information from a manhole in a city area, such as on a road, where the proximity thereof is not easy, without requiring the user to directly approach the station.

Second Example

The manhole cover type omnidirectional antenna of the present invention described in this embodiment is the same as or very similar to the first embodiment except that it can increase the durability and rigidity of the body which is a planar multi-plate structure by the structural shape of the shorting strip can do. Therefore, the same or corresponding elements in FIGS. 2 to 17 will be given the same or similar reference numerals, and a description thereof will be omitted here.

FIG. 8 is an exploded perspective view of a main body of a manhole cover type omni-directional antenna according to a second embodiment of the present invention, and FIG. 9 is a sectional view of the main body shown in FIG.

8 or 9, the second embodiment provides a main body 200a serving as an antenna. The main body 200a is installed in the groove of the upper surface of the manhole cover, And a lower plate 210a disposed on the bottom surface of the groove for wireless communication.

The main body 200a includes a connector 400 connected to a cable for a wireless transmission device and a metal pole 220 disposed on the connector 400. The connector 400 is connected to a cable for a wireless transmission device, A metal pole 220 connected to a lower end of the metal pole 220 and vertically extending through the lower plate 210a to a height corresponding to a distance between the plates and connected to an upper end of the metal pole 220, And an upper plate 230a which is parallel to the lower plate 210a and serves as a radiator.

The main body 200a may include at least one shorting strip 240a connecting the top plate 230a and the bottom plate 210a to each other at a position spaced from the metal pole 220. [

The main body 200a of the second embodiment may also include a radome that is fitted in the groove to cover the main body 200a and maintains the same level as the upper surface of the manhole cover.

The upper plate 230a may include a slot 231 formed in the upper plate 230a so as to be spaced apart from the metal pole 220 on the basis of a position where the upper plate 230a does not overlap with the shorting strip 240a.

The shorting strips 240a may be formed on the bottom or upper surface of the upper plate 230a or on the upper surface or the bottom surface of the lower plate 210a by a shorting part 241 for shorting the upper plate 230a and the lower plate 210a to each other. And a column portion 242 that contacts the upper plate 230a with respect to the lower plate 210a.

The end of the column 242 may contact the bottom or top surface of the top plate 230a or the top or bottom surface of the bottom plate 210a by direct contact or welding.

For example, the post 242 may be an integral wing portion or an integral support structure that extends the shorting portion 241 or may be a support structure disposed at a distance from the shorting portion 241 to increase the durability and rigidity of the main body 200a The effect can be achieved.

8, the shorting strip 240a has an upper end portion 241a or a lower end portion 241b which is further protruded upward or downward as compared with the pillar portion 242, and the shorting portion 241 A stepped portion 243 is formed between the upper end portion 241a of the shorting portion 241 and the upper surface of the column portion 242 or between the lower end portion 241b of the shorting portion 241 and the bottom surface of the column portion 242 .

The upper plate 230a is formed with an upper connection hole 232 passing through the upper plate 210a in the direction of the upper plate 210a and with reference to an arrangement direction orthogonal to the arrangement direction of the slots 231 .

The lower plate 210a is also formed with a lower connection hole 212 with respect to a location where the upper connection hole 232 meets the thickness passing direction.

The upper end portion 241a of the shorting portion 241 of the shorting strip 240a is fitted in the upper connecting hole 232 formed in the upper plate 210a and the lower end portion 241a of each shorting portion 241 is connected to the lower plate 210a And the lower connecting hole 212 formed in the lower connecting hole 212. Here, each of the fitted portions can be fixed by welding.

The upper plate 230a of the second embodiment is also short-circuited via the shorting portion 241 of the shorting strip 240a with respect to the lower plate 210a. Here, the short-circuit portion 241 is made of electrically conductive material or circuit line or pattern, and not only physically but also electrically connects the top plate 230a and the top plate 210a to each other.

The top plate 230a includes a first substrate 233 supported by the shorting strip 240a and formed in a circular shape and serving as a dielectric, a circular patch portion 233 attached to the top surface of the first substrate 233 234). Particularly, the circular patch portion 234 has a feeding pattern connected to the metal pole 220 and a radiation pattern connected to the feeding pattern to convert an electrical signal into an electromagnetic wave. Here, the feed pattern or the radiation pattern may be determined to correspond to the antenna characteristics, and thus may not be limited to a specific pattern.

The lower plate 210a is attached to the lower surface or the upper surface of the second substrate 214 and a second substrate 214 spaced apart from the lower plate 230a by the shorting strip 240a, And a ground plane 213 electrically connected to the short-circuit portion 241a of the strip 240a.

8 or 9, the main body 200a of the second embodiment includes a first substrate 233 and a second substrate 214 in the form of a printed circuit board (PCB) to which an antenna component is applied, It can be operated at the unlicensed frequency band of 940MHz.

Particularly, since the main body 200 has a small size of about 1.2 cm in thickness and can be realized in a very small size compared with a general manhole cover, it is very easy to mount or apply the groove to the existing manhole cover .

FIG. 10 is a graph showing frequency characteristics of the antenna when the body shown in FIG. 8 is applied to a manhole cover.

Referring to FIG. 10, the antenna manufactured by the structure of FIG. 8 or FIG. 9 is applied to a manhole cover to show frequency characteristics.

The main body of the manhole cover type omnidirectional antenna is manufactured to be smaller than the manhole diameter M in consideration of the general manhole diameter M of the manhole cover. Considering the input return loss versus frequency, the manhole cover type omnidirectional antenna having the above-described body works well with a bandwidth of about 14 MHz and 20 MHz based on a center frequency of 920 MHz.

11 to 14 are graphs showing radiation characteristics related to antenna gain and radiation pattern of a manhole cover type omnidirectional antenna according to manhole diameters.

)에 대응한 방사패턴이 전방향성 특성을 발휘하고 있다.Figs. 11 and 12 show the case where the manhole diameter M of Fig. 10 is 20 cm, and the antenna gain (dB) and the electric field intensity

) Exhibit an omni-directional characteristic.

Fig. 13 and Fig. 14 show that even when the manhole diameter M of 30 cm is shown in Fig. 10, the antenna gain (dB) is very suitable for the wireless sensor network or the wide area wireless communication network and the radiation pattern also exhibits the omni-directional characteristic .

FIG. 15 is a graph for explaining a formation pattern of a radiation pattern of a conventional antenna according to a comparative example of the present invention, FIG. 16 is a graph for explaining a shape of a radiation pattern of a manhole cover type omni-directional antenna shown in FIG. 2 or FIG. FIG.

Referring to Fig. 15, the short circuit strip 53 of the comparative example according to the prior art is disposed symmetrically about the metal pole 52 of the comparative example. This comparative example relates to a radiating part which does not have a slot having the same technical characteristics as those of the first or second embodiment. In the comparative example, when the antenna 50 is mounted in the cavity 51 of the manhole cover 50, the main radial shape 54 of the comparative example is formed in an eight- Shape, so that it causes a problem that the omnidirectional characteristic can not be exhibited. An eight-letter-like main emission pattern 54 is formed with reference to the orthogonal direction orthogonal to the arrangement direction of the shorting strips 53 of the comparative example. This is because the current distribution of the radiating portion of the comparative example is largely mutually coupled with the edge of the manhole at the edge in the orthogonal direction.

16, in order to realize omnidirectional characteristics while solving the above problems, the present invention is characterized in that the slots 231 are symmetrically arranged in a direction orthogonal to the shorting strip 232, The position of the slot 231 (for example, the distance from the feeding point to the slot) and the length of the slot 231 are adjusted as described with reference to FIG. 3 so that the omnidirectional antenna 235 exhibits omnidirectional characteristics.

16, the position and length of the slot 231 are adjusted to obtain the radiating pattern 235 having the omnidirectional characteristic. The surface current distribution of the edge of the top plate which is the radiating part is uniformly changed by the slot 231 and the surface current at the edge of the top plate which is the radiating part is combined with the groove edge of the manhole, In particular, the position and length of the slot 231 can be changed by changing the position and length of the shorting strip 232 so that the radial shape 235 is changed.

17 is a three-dimensional graph showing the radiation characteristics of a manhole cover type omni-directional antenna mounted on a manhole cover.

17, the antenna and the manhole cover according to the present invention, which are manufactured as prototypes using the antenna design and manufacturing method features described above in detail, have a general manhole diameter and a manhole diameter. As shown in the experiment result of FIG. 17, It can be seen that even if mounted on the XY plane, the radiation pattern is omnidirectional, and that the radiation quality is as reliable as that required by the wireless sensor network.

Thus, the present invention of the second embodiment and the first embodiment may be very suitable for a wireless sensor network or a wide area wireless communication network for remotely collecting and managing sensing information by various sensors in an underground space.

That is, when a main body, that is, an antenna is fabricated by using the constituent elements of this embodiment and applied to a manhole cover, wireless communication is possible from a manhole to a ground position over a long distance. It is possible to form a wireless network and collect and manage sensing information in a manhole at a long distance, thereby forming a large-scale information network in the network.

The foregoing description is merely illustrative of the technical idea of the present invention and various changes and modifications may be made without departing from the essential characteristics of the present invention. Therefore, the embodiments described in the present invention are not intended to limit the scope of the present invention, but are intended to be illustrative, and the scope of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas which are equivalent or equivalent thereto should be interpreted as being included in the scope of the present invention.

100: Manhole cover 110: Home
120: Cable hole 200, 200a:
210, 210a: lower plate 220: metal pole
230, 230a: upper plate 240, 240a: shorting strip
300: Radome 400: Connector
500: gateway 600: wireless transmission device
700: Sensor 800: Cable

Claims (17)

A manhole cover provided in a manhole on the ground surface;
A main body installed in the groove of the upper surface of the manhole cover and adapted to convert an electrical signal into an electromagnetic wave to wirelessly communicate with a gateway remote from the manhole cover;
A radome fitted in the groove to cover the main body and maintaining the same level as the upper surface of the manhole cover; And
And a connector connected to a cable that electrically connects the main body and the wireless transmission device to each other,
The main body is a short monopole type and is impedance matched to a shorting strip so as to exhibit small antenna performance in the direction of the surface of the main body and the direction of the main surface of the main body. The slots are symmetrically arranged along a direction orthogonal to the arrangement direction of the shorting strip, Characterized by exhibiting a directional characteristic
Manhole Cover Omnidirectional Antenna.
The method according to claim 1,
The wireless transmission apparatus includes:
And providing the electrical signal corresponding to the sensing information input from the sensor to the main body through the cable and the connector, the sensor being connected to a plurality of sensors disposed in the manhole
In manhole cover type omnidirectional antenna.
The method according to claim 1,
The groove
A circular side surface disposed in the manhole cover, the circular side surface being smaller than the manhole cover but having a larger diameter than the main body,
A bottom surface horizontally connected to the side surface at a depth less than the thickness of the manhole cover, and
Including a cable hole through which the connector is inserted or through which the cable passes
In manhole cover type omnidirectional antenna.
The method of claim 3,
The main body includes:
Having a body diameter smaller than the groove diameter
In manhole cover type omnidirectional antenna.
The method according to claim 1,
The main body includes:
A lower plate disposed on a bottom surface of the groove of the manhole cover with respect to a cable hole of the manhole cover into which the connector is inserted and serving as a ground plane,
A metal pole extending from the connector and extending vertically through the bottom plate to a height corresponding to a distance between the plates,
An upper plate connected to an upper end of the metal pole and maintaining a parallel relationship with the lower plate and having the same body diameter as the lower plate,
A shorting strip connecting the top plate and the bottom plate to each other at a position spaced from the metal pole, and
And a slot formed in the upper plate so as to be spaced from the metal pole with respect to a place not overlapping the shorting strip
In manhole cover type omnidirectional antenna.
6. The method of claim 5,
Wherein the top plate comprises:
A point where the upper end of the upper plate and the upper end of the metal pole are connected to each other is used as a feeding point
In manhole cover type omnidirectional antenna.
6. The method of claim 5,
Wherein the top plate comprises:
Short-circuited to the lower plate through the short-circuiting strip
In manhole cover type omnidirectional antenna.
6. The method of claim 5,
The main body includes:
And a planar multi-plate structure formed by the upper plate and the lower plate parallel to each other with the metal pole and the shorting strip interposed therebetween
In manhole cover type omnidirectional antenna.
6. The method of claim 5,
The main body includes:
Wherein the electrical signal supplied through the connector is converted into the electromagnetic wave corresponding to the shape of the planar multiplate structure so that the angle between the main radiation direction of the electromagnetic wave and the ground surface is small and omni-
In manhole cover type omnidirectional antenna.
6. The method of claim 5,
The main body includes:
To form a large-scale information network in a network
In manhole cover type omnidirectional antenna.
6. The method of claim 5,
The shorting strip,
The upper end of the shorting strip is fitted in the upper connecting hole of the upper plate, the lower end of the shorting strip is fitted in the lower connecting hole of the lower plate, and is fixed by welding
In manhole cover type omnidirectional antenna.
A lower plate provided in a groove on an upper surface of the manhole cover;
A connector disposed on the lower plate and connected to a cable for a wireless transmission device;
A metal pole connected to the lower end of the connector and extending vertically through the lower plate to a height corresponding to a distance between the plates;
An upper plate connected to the upper end and being parallel to the lower plate and serving as a radiator;
A shorting strip connecting the top plate and the bottom plate to each other at a position spaced from the metal pole; And
And a radome fitted in the groove to cover the main body and maintaining the same level as the upper surface of the manhole cover
In manhole cover type omnidirectional antenna.
13. The method of claim 12,
In the radome,
And a coupling groove formed in the radome to receive the upper plate, the lower plate, the metal pole, and the shorting strip, the coupling plate having a diameter and a thickness corresponding to the groove
In manhole cover type omnidirectional antenna.
13. The method of claim 12,
Wherein the top plate comprises:
And a slot formed in the upper plate so as to be spaced from the metal pole with respect to a place not overlapping the shorting strip
In manhole cover type omnidirectional antenna.
13. The method of claim 12,
The shorting strip,
A shorting part for shorting the upper plate and the lower plate to each other;
And a column portion which contacts the bottom or top surface of the top plate and the bottom or top surface of the bottom plate and supports the top plate with respect to the bottom plate
In manhole cover type omnidirectional antenna.
13. The method of claim 12,
Wherein the top plate comprises:
A first substrate supported by the shorting strip and formed in a circular shape and serving as a dielectric,
And a circular patch portion attached to the upper surface of the first substrate and having a feeding pattern connected to the metal pole and a radiation pattern connected to the feeding pattern and having a radiation pattern for converting an electric signal into an electromagnetic wave
In manhole cover type omnidirectional antenna.
16. The method of claim 15,
Wherein the lower plate comprises:
A second substrate spaced apart from the lower plate by the shorting strip,
And a ground surface attached to the bottom or top surface of the second substrate and electrically connected to the shorting portion of the shorting strip
In manhole cover type omnidirectional antenna.

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