JP3808934B2 - Two-stage antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a two-stage antenna in which antennas are arranged integrally in two upper and lower stages along a vertical axis so that the two upper and lower antennas can be used properly.
[0002]
[Prior art]
In the mobile communication field, to compensate for bidirectional communication quality, two independent antennas are used to reduce the influence of the height pattern of electric field strength. Receive or transmit.
However, if two independent antennas are installed individually, the installation place is twice as much, and it takes a lot of time to install them.
Therefore, conventionally, for example, as described in Japanese Patent Publication No. 1-51204, a two-tiered sleeve antenna has been proposed.
[0003]
[Problems to be solved by the invention]
The conventional sleeve antenna has a complicated structure in which a plurality of cylindrical conductors are coaxially arranged, and cannot be manufactured unless a special cable or conductor is used. Therefore, an increase in cost is unavoidable and difficult to manufacture. .
[0004]
[Means for Solving the Problems]
The present invention has been developed for the purpose of providing a two-stage antenna that has a simple structure and sufficiently exhibits the performance of each of the upper antenna and the lower antenna, and the configuration thereof is a dielectric substrate formed vertically. An upper stage in which wide radiating elements and narrow feeding elements are alternately provided along the longitudinal direction on both the front and back surfaces of the plate, and the radiating elements and the feeding elements are arranged to face each other on the front and back surfaces. In a two-stage antenna having an antenna and a lower antenna , electrical conduction between the upper and lower antennas is made between the feeding element on the front surface and the feeding element on the rear surface, and the central conductor is connected to the radiating element of the upper antenna. The coaxial cable for feeding the upper antenna is arranged so as to run vertically through the center of the surface of the radiating element and the feeding element formed on one side of the dielectric substrate in the lower antenna. To the outer conductor of a longitudinal portion of the coaxial cable for the upper antenna feeding, achieving electrical connection by soldering over the radiating element and the feed element and the entire section of said lower antenna, the lower antenna feed element of the lower antenna A power supply coaxial cable is electrically connected, and each of the upper and lower antennas has a quarter-wave branch line, a feed element extension, and a leakage current blocking section of an external conductor at the lower ends of both front and back surfaces. This is because a leakage current blocking unit is interposed.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a two-stage antenna according to the present invention will be described with reference to the drawings.
1 to 4 are exploded views, FIG. 5 is an end view taken along line VV of FIG. 1, FIG. 6 is an assembly view, 1 is an upper antenna, and 2 is a lower antenna.
In these, conductor foils 4 such as copper foils are attached to both front and back surfaces of a dielectric substrate 3 such as glass, cloth, and glass nonwoven fabric base epoxy resin formed in a long length.
In the conductor foil 4, the wide portion is the radiating element 4a of the antenna, and the narrow portion is the feeding element 4b.
P, P... Are boundaries between the radiating element 4a and the feeding element 4b. The front side radiating element 4a has the back side feeding element 4b, and the front side feeding element 4b has the back side radiating element 4a. The elements are arranged so as to face each other to form a so-called collinear antenna.
The length in the longitudinal direction of the radiating element 4a and the feeding element 4b is a length obtained by multiplying a half wavelength of the radio wave to be used by a wavelength shortening rate determined by the material of the dielectric substrate 3.
In this example, the antenna is for a 1.9 GHz band, and the length of each element in the longitudinal direction is about 40 mm.
The width of the feeding element 4b is determined so as to have a desired impedance value that can efficiently pass a signal from the radiating element 4a at the front stage to that at the rear stage. In this example, the width is about 4 It is 0.5 mm.
For the width of the radiating element 4a, a predetermined value larger than that of the feeding element 4b is selected in order to efficiently perform radiation, and in this example, the width is about 19 mm.
The distance between the front side element and the back side element, that is, the thickness dimension of the dielectric substrate 3 is 1.6 mm, and the thickness of the conductive foil 4 constituting the radiation element 4a and the feeding element 4b is 35 microns.
[0006]
Next, the upper antenna 1 will be described.
In order to prevent current from leaking from the lower antenna 2 to the upper antenna 1 side, an upper front leakage current blocking unit 5 is provided at the lower end of the upper antenna 1 surface.
The upper front leakage current blocking unit 5 includes a quarter-wavelength branch line 5a having an open end formed by the conductor foil 4, an upper feed element extension 5b, and a coaxial cable 6 for feeding power to the upper antenna 1 described later. It is formed by a leakage current blocking section A provided at the tip.
The front end of the coaxial cable 6 is stripped, and the outer conductor 6a and the center conductor 6b are exposed.
The entire outer conductor 6a in the leakage current blocking section A is soldered along the feeding element extension 5b so that a wide range of electrical connection is achieved.
The central conductor 6b of the coaxial cable 6 is soldered to the radiating element 4a, and 1a and 1b serve as feeding points for the upper antenna 1.
On the other hand, an upper back side leakage current blocking unit 7 is provided at the lower bottom of the back side of the upper stage antenna 1 in order to prevent current from leaking from the upper stage antenna 1 to the lower stage antenna 2 side.
The upper back side leakage current blocking unit 7 is provided with a quarter-wavelength branch line 7 a having an open end made of the conductive foil 4 and an upper feed element extension 7 b.
The branch line 7a is provided in the opposite direction to the front-side branch line 5a.
The feed element extensions 5b and 7b are electrically connected to each other by a through hole 4d.
[0007]
Next, details of the lower antenna 2 will be described.
In the same manner as the upper antenna 1, a lower front side leakage current blocking unit 8 is provided at the lower end of the lower antenna 2 in order to prevent current from leaking from the lower antenna 2 to the power supply connector 10. .
The lower-stage front-side leakage current blocking section 8 includes an open-ended quarter-wavelength branch line 8a formed by the conductive foil 4, a lower-stage feed element extension section 8b, and a lower-end antenna 2 feeding coaxial cable 11 to be described later. And a leakage current blocking section B provided in the section.
The tip of the coaxial cable 11 is stripped, and the outer conductor 11a and the center conductor 11b are exposed.
The entire outer conductor 11a in the leakage current blocking section B is soldered along the feeding element extension 8b, so that a wide range of electrical connection is achieved.
On the other hand, on the back side of the lower antenna 2, the above-described coaxial cable 6 with the vinyl coating peeled off to expose the outer conductor 6 a is arranged so as to extend vertically below the lower antenna 2 through the center of the conductor foil 4. .
In the outer conductor 6 a of the coaxial cable 6, C indicates a feeding element section, and shows a portion corresponding to the feeding element 4 b on the back side of the lower antenna 2.
D indicates a radiating element section, and indicates a portion corresponding to the radiating element 4 a on the back side of the lower antenna 2.
Each feeding element section C of these coaxial cables is connected to the feeding element 4b in contact with itself over the entire section by soldering 17, and each radiating section D is also connected to the radiating element 4a in contact with itself over the entire section 17 and solder 17. Connected by attaching.
[0008]
Next, the lower back side leakage current blocking unit 9 provided at the lower end of the back side of the lower antenna 2 will be described.
The lower stage back side leakage current blocking unit 9 blocks leakage from the lower stage antenna 2 to the power feeding connector 12 side. The quarter wavelength branch line 9a formed by the conductive foil 4, the feeding element extension 9b, It consists of the leakage current blocking section E of the conductor 6a.
The entire outer conductor 6a of the leakage current blocking section E is soldered along the feeder element extension 9b corresponding to itself.
The outer diameter of the outer conductor 6a of the coaxial cable 6 is 3.5 mm.
The upper and lower antennas 1 and 2 are built in a cylindrical resin cover 13 made of a synthetic resin with low high-frequency loss, and the coaxial cables 6 and 11 are provided at the base end of the resin cover 13 respectively. The cable outlet 14 is led out.
A holding member 15 made of foam rubber is interposed between the resin cover 13 and the upper and lower antennas 1 and 2, and the antennas 1 and 2 are held at the center of the resin cover 13.
Reference numeral 16 denotes a mounting portion of the antenna F.
[0009]
A signal flow when the two-stage antenna F formed as described above is used as, for example, a transmission antenna will be described.
A transmission signal from the power supply connector 12 is applied to the power supply points 1 a and 1 b of the upper antenna 1.
This signal is efficiently radiated by the radiation elements 4a on the front and back surfaces of the upper antenna 1 without leakage of current in the direction of the lower antenna 2 due to the action of the leakage current blocking unit 7. The
On the other hand, the transmission signal from the power supply connector 10 is applied to the power supply points 2 a and 2 b of the lower antenna 2.
This signal is generated by the leakage current blocking units 8, 9, and 5 in the direction of the power feeding connector 10 by the leakage current blocking unit 8, in the direction of the power feeding connector 12 by the leakage current blocking unit 9, and the leakage current. All currents are efficiently radiated by the radiating element 4a of the lower antenna 2 without any current leaking in the direction of the upper antenna 1 by the blocking unit 5.
At this time, the outer conductor 6a of the coaxial cable 6 that vertically cuts the center of the back surface of the lower antenna 2 is electrically connected to and integrated with the radiating elements 4a and the feeding elements 4b of the lower antenna 2. Rather, it contributes to the efficient emission of radio waves in cooperation with the radiation element 4a.
The directivity characteristics of the antenna of the above embodiment are shown in FIGS.
As clearly shown in the figure, each of the upper antenna 1 and the lower antenna 2 is sharp in the vertical direction, shows uniform directivity in the horizontal direction, and is as high as 30 dB or more between the two antennas. Isolation can be secured.
[0010]
The above embodiment can be suitably used for diversity reception (including transmission) that is switched according to the height pattern of the electric field strength even when it is installed in a base station and a mobile body. is there.
Each of the upper and lower antennas can be appropriately changed, for example, by forming a metal plate that is press-formed from both sides on a dielectric substrate, or by using a double-sided printed substrate.
In addition, the use of a conductive pipe-like material for the outer conductor of the coaxial cable can stabilize the performance during mass production.
Furthermore, the lead-out portion of the coaxial cable 6 may be drawn not only from the side of the resin cover but also from the lower end surface of the resin cover, and the lead-out portion is connected to a connector directly attached to the resin cover. But it doesn't matter.
In the embodiment, the outer conductor 6a of the coaxial cable 6 is soldered for electrical connection with each radiating element 4a and each feeding element 4b. However, it may be connected using a conductive adhesive. Alternatively, the connection may be made using a metal fitting having a Ω-shaped cross section.
Further, the upper antenna and the lower antenna can be assembled so that both antenna surfaces are continuous without giving a phase difference of 90 degrees.
The resin cover used in the present invention can be formed in a polygon other than a circular cross section, for example, it can be bent by adopting a flexible resin cover, and a damage preventing effect can be expected. Since it has a simple structure in which antennas made of printed circuit boards are connected in cascade, it is easy to manufacture.
In the present invention, the upper antenna and the lower antenna do not necessarily mean that the upper antenna is arranged at the upper part, and the two-stage antenna of the embodiment is upside down to the arm of the utility pole. Installed and used in a suspended state.
[0011]
Next, different embodiments of the dielectric substrate used in the two-stage antenna will be described.
FIG. 8 shows an example in which the upper antenna 1 and the lower antenna 2 are combined to form a single substrate.
Members having the same or equivalent functions as those in the previous example are indicated by the same reference numerals with the letter “e”, and redundant description is omitted.
When this substrate is used, a two-stage antenna can be assembled more easily.
[0012]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a two-stage antenna that has a simple structure and sufficiently exhibits the performances of the upper antenna and the lower antenna.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating the front side of an upper antenna and a lower antenna by disassembling the two-stage antenna according to the embodiment.
FIG. 2 is an explanatory diagram showing the rear side of the upper antenna and the lower antenna by disassembling the two-stage antenna of the embodiment.
FIGS. 3A and 3B are explanatory views showing an upper antenna from which a coaxial cable is separated, in which FIG.
4A and 4B are explanatory diagrams showing a lower antenna from which a coaxial cable is separated, in which (a) shows the front surface and (b) shows the back surface.
FIG. 5 is an explanatory view showing an end face of the VV line cutting part of FIG. 1;
FIG. 6 is an assembly explanatory diagram of a two-stage antenna.
FIG. 7 is an explanatory diagram showing directivity characteristics of upper and lower antennas.
FIG. 8 is an explanatory view showing a state where an upper antenna and a lower antenna separated from a coaxial cable are integrally formed.
[Explanation of symbols]
1 .... upper antenna, 2 .... lower antenna, 3 .... dielectric substrate, 4 .... conductive foil, 4a ..., radiating element, 4b ..., feeding element, 5 .... upper front leakage current blocking section, ... Coaxial cable, 7 ・ ・ Upper back side leakage current blocking part, 8 ・ ・ Lower stage leather leakage current blocking part, 9 ・ ・ Lower back side leakage current blocking part, 10 ・ ・ Connector, 11 ・ ・ Coaxial cable 12 ・ ・ Connector, 13 ..Resin covers.

Claims (1)

Wide radiating elements and narrow feeding elements are alternately provided along the longitudinal direction on both front and back surfaces of the vertically formed dielectric substrate, and the radiating elements and the feeding elements oppose each other on the front and back surfaces. In a two-stage antenna comprising an upper stage antenna and a lower stage antenna arranged so as to
In the upper and lower antennas, the upper and lower feeder elements are electrically connected to each other, and a coaxial cable for feeding the upper antenna, whose central conductor is connected to the radiating element of the upper antenna, is used as a dielectric in the lower antenna. The radiating element and the feeding element formed on one side of the substrate are arranged so as to be longitudinally cut in the center of the surface of the radiating element and the feeding element, and the outer conductor of the longitudinal section in the coaxial cable for feeding the upper antenna Are connected by soldering over the entire section, and a coaxial cable for feeding the lower antenna is electrically connected to the feeding element of the lower antenna, and the lower ends of the front and back surfaces of the upper antenna and the lower antenna are each 4 minutes. A leakage current blocking section consisting of a one-wavelength branch line, a feed element extension, and a leakage current blocking section of the outer conductor. A two-stage antenna characterized by

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