JPH04358404A - Polyrod helical array antenna - Google Patents

Abstract

PURPOSE:To secure the even antenna performance by providing a polyrod having its tip thinned gradually and a coil at the base-part of the polyrod, and forming a connection part with the coil initiation released and the coil termination extended linearly and downward from the center of the polyrod respectively. CONSTITUTION:Many polyrod helical radiation elements 1a, 1b...1n are set in parallel to a metallic plate 4, and a wave directing line is electrically short- circuited at the periphery of the plate 4 via a metallic matter 5. A feeding part is provided at the center part of the plate 4 by means of a contact plug 7 where a central conductor is inserted into the line 6. Then a cover 2 is provided at the periphery of those radiation elements. Each of the radiation elements uses a polyrod made of a dielectric material like polystyrene, etc., and has a rod structure that is gradually thinned toward its tip. Then a coil is attached to the base part of the polyrod. A connection part is formed with the coil initiation released and the coil termination extended linearly and downward from the lower center of the polyrods 1a, 1b...1n respectively.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyrod helical array antenna for satellite broadcast reception.

0002

2. Description of the Related Art Satellite broadcasting has a wide service area, and unlike terrestrial broadcasting, can receive high-quality reception without ghost interference caused by reflections from buildings, etc., and is therefore becoming more popular year by year. However, when receiving satellite broadcasting, the transmission power from the satellite is weaker than that of terrestrial broadcasting, and 12 GHz
By using high frequencies in the band, the receiving antenna often uses a high gain parabolic antenna.

However, the receiving efficiency of parabolic antennas relative to the aperture area is about 70%, and in order to achieve further miniaturization, it is desired to develop highly efficient receiving antennas. Recently, a helical planar antenna as shown in FIG. 3 has been considered as an antenna with high efficiency. This helical planar antenna consists of parallel metal plates 32, 33 whose spacing is narrower than the wavelength of radio waves, and these parallel metal plates 32, 33.
A large number of helical circularly polarized wave elements 31a, 31ab, . The received radio waves are received by a large number of helical circularly polarized wave elements 31a and 31b.
,...31n, are synthesized in the same phase within the waveguide 34, and outputted from the probe 36.

0004

[Problems to be Solved by the Invention] However, in the conventional helical planar antenna, the helical circularly polarized wave elements 31a, 3
Air-core coils are used as 1b,...31n, and as a result, the radiation directivity of a single coil is broad in all directions, and when a large number of coils are arrayed, the reception efficiency for the aperture area of the helical planar antenna is approximately 80%. ~90%. In addition, when a flat antenna is subjected to vibrations caused by wind, etc., it is difficult to maintain the precision of the winding pitch of the coil at all times, and when installing the coils, the workability is extremely poor due to the coils intertwining with each other. When inserting the coil into the parallel metal flat plate 32, an insertion force is applied directly to the coil, making it difficult to assemble the coil uniformly.

The present invention has been made in view of the above-mentioned circumstances, and provides a high-performance polyrod helical array that improves the directivity characteristics of circularly polarized wave radiating elements, improves antenna reception efficiency, and further improves ease of installation. The purpose is to provide an antenna.

[0006]

[Means for Solving the Problems] A polyrod helical array antenna according to the present invention has a coil attached to the base of a polyrod formed into a rod shape using a dielectric material, and the starting end of the coil is released and the terminal end is attached above the polyrod. A large number of polyrod helical radiating elements are provided which extend straight downward from the center of the base of the polyrod to serve as coupling parts, and a large number of holes are formed on one side of a waveguide surrounded by a metal material to couple the polyrod helical radiating elements. The present invention is characterized in that a power supply section is inserted into the waveguide and a power supply section is provided on the other surface of the waveguide.

[0007]

[Operation] Radio waves received by the polyrod helical radiating element efficiently propagate through the dielectric and are coupled to the coil at the base of the polyrod. By using a dielectric as the material constituting the radiating element, the speed of radio wave propagation in the dielectric can be slowed down, and as a result, the directivity of the radiating element becomes sharper in the front direction, and the radiating element alone Directional characteristics are improved. Therefore, a large gain can be obtained when polyrod helical radiating elements are arrayed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the polyrod helical array antenna of the present invention, in which (a) is a front view and (b) is a side sectional view.

As shown in FIG. 1, the polyrod helical array antenna of the present invention includes a large number of polyrod helical radiating elements 1a, 1b, . A waveguide 6 is formed by arranging second metal plates 4 facing each other in parallel and electrically short-circuited by a metal body 5 at the periphery thereof, and a waveguide with a center conductor at the center of the second metal plate 4. a power supply section consisting of a plug 7 inserted into 6;
It is composed of a cover 2 provided around polyrod helical radiating elements 1a, 1b, . . . , 1n.

[0010] The polyrod helical radiating element 1a, 1
b, . . . , 1n are configured as shown in FIG. That is, polyrod helical radiating elements 1a, 1b,..., 1n
is a rod-shaped structure with a tapering tip, using resin materials that exhibit dielectric properties such as Teflon, polystyrene, polyethylene, and polystyrene, as well as other dielectric materials such as sintered ferrite and titanium oxide. A poly rod 21 and a coil 22 are attached to its base, and the coil 22
The starting end of the polyrod 21 is opened, and the terminal end is extended in a straight line downward from the center of the lower part of the polyrod 21 to form a joint part 23.

[0011] Further, around the connecting part at the center of the lower part of the poly rod 21, a projection part 24 is provided whose tip end is divided into a plurality of parts and which are inserted into a hole provided in the first metal plate 3 and fixed therein. That is, the protrusion 24 is formed so that the outer diameter of the middle part is slightly larger than that of the tip, and the protrusion 24 is inserted into the hole provided in the first metal plate 3.
The structure is such that the polyrod 21 is deformed inward by the force when it is inserted, and after insertion, the reaction force presses and holds the polyrod 21 itself against the inner wall of the hole.

The tip of the poly rod 21 has a structure that is tapered gradually from the base, for example, a conical shape, to match the impedance between the space and the dielectric material, so that the received radio waves efficiently propagate through the dielectric material, and the coil at the base of the poly rod 21 is combined with By using a dielectric as the material constituting the radiating element, the speed of radio wave propagation in the dielectric can be slowed down, and as a result, the directivity of the radiating element becomes sharper in the front direction, resulting in polyrod helical radiation. Elements 1a, 1b,..., 1
We are trying to improve the directivity characteristics of n alone. Therefore, it is possible to improve the gain when the polyrod helical radiating elements 1a, 1b, . . . , 1n are arrayed.

[0013] The length to the tip of the polyrod 21 is normally selected to be 3 to 5λ relative to the reception wavelength λ, but in cases where a thin design of the antenna is required in addition to the antenna's directivity and gain, or where economy is taken into consideration. , 3λ or less can be used.

[0014] In the 12 GHz frequency band of BS satellite broadcasting, polyrod helical radiating elements 1a, 1b,..., 1n
In this example, the length of the poly rod 21 is approximately 46 mm.
Coil 22 at the base of a polyethylene rod with a diameter of 7 mm.
The coil 22 is made of a material having an introduction groove, for example, a copper wire with a wire diameter of 0.7 mm, the number of turns is 2 turns, and the outer diameter of the coil 22 is about 7.2 mm. Here, in the case of an air-core coil, the outer circumferential length of the coil 22 is approximately equal to the free space wavelength λ of the receiving frequency, but it is made smaller in consideration of the shortening rate of the dielectric material.

Here, the starting end of the coil 22 is connected to the polyrod 2
After fitting it into the introduction groove 1, it is heated and fused to form the coil 22.
The starting end of the coil 22 is fixed in such a way that it cannot be unraveled, but it is also possible to fix the starting end of the coil 22 using a molding method in which a coil is wound into a specified shape in advance and set in a mold, and resin is injected around it. be.

[0016] Furthermore, polyrod helical radiating elements 1a,
The length at which the coupling portions 23 of 1b,..., 1n are inserted into the waveguide 6 is made longer as they are positioned outward from the plug 7, and by making strong coupling with the waveguide 6, the polyrod helical radiating elements 1a, 1n are inserted into the waveguide 6.
The received signal levels among the antennas 1b, . . . , 1n are made uniform to achieve optimal directivity and increase antenna gain.

Polyrod helical radiating elements 1a, 1b,
..., 1n on the first metal plate 3, FIG.
), the center O of the first metal plate 3, that is, the second
A large number of holes are provided concentrically from the position of the plug 7 provided in the metal plate 4.

The distance between these holes is 0 for the reception wavelength λ.
．． Polyrod helical radiating elements 1a, 1b, .
The interval between 1n is 0.7 to 0.9 with respect to the receiving wavelength λ.
They are arranged at intervals chosen as λ. In this embodiment, a large number of polyrod helical radiating elements 1a, 1b, ..., 1n are arranged concentrically, and the mutual spacing is selected to be 0.7 to 0.9λ with respect to the reception wavelength λ. A similar effect can be obtained by configuring it in a polygonal or spiral shape, if available. In addition, in special cases, ie, when increasing the antenna gain and sacrificing the sidelobe characteristics, 1
It is also possible to set the interval to λ or more.

Polyrod helical radiating elements 1a, 1b,
..., 1n, the received signal is coupled into the waveguide 6, and then transmitted through the waveguide 6 and coupled to the probe formed by the center conductor of the plug 7 in the center. Therefore, each polyrod helical radiating element 1a, 1b,..., 1n
Since the phase relationship of the received signals of the polyrod helical radiating elements 1a, 1b, . The mounting angles of 1b, . Therefore, polyrod helical radiating elements 1a, 1b,..., 1n
A key 25 is attached to the side surface of the protrusion 14, and the shape of the hole is Daruma-shaped so that it can be inserted at a specified angle into the numerous holes provided in the first metal plate 3 constituting the waveguide 6. There is.

The distance between the metal plates 3 and 4 is selected within the range of λ/2 or less with respect to the wavelength λ of the received signal, and in the embodiment, 7
．． It is 5mm. In addition, the metal body 5 outside the waveguide 6 and the polyrod helical radiating element 1a located at the outermost periphery
, 1b, ..., 1n is set to approximately λ/4 with respect to the wavelength λ in the waveguide 6, so that the polyrod helical radiating elements 1a and 1n located at the outermost circumference are coupled to the waveguide 6. Since the received signal is reflected by the wall surface of the metal body 5, the phase of the reflected wave at the positions of the polyrod helical radiating elements 1a and 1n is made the same phase, thereby reducing loss due to cancellation of the received signal.

The length of the center conductor of the plug 7 provided at the center of the second metal plate 4 is selected to be approximately λ/4 with respect to the wavelength λ of the received signal, but the impedance of the antenna is In order to match the impedance with other devices, adjust the length of the center conductor or attach a dielectric pipe such as Teflon to the center conductor.

The cover 2 is a protective cover made of a resin material provided on the front surface to protect the polyrod helical radiating elements 1a, 1b, . . . , 1n, which affect the performance of the antenna, from the external environment. It also has the function of decorating. In this case, the material and thickness of the cover 2 are selected so that the loss of the received signal is minimized.

Although the embodiments of the polyrod helical array antenna have been described above, the present invention is not limited to the above embodiments, and further improvements in details can be made. For example, if the antenna is relatively large, cover 2 should be used to increase the strength of cover 2 and prevent deflection.
It is necessary to increase the plate thickness, but increasing the plate thickness increases loss. For this reason, it is possible to increase the strength by adding an arch-like bulge to the center of the thin cover 2, to make the thickness of the cover 2 thinner by appropriately providing ribs on the inside of the cover 2 for reinforcement, or to make the thickness of the cover 2 thinner. 1a, 1b,..., 1
The periphery of the cover 2 is filled with a low-loss material such as styrofoam to prevent the cover 2 from bending. Alternatively, a low-loss material such as a cylindrical polystyrene foam is attached to the space between the center O of the metal plate 3 and the cover 2, where the polyrod helical radiating elements 1a, 1b, ..., 1n are not fixed, to prevent the cover 2 from deflecting. things are possible.

Furthermore, in the embodiment, the plug 7 is provided as the output of the antenna, that is, the power feeding section, but normally a converter is connected to the output of the antenna. Converter is 12GHz
After low-noise amplification, the received signal in the 1G band is frequency-converted and
Since the conversion is to an intermediate frequency in the Hz band, a wire corresponding to the center conductor of the connector 7 is provided as a probe at the input of the low-noise amplifier circuit, and the wire is directly inserted into the waveguide 6 without going through the connector 7 for coupling. It is also possible to do so. In addition, when the input section of the converter is a waveguide, it is possible to configure a power feeding section by providing a conical reflector on the back surface of the first metal plate 3.

In the embodiment, the inside of the waveguide 6 is a space filled with foamed polystyrene, Teflon material, etc. to hold the polyrod helical radiating elements 1a, 1b, . . . , 1n, and the first metal plate 3 is Decrease the plate thickness or
It is also possible to reduce the weight of the antenna by using a metal thin film sheet as the metal plate 3.

Further, in the embodiment, the first metal plate 3, the second metal plate 4, and the metal body 5 are constructed separately, but the periphery of the second metal plate 4 is bent by forming by pressing or the like. The second metal plate 4 and the metal body 5 can be integrally formed by processing, or the first metal plate 3 and the metal body 5 can be integrally formed by bending the periphery of the first metal plate 3. can.

Furthermore, in the above embodiment, the antenna components such as the first metal plate 3 and the second metal plate 4 are circular.
It can also be square, rectangular, or polygonal. In this case, polyrod helical radiating elements 1a, 1b,...,1
In order to match the phase of n, it is necessary to perform rotational adjustment of the mounting angle.

Polyrod helical radiating element 1a of the embodiment
, 1b, . . . , 1n are shown as conical shapes with gradually tapered tips, but the tips can be made into various shapes such as rounded or trapezoidal to make them easier to mold.

Furthermore, polyrod helical radiating elements 1a,
Although the coils 1b, . . . , 1n are arranged outside the base of the polyrod in the embodiment, they can be embedded inside the base of the polyrod to facilitate molding.

[0030]

Effects of the Invention As detailed above, according to the present invention, since a coil and a polyrod are combined as a radiating element, the polyrod helical radiating element has sharper directivity and gain than a coil alone. This results in an effect equivalent to that of a large antenna whose effective aperture area is relatively increased by the increase in gain. Therefore, it is possible to increase the gain when an array is configured with a large number of polyrod helical radiating elements. The effect of increasing the effective aperture area due to the radiating elements at the center of the antenna surface is small because they influence each other, but the effect of increasing the effective aperture area due to the radiating elements at the outer periphery is large, so the number of radiating elements at the center and the number of radiating elements at the outer periphery are small. It can be considered that the larger the ratio of the number of radiating elements, that is, the smaller the diameter of the antenna, the greater the effective aperture area, and the higher the receiving efficiency can be obtained. In the example, a receiving efficiency of 90 to 95% was obtained for the aperture surface of the antenna having a diameter of 300 mm. Therefore, when the same antenna gain is required, the polyrod helical array antenna can be constructed smaller than the conventional antenna, and the antenna itself and packaging materials can be saved, and transportation costs can be reduced.

Furthermore, since the coil and polyrod are combined as the radiating element, deformation of the coil when the radiating element is assembled can be prevented, and the performance of the antenna can be made uniform. Furthermore, the antenna is not easily affected by vibrations caused by wind or the like after the antenna is transported or installed, and its performance can always be kept stable, making it possible to provide an inexpensive antenna.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a polyrod helical array antenna according to an embodiment of the present invention, in which (a) is a front view and (b) is a side sectional view.

FIG. 2 is a configuration diagram of a polyrod helical radiating element in the same embodiment.

FIG. 3 is a diagram showing the structure of a conventional helical planar antenna.

[Explanation of symbols]

1a to 1n... Polyrod helical radiating element, 2... Cover, 3... First metal plate, 4... Second metal plate, 5... Metal body,
6... Waveguide, 7... Plug, 21... Poly rod, 22... Coil, 23... Coupling portion, 24... Protrusion, 25... Key, 31a
~31n...Helical circularly polarized wave element, 32, 33...Parallel metal flat plate, 34...Waveguide, 35...Metal ring, 36...Probe.

Claims (7)

[Claims] Claim 1: A coil is attached to the base of a polyrod formed into a rod shape using a dielectric material, the starting end of this coil is released, and the terminal end is extended straight downward from the center of the base of the polyrod to form a joint part. A large number of holes are formed in one side of a waveguide that includes a large number of polyrod helical radiating elements and is surrounded by a metal material, and a coupling part of the polyrod helical radiating elements is inserted into the waveguide, and a feeding part is provided on the other side of the waveguide. A polyrod helical array antenna characterized by being provided with. 2. The polyrod helical radiating element comprises:
The tip of the polyrod is gradually tapered to delay the phase of radio waves at the center, and the distance from the tip to the base is several wavelengths or less relative to the wavelength of the receiving frequency, and the length of the outer circumference of the polyrod is dielectrically adjusted to the receiving wavelength. 2. The polyrod helical array antenna according to claim 1, wherein the polyrod helical array antenna is set to be approximately equal to a value multiplied by a body shortening rate. 3. The connection between the polyrod helical radiating element and the hole provided on one side of the waveguide is achieved by providing a plurality of protrusions at the bottom of the polyrod, and the reaction force after insertion causes the protrusions to close to the inner surface of the hole. 2. The polyrod helical array antenna according to claim 1, wherein the polyrod helical array antenna is configured to be crimped and fixed to the polyrod helical array antenna. 4. The waveguide includes a first metal plate on which a large number of holes are formed and a second metal plate on which a power feeding section is formed, with an interval of λ/2 or less relative to the wavelength λ of the receiving frequency. Face to face,
The polyrod helical array antenna according to claim 1, wherein the polyrod helical array antenna is configured to be held by a metal body that electrically shorts the periphery. 5. The polyrod helical array according to claim 4, wherein the holes formed in the first metal plate are arranged at equal intervals of 0.7 to 1λ with respect to the reception wavelength λ. antenna. 6. The metal body electrically short-circuited around the first metal plate and the second metal plate is located approximately 1/4λ away from the outermost hole of the first metal plate, and 5. The polyrod helical array antenna according to claim 4, wherein the polyrod helical array antenna is configured so that the radio waves received and coupled by the rod helical radiating element are reflected in the same phase at the outermost hole position. 7. The power feeding section provided at the center of the second metal plate is inserted into the waveguide using the center pin of the coaxial plug as a probe and having a length of about 1/4λ. 5. The polyrod helical array antenna according to claim 4.