JPH08204434A - Helical antenna - Google Patents

Abstract

PURPOSE: To provide an inexpensive and practical helical antenna, to change easy its helix angle, sufficient in strength and stable in form. CONSTITUTION: The sleeves 11 of a hollow dielectric are arranged along a shaft. The hollow shaft 12 of the hollow dielectric is arranged between the sleeves 11. A conduction wire 3 is wound through a guide 13 provided in the sleeve 11 in spiral shape, and it is covered with a radome 6. One terminal of each hollow shaft 12 is fitted in the sleeve 11 with a right-turn screw and the other terminal of the hollow shaft 12 with a left-turn screw. An angle of rotation of each sleeve 11 is synchronized with each other, and each hollow shaft 12 is rotated by synchronizing with a driving shaft 14.

Description

Detailed Description of the Invention

[0001]

[Industrial field of use] In recent years, mobile communication such as car phones and mobile phones has been popular, and it is hoped that not only services will be limited to urban areas and highways but also service areas will be expanded to mountainous areas and inshore areas. It is rare. A base station that relays the communication of a mobile station is indispensable for mobile communication, but a huge number of base stations are required to be able to communicate from anywhere at any time,
Considering line demand and base station construction costs, it is economically limited to develop a service area in a mountainous area or near sea. If a communication satellite in a geostationary orbit is used as a relay station and a communication line is connected between an outdoor mobile station and the satellite, it is possible to economically construct a line that covers all of Japan, including the near sea. is there. When the gain of the mobile station antenna used for such satellite communication is increased, the beam becomes sharper, so it is necessary to track the satellite according to the movement of the mobile station. Conversely, if the antenna is omnidirectional, tracking is unnecessary. On the other hand, the gain required on the line cannot be obtained. Therefore, if the directivity is conical, that is, it has directivity in the elevation angle direction of the satellite and is omnidirectional in the circumferential direction, by setting the axis of the cone beam almost vertically, it is possible to communicate regardless of the bearing of the satellite, It is extremely advantageous as a mobile station antenna. Moreover, if the polarized wave used is a circular polarized wave used in satellite broadcasting, it is not necessary to adjust the plane of polarization for the shaking of the mobile station. There is a helical antenna as an antenna type having such a circularly polarized conical beam, but since Japan has a bow-shaped country, the elevation angle of the satellite seen from various places is wide and depending on the gain required for the antenna. It is desired that the elevation angle of the beam of the helical antenna can be changed.
The present invention relates to a mechanism for changing the directivity of a helical antenna used for such satellite-based mobile communication.

[0002]

2. Description of the Related Art FIG. 12 is a diagram showing a conventional helical antenna whose structure is shown in, for example, IEICE Technical Report A.P. 91-38. In the figure, 1 is a core material of cylindrical expanded polyethylene, 2a and 2b are two spiral grooves with a pitch angle α (pitch P) provided facing the core material 1 by 180 °, and 3a and 3b are fitted in the spiral groove 2. 2 conductor wires, 4
Is a balun, 5 is a coaxial line of a steel pipe passing through the inside of the core material 1, 6
Is a glass fiber reinforced resin radome. The outer diameter D of the core material 1 is about 0.1λ with respect to the wavelength λ of the radio wave used, and the pitch angle α of the spiral groove 2 is selected so that D / P is about 0.2. The length of the conductor wire 3 is usually 3 turns or more, here 6 turns, with the pitch of the spiral groove 2 being one roll. Since the diameter of the conductor wire 3 is selected to be sufficiently smaller than the wavelength λ, it is usually difficult to make it self-sustaining. Therefore, the conductor wire 3 is inserted into the spiral groove 2 provided in the core material 1 to maintain its shape.
Balun 4 is, for example, Antenna Engineering Handbook p243,
The split coaxial type balun shown in Fig. 3 ・ 20 (Electronic Communication Institute bias, 1980) has a coaxial line 5 as shown in Fig. 13.
The inner conductor 7 and the outer conductor 8 at the ends of are connected by a short-circuit piece 9, and the outer conductor 8 is provided with a slit 10 having a length of λ / 4.
The conductor lines 3a and 3b are connected to the outer conductor 8 divided by 0. The radome 6 covers the conductor wire 3 and the balun 4 and protects them from wind and rain and erosion.

Since the conventional helical antenna is constructed as described above, when considered as a transmitting antenna, the unbalanced transmission mode of the coaxial line 5 is converted into the balanced transmission mode by the balun 4, and the conductor lines 3a and 3b are converted. Balanced power supply.
Since the balanced-fed conductor lines 3a and 3b are fed in opposite phases, they radiate circularly polarized waves, but the angle θ from the direction orthogonal to the axis of the helical antenna shown in FIG. A beam having a peak in the direction and rotationally symmetrical about the axis, that is, a cone beam is formed. The elevation angle θ of the cone beam is related to the pitch angle α. As shown in FIG. 14, when the pitch angle α is small, the elevation angle θ is large, and when the pitch angle α is large, the elevation angle θ is small. This relationship is approximately represented by "Equation 1". Therefore, if the pitch angle α is selected so that the elevation angle of the satellite in the area and the elevation angle θ of the conical beam of the helical antenna match, and the helical antenna is mounted vertically on a moving body such as an automobile, the required antenna gain in the elevation direction of the satellite is obtained. Since it has non-directionality in the circumferential direction, it can be transmitted and received immediately by connecting to a wireless device. Since the beam in the elevation direction is not sharp, the line can be maintained without being tracked even when the vehicle moves or turns without being substantially affected by the inclination of the general road.

[0004]

[Equation 1]

[0005]

As described above, the conventional helical antenna can perform satellite communication as if it were receiving a radio broadcast by a rod antenna, but it is a service desired for mobile communication. When considering the area, there is a limit to the area to which one helical antenna can be applied as shown below.

Since Japan has an arched land, the elevation angle of the satellite seen from various places is wide, for example, 13 east longitude.
For satellites stationary at 5 °, the elevation range is 37 ° (Hokkaido) to 53 ° (Kyushu) even within the mainland. If a car traveling from Hokkaido to Kyushu wants to cover it with one antenna, it is necessary to have a beam width of 16 ° or more centering on an elevation angle of 45 ° and satisfying the required gain. The required gain and the beam width have a contradictory relationship from the viewpoint of directivity gain. As shown in FIG. 15, if the required gain is as low as G1, the beam width is as wide as B1 and the required gain is G2. The higher the width, the narrower the beam width becomes as B2. Furthermore, the elevation angle θ of the conical beam of the helical antenna has the property of changing with frequency. That is, since the helical antenna is a traveling waveform antenna, the phase distribution of the current along the conductor wire 3 changes depending on the frequency, and as the frequency increases, the elevation angle θ also increases. This is the approximate expression shown in "Equation 1", and can be understood from the fact that the elevation angle θ is a function of the wavelength λ. In satellite communication, the frequencies are different in upstream and downstream, so in order to obtain the same gain in transmission and reception, the antenna is used in the direction around the elevation angle where the transmission beam intersects the reception beam, that is, in the elevation angle direction shown by the arrow in FIG. There is a need to.

As described above, since the beam width that satisfies the required gain in the conventional helical antenna is limited by the required gain and the frequency range used, the elevation angle of the satellite in the area where it is used is limited unless the required gain is low. Depending on the situation, it is the actual situation that the antenna is exchanged, the transmission-dedicated antenna and the reception-dedicated antenna are separately used, or a plurality of transmission / reception antennas are prepared and switched by a switch. After all, the need for a plurality of antennas not only raises the price, but also significantly impairs the handling and installation.

Such a problem can be solved if the elevation angle α can be easily changed, and it is easily conceivable that the diameter D or the pitch angle α can be changed from "Equation 1".
For example, since the conductor wire 3 retains its shape by the core material 1, the core material 1 is abolished and the conductor wire 3 is made thick enough to be self-supporting, and tensile or compressive force is applied to both ends as schematically shown in FIG. , The shape can be changed as if the coil spring were expanded and contracted. However, in this method, since the conductor wire 3 is made thicker and the rigidity is increased, the stress generated in the conductor wire 3 due to the deformation is increased, and the conductor wire 3 is permanently deformed by one expansion or contraction or repeated expansion and contraction. The conductor wire 3 is destroyed by metal fatigue. If the stress is set within the elastic range or within the fatigue fracture strength in order to avoid permanent deformation and fracture, it is difficult to make it self-sustaining because the rigidity is low. Not only is the conductor wire that cannot be self-sustaining, the pitch angle is unstable, but the conductor wire itself vibrates significantly with the vibration of a moving body such as an automobile as an exciting force, and the pitch of each turn fluctuates with time. Then, the beam shape and impedance change and it cannot be put to practical use. Further considering the changes in the diameter D and the pitch angle α due to expansion and contraction, it can be easily inferred from the fact that the conductor wire becomes a straight line when the conductor wire is fully extended. On the contrary, it is obvious that the diameter D increases as the pitch angle α is reduced by shrinking. As the pitch angle α increases from “Equation 1”, the elevation angle θ tends to decrease, and when the diameter D decreases, the elevation angle θ tends to increase. As a result, the change in elevation angle due to expansion and contraction is offset, and the effect is small. Practicality is poor in terms of strength and electrical characteristics.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to obtain an inexpensive and practical helical antenna in which the pitch angle can be easily changed, the mechanical strength is sufficient and the form is stable. It is an object.

[0010]

In the helical antenna according to the first embodiment of the present invention, hollow dielectric sleeves are arranged at equal intervals along the axis, and the hollow dielectric hollow shafts are arranged between the sleeves. The conductor wire is spirally wound through a guide provided on the sleeve and covered with a radome.One end of each hollow shaft is right-threaded, and the other end of the hollow shaft is left-threaded to fit with the sleeve. The rotation angles of the sleeves are synchronized, and the hollow shafts are synchronously rotated by the drive shaft.

Also, in the helical antenna according to the sixth embodiment of the present invention, hollow dielectric sleeves are arranged at equal intervals along the axis, and hollow shafts of the hollow dielectric are arranged between the sleeves. A conductor wire is spirally wound through a guide provided and covered with a radome. One end of each hollow shaft has a pitch p1 and the other end of the hollow shaft has a pitch p.
In step 2, the sleeves are fitted to each other, the rotation angles of the sleeves are synchronized, and the hollow shafts are synchronously rotated by the drive shaft.

In the helical antenna according to the seventh embodiment of the present invention, hollow dielectric sleeves having different lengths are arranged along the axis, and the hollow dielectric hollow shafts are arranged between the sleeves. The conductor wire is spirally wound through a guide provided on the cover and covered with a radome.One end of each hollow shaft is fitted with a right-hand thread, and the other end of the hollow shaft is fitted with a left-hand thread. The hollow shafts are synchronized and the hollow shafts are synchronously rotated by the drive shaft.

In the helical antenna according to the eighth embodiment of the present invention, sleeves of hollow dielectrics having different lengths are arranged along the axis, and the hollow shafts of the hollow dielectrics are arranged between the sleeves. A conductor wire is spirally wound through a guide provided on the sleeve and covered with a radome. One end of each hollow shaft is fitted with a sleeve at a pitch p1 and the other end of the hollow shaft is fitted with a sleeve at a pitch p2. The hollow shafts are synchronized and the hollow shafts are synchronously rotated by the drive shaft.

Further, in the helical antenna according to the first embodiment of the present invention, the drive shaft has a hollow cross section.

The helical antenna according to the ninth embodiment of the present invention covers the conductor wire with a tube made of a dielectric material longer than the conductor wire.

[0016]

According to the first embodiment of the present invention, when the drive shaft is rotated, the distance between each sleeve is expanded and contracted by the right screw and the left screw of the hollow shaft, and the pitch angle of the conductor wire is increased with the expansion and contraction. Change.

According to the sixth embodiment of the present invention,
When the drive shaft is rotated, the distance between each sleeve expands and contracts according to the pitch difference between the screws on both ends of the hollow shaft, and the pitch angle of the conductor wire changes with this expansion and contraction.

According to the seventh embodiment of the present invention,
When the drive shaft is rotated, the distance between each sleeve expands and contracts by the right and left screws of the hollow shaft, and the pitch angle of the conductor wire that changes continuously with this expansion and contraction becomes another pitch angle that changes continuously. Change.

According to the eighth embodiment of the present invention,
When the drive shaft is rotated, the distance between each sleeve expands and contracts according to the pitch difference between the screws on both ends of the hollow shaft, and with this expansion and contraction, the continuously changing pitch angle of the conductor wire changes continuously. Change to pitch angle.

Further, according to the first embodiment of the present invention, the hollow cross section of the drive shaft provides a space for passing the coaxial line.

According to the ninth embodiment of the present invention,
The dielectric tube and sleeve define the pitch angle.

[0022]

【Example】

Example 1. FIG. 1 is a diagram showing an embodiment of the present invention,
The conductor wire 3, the balun 4, the coaxial line 5, and the radome 6 are exactly the same as those of the conventional helical antenna. In the figure, reference numeral 11 denotes N (N is an integer of 1 or more) +1 cylindrical polypropylene sleeves arranged at equal intervals of pitch P, 1
2 is a hollow shaft made of N polypropylenes arranged between N + 1 sleeves, 13 is a guide protruding from the outer surface of the sleeve 11 to the radome 6 side, and the conductor wire 3 is passed therethrough. 14 is an inside of the sleeve 11 and the hollow shaft 12. Is a drive shaft having a rectangular hollow cross-section that penetrates through the drive shaft 14. Reference numeral 15 denotes a right-handed female thread (right female thread) formed on the inner surface of the sleeve 11 on one side, and 16 denotes the sleeve 11
Female thread (left female thread) formed on the inner surface of the other side of the hollow shaft, 17 is a male thread of the right thread formed on one side of the hollow shaft 12 (right male thread), and 18 is the other of the hollow shaft. A left-handed external thread (left-handed thread) formed on one side, 19 is a rotation restricting piece protruding from one side of the sleeve 11 to the adjacent sleeve 11 side, and 20 is adjacent to the other side of the sleeve 11. It is a rotation regulating groove that slidably fits in the longitudinal direction with the rotation regulating piece 19 that is formed.

Since the inner surface of the hollow shaft 12 and the outer surface of the drive shaft 14 are fitted to each other in a rectangular cross section, the hollow shaft 12 can freely slide in the axial direction of the drive shaft 14, and when the drive shaft 14 is turned, it becomes hollow. The shaft 12 rotates together with the drive shaft 14, that is, the drive shaft 14
The N hollow shafts 12 rotate in synchronism with the rotation. Since the adjacent sleeve 11 and the sleeve 11 are fitted to each other by the rotation restricting piece 19 and the rotation restricting groove 20, they can freely slide in the axial direction within the range of the length of the rotation restricting piece 19 to change the distance between them. In the direction, N + 1 pieces rotate in synchronization. Sleeves 11 are connected to both sides of one hollow shaft 12, respectively, and the right male screw 17 of the i-th hollow shaft 12 is fitted with the right female screw 15 of the i-th sleeve 11, and the i-th hollow shaft 12 The left male screw 18 of is engaged with the left female screw 16 of the (i + 1) th sleeve 11. In this way, the sleeve 11 and the hollow shaft 12 are paired with the right-hand thread and the left-hand thread
A plurality of pairs of which are alternately connected are stacked. The pitch of the right-hand screw and the left-hand screw is the same x.

Since N + 1 guides 13 protruding from the sleeve 11 appear at the same intervals, when the conductor wires 3 are sequentially passed through the guides 13, the conductor wires 3 are spirally wound as in the conventional structure. The outer diameter of this guide 13 is slightly smaller than the inner diameter of the radome 6, and is selected so that the conductor wire 3 can be inserted into the gap between the sleeve 11 and the radome 6. And the first sleeve 11 is fixed to the radome 6,
The starting end of the conductor wire 3, that is, the end on the side connected to the balun 4 is also 1.
It is fixed to the second sleeve 11.

In the helical antenna constructed as described above, when the radome 6 is fixed and the drive shaft 14 makes one rotation in the direction of the white arrow in the figure, the hollow shaft 12 also makes one rotation in the direction of the white arrow. To do. Since the first sleeve 11 and the first hollow shaft 12 form a pair of right-hand threads, and the first sleeve 11 is fixed to the radome 6,
As shown in (a), when the first hollow shaft 12 makes one rotation, the first hollow shaft 12 moves toward the first sleeve 11 by the distance x. The first hollow shaft 12 is a pair of left screw and the second sleeve 11, and the rotation angle of the first sleeve 11 and the second sleeve 11 is synchronized by the rotation restricting piece 19 and the rotation restricting groove 20. Therefore, the second sleeve 11 moves a distance x with respect to the first hollow shaft 12. As a result, the second sleeve 11 moves a distance 2x with respect to the first sleeve 11, that is, the first sleeve 11 and the second sleeve 11.
The spacing of the second sleeve 11 is reduced by 2x. I in the same way
The distance between the 1st and (i + 1) th sleeve 11 is also reduced by 2x,
When the drive shaft 14 makes one rotation, the distance between the sleeves is reduced by 2x.

In FIG. 2B, the circumference of the virtual cylinder around which the conductor wire 3 is wound is plotted along the abscissa, and the length of the helical antenna is plotted along the ordinate. In the figure, the conductor wire 3 is represented by a straight line having the same inclination as the pitch angle α, and the number of turns of the conductor wire 3 shown along the horizontal axis simultaneously indicates the position of the guide 13. The initial length of one turn of the helical antenna is the length of the circumference of the virtual cylinder multiplied by tan α, that is, the pitch P.
Guides 13 provided on the sleeve 11 at equal intervals
The interval of is consistent with this. Now, when the distance between the sleeves is reduced by 2x, the conductor wire 3 is constrained from moving in the radial direction in the gap between the sleeve 11 and the radome 6, so that the diameter of the virtual cylinder does not change, and the circumferential direction of the guide 13 does not change. Since the position is also unchanged, the length of one turn of the helical antenna shifts from P to P ′, which is 2 ×. Since the starting end of the conductor wire 3 is fixed to the first sleeve 11, the conductor wire 3 moves to the position represented by the broken line having the inclination of the pitch angle α ′. That is, only the pitch angle is reduced without changing the diameter of the helical antenna. When the rotation direction of the drive shaft 14 is opposite, the pitch angle similarly increases.

That is, when the drive shaft 14 is rotated with respect to the radome 6, only the pitch angle can be changed without changing the diameter of the helical antenna. Therefore, the elevation angle of the cone beam can be changed very easily. ,
One helical antenna can be used for satellite communication.

Since the N + 1 sleeves 11 and the N hollow shafts 12 may be the same, they can be manufactured by injection molding of polypropylene easily, in large quantities, and at a low cost, so that the cost of parts is slightly increased. , It is much cheaper than switching by preparing multiple helical antennas.

Example 2. In the first embodiment, the rotation restricting piece and the rotation restricting groove synchronize the rotation of the sleeves with each other.
Is the one in which the radome and sleeve are fitted together and the rotation is restricted. Reference numeral 21 denotes a boss protruding from the outer surface of the sleeve 11 toward the radome 6 side, and 22 is a groove provided in a part of the cross section of the radome 6 so as to correspond to the boss 21.
Reference numeral 1 denotes a radome 6 whose movement in the axial direction is fixed.

In the helical antenna constructed as described above, the rotation of the sleeve 11 is restricted by the radome 6 by the boss 21 and the groove 22, but the sleeve 1 other than the first one is rotated.
1 is movable in the axial direction. When the radome 6 is fixed and the drive shaft 14 is rotated, the hollow shaft 12 is rotated as in the first embodiment.
Is rotated and the distance between the sleeves 11 is changed, so that the elevation angle of the cone beam can be easily changed. Here, the sleeve provided with the boss is the same in that it can be easily molded by injection molding, and the groove of the radome can be manufactured by drawing or extrusion molding or by post-processing a round pipe with a broach.

Example 3. FIG. 4 shows another embodiment in which the rotations of the sleeves are synchronized with each other. Reference numeral 23 denotes a rotation restricting pin protruding from one side of the sleeve 11 to the adjacent sleeve 11 side, and 24 denotes another rotation limiting pin of the sleeve 11. It is a rotation restriction hole that slidably fits in the longitudinal direction with the rotation restriction pin 23 adjacent to the side.

Example 4. In the first embodiment, the drive shaft having a rectangular hollow cross section is used, but as shown in FIG. 5, the drive shaft 14 has a triangular, hexagonal or JIS B 160 cross section.
If the drive shaft has a non-rotationally symmetric cross section, such as the spline specified in 1, the hollow shaft can be rotated in synchronization in the same manner.

Example 5. In the above-mentioned embodiment, a so-called two-wire helical antenna having two conductor wires has been described, but one conductor wire shown in Antenna Engineering Handbook p73, 3 ・ 2.5 (edited by The Institute of Electronics, Information and Communication Engineers, 1979). It can also be applied to the case of changing the pitch angle of a general helical antenna such as a helical antenna or a four-wire winding antenna. FIG. 6 shows a helical antenna having one conductor wire 3 and 25 a reflector. In this case, since the circular knitting wave is radiated toward the end of the conductor wire, it is possible to rotate the drive shaft 14 from the side of the reflector by using a solid cross section.

Embodiment 6 FIG. In the first embodiment, the right screw and the left screw are used for the sleeve and the hollow shaft, but in FIG. 7, screws having the same winding direction but different pitches are used. In the figure, 26 is a right-handed internal thread having a pitch p1 formed on the inner surface of one side of the sleeve 11 (p1 female thread), and 27 is a right-handed thread having a pitch p2 formed on the inner surface of the other side of the sleeve 11. Female thread (p2 female thread), 28 is a right-handed male thread of a pitch p1 formed on one side of the hollow shaft 12 (p1 male thread), and 29 is a right-handed pitch of p2 formed on the other side of the hollow shaft. It is a male screw (p2 male screw). P here
1> p2. p1 male screw 28 of the i-th hollow shaft 12
Fits with the p1 female screw 26 of the i-th sleeve 11,
The p2 male thread 29 of the th hollow shaft 12 is fitted with the p2 female thread 27 of the i + 1 th sleeve 11.

When the radome 6 is fixed and the drive shaft 14 is rotated once in the direction of the white arrow in the figure, the hollow shaft 12 is also rotated once in the direction of the white arrow. The first sleeve 11 and the first hollow shaft 12 form a screw pair with a pitch p1.
Since the first sleeve 11 is fixed to the radome 6, when the first hollow shaft 12 makes one rotation, the first sleeve 11 moves toward the first sleeve 11 by the distance p1. First hollow shaft 1
2 has a thread pair with the second sleeve 11 having a pitch p2, and the rotation angles of the first sleeve 11 and the second sleeve 11 are synchronized by the rotation restricting piece 19 and the rotation restricting groove 20. The second sleeve 11 moves a distance p2 in the direction away from the first hollow shaft 12. As a result, the second sleeve 11 is compared to the first sleeve 11.
Moves a distance p1p2, that is, the distance between the first sleeve 11 and the second sleeve 11 is reduced by p1-p2. Similarly, the distance between the i-th sleeve and the i + 1-th sleeve is reduced by p1-p2, and when the drive shaft 14 makes one rotation, the distance between the sleeves is reduced by p1-p2.

Therefore, although the pitch angle α can be changed as in the first embodiment, the sleeve interval can be changed by a minute amount of p1 to p2 by one rotation of the drive shaft, which is suitable for a helical antenna that requires fine adjustment. There is.

Example 7. Further, in the above-described first embodiment, the conductor wire pitch angle is described as being constant, but the Antennas-
second edition p330, Figur
It is also applicable to the helical antenna shown in e7-59 (J. D. Kraus, 1988) where the pitch angle is not constant. In this case, there are a plurality of sleeves 11 as shown in FIG.
A helical antenna with a continuously changing pitch angle can be realized if the lengths of the left and right screws are different, and if necessary, the pitches of the right-hand screw and the left-hand screw are changed as xa, xb, xc ... It can be set to obtain a variable angle characteristic.

Example 8. FIG. 9 shows a helical antenna having a continuously changing pitch angle with a plurality of sleeves 11 having different lengths as in the case of the seventh embodiment, and the screw pitches of p1 and p2 shown in the sixth embodiment are changed. p1a, p
2a, p1b, p1b, ... As a desired pitch angle variable characteristic.

Example 9. In the embodiment shown in FIG. 10, the conductor wire 3 is used.
The conductor wire 3 is covered with a longer dielectric tube, for example, a tube 30 of tetrafluoroethylene resin. FIG.
In FIG. 1 (a), the horizontal axis represents the circumference of the virtual cylinder around which the conductor wire 3 is wound, and the vertical axis represents the length of the helical antenna. When the pitch angle is varied in a small pitch angle range, for example, when the pitch angle is varied, the end of the conductor wire indicated by A in the drawing is not constrained by the guide, so that the form, that is, the pitch angle becomes indefinite. If the conductor wire 3 is covered with a tube 30 longer than the conductor wire 3 and the tube 30 is passed through a guide, the pitch angle is determined by this tube. Therefore, as shown in FIG. Can be defined.

By the way, in the above embodiment, the conductor wire is described as being supported by the guide for each winding, but it is sufficient that the conductor wire has sufficient rigidity and strength necessary for maintaining the shape, and in some cases, 2 The number of guides and sleeves provided with guides may be increased or decreased, for example, by supporting each winding or every 1/2 winding.

In the above embodiment, the dielectric material used as the material for the sleeve and the hollow shaft is polypropylene.
Needless to say, tetrafluoroethylene resin and polyacetal resin are not limited thereto.

[0042]

Since the helical antenna of the present invention is constructed as described above, it has the following effects.

According to the present invention, a helical antenna whose pitch angle can be varied can be obtained at a low cost by a simple operation of rotating the drive shaft.

Further, according to the present invention, it is possible to inexpensively obtain the helical antenna whose pitch angle can be changed by the simple operation of rotating the drive shaft.

According to the present invention, it is possible to obtain a helical antenna in which a continuously changing pitch angle of a conductor wire changes to another continuously changing pitch angle by a simple operation of rotating a drive shaft. .

Further, according to the present invention, it is possible to obtain a helical antenna in which a continuously changing pitch angle of a conductor wire changes to another continuously changing pitch angle by a simple operation of rotating a drive shaft. .

Furthermore, according to the present invention, it is possible to obtain a helical antenna which internally includes a coaxial line for feeding power.

Further, according to the present invention, it is possible to obtain the helical antenna in which the pitch angle is correctly defined even if the pitch angle is largely changed.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing an operation of the first embodiment of the present invention.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a diagram showing Embodiment 3 of the present invention.

FIG. 5 is a diagram showing a fourth embodiment of the present invention.

FIG. 6 is a diagram showing Embodiment 5 of the present invention.

FIG. 7 is a diagram showing a sixth embodiment of the present invention.

FIG. 8 is a diagram showing Embodiment 7 of the present invention.

FIG. 9 is a diagram showing an eighth embodiment of the present invention.

FIG. 10 is a diagram showing Embodiment 9 of the present invention.

FIG. 11 is a diagram showing an operation of the ninth embodiment of the present invention.

FIG. 12 is a diagram showing a conventional helical antenna.

FIG. 13 is a diagram showing a balun of a conventional helical antenna.

FIG. 14 is a diagram showing a radiation characteristic of a conventional helical antenna.

FIG. 15 is a diagram showing a beam width of a conventional helical antenna.

FIG. 16 is a diagram showing frequency characteristics of a conventional helical antenna.

FIG. 17 is a diagram showing changes in a conventional helical antenna.

[Explanation of symbols]

1 core material, 2 spiral groove, 3 conductor wire, 4 balun, 5
Coaxial line, 6 radome, 7 inner conductor, 8 outer conductor,
9 short-circuit piece, 10 slits, 11 sleeve, 12 hollow shaft, 13 guide, 14 drive shaft, 15 right female screw,
16 Left female thread, 17 Right male thread, 18 Left male thread, 1
9 rotation regulating piece, 20 rotation regulating groove, 21 boss, 22
Groove, 23 rotation restriction pin, 24 rotation restriction hole, 25
Reflector, 26 p1 female thread, 27 p2 female thread, 28
p1 male thread, 29 p2 male thread, 30 tube.

Claims (6)

[Claims] 1. A helical antenna in which one or a plurality of conductor wires are spirally wound along a virtual cylindrical surface at a constant pitch angle, and N (N) is provided at predetermined intervals along the axis of the virtual cylindrical surface. Is an integer greater than or equal to 1) +1 pieces, N + 1 pieces are synchronously rotated around the axis of the virtual cylindrical surface, and a hollow dielectric sleeve is provided with a predetermined distance from the outer diameter of the sleeve, and the inner surface is the virtual cylindrical surface. A radome on the outside of the sleeve, a guide protruding from the sleeve to the side of the radome, passing through the conductor wire, restraining the conductor wire from moving in the circumferential direction of the sleeve, and a drive shaft penetrating the inside of the sleeve. ,
Located between the N + 1 sleeves, one end mates with one end of the corresponding sleeve in a right-hand thread and one end on the other side mates in a left-hand thread with another end of the corresponding sleeve. And a helical antenna which is slidable along the axis of the drive shaft and which is fitted with the drive shaft in synchronization with the rotation of the drive shaft. . 2. A helical antenna in which one or a plurality of conductor wires are spirally wound along a virtual cylindrical surface at a constant pitch angle, and N (N) is provided at predetermined intervals along the axis of the virtual cylindrical surface. Is an integer greater than or equal to 1) +1 pieces, N + 1 pieces are synchronously rotated around the axis of the virtual cylindrical surface, and a hollow dielectric sleeve is provided with a predetermined distance from the outer diameter of the sleeve, and the inner surface is the virtual cylindrical surface. A radome on the outside of the sleeve, a guide protruding from the sleeve to the side of the radome, passing through the conductor wire, restraining the conductor wire from moving in the circumferential direction of the sleeve, and a drive shaft penetrating the inside of the sleeve. ,
It is arranged between the N + 1 sleeves, one end of which forms a thread pair of pitch p1 with one end of the corresponding sleeve, and the other end of which forms a thread pair of pitch p2 with one end of another corresponding sleeve. And N hollow shafts of hollow dielectrics that are fitted and slidable along the axis of the drive shaft and that are fitted to the drive shaft in synchronization with the rotation of the drive shaft. Helical antenna. 3. A helical antenna in which one or a plurality of conductor wires are spirally wound along a virtual cylindrical surface at a pitch angle that continuously changes, and N (N is 1 or more integers) +1 arranged, N + 1 sleeves of different lengths in which N + 1 synchronously rotate around the axis of the virtual cylindrical surface are provided, and an outer diameter of the sleeve is provided at a predetermined interval and the inner surface is A radome outside the virtual cylindrical surface, a guide protruding from the sleeve to the side of the radome and passing through the conductor wire, and a guide for restraining the conductor wire from moving in the circumferential direction of the sleeve, and penetrating the inside of the sleeve. Is arranged between the drive shaft and the N + 1 sleeves,
One end is a kinematic pair of the right screw and one end of the corresponding sleeve,
One end on the other side is fitted with one end of another corresponding sleeve in a pair of left-hand threads, slidable along the axis of the drive shaft, and fitted in synchronization with the rotation of the drive shaft. A helical antenna comprising a hollow shaft of N hollow dielectrics. 4. A helical antenna in which one or a plurality of conductor wires are spirally wound along a virtual cylindrical surface at a pitch angle that continuously changes, and N (N: 1 or more integers) +1 arranged, N + 1 sleeves of different lengths in which N + 1 synchronously rotate around the axis of the virtual cylindrical surface are provided, and an outer diameter of the sleeve is provided at a predetermined interval and the inner surface is A radome outside the virtual cylindrical surface, a guide projecting from the sleeve to the radome side to pass the conductor wire, restrain the conductor wire from moving in the circumferential direction of the sleeve, and a drive that penetrates the inside of the sleeve. Is arranged between the shaft and the N + 1 sleeves, one end of which forms a thread pair with one end of the corresponding sleeve at a pitch p1 and the other end of which has a screw pair of one end at a pitch p2 with another corresponding sleeve. And N hollow shafts of hollow dielectrics that are fitted evenly and are slidable along the axis of the drive shaft and that are fitted to the drive shaft in synchronization with the rotation of the drive shaft. Helical antenna characterized by. 5. The helical antenna according to claim 1, wherein the drive shaft has a hollow cross section, and a coaxial line for feeding a conductor wire is passed inside the drive shaft. 6. The helical antenna according to claim 1, wherein the conductor wire is covered with a tube made of a dielectric material longer than the conductor wire.