JP5301349B2 - Collinear antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a collinear antenna reducing side robes. <P>SOLUTION: In the collinear antenna 1 stacked in 15 steps, each step in the first step sleeve element 11 to the 15th step sleeve element 25 is constituted of an upper step sleeve and a lower step sleeve which constitute a dipole antenna. To the sleeve element at each step, a frequency signal is supplied from a coaxial cable 31 to which an antenna power feed part 32 is connected. An interval Fg between the upper step sleeve and the lower step sleeve at each step is gradually made into a large interval from the lower stage to the upper stage. Thus, the side robes of the collinear antenna 1 are reduced. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a collinear antenna with good radiation characteristics.

A schematic configuration of an example of a conventional collinear antenna is shown in FIG.
A conventional collinear antenna 100 shown in FIG. 11 is configured by stacking 15 sleeve elements each constituting a dipole antenna. In the collinear antenna 100, a second-stage sleeve element 112 is stacked on the first-stage sleeve element 111, and a third-stage sleeve element 113 is stacked on the second-stage sleeve element 112. A fourth-stage sleeve element 114 is stacked on 113, a fifth-stage sleeve element 115 is stacked on the fourth-stage sleeve element 114, and a sixth-stage sleeve element 115 is stacked on the fifth-stage sleeve element 115. 116 are stacked, and a 15th-stage sleeve element 125 is stacked on the uppermost stage. The central portion of the first-stage sleeve element 111 to the fifteenth-stage sleeve element 125 is excited by a coaxial cable 131 serving as a transmission line, and an antenna feeder 132 is connected to the lower end of the coaxial cable 131. Is introduced into the first-stage sleeve element 111.

Each of the sleeve elements 111 to 125 is a dipole antenna in which a cylindrical upper sleeve pipe and a lower sleeve pipe are opposed to each other, and a predetermined sleeve pipe interval between the upper sleeve element and the lower sleeve element is Fg ₁ to Fg _15. It is said that. The sleeve pipe intervals Fg _{1 to} Fg ₁₅ in the sleeve elements 111 to 125 are set to the same interval. For example, the sleeve pipe intervals Fg _{1 to} Fg ₁₅ are set to about 5 mm. The electrical length of the upper sleeve pipe and the lower sleeve pipe constituting the dipole antenna is approximately λ / 4 when the wavelength of the frequency signal fed from the antenna feeding unit 132 is λ. In addition, the electrical length of the coaxial cable 131 between the power feeding portions is set to about 1λ so that the sleeve elements 111 to 125 of each stage are excited in the same phase. The physical length of the coaxial cable 131 is a length corresponding to the wavelength shortening rate of the coaxial cable 131.

JP-A-5-267932 Japanese Utility Model Publication No. 4-48003

  In the conventional collinear antenna 100, the frequency signal supplied from the antenna feeder 132 is a frequency f (f = 2560 MHz), and the sleeve pipe spacings Fg1 to Fg15 of each stage in the first stage sleeve element 111 to the 15th stage sleeve element 125 are set. FIG. 12 shows a theoretical calculation value of the radiation directivity characteristic in the vertical plane (ZX plane) when the thickness is about 5 mm. In this case, the electrical length of the coaxial cable 131 between the sleeve feeding portions in each stage is adjusted to be slightly shorter than 1λ when the wavelength of the frequency f is λ so that the tilt angle is about 5 ° downward. ing. In the radiation directivity characteristic shown in FIG. 12, the gain is normalized to 0 dB. Referring to FIG. 12, the first-stage sleeve element 111 to the 15th-stage sleeve element 125 are fed in substantially the same phase, and the horizontal direction is ± 95 °. A radiation beam having almost the same intensity is generated. In this case, only a small number of side lobes are generated, and the side lobe level is about −13 dB or less. FIG. 13 shows measured values of radiation directivity characteristics in the vertical plane (ZX plane) of the conventional collinear antenna 100 under the same conditions. In FIG. 13, the gain is normalized to 0 dB. With reference to the radiation directivity characteristic shown in FIG. 13, a radiation beam having substantially the same intensity is generated in the horizontal direction of ± 95 °, and the tilt angle is about 5 °. You can see that. However, there is a problem that a large number of side lobes are generated in a direction that is not originally desired from the theoretical calculation value.

  Accordingly, an object of the present invention is to provide a collinear antenna capable of reducing side lobes in a collinear antenna stacked in multiple stages.

  In order to achieve the above object, a collinear antenna of the present invention comprises an upper sleeve and a lower sleeve that are arranged to face each other. The sleeve elements stacked in multiple stages, and the sleeve elements stacked in the multiple stages A transmission line that feeds power to the power feeding part of each of the sleeve elements that is formed by passing through the upper sleeve and the lower sleeve, and a power feeding part that supplies a frequency signal to the transmission line. The most important feature is that the distance between the upper sleeve and the lower sleeve constituting the element is set to be gradually increased from the lower stage to the upper stage.

  In the collinear antenna of the present invention, since the interval between the upper sleeve and the lower sleeve constituting the sleeve element is set to be gradually increased from the lower stage toward the upper stage, it is transmitted to the sleeve element of each stage. The excitation amplitude increases gradually from the lower stage to the upper stage. Thereby, the side lobe of a collinear antenna can be reduced.

It is a figure which shows schematic structure of the collinear antenna concerning the Example of this invention. It is a figure which shows the structure of the collinear antenna concerning the Example of this invention. It is a figure which shows the theoretical calculation value of the radiation directional characteristic in the vertical plane in the collinear antenna concerning this invention. It is a figure which shows the actual value of the radiation directional characteristic in the vertical surface in the collinear antenna concerning this invention. It is a perspective view which shows the structure of the unit sleeve in the collinear antenna of this invention. It is sectional drawing which shows the detailed structure of the uppermost sleeve element of the collinear antenna concerning this invention. It is sectional drawing which shows the detailed structure of the sleeve element of the intermediate | middle stage of the collinear antenna concerning this invention. It is a figure which shows the space | interval between the sleeve electric power feeding parts of the collinear antenna concerning this invention. It is sectional drawing which shows the other detailed structure of the sleeve element of the intermediate | middle stage of the collinear antenna concerning this invention. It is sectional drawing and a top view which show the structure of the gap | interval spacer of the sleeve element in the collinear antenna of this invention. It is a figure which shows an example of a structure of the conventional collinear antenna. It is a figure which shows the theoretical calculation value of the radiation directivity characteristic in the vertical plane in the conventional collinear antenna. It is a figure which shows the actual value of the radiation directivity characteristic in the vertical plane in the conventional collinear antenna.

FIG. 1 shows a schematic configuration of a collinear antenna according to an embodiment of the present invention.
The collinear antenna 1 according to the embodiment of the present invention shown in FIG. 1 is configured by stacking 15 sleeve elements each constituting a dipole antenna. That is, the second-stage sleeve element 12 is stacked on the first-stage sleeve element 11, and the third-stage sleeve element 13 is stacked on the second-stage sleeve element 12. The fourth-stage sleeve element 14 is stacked, the fifth-stage sleeve element 15 is stacked on the fourth-stage sleeve element 14, and the sixth-stage sleeve element 16 is stacked on the fifth-stage sleeve element 15. Has been. Furthermore, a 15th-stage sleeve element 25 is stacked on the uppermost stage, and a 14th-stage sleeve element 24 is stacked below the 15th-stage sleeve element 25. The first-stage sleeve element 11 to the 15th-stage sleeve element 25 are supplied with power from a coaxial cable 31 serving as a transmission line at substantially the center thereof, and an antenna power supply part 32 is connected to the lower end of the coaxial cable 31. Yes. A frequency signal having a frequency f1 is supplied from the antenna feeding unit 32.

FIG. 2 shows the configuration of the collinear antenna 1 according to the present invention. As shown in FIG. 2, each sleeve element 11 to 25 constituting the collinear antenna 1 is a cylindrical upper stage made of metal as will be described later. The sleeve pipe and the lower sleeve pipe face each other to form a dipole antenna, and a predetermined sleeve pipe interval at which the upper sleeve element and the lower sleeve element face each other is Fg ₁ to Fg ₁₅ . The sleeve pipe intervals Fg _{1 to} Fg ₁₅ in the sleeve elements 11 to 25 are gradually increased from the lower stage toward the upper stage. For example, the sleeve pipe interval Fg ₁ of the first stage sleeve element 11 is about 1 mm and the second stage. The sleeve pipe spacing Fg ₂ of the sleeve element 12 is about 2 mm, the sleeve pipe spacing Fg ₃ of the third stage sleeve element 13 is about 3 mm, and the sleeve pipe spacing Fg ₄ of the fourth stage sleeve element 14 is about 4 mm. 15 to 15 stage sleeve element 25 sleeve pipe spacing Fg ₅ ~Fg ₁₅ is set to about 5 mm.

  Further, the electrical length of the upper sleeve pipe and the lower sleeve pipe constituting the dipole antenna is about λ1 / 4 when the wavelength of the frequency f1 is λ1, and the distance between the feeding portions of the adjacent sleeve elements 11 to 25 is The electrical length is not longer than about 1λ1. The first-stage sleeve element 11 to the 15th-stage sleeve element 25 fed from the coaxial cable 31 are excited in the same phase by the frequency signal of the frequency f1 in the respective feeding portions. For this reason, the electrical length of the coaxial cable 31 between the adjacent feeding portions of the first-stage sleeve element 11 to the 15th-stage sleeve element 25 is about 1λ1 or an integral multiple thereof. However, when the radiation beam of the collinear antenna 1 is tilted downward, the electrical length of the coaxial cable 31 between the feeding portions at each stage is slightly shorter than about 1λ1. The physical length of the coaxial cable 31 is a length corresponding to the wavelength shortening rate of the coaxial cable 31.

In the collinear antenna 1 according to the present invention, the frequency signal supplied from the antenna feeding unit 32 is set to the frequency f1 of 2560 MHz, and the sleeve pipe intervals Fg _{1 to} Fg ₁₅ of each stage in the first-stage sleeve element 11 to the 15th-stage sleeve element 25. FIG. 3 shows theoretical calculation values of the radiation directivity characteristics in the vertical plane (ZX plane) when the distance is about 1 mm to about 5 mm as described above. In this case, the electrical length of the coaxial cable 31 between the sleeve feeding portions in each stage is adjusted to be slightly shorter than 1λ1 so that the tilt angle is directed downward by about 5 °. In FIG. 3, the gain is normalized to 0 dB, and referring to the radiation directivity characteristic shown in FIG. 3, the first-stage sleeve element 11 to the 15th-stage sleeve element 25 are supplied with substantially the same phase and have a horizontal direction of ± 95 °. A sharp radiation beam with almost the same intensity is generated. In this case, the side lobe is reduced as shown by the wavy circle range shown in the figure, and the side lobe level is about -17 dB or less. And the measured value of the radiation directivity characteristic in the vertical plane (ZX plane) of the collinear antenna 1 concerning this invention which made the said conditions the same is shown in FIG. In FIG. 4, the gain is normalized to 0 dB. With reference to the radiation directivity characteristic shown in FIG. 4, a sharp radiation beam having substantially the same intensity is generated in the horizontal direction of ± 95 °, and the tilt angle is about 5 You can see that it is °. In this case, it can be seen that the side lobes that are larger than the theoretical calculation values are reduced, as shown by the range of the wavy line shown in the figure.

Consider that the side lobe is reduced in this way.
Since the conventional collinear antenna 1 shown in FIG. 11 has a structure in which the stacked sleeve elements are excited by the series feeding method from the lowest stage to the uppermost stage. The excitation amplitude ratio for the sleeve element has been determined. In addition, in the structure of the conventional collinear antenna 100, design related to various antenna performances such as tilt angle control for directing the beam in a desired direction and the sleeve length for resonating each sleeve element itself at the excitation frequency are fixed. Due to the intervening factor, the design factor for controlling the excitation amplitude of the high-frequency signal transmitted to the sleeve element at each stage is limited. As a result, in the conventional collinear antenna 100, the excitation amplitude of the high-frequency signal transmitted to the sleeve elements 111 to 125 of each stage is substantially the same, which is originally desired in addition to the main beam radiated in a desired angular direction. It is considered that unnecessary radiation (side lobe) in a direction with no angle is likely to occur.

Therefore, in the collinear antenna 1 according to the present invention, the sleeve pipe intervals Fg _{1 to} Fg ₁₅ where the upper sleeve element and the lower sleeve element of the sleeve elements 11 to 25 of each stage face each other are gradually increased from the lower stage toward the upper stage. To change. As a result, the impedance inherent to the antenna in each of the sleeve elements 11 to 25 changes so as to gradually increase from the lower stage to the upper stage, and the excitation amplitude in the sleeve elements 11 to 25 of each stage is not equal, but from the lower stage. The non-uniform amplitude becomes gradually larger toward the upper stage. As a result, the side lobe in the radiation directivity characteristic of the collinear antenna 1 according to the present invention can be reduced.

Next, the structure of the unit sleeve 2 which comprises the sleeve elements 11-25 of each step is shown in a perspective view in FIG.
As shown in FIG. 5, the unit sleeve 2 is arranged such that the lower end surface of a cylindrical upper sleeve pipe 2a made of metal faces the upper end surface of a cylindrical lower sleeve pipe 2b. The first-stage sleeve element 11 to the fifteenth-stage sleeve element 25 of the collinear antenna 1 according to the present invention shown in FIG. 2 are constituted by the unit sleeve 2 shown in FIG. That is, the first-stage sleeve element 11 is configured by facing the upper-stage sleeve pipe 11a and the lower-stage sleeve pipe 11b, and the second-stage sleeve element 12 is configured by facing the upper-stage sleeve pipe 12a and the lower-stage sleeve pipe 12b, The third-stage sleeve element 13 is configured by facing an upper-stage sleeve pipe 13a and a lower-stage sleeve pipe 13b, and the fourth-stage sleeve element 14 is configured by facing an upper-stage sleeve pipe 14a and a lower-stage sleeve pipe 14b. The eye sleeve element 15 is configured by an upper sleeve pipe 15a and a lower sleeve pipe 15b facing each other. The uppermost fifteenth sleeve element 25 is constituted by an upper sleeve pipe 25a and a lower sleeve pipe 25b facing each other.

Next, the configuration of the uppermost sleeve element 40 corresponding to the 15th-stage sleeve element 25 in the collinear antenna 1 according to the present invention shown in FIG.
As shown in FIG. 6, the uppermost sleeve element 40 has a lower end surface of a cylindrical upper sleeve pipe 40a made of metal and an upper end surface of a cylindrical lower sleeve pipe 40b made of metal facing each other. Has been placed. A metal upper joint 40c is fitted inside the lower end of the upper sleeve pipe 40a, and a metal lower joint 40d is fitted inside the upper end of the lower sleeve pipe 40b. In the lower sleeve pipe 40b, a coaxial cable 50 inserted through an adjacent lower stage sleeve element is inserted, and the coaxial cable 50 is inserted into an insertion hole formed at a substantially central portion of the lower joint 40d. The outer conductor 50c of the coaxial cable 50 is electrically connected to the lower joint 40d.

  Further, the outer conductor 50c of the coaxial cable 50 is removed at the boundary portion between the lower sleeve pipe 40b and the upper sleeve pipe 40a, and the insulator 50b that holds the center conductor 50a substantially on the center axis of the outer conductor 50c is exposed. . The insulator 50b is removed at a portion beyond the boundary portion to expose the central conductor 50a, and the central conductor 50a is inserted into an insertion hole formed at a substantially central portion of the upper joint 40c. In the insertion hole, the upper joint 40c is electrically connected. In this way, the upper joint 40c and the lower joint 40d arranged to face each other with the sleeve pipe interval Fg constitute a sleeve feeding portion 40e serving as an excitation slot, and the sleeve feeding portion 40e constitutes a dipole antenna. The upper sleeve pipe 40a and the lower sleeve pipe 40b are excited by the frequency signal transmitted through the coaxial cable 50.

Next, FIG. 7 is a cross-sectional view of the configuration of the intermediate stage sleeve element 41 corresponding to the sleeve elements excluding the 15th stage sleeve element 25 in the collinear antenna 1 according to the present invention shown in FIG.
The intermediate sleeve element 41 shown in FIG. 7 is arranged such that the lower end surface of a cylindrical upper sleeve pipe 41a made of metal and the upper end surface of a cylindrical lower sleeve pipe 41b made of metal face each other. ing. A metal upper joint 41c is fitted inside the lower end of the upper sleeve pipe 41a, and a metal lower joint 41d is fitted inside the upper end of the lower sleeve pipe 41b. A coaxial cable 50 led out from an adjacent lower stage sleeve element is inserted into the lower sleeve pipe 41b, and the coaxial cable 50 is an insertion hole formed substantially at the center of the lower joint 41d. The outer conductor 50c is electrically connected to the lower joint 41d. The coaxial cable 50 led out from the lower sleeve pipe 41b is inserted into the upper sleeve pipe 41a, and the coaxial cable 50 is inserted into an insertion hole formed at substantially the center of the upper joint 41c, and the outer conductor 50c. Are electrically connected to the upper joint 41c.

  Further, the outer conductor 50c of the coaxial cable 50 is removed at the boundary between the lower sleeve pipe 41b and the upper sleeve pipe 41a, and the insulator 50b is exposed. The center conductor 50a located inside the insulator 50b and the upper joint 41c and the lower joint 41d arranged to face each other constitute a sleeve feeding portion 41e serving as an excitation slot. The sleeve feeding portion 41e forms a dipole antenna. The upper sleeve pipe 41a and the lower sleeve pipe 41b constituting the above are excited by the frequency signal transmitted through the coaxial cable 50. The coaxial cable 50 is led out from the upper end of the upper sleeve pipe 41a toward the upper sleeve element.

  In FIG. 8, the distance L between the sleeve feeding portion 42 e of the n-th stage sleeve element 42 and the sleeve feeding portion 43 e of the n + 1-th stage sleeve element 43 adjacent to the n-th stage sleeve element 42 is n + 1-th stage sleeve element 43. This corresponds to the physical length of the coaxial cable 50 between the two. In the collinear antenna 1 according to the present invention shown in FIGS. 1 and 2, when the radiation beam is not tilted, in each sleeve feeding portion of the first-stage sleeve element 11 to the 15th-stage sleeve element 25 fed from the coaxial cable 31. Excited in the same phase by the frequency signal of frequency f1. In addition, when the radiation beam of the collinear antenna 1 is tilted downward, a phase difference is generated in the excitation phase in the sleeve feeding portion of each stage. That is, in the coaxial cable 50 shown in FIG. 8, by changing the physical length L between the adjacent sleeve feeding portion 42e and the sleeve feeding portion 43e, the excitation phase between the sleeve feeding portion 42e and the sleeve feeding portion 43e is changed. A phase difference is generated. In this case, the radiation length of the collinear antenna 1 is changed by changing the length of the physical length L so that the electrical length of the coaxial cable 50 between the adjacent sleeve feeding portion 42e and the sleeve feeding portion 43e is slightly shorter than about 1λ1. It can be tilted downward. The physical length L of the coaxial cable 50 is a length obtained by multiplying the electrical length of the coaxial cable 50 by the wavelength reduction rate.

Next, FIG. 9 is a sectional view showing a modified example of the configuration of the intermediate sleeve element 41 corresponding to the sleeve elements excluding the 15th-stage sleeve element 25 in the collinear antenna 1 according to the present invention shown in FIG.
In the intermediate sleeve element 44 shown in FIG. 9, the upper sleeve pipe 44a and the lower sleeve pipe 44b are fixed to face each other with an insulating gap spacer 45 with a predetermined gap as the sleeve pipe interval Fg. In this case, there is a lower end surface of the upper sleeve pipe 44a in which the upper joint 44c is inserted inside the lower end portion, and an upper end surface of the lower sleeve pipe 44b in which the metal lower joint 44d is inserted and inserted inside the upper end portion. A ring-shaped portion protruding inward from the inner peripheral surface of the gap spacer 45 is inserted therebetween.

Here, the structure of the gap spacer 45 is shown in FIGS. FIG. 10A is a front view showing the structure of the gap spacer 45 in a sectional view, and FIG. 10B is a top view showing the structure of the gap spacer 45. The main body 45a of the gap spacer 45 shown in these drawings has a cylindrical shape with a through hole 45c formed throughout, and a ring-shaped portion 45e that protrudes inward is formed at a substantially central portion of the inner peripheral surface. An insertion hole 45d through which the coaxial cable 50 is inserted is provided substantially at the center of the ring-shaped portion 45e. The thickness of the ring-shaped portion 45e is substantially the same as the sleeve pipe interval Fg in the provided sleeve element.
When assembling the intermediate sleeve element 44, the upper portion of the lower sleeve pipe 44b is inserted into the through hole 45c of the gap spacer 45 from below, and the coaxial cable 50 is inserted into the insertion hole 45d of the gap spacer 45 at this time. . Next, the coaxial cable 50 is inserted into the upper joint 44c from below, and the lower portion of the upper sleeve pipe 44a is inserted into the through hole 45c of the gap spacer 45 from above. As a result, the upper surface of the lower sleeve pipe 44b and the lower surface of the upper sleeve pipe 44a are assembled so as to face each other with a distance corresponding to the thickness of the ring-shaped portion 45e of the gap spacer 45. By configuring each stage 11-25 in the collinear antenna 1 with the intermediate-stage sleeve element 41 shown in FIG. 9, the sleeve pipe interval Fg can be reliably set and maintained at the specified interval in each stage 11-25. In addition, the mechanical strength can be improved. In the uppermost fifteenth sleeve element 25, the central conductor of the coaxial cable 50 is connected to the upper joint 44c, and the coaxial cable 50 is deformed to be cut at that portion.

In the collinear antenna according to the present invention described above, the sleeve pipe interval Fg, which is the interval between the feeding portions provided in each unit sleeve, is confronted while maintaining the parallelism between the upper and lower joints, which are conductors. Each joint is electrically connected to an upper sleeve pipe or a lower sleeve pipe forming an element. The surfaces where the joints face each other are smooth, and the capacity between the joints changes depending on the distance between the sleeve pipe intervals Fg and the area of the joints facing each other. The capacitance (capacitance) C between the joints is
C = εr · ε0 * S / Fg
The capacitance C can be obtained from the derivation formula. In the derivation formula, εr is the relative permittivity of the dielectric interposed in the sleeve pipe interval Fg, ε0 is the permittivity in vacuum, and S is the area of the opposing joint.

  From this derivation formula, for example, when the parallel interval between the joints is narrowed to reduce the sleeve pipe interval Fg, the capacity C increases. On the other hand, when the parallel interval between the joints is increased to increase the sleeve pipe interval Fg, the capacity C decreases. Thus, the capacitance C between the joints changes depending on the dimension of the sleeve pipe interval Fg, and the feeding point impedance of each unit sleeve changes. When the feeding point impedance of each unit sleeve changes, the current amplitude at the excitation frequency changes, and as a result, the excitation amplitude mode of each unit sleeve stacked in multiple stages can be electrically controlled. By utilizing this, the collinear antenna according to the present invention controls the radiation directivity characteristics of the collinear antenna by changing the feeding portion gap Fg in each unit sleeve and adjusting the excitation amplitude of each unit sleeve. ing.

  Such a collinear antenna according to the present invention is configured by stacking sleeve elements in a straight line in multiple stages, and a part of the number of collinear antenna arrangement stages, or a sleeve pipe interval of a sleeve feeding portion in a plurality of stages of sleeve elements. By changing Fg, the excitation amplitude of the high-frequency signal is changed, and the radiation directivity characteristic of the collinear antenna is controlled. In particular, the characteristics of the main beam that radiates in a desired radiation direction can be maintained, and a series-fed collinear antenna in which the side lobe level that is unnecessary radiation is reduced can be obtained. Further, as a design value applied to the collinear antenna, the above-mentioned frequency 2560 MHz is a representative value, and other frequencies may be adopted. Further, as for the dimension of the sleeve pipe interval Fg, the above-described dimension is one design example, and is not limited to this dimension as long as the dimension gradually increases from the lower stage to the upper stage.

The number of stacks of sleeve elements is changed depending on the directivity required for the collinear antenna. In this case, the number of stacks of sleeve elements satisfying the performance required for the main beam having radiation directivity characteristics, the interval between sleeve elements involved in directivity synthesis, and the like are set.
Furthermore, in the collinear antenna according to the present invention, the coaxial cable used as the transmission line is a coaxial cable such as a semi-rigid cable, a semi-flexible cable, or a flexible cable, or a microstrip line or a coplanar using a dielectric substrate as the transmission line. Lines, triplate lines, etc. may be used.

1 collinear antenna, 2 unit sleeve, 2a upper sleeve pipe, 2b lower sleeve pipe, 11 first stage sleeve element, 11a upper sleeve pipe, 11b lower sleeve pipe, 12 second stage sleeve element, 12a upper sleeve pipe, 12b lower sleeve Pipe, 13 3rd sleeve element, 13a Upper sleeve pipe, 13b Lower sleeve pipe, 14 4th sleeve element, 14a Upper sleeve pipe, 14b Lower sleeve pipe, 15 5th sleeve element, 15a Upper sleeve pipe, 15b Lower stage Sleeve pipe, 16 6th-stage sleeve element, 24 14th-stage sleeve element, 25 15th-stage sleeve element, 25a Upper-stage sleeve pipe, 25b Lower-stage sleeve pipe, 31 Coaxial cable, 32 Antenna feed section, 40 Uppermost-stage three Element, 40a Upper sleeve pipe, 40b Lower sleeve pipe, 40c Upper joint, 40d Lower joint, 40e Sleeve feeder, 41 Middle sleeve element, 41a Upper sleeve pipe, 41b Lower sleeve pipe, 41c Upper joint, 41d Lower joint, 41e Sleeve feeding section, 42 n-th stage sleeve element, 42e Sleeve feeding section, 43 n + 1 stage sleeve element, 43e Sleeve feeding section, 44 middle stage sleeve element, 44a Upper stage sleeve pipe, 44b Lower stage sleeve pipe, 44c Upper stage joint, 44d Lower stage Joint, 45 Gap spacer, 45a body part, 45c through hole, 45d insertion hole, 45e ring-shaped part, 50 coaxial cable, 50a center conductor, 50b insulator, 50c outer conductor, 100 collinear N, 111 1st stage sleeve element, 112 2nd stage sleeve element, 113 3rd stage sleeve element, 114 4th stage sleeve element, 115 5th stage sleeve element, 116 6th stage sleeve element, 125 15th stage sleeve element 131 coaxial cable, 132 antenna feeder, Fg _{1 to} Fg ₁₅ sleeve pipe spacing

Claims (2)

A sleeve element composed of an upper sleeve and a lower sleeve arranged to face each other and stacked in multiple stages,
A transmission line that feeds through the sleeve elements stacked in multiple stages and feeds power to each of the sleeve elements, the upper sleeve and the lower sleeve being configured to face each other;
A power supply section for supplying a frequency signal to the transmission line,
The collinear antenna is characterized in that an interval between the upper sleeve and the lower sleeve constituting the sleeve element is set to an interval that gradually increases from the lower stage toward the upper stage.   The distance between the upper sleeve and the lower sleeve constituting the lowermost sleeve element is about 1 mm, and the distance between the upper sleeve and the lower sleeve constituting the uppermost sleeve element is about 5 mm. The collinear antenna according to claim 1, wherein the collinear antenna is provided.

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