JP2007129551A - Antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna having excellent productive efficiency while having a wideband. <P>SOLUTION: The antenna 1 has radiators 2 and 3 having loops having the same size. Accordingly, parts can be used in common while one kind of a jig for bending bars and pipes for conductors when the radiators 2 and 3 are formed is also sufficient. Consequently, the productive efficiency of the antenna can be improved. The impedance of parallel lines LN is enhanced by adjusting the line diameters and intervals of the parallel lines LN, and a VSWR can be lowered and a gain increased in the wideband by connecting T matching apparatuses 6 to the radiator 2. The VSWR and the gain can be adjusted by a matching element 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an antenna, and more particularly to an antenna with excellent production efficiency.

  There are various types and shapes of antennas depending on the purpose of use. For example, an antenna having a conductor rod in a loop shape and a radiator (hereinafter also referred to as a loop radiator) fed between both ends thereof is known.

  As an example of an antenna having a loop radiator, Japanese Utility Model Laid-Open No. 48-049930 (Patent Document 1) has a waveguide, a radiator, and a reflector formed in an annular shape, and these elements are placed horizontally. A transmission / reception antenna attached to be suspended from a metal pipe is disclosed. This antenna makes it possible to prevent deformation and breakage due to strong winds by stabilizing the mechanical strength.

In the loop radiator, the frequency band characteristics can be adjusted by changing the length (peripheral length) of the entire circumference of the loop. As a conventional antenna using such a property, there is an antenna that includes two loop radiators having different perimeters and can widen a band by feeding phase difference to the two loop radiators.
Japanese Utility Model Publication No. 48-049930

  When the peripheral lengths of the plurality of loop radiators are different from each other, various problems arise in producing the antenna. First, the number of parts increases. Further, when forming a loop radiator, it is necessary to bend a conductor rod or tube, and a jig for that purpose is also required for each loop diameter. These points can be a factor of reducing the efficiency in producing the antenna.

  However, the band cannot be expanded even if the diameters of the plurality of loop radiators are equal to each other. Therefore, in the conventional antenna, performance is given priority over production efficiency.

  An object of the present invention is to provide an antenna having excellent production efficiency and a wide band.

  In summary, the present invention is an antenna that includes a first radiator, a second radiator, a parallel line, a matching device, and a matching adjustment element. The first radiator is formed in a loop shape. The second radiator has the same shape as the first radiator, and is arranged in parallel with the first radiator at a distance of a quarter of the center wavelength of the radio wave along the transmission / reception direction of the radio wave. The parallel line connects the first and second radiators. The matching unit is provided corresponding to the first radiator. The alignment element is loaded on the first radiator.

  Preferably, the parallel line includes first and second conductors having the same diameter. The impedance of the parallel lines changes according to the ratio of the distance between the first and second conductors with respect to the diameter. The ratio is determined to be between 8 and 15.

More preferably, the ratio is defined to be between 10 and 12.
Preferably, the first radiator has first and second feeding points. The second radiator has third and fourth feeding points. The parallel line includes a first conducting wire and a second conducting wire. The first conducting wire is provided so as to extend from the third feeding point through the first feeding point. The second conducting wire is provided so as to extend from the fourth feeding point through the second feeding point. The matching adjustment element includes: a first tip portion that is a portion from the position of the first feeding point to an end opposite to the third feeding point in the first conducting wire; A second tip portion that is a portion from the position of the second feeding point to the end opposite to the fourth feeding point.

  Preferably, a 1st radiator and a matching device are comprised by conducting wire. The wire diameter of the matching device is smaller than the wire diameter of the first radiator.

More preferably, any of the antennas described above further includes a reflector.
More preferably, the antenna further comprises at least one director.

  More preferably, the radio wave is a UHF (Ultra High Frequency) band radio wave.

  According to the antenna of the present invention, since each of the two radiators formed in a loop shape has the same size (same peripheral length), the production efficiency can be increased.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

[Embodiment 1]
FIG. 1 is a schematic diagram illustrating a basic configuration of the antenna according to the first embodiment.

  Referring to FIG. 1, antenna 1 is an antenna that transmits radio waves in the UHF (Ultra high frequency) band. A radio wave WV1 indicates a radio wave transmitted from the antenna 1. The antenna 1 may be a receiving antenna. Further, the radio wave WV1 may be a radio wave in a VHF (Very high frequency) band.

  The antenna 1 includes radiators 2 and 3, parallel lines LN connecting the radiators 2 and 3, and a T matching unit 6. These elements are constituted by “conductive wires”. The “conductive wire” in the present invention includes a metal wire, a rod, a tube, and the like.

  Radiator 2 is formed in a loop shape and has feed points 2A and 2B. Radiator 3 has the same shape as radiator 2. That is, the perimeter of radiator 3 is the same as that of radiator 2. Radiator 3 is arranged in parallel with radiator 2 along the transmission direction of radio wave WV1, with a distance of about one quarter (λ / 4) of center wavelength λ of radio wave WV1. Radiator 3 has feed points 3A and 3B.

  The circumferential length of each of the radiators 2 and 3 is set to be substantially equal to the length of one wavelength of the center wavelength λ, for example. A loop radiator having a circumference of one wavelength can be approximated to a structure in which two half-wave dipole antennas are arranged, and thus is superior in characteristics such as gain than one half-wave dipole antenna.

  The parallel line LN is provided to feed the radiators 2 and 3. The parallel line LN includes conducting wires 4 and 5 having the same diameter. The directions of the conducting wires 4 and 5 are parallel to the transmission / reception direction of the radio wave WV1.

  The conducting wire 4 electrically connects the feeding points 2A and 3A. The conducting wire 5 electrically connects the feeding points 2B and 3B. As a result, the radiators 2 and 3 are fed in the same phase, and the directivity is enhanced in front of the radiator 3, that is, in the transmission direction of the radio wave WV1.

  Since the radiators 2 and 3 have the same perimeter, their impedances are the same. Further, since the perimeter is about one wavelength, the impedance is generally about 120Ω. In the present embodiment, the impedance (characteristic impedance) of the parallel line is increased by adjusting the wire diameter and interval of the parallel line LN constituted by the conductive wires 4 and 5. By increasing the impedance of the parallel line LN, the impedance at the feeding points 2A and 2B is increased, and the VSWR (Voltage Standing Wave Ratio) can be lowered.

  The T matching unit 6 is provided corresponding to the radiator 2. The T matching unit 6 matches the impedance of the radiator 2 with the impedance of the parallel line LN. Thereby, the loss of the antenna 1 can be reduced. Matching is possible by changing the wire diameter and length of the T matching device 6 and the distance between the radiator 2 and the T matching device 6.

  In a state where the antenna 1 is installed, both ends of the T matching device 6 are connected to the intersection of the horizontal axis passing through the center point of the loop of the radiator 2 and the loop of the radiator 2. Both ends of the T matching device 6 are provided so as to be parallel to the X1 direction of FIG. In the T matching unit 6, the portions other than both ends are folded back toward the feed points 2A and 2B.

  The antenna 1 further includes a matching adjustment element 8 loaded on the radiator 2. The matching adjustment element 8 corresponds to the “matching adjustment element” of the present invention. The matching adjustment element 8 functions to further reduce the loss of the antenna 1 by adjusting the above-described matching by the T matching unit 6. Thereby, the gain and VSWR of the antenna 1 are adjusted to be optimum.

  The alignment adjusting element 8 includes a leading end portion 4A of the conducting wire 4 and a leading end portion 5A of the conducting wire 5. The conducting wire 4 is provided so as to extend from the feeding point 3A through the feeding point 2A. The conducting wire 5 is provided so as to extend from the feeding point 3B through the feeding point 2B.

  4 A of front-end | tip parts are the parts from the position of feeding point 2A to the end on the opposite side to feeding point 3A among the conducting wires 4. FIG. 5 A of front-end | tip parts are the parts from the position of the feeding point 2B to the end on the opposite side to the feeding point 3B among the conducting wires 5. The impedance of the radiator 2 is adjusted by the inductance component or capacitance component of the tip portions 4A and 5A. Specific adjustment methods include a method of changing the distance between the tip portions 4A and 5A (widening or narrowing the distance between the tip portions 4A and 5A) and a method of changing the length of the tip portions 4A and 5A.

  The matching adjustment element 8 is not limited to the configuration shown in FIG. 1 and may be a capacitive element or a coil. However, by using the leading end portion of the conducting wire as the matching adjustment element 8, the number of parts can be reduced and the structure of the antenna can be simplified.

  A conventional antenna having a plurality of loop radiators generally widens the band by changing the circumferential lengths of the loop radiators. On the other hand, the antenna 1 includes radiators 2 and 3 having the same loop size. This makes it possible to share parts, and only one type of jig for bending the conductor rods and tubes when forming the radiators 2 and 3 is sufficient. Therefore, the antenna production efficiency can be increased. Further, by adjusting the wire diameter and interval of the parallel line LN to increase the impedance of the parallel line LN, and connecting the T matching unit 6 to the radiator 2, the VSWR is lowered and the gain is improved in a wide band. be able to. Further, the VSWR and the gain can be adjusted by the matching adjustment element 8. From the above, according to the present embodiment, it is possible to provide an antenna having excellent production efficiency and a wide band.

  Next, a specific example of the antenna 1 is shown. In the following, the X1 direction and the X2 direction in FIG. 1 are referred to as “rear direction” and “side direction” of the antenna 1, respectively. The X1 direction and the X2 direction indicate a parallel direction and a vertical direction with respect to the transmission direction of the radio wave WV1, respectively.

  FIG. 2 is a view of the antenna according to the first embodiment when viewed from the back side. 2 shows a cross section of the antenna on a plane that passes through the feed points 2A and 2B of FIG. 1 and is parallel to the X2 direction.

FIG. 3 is an enlarged view of a portion A in FIG.
2 and 3, antenna 1A is an antenna that can transmit and receive radio waves in the UHF low channel band. Here, the “UHF low channel band” means a frequency band of 470 to 596 MHz.

  The antenna 1 </ b> A has a configuration in which the antenna 1 shown in FIG. 1 further includes connection fittings 11 and 12, an insulating portion 13 </ b> A and a metal rod 14. The diameter of the radiator 2 is about 195 mm. The space | interval of the conducting wires 4 and 5 is about 46 mm.

  Each of the conducting wires 4 and 5 is attached to the insulating portion 13A by connecting fittings 11 and 12. The radiator 2 is attached to the insulating portion 13 </ b> A by the connection fitting 12. Thereby, the conducting wires 4 and 5 are electrically connected to the radiator 2. The insulating part 13A is installed on the metal rod 14.

  The connection fitting 12 is, for example, a rivet or a metal screw. The two connection fittings 12 are provided so as to pass through the feeding points 2A and 2B of the radiator 2, respectively, and the distance between them is about 30 mm.

  In FIG. 2, the center point M is the center point of the loop of the radiator 2. The horizontal axis H is a horizontal axis when the antenna 1 is installed, and passes through the center point M. Both ends of the T matching device 6 are provided on the intersection of the horizontal axis H and the radiator 2.

FIG. 4 is a view of the antenna 1A of FIG. 2 as viewed from the side.
FIG. 5 is an enlarged view of portion B of FIG.

  Referring to FIGS. 4 and 5, the diameter of each of radiators 2 and 3 is about 8 mm. The distance between the radiators 2 and 3 is about 135 mm.

  The distance between the T matcher 6 and the radiator 2 is about 30 mm. The wire diameter of the conducting wire 4 is about 4 mm. Further, the length of the tip portion 4A constituting the matching adjustment element 8 is about 35 mm. Although the conducting wire 5 is not shown in FIGS. 4 and 5, the wire diameter of the conducting wire 5 is about 4 mm, and the length of the tip portion 5A of the conducting wire 5 is about 35 mm.

  The conducting wires 4 and 5 are connected to two feeding points (feeding points 3A and 3B in FIG. 1) of the radiator 3 by the same connection form as in FIGS. Further, radiator 3 and conducting wires 4 and 5 are attached to insulating portion 13B. The insulating portion 13B is installed on the metal rod 14.

Next, the relationship between the wire diameter of the conducting wires 4 and 5 and the interval will be described.
In the case of the antenna 1A, considering that the impedance of the radiators 2 and 3 is about 120Ω, the preferable impedance range of the parallel line LN is about 330 to about 400Ω, and the more preferable range is about 360 to about 380Ω. . By setting the impedance of the parallel line in such a range, it becomes possible to improve the VSWR over the entire frequency band of 470 to 590 MHz.

  In addition, since the feeding point impedance at the feeding points 2A and 2B at this time is about 200Ω, matching with the coaxial cable is facilitated when feeding the antenna 1A from the transmission / reception circuit (not shown) via the coaxial cable.

When the wire diameter of the conducting wires 4 and 5 is d and the distance between the conducting wires 4 and 5 is D, the impedance of the parallel line LN is generally expressed as 276 × log ₁₀ (2D / d). As described above, the impedance of the parallel line LN changes according to the ratio of the distance D to the wire diameter d (= D / d). If D / d is between 8 and 15, the impedance is between about 330 and about 400Ω. If D / d is between 10 and 12, the impedance is between about 360 and about 380Ω. In the antenna shown in FIGS. 2 to 5, D / d = 46/4 = 11.5 is set.

  In setting the wire diameter d and the distance D so as to satisfy the above-mentioned D / d condition, it is necessary to consider the installation conditions of the antenna. In particular, when there is a possibility of installing an antenna in an area where there is a large amount of snowfall, it is better to increase the wire diameter of the conducting wires 4 and 5 to widen the interval between the conducting wires 4 and 5. The reason for this is that the possibility of snow falling across the conductors 4 and 5 is reduced, so that it is possible to prevent the problem of breakage and the deterioration of electrical characteristics.

  However, when the wire diameters and intervals of the conducting wires 4 and 5 are increased, there arises a problem that the antenna is enlarged. Conversely, if the wire diameter d of the conducting wires 4 and 5 is small, it is difficult for snow to accumulate between the conducting wires 4 and 5, but the strength of the antenna itself is reduced.

  Considering these points, in the antenna 1A, the wire diameters of the conducting wires 4 and 5 are set to 4 mm. However, if D / d satisfies the above-mentioned range, the wire diameters and intervals of the conducting wires 4 and 5 can be appropriately determined as necessary.

  Similarly, it is necessary to prevent deterioration of electrical characteristics due to snow on the T matching unit 6. For this reason, the wire diameter (about 4 mm) of the T matching device 6 is set smaller than the wire diameter (about 8 mm) of the radiator 2.

  6 is a view of the insulating portion 13A of FIG. 2 as viewed from a direction orthogonal to the surface on which the conducting wires 4 and 5 are installed.

  Referring to FIG. 6, a power feeding cable 15 is connected to the connection fittings 11 and 12. The feeding cable 15 constitutes a parallel line, and is connected to the coaxial cable 17 via a balun (balun: balun). The transformation ratio of the balun 16 is set to 4: 1 (= 200: 50). In many cases, the impedance of the coaxial cable 17 is 50Ω. Therefore, since the antenna 1A and the coaxial cable 17 can be matched, power loss between the transmission / reception device (not shown) and the antenna 1A can be reduced. The balun 16 is configured by using, for example, a transformer or a branch conductor.

  Subsequently, in order to understand the effect of the antenna 1A, a comparative example of the antenna 1A and characteristics of the comparative example will be described. First, a configuration of a conventional antenna including a plurality of loop elements is shown.

  FIG. 7 is a view of a conventional antenna viewed from the same direction as FIG. 7 shows a cross section of the antenna on a plane that passes through the feed points 2A and 2B of FIG. 1 and is parallel to the X2 direction, as in FIG.

  7 and 2, antenna 1B differs from antenna 1A in FIG. 2 in that it includes radiators 2 and 3 of different sizes. In antenna 1B, the loop diameters of radiators 2 and 3 are about 205 mm and about 185 mm, respectively. The distance between the conductors 4 and 5 is about 30 mm, which is narrower in the antenna 1B than in the antenna 1A.

8 is a view of the antenna 1B of FIG. 7 as viewed from the same direction as FIG.
Referring to FIGS. 8 and 4, the difference between antenna 1B and antenna 1A is that the wire diameter of conductive wire 4, the presence / absence of tip portion 4A, the wire diameter of T matcher 6, and T matcher 6 and radiator 2 are different. Is the interval. These differences will be described in order.

  First, the wire diameter of the conducting wire 4 is 8 mm for the antenna 1B and 4 mm for the antenna 1A. Next, the tip 4A is not provided on the antenna 1B. The wire diameter of the T matching unit 6 is 8 mm for the antenna 1B and 4 mm for the antenna 1A. Finally, the distance between the T matching device 6 and the radiator 2 is 20 mm for the antenna 1B and 35 mm for the antenna 1A.

  Next, the configuration of the comparative example will be described. In the comparative example, a part of the antenna 1A or a part of the antenna 1B is changed.

FIG. 9 is a diagram showing a comparative example of the antenna 1A in a table format.
Referring to FIG. 9, for each of the conventional antenna (antenna 1B), the antenna of the present invention (antenna 1A) and the four comparative examples (comparative examples 1 to 4), (1) the loop diameter of radiators 2 and 3 (2) the wire diameter of the conducting wires 4 and 5, (3) the spacing between the conducting wires 4 and 5, (4) the wire diameter of the T matching device 6, and (5) the spacing between the T matching device 6 and the radiator 2. (6 The presence / absence of the matching adjustment element 8 is indicated.

  The comparative example 1 is different from the above (1) with respect to the conventional antenna, and the loop diameters of the two radiators are both about 195 mm.

  In Comparative Example 2, the above (4) and (5) are different from the antenna of the present invention, the wire diameter of the T matching device 6 is about 8 mm, and the distance between the T matching device 6 and the radiator 2 is about 20 mm. .

  The comparative example 3 is different from the above (2) and (3) with respect to the antenna of the present invention, and the wire diameters and intervals of the conducting wires 4 and 5 are about 8 mm and about 30 mm, respectively (D / d = 3.75). .

  In the comparative example 4, the above (6) is different from the antenna of the present invention, and the matching adjustment element 8 is not provided.

  Then, the result of having measured the gain and VSWR about each of Comparative Examples 1-4 and the antenna 1A is shown below. The antenna performance is better as the gain is higher and the VSWR is lower.

FIG. 10 is a diagram showing the results of measuring the gain and VSWR of Comparative Example 1.
FIG. 11 is a diagram showing the results of measuring the gain and VSWR of Comparative Example 2.

FIG. 12 is a diagram showing the results of measuring the gain and VSWR of Comparative Example 3.
FIG. 13 is a diagram showing the results of measuring the gain and VSWR of Comparative Example 4.

FIG. 14 is a diagram illustrating a result of measuring the gain and VSWR of the antenna 1A.
10 to 14, the frequency range in each figure is a range of 470 to 620 MHz including the above-described UHF low channel band. Curves G1 to G5 are curves indicating the gains of Comparative Examples 1 to 4 and the antenna 1A, respectively. Curves V1 to V5 are curves indicating VSWRs of Comparative Examples 1 to 4 and the antenna 1A, respectively.

  In FIGS. 10 to 14, since there are differences in gain change and VSWR change particularly in the frequency range of 470 MHz to 500 MHz, this point will be described.

  In FIG. 10, the decrease in gain is large and changes from about 5.6 dB to about 4.4 dB. Moreover, the rise of VSWR is large. FIG. 10 shows that good characteristics cannot be obtained by simply arranging the sizes of the loop radiators.

  In FIG. 11 and FIG. 12, a decrease in gain and an increase in VSWR are observed as in FIG. However, the decrease in gain is slightly slower than in FIG. 11 and 12, it is necessary to set the impedance of the parallel line LN within a predetermined range and match the impedance of the radiator 2 to the impedance of the parallel line LN in order to obtain good characteristics. Indicates.

  In FIG. 13, the gain change becomes small and the change in VSWR becomes smaller than that in FIG. In addition, the VSWR becomes smaller overall as compared with FIG. In FIG. 14, the change in gain is similar to that in FIG. 13, but the change in VSWR is smaller than that in FIG.

  Comparing FIG. 13 and FIG. 14, the gain in 470 to 560 MHz is higher in FIG. 14 and the VSWR in 470 to 590 MHz is lower. This means that the characteristics of the antenna 1A are good to some extent even without the matching adjustment element 8. However, as a result of adjusting the matching between the radiator 2 and the parallel line LN by the matching adjustment element 8, the characteristics of the antenna 1A are improved. Shows improvement.

  As described above, according to the first embodiment, since the parts can be made common by equalizing the sizes of the two loop radiators, the production efficiency of the antenna can be increased.

  Further, according to the first embodiment, the impedance at the feeding point of the radiator is matched with the impedance determined by appropriately setting the wire diameter and the interval of the parallel lines, so that the VSWR can be obtained in a wide frequency band. Can be lowered. In addition, it is possible to prevent deterioration of the electrical characteristics of the antenna due to snowfall by widening the interval while reducing the wire diameter of the parallel lines.

  Further, according to the first embodiment, it is possible to prevent deterioration of electrical characteristics due to snowfall by appropriately setting the wire diameter of the T matching device.

  Further, according to the first embodiment, the antenna characteristics can be enhanced by using a part of each of the two conducting wires constituting the parallel line as a matching circuit between the radiator and the parallel line. Moreover, the number of parts can be reduced and the structure of the antenna can be simplified.

[Embodiment 2]
FIG. 15 is a top view of the antenna according to the second embodiment.

FIG. 16 is a rear view of the antenna according to the second embodiment.
FIG. 17 is a side view of the antenna according to the second embodiment.

  Referring to FIGS. 15 to 17, antenna 21 further differs from antenna 1 </ b> A shown in FIGS. 2 to 5 in that it includes a reflector 22 and five waveguides 23. Since other parts of antenna 21 have the same configuration as antenna 1A, the following description will not be repeated.

  The reflector 22 and the director 23 are formed in a loop shape using a conducting wire. The loop diameters of the reflector 22 and the director 23 are about 217 mm and about 147 mm, respectively.

  The total length of the antenna 21 is about 1010 mm. The distance between the radiator 2 and the reflector 22 is about 145 mm. The distance between the radiator 3 and the waveguide 23 is about 130 mm. The plurality of waveguides 23 are provided at an interval of about 110 mm. However, each dimension shows an example and is not limited to the above-mentioned values.

  15 to 17 show an example of the configuration of the antenna according to the second embodiment. Therefore, the antenna 21 may include only the reflector 22 of the reflector 22 and the director 23. Alternatively, the antenna 21 may be configured to include a reflector 22 and at least one director 23. The antenna according to the second embodiment can have a higher gain and lower VSWR than the first embodiment by having such a configuration.

  The antenna 21 further includes a mast mounting bracket 24. The mast mounting bracket 24 is attached to the metal rod 14 in order to attach the antenna 21 to the mast (not shown).

FIG. 18 is a diagram showing the gain and VSWR of the antenna 21 shown in FIGS.
Referring to FIG. 18, curve G6 shows a change in gain, and curve V6 shows a change in VSWR. Comparing FIG. 18 with FIG. 14, the antenna 21 has a higher gain overall and a lower VSWR than the antenna 1A.

  As described above, according to the second embodiment, it is possible to improve the characteristics by adding a reflector or a reflector and at least one waveguide to the antenna of the first embodiment.

  In the above description, the frequency band of the antennas of the first and second embodiments is 470 to 596 MHz. This frequency band corresponds to 13 to 33 channels of terrestrial digital broadcasting in Japan. Therefore, the antennas of Embodiments 1 and 2 can be applied as transmission antennas (or reception antennas) for digital terrestrial broadcasting. However, the frequency band of the antenna of the present invention is not limited in this way, and can be appropriately determined according to the application.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a schematic diagram showing a basic configuration of an antenna according to Embodiment 1. FIG. It is the figure which looked at the antenna of Embodiment 1 from the back direction. It is the figure which expanded the part A of FIG. It is the figure which looked at the antenna 1A of FIG. 2 from the side surface direction. It is the figure which expanded the part B of FIG. It is the figure which looked at 13 A of insulation parts of FIG. 2 from the direction orthogonal to the surface where the conducting wires 4 and 5 are installed. It is the figure which looked at the conventional type antenna from the same direction as FIG. It is the figure which looked at the antenna 1B of FIG. 7 from the same direction as FIG. It is a figure which shows the comparative example of 1 A of antennas in a table format. It is a figure which shows the result of having measured the gain and VSWR of the comparative example 1. FIG. It is a figure which shows the result of having measured the gain and VSWR of the comparative example 2. FIG. It is a figure which shows the result of having measured the gain and VSWR of the comparative example 3. FIG. It is a figure which shows the result of having measured the gain and VSWR of the comparative example 4. FIG. It is a figure which shows the result of having measured the gain and VSWR of the antenna 1A. FIG. 6 is a top view of the antenna according to the second embodiment. FIG. 10 is a rear view of the antenna according to the second embodiment. 6 is a side view of an antenna according to Embodiment 2. FIG. It is a figure which shows the gain and VSWR of the antenna 21 shown in FIGS.

Explanation of symbols

  1, 1A, 1B, 21 Antenna, 2, 3 Radiator, 2A, 2B, 3A, 3B Feed point, 4A, 5A Tip, 4, 5 Conductor, 6 T matcher, 8 Matching element, 11, 12 Connecting bracket , 13A, 13B insulation part, 14 metal rod, 15 feeding cable, 16 balun, 17 coaxial cable, 22 reflector, 23 waveguide, 24 mast mounting bracket, H horizontal axis, G1-G6, V1-V6 curve, LN Parallel line, M center point, WV1 radio wave.

Claims (8)

A first radiator formed in a loop;
A second radiator having the same shape as the first radiator and arranged in parallel with the first radiator at a distance of a quarter of the center wavelength of the radio wave along the radio wave transmission / reception direction When,
A parallel line connecting the first and second radiators;
A matching unit provided corresponding to the first radiator;
An antenna comprising: a matching adjustment element loaded on the first radiator. The parallel lines are
Including first and second conductors having equal diameters to each other;
The impedance of the parallel lines changes according to the ratio of the distance between the first and second conductors with respect to the diameter,
The antenna of claim 1, wherein the ratio is defined to be between 8 and 15.   The antenna of claim 2, wherein the ratio is defined to be between 10 and 12. The first radiator has first and second feeding points;
The second radiator has third and fourth feed points;
The parallel lines are
A first conductor provided to extend from the third feeding point through the first feeding point;
A second conducting wire provided to extend from the fourth feeding point through the second feeding point, and
The matching adjustment element is
Of the first conducting wire, a first tip portion that is a portion from the position of the first feeding point to an end opposite to the third feeding point;
2. The antenna according to claim 1, comprising a second tip portion that is a portion from a position of the second feeding point to an end opposite to the fourth feeding point in the second conducting wire. The first radiator and the matching unit are constituted by conductive wires,
The antenna according to claim 1, wherein a wire diameter of the matching device is smaller than a wire diameter of the first radiator.   The antenna according to any one of claims 1 to 5, further comprising a reflector.   The antenna of claim 6, further comprising at least one director.   The antenna according to any one of claims 1 to 7, wherein the radio wave is a radio wave in a UHF (Ultra High Frequency) band.

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