JP3273463B2 - Broadband antenna device using semicircular radiating plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, 0.5 to 13 GHz.
More particularly, the present invention relates to an antenna device using a semicircular or semicircular ribbon-shaped radiation plate.

[0002]

2. Description of the Related Art As examples of conventional broadband antennas, literatures,
RMTaylor., “A Brodband Omnidirectional Antenna,
”IEEE AP-S International Symposium, 1994, p1294.
2 shows an antenna device using a semicircular conductor plate.
FIG. 1 shows an example of the configuration. This antenna device has two elements. One element is composed of two semicircular conductor plates 12 _1a , 12 _2a, and the two conductor plates 12 _1a , 12 _2a coincide with each other at the center line Ox passing through the vertex of each semicircular arc. And they are combined so as to cross each other at right angles. Similarly, the other element is formed by combining semicircular conductive plates 12 _1b and 12 _{2b such} that the center lines passing through the vertices Ox of the respective semicircular arcs coincide with each other and intersect at right angles with each other. I have. The two elements are arranged such that the vertices of each arc face each other. The power supply section is provided between the apexes of the arcs of the two elements, and a coaxial cable 31 for power supply is disposed at the center of one element and its outer conductor is in contact with the element.

FIG. 2 shows a simplified configuration example of the antenna device shown in FIG. This simplified antenna device includes semicircular conductor plates 12a and 12b. Conductor plate 12
a and 12b are arranged so that the vertices of each semicircular arc face each other. The power supply section is composed of the two conductor plates 12a and 12b.
, And power is supplied by a coaxial cable 31 installed on the conductor plate 12b.

FIG. 3 shows VSWR characteristics of the antenna device shown in FIG. As shown in this figure, it can be seen that the simplified antenna device has wideband characteristics. This characteristic was obtained by setting the radius r of the semicircular shape of the radiation plates 12a and 12b to r = 6 cm. The lower limit band where VSWR <2.0 is 600 MHz. At this time, since the wavelength λ of the lower limit frequency is about 50 cm, it is understood that approximately (1/8) λ is necessary as the length of the radius r. The radiation characteristic of the antenna device of FIG. 1 is non-directional in a plane perpendicular to the center line Ox, while the radiation characteristic of the antenna device of FIG. 2 is non-directional from the lower limit frequency to almost twice the frequency. In the higher frequency range, the radiating plate 12a has strong directivity in the same direction as the radiation plate 12a in a plane perpendicular to the center line Ox.

[0005]

As described above, the conventional antenna device shown in FIG. 1 has a large occupied space because two sets of upper and lower antenna elements are formed by intersecting and combining two fan-shaped radiation plates. 2 and the fan-shaped semicircular radiating plate also requires a large occupied area in the simplified antenna device of FIG. In addition, a semicircular conductor plate having a radius of at least about 1/8 wavelength of the lowest resonance wavelength is required for its size, and even in the simple type, 2r × 2r in length and width, that is, (1/4) λ × (1 /
4) An antenna area of λ is required. Therefore, the conventional antenna device requires a large space in volume and area, and when trying to lower the lower limit frequency, there is a problem that the size of the antenna device increases in inverse proportion to the lower limit frequency.

An object of the present invention is to solve such a problem and to provide a smaller antenna device having the same electrical characteristics as the conventional one, or an antenna device smaller than the conventional one and capable of obtaining a lower minimum resonance frequency than the conventional one. The purpose is to provide.

[0007]

An antenna device according to a first aspect of the present invention has a substantially semicircular notch formed at the center of a semicircular conductor plate as a radiation plate. Features. On a plane perpendicular to the radiating plate having this cutout, a plane conductor ground plane is provided facing the arc vertex, and the arc vertex is used as a feeding point, and power is supplied to the ground plane, or Another radiating plate having substantially the same semicircular shape as the radiating plate is provided so that the arc vertices of the radiating plates face each other, and the arc vertices are used as feed points to supply power therebetween.

In the semicircular cutout of the semicircular radiation plate,
At least one radiating element different from the semicircular type may be arranged and connected near the feeding point. An antenna device according to a second aspect of the present invention is characterized in that a semicircular conductor plate as a radiation plate is bent into a cylindrical shape. In the antenna device according to the second aspect, a planar conductor ground plane facing the arc vertex and perpendicular to the cylindrical axis is provided, and the arc vertex is set as a feeding point, and power is supplied to the plane conductor ground plane, or Another semi-circular radiating plate having an arc vertex opposed to the arc vertex of the cylindrical radiating plate may be provided in parallel with the cylindrical axis, and the arc vertices may be used as feeding points and power may be supplied between them. Good.

In the antenna device according to the second aspect, when a semicircular notch is formed in a semicircular radiating plate forming a cylinder, at least one radiating element different from the semicircular type is formed in the notch. And may be connected near the feeding point. According to the antenna devices according to the first and second aspects of the present invention, the occupied space of the antenna element is reduced by forming the notch in the semicircular radiating plate and / or forming the semicircular radiating plate in a cylindrical shape. VSWR characteristics can be improved while maintaining the same wideband characteristics as before.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an embodiment of the present invention, a semi-circular radiating plate as one radiating element of the dipole type antenna shown in FIG. 1 and a plane conductor ground plate acting as a mirror image surface will be described. First, a monopole antenna that operates equivalent to the antenna of FIG. 1 will be considered. That is, as shown in FIG. 4, the semicircular radiating plate 12 is vertically arranged in the shape of a plane conductor ground plate 50 such that the arc vertices 21 are in close proximity to the ground plate 50, and the semicircular radiating plate 12 is arranged on the arc vertex of the semicircular radiating plate 12 and the ground plate 50 The antenna was constructed by connecting the center conductor and the outer conductor of the coaxial feed cable, and the following analysis was performed. The conductor ground plane 50 of FIG. 4 forms a mirror image of the radiation plate 12, and thus operates equivalent to the antenna of FIG.

(A) As a result of analyzing the distribution of the high-frequency current of 5 GHz flowing through the radiation plate 12 by the finite element method, as shown in FIG. 5A, the current jumps into a band-like region along the circumference of the semicircular radiation plate 12. It was found that a region with a high density occurred, and the current flowing in the semicircular central region was negligibly small. That is, it was found that the arc-shaped belt region greatly contributed to the radiation.

(B) In FIG. 4, the shape of the semi-circular radiating plate 12 is generally defined as an ellipse including a circle, and the VSWR characteristic based on the magnitude relationship between the first and second radii L ₁ and L ₂ orthogonal to each other. Was measured for the following three cases. (1) L ₁ = L ₂ = 75mm (ie, in the case of a semicircle) (2) L ₁ = 75mm, L ₂ = 50mm (ie, L ₁ > L ₂ ) (3) L ₁ = 40mm, L ₂ = 75mm ( That is, L ₁ <L ₂ ). The measurement results of VSWR in these three cases are shown in FIG.
a, broken line 5b, and thick broken line 5c. When L ₂ is changed, the band lower limit frequency changes (as L ₂ decreases, the band lower limit frequency increases). However, even if the semicircle is changed to an ellipse, no significant change is observed in the VSWR characteristic, and the radiation plate 12 It turns out that it doesn't have to be a perfect semicircle.

Using the result of the analysis (a), the semicircular area inside the semicircular radiating plate is cut away while leaving the arc-shaped band area, and the cut space is used for other types of antenna elements, electronic components, Used for arranging electronic circuits. According to the result of the analysis (b), there is no significant difference in the characteristics regardless of whether the shape of the semicircular radiation plate is a semicircle or a semiellipse. This is also true for the arc-shaped ribbon-shaped radiating conductor in the embodiment of the present invention described below.

First Embodiment FIG. 6 is a diagram showing a first embodiment of the present invention, and shows a structure of an antenna device in a perspective view. This antenna device is constituted by arc-shaped radiation plates 11a and 11b formed by cutting out two substantially semicircular conductor plates (for example, a copper plate, an aluminum plate, etc.) and cutting out smaller concentric substantially semicircular portions. You. The outer circumferences of the arc-shaped radiating plates 11a and 11b may be semicircular or semielliptical, and similarly, the inner circumference (notch) may be semicircular or semielliptical. The two radiating plates 11a and 11b are arranged such that the vertices 21a and 21b of the respective arcs are opposed to each other, and the feeder 30 is provided between the vertices 21a and 21b. The two radiating plates 11a and 11b are respectively provided with substantially semicircular cutouts 41a and 41b concentrically with the center of the semicircular circle. When the radiation plates 11a and 11b are semicircular, and the notches 41a and 41b are, for example, semi-ellipses having a long axis in the horizontal direction, the radiation plates 11a and 11b
The width W gradually decreases or increases toward the tip of 11b.
In the case of having a long axis in the vertical direction, W gradually increases toward the tip. By providing the cutouts 41a and 41b in this way, it is possible to arrange other elements in those cutouts, which is compared with a conventional configuration using a completely semicircular conductor plate as a radiation plate. Thus, space efficiency can be improved.

7 to 9 show different examples of power supply in the antenna device of the embodiment of FIG. 7, the coaxial cable 31 is arranged along the center line Ox of the radiation plate 11b. On the other hand, in the configuration shown in FIG. 8, the coaxial cable 31 is arranged along the semicircular outer periphery of the radiation plate 11b. Further, in the configuration of FIG.
Is used. In each case, the feed is provided by two radiating plates 11a,
This is performed between the vertexes 21a and 21b of 11b.

An experiment was conducted to confirm the performance of the antenna device. FIG. 10 shows three views of the antenna device used in the experiment, and FIG. 11 shows VSWR characteristics measured by the experiment. As the antenna device, the outer shape of each of the radiation plates 11a and 11b is a semicircle having a radius a = 75 mm, and the cutout portions 41a and 41b are respectively provided.
Has a radius b concentric with the outer shape of the radiation plates 11a and 11b, respectively.
= 55 mm semicircle. Therefore, the width W of each of the radiation plates 11a and 11b is W = 20 mm. For feeding, a coaxial cable 31 arranged along the central axis of the radiation plate 11b was used. The center conductor of the coaxial cable 31 was connected to the apex 21a of the radiation plate 11a, and the outer conductor was connected to the other radiation plate 11b. VS obtained
Comparing the WR characteristics with the characteristics of the conventional example shown in FIG.
In the frequency region higher than Hz, the VSWR is suppressed to about 2 or less, and it can be seen that the band characteristic is almost the same as that of the conventional example even if the notch is provided in the radiation plate. By providing the cutout portion in this manner, a circuit device, another radiating element, and the like can be provided in this portion, which is excellent in space efficiency.

Second Embodiment FIG. 12 is a view showing a second embodiment of the present invention, and shows the structure of an antenna device in a perspective view. This antenna device has a structure in which two conductor plates each having a substantially semicircular shape, as in the conventional example of FIG. 1, are combined so that the vertexes and center lines of the respective arcs substantially coincide with each other and are orthogonal to each other. 6 are used, and an arc-shaped radiating plate similar to that described in the embodiment of FIG. 6 is used for each conductor plate constituting one of the two sets of elements. That is, one set of elements has two semi-circular plates 11 _1a , 11 _1a , 11
_2a is configured by matching the vertex 21a of the arc with the respective center lines Ox passing through the vertex and intersecting each other at a right angle. Similarly, the other set of elements has two substantially semicircular radiating plates 12 _1b , 12 _2b
Are arranged so that the vertices of the outer shape and the respective center lines passing through the vertices coincide with each other and intersect at right angles. The two sets of elements are arranged such that the vertices 21a and 21b of the arcs of the radiating plates 11 _1a , 11 _2a and 12 _1b and 12 _2b that face each other, and the vertices 21a and 21b of the two sets of elements are The feed point. In this example, a coaxial cable 31 is used for power supply, the center conductor of the coaxial cable 31 is connected to the apex portions 21a of the radiation plates 11 _1a and 11 _2a , and the outer conductor is apex portions of the radiation plates 12 _1b and 12 _2b . Connected to 21b. As a power supply method, two parallel wires or the like can be used instead of the coaxial cable 31.

Even in such a configuration, the same broadband characteristics as those of the conventional example shown in FIG. 1 can be obtained. Accordingly, high space efficiency can be obtained as in the first embodiment, and
By forming the radiating element from a plurality of radiating plates, the directivity in the horizontal plane can be made non-directional. Third Embodiment FIG. 13 is a view showing a third embodiment of the present invention, and is a perspective view showing the structure of a monopole antenna device corresponding to the dipole antenna of the embodiment shown in FIGS. The antenna device includes a radiating plate 11 formed of a substantially semicircular arc-shaped band-shaped conductor plate and provided with a substantially semicircular notch 41 at the center of the semicircular circle, and an arc of the radiating plate 11. And a plane conductor ground plane 50 in which the apexes are arranged close to each other. Between the apex 21 of the radiation plate 11 and the plane conductor ground plate 50
Includes a center conductor and outer covering conductor of the coaxial feeder cable it
It is being connected. Power is supplied by the coaxial cable 31 that has passed through the through hole provided in the plane conductor ground plane 50. That is, in the coaxial cable 31, the center conductor is the flat conductor ground plane 50.
And the outer conductor is connected to the plane conductor ground plane 50.

The experiment was conducted by changing the shape of the notch 41 as shown in FIG. 13 to a semi-elliptical shape instead of a semi-circular shape concentric with the semi-circular radiating plate. Specifically, by changing the width W ₁ at both ends of the radiation plate and the width W 2 passing through the feeding point in FIG. 13, W ₁ = W ₂ ,
Measurements were made for W ₁ > W ₂ and W ₁ <W ₂ . FIG.
Shows the measured parameters and the VSWR characteristics at that time. Compared to the case of the semicircular notch, the VSWR value near 1.5 GHz was worse in the case of the semielliptical notch indicated by the wavy line, but no change was observed in the VSWR characteristics as a whole, and the notch shape was The result was that it was not necessary to be limited to a semicircle. The difference in the VSWR value near 1.5 GHz is due to the difference in the notch area.

Fourth Embodiment FIG. 15 is a view showing a fourth embodiment of the present invention.
Structure of another strip arcuate radiating plate 11 antenna device matched disposed perpendicular to each other the radiation plate 11 ₁ and the arc vertex and the center line ₂ a to the third embodiment is shown by a perspective view. That is, it has a substantially semicircular shape, and the central portion has the cutout portion 41.
The two radiating plates 11 ₁ and 11 ₂ provided with
1 and the respective center lines Ox passing through the vertices are made coincident with each other, and are combined so as to intersect at right angles with each other to constitute one element. Is done. Power is supplied by the coaxial cable 31 which passes through a through hole provided in the plane conductor ground plane 50 between the apex portion 21 of the element as a power supply point and the plane conductor ground plane 50.

[0021] In the third and fourth embodiments shown in FIGS. 13 and 15, by using the plane conductor ground plate 50, sandwiching the radiation plate 11 or 11 _1, 11 ₂ of the electrical mirror image plane conductor ground plate 50 Formed on the back side. Therefore, the radiating element (radiating plate 1)
1 or 11 ₁ , 11 ₂ ) is only half as compared with the first and second embodiments, respectively, while realizing the same broadband characteristics.
The antenna height can be reduced to half. By suppressing the height of the antenna and providing the notch 41 in the radiation plate, an antenna device with good space efficiency can be realized.

Fifth Embodiment FIG. 16 is a view showing a fifth embodiment of the present invention, and shows the structure of an antenna device in a perspective view. In this antenna device, a radiating element having a shape different from a semicircular shape is further provided in the cutout portion 41 of the radiating plate of the embodiment of FIG. That is, the radiation plate 11, which is formed of a substantially semicircular band-shaped conductor plate and has a semicircular notch 41 at the center of the semicircular circle, and the apex of the circular arc of the radiation plate 11 are A coaxial cable 31 for feeding power through a through hole provided in the plane conductor ground plane 50 to a feeder point 21 provided between the plane conductor ground plane 50 and the apex of the radiation plate 11 and the plane conductor ground plane 50. And a radiation plate 1
A meander monopole 61 is arranged in one notch 41, and a feed point, which is one end thereof, is connected to the center of the arc-shaped radiating plate 11 closest to the feed point. Coaxial cable 31
Are connected to the apexes of the radiation plate 11 through the through holes of the plane conductor ground plane 50, and the outer conductor is a plane conductor ground plane 5
Connected to 0. The meander monopole 61 is the radiation plate 11
The power supply to the meander monopole 61 is performed via the radiation plate 11.

In this embodiment, a meander-shaped antenna that resonates at a frequency lower than the lowest resonance frequency of the first antenna is incorporated as the second antenna in the first antenna having the structure shown in FIG. I have. The meander monopole 61 constituting the meander-shaped antenna will be described in detail. Since the meander monopole 61 can make the current path longer than the semicircle of the radiation plate 11, the meander monopole 61 can resonate at a frequency lower than the lowest resonance frequency in the antenna device of the above-described embodiment. Therefore, by incorporating the meander monopole 61, resonance can be achieved even outside the band of the antenna device of the above-described embodiment, and multi-resonance can be achieved. In particular, by setting the resonance frequency of the meander monopole 61 lower than the resonance frequency of the radiation plate 11, the lowest resonance frequency can be reduced without changing the size.

Sixth Embodiment FIG. 17 is a perspective view showing a sixth embodiment of the present invention, and FIGS. 18 and 19 show measurement results of the VSWR characteristics. This antenna device shown in FIG. 17 is a dipole antenna in which a semi-circular second radiating plate 11b is provided instead of the ground plate 50 in the embodiment of FIG. That is, a radiation plate 11a having a substantially semicircular arc shape and a radiation plate 11b having a semicircular shape are provided.
11a and 11b are arranged such that the vertices 21a and 21b of the respective arcs face each other as feed points. A coaxial cable 31 is connected to these feeding points 21a and 21b. A meander monopole 61 is disposed in the cutout portion 41 of the radiation plate 11a, and the lower end thereof is integrally connected to the center of the inner circumference of the semicircular band. The center conductor of the coaxial cable 31 is connected to the vertex 21a of the radiation plate 11a, and the outer conductor is connected to the radiation plate 11b. Power is supplied to the meander monopole 61 through the radiation plate 11a.

Here, the radiation plate 11a is formed such that its outer shape has a radius a =
A semicircle of 75 mm, the shape of the notch 41 is a semicircle with a radius b = 55 mm concentric with the outer shape of the radiation plate 11a, and the width W of the radiation plate 11a is W =
The antenna device was formed so as to have a thickness of 20 mm, and the resonance frequency of the meander monopole 61 was adjusted to be 280 MHz, and the VSWR characteristics of the antenna device were measured. FIG. 18 shows the entire band of the measurement result, and FIG. 19 shows an enlarged view of the 0 to 2 GHz band. These figures are measurement data for the same antenna device except for the frequency scale on the horizontal axis.

FIG. 18 shows that the same characteristics as those of the conventional antenna device are obtained for the band and the VSWR. Also, from FIG. 19, it can be seen that by incorporating the meander monopole 61, resonance occurs even at 280 MHz.
From this measurement result, it can be seen that multi-resonance can be achieved without changing the size of the antenna device, and it is possible to lower the lowest resonance frequency.

FIGS. 20 to 22 show modifications of the embodiment shown in FIG. In these examples, the radiation plate 1
Each as a radiating element incorporated in the first notch portion 41, the two meander monopoles 61 _1, 61 _2, two helical antennas 62 _1, 62 ₂ and resistively loaded monopole 63 is used. The radiating element incorporated in the notch 41 may have any other shape as long as it fits in the notch 41. 20 and 21 show examples in which two elements are incorporated, respectively, but the number is not limited. Power is supplied to the built-in radiating element by connecting the radiating element to the radiating plate 11.

When a plurality of other radiating elements are incorporated in the cutout portion 41 of the radiating plate 11 as shown in FIG. 20 or FIG. 21, if the resonance frequencies of the respective radiating elements are different, furthermore, Multi-resonance becomes possible. FIG.
By using a broadband antenna such as the resistive monopole 63 shown in FIG. 2 and setting the resonance frequency thereof lower than that of the semicircular conductor monopole antenna including the semicircular radiating plate 11, the antenna device is not enlarged. Therefore, the lowest resonance frequency can be lowered, and a wider band can be achieved. Seventh Embodiment In each of the above-described embodiments, at least one semi-circular radiating plate is formed concentrically with a semi-circular notch of a smaller shape to cut other types of antenna elements or circuit elements. Although the case where a space that can be arranged in the notch is formed is shown, in the following embodiment, at least one substantially semicircular radiating plate is wound once in a substantially cylindrical shape, thereby occupying the lateral direction. An embodiment of the antenna device when the length is shortened is shown.

FIG. 23 is a view showing a seventh embodiment of the present invention, and shows the structure of an antenna device in a perspective view. This antenna device has a radiation plate 13 having a structure in which a substantially semicircular conductor plate is wound once in a cylindrical shape so that the straight sides thereof are substantially circular.
a and a radiation plate 12b composed of a semicircular conductor plate. These radiating plates 13a and 12b have a center line Ox.
And the vertices 21a, 21b of the respective arcs
Are arranged to face each other. These vertex portions 21a,
A power supply unit 30 is provided between the power supply points 21b.

The antenna device shown in FIG. 24 has a structure in which two semicircular conductor plates are wound once around a common column having a center line (radius of a semicircle) Ox passing through a vertex of a semicircle as a generating line. Radiation plates 13a and 13b are provided, and the vertices 21a and 21b of the arcs of the two semicircular conductors are arranged in close proximity to each other. That is, the semicircular radiation plate is wound once so that the straight sides form a circle.

As shown in FIG. 23, one of the two radiating plates constituting one antenna device may be wound once to form a cylindrical radiating plate 13a. As shown in FIG. 24, both radiation plates may be wound once into a cylindrical shape to form radiation plates 13a and 13b. In each case, the curved radiation plate 13a (FIG. 23) or 13a, 13
Regardless of whether or not both ends in the circumferential direction of b (FIG. 24) are in contact with each other, there is no significant difference in the VSWR characteristics as described later.

In the embodiment shown in FIGS. 23 and 24, a small gap 10 is provided between the circumferential ends of the radiation plate 13a (also 13b in FIG. 24) which is wound once in a cylindrical shape so as not to contact each other. Have been. A straight line d connecting the center line Ox of the cylindrical radiation plate 13a and the center of the interval 10;
It is preferably substantially perpendicular to the center line Ox of a. In FIG. 24, the straight lines d connecting the center line Ox shared by the radiation plates 13a and 13b and the interval 10 are preferably substantially parallel to each other. The radiating plates 13a and 13b are preferably of the same size in the expanded state. The curved shape of the radiation plate 13a or 13b is not limited to a cylindrical shape, and may be an elliptical cylindrical shape, that is, it may be a substantially cylindrical shape.

By using the cylindrical conductor plate as the radiation plate in this manner, the width occupied by at least one radiating element is smaller than that of the conventional example, as compared with the conventional configuration using a flat conductor plate as the radiation plate. The space efficiency can be increased by only about 1/3 in comparison. 25, 26 and 2
7 shows an example of a configuration for feeding power to the antenna device shown in FIG. In the configuration of FIG.
1 is arranged along the center line Ox passing through the vertex of the radiation plate 13b. On the other hand, in the configuration of FIG. 26, the coaxial cable 31 is arranged along a semicircular arc of the radiation plate 13b. FIG. 2
In the configuration of No. 7, two parallel wires 33 are used for power supply, and are arranged between the radiation plates 13a and 13b. In either case, power is supplied between the two radiating plates 13a, 12b (or 13a, 13b) using the apexes 21a, 21b as power feeding points. Eighth Embodiment FIG. 28 is a diagram showing an eighth embodiment of the present invention, and shows the structure of an antenna device in a perspective view. This antenna device is, for example, in the embodiments shown in FIGS.
Instead of providing the radiation plate 12b or 13b, a ground plate 50 made of a plane conductor plate is provided as in FIG. That is, the radiation plate 1
3 is similar to the case of FIG. 25, and the substantially semicircular conductor plate is formed in a cylindrical shape such that the center line Ox passing through the apex of the semicircular arc is parallel to the center axis of the cylinder. A plane conductor ground plane 50 which is disposed close to the apex 21 of the circular arc of the radiation plate 13 and substantially perpendicular to the center line Ox passing therethrough.
Is provided. The apex portion 21 of the radiating plate 13 is used as a feeding point, and the through-hole 5 formed in the plane conductor
Power is supplied from the coaxial cable 31 passed through the cable 1. That is, the center conductor of the coaxial cable 31 is connected to the apex 21 of the radiation plate 13, and the outer conductor is connected to the plane conductor plate 50.

In the eighth embodiment, an electric mirror image of the radiating element 13 is formed on the back side of the ground plane 50 by the plane conductor ground plane 50. Therefore, the number of radiating elements is half that of the seventh embodiment (FIGS. 23 to 27), and the antenna height can be reduced to half while realizing the same broadband characteristics. With such a configuration, the antenna height can be suppressed and an antenna device with good space efficiency can be realized.

An experiment was conducted to confirm the performance of the antenna device. 29A, 29B, and 29C show a front view, a plan view, and a right side view of the antenna device used in the experiment, respectively, and FIG. 29D shows a developed view of the radiation plate 13. The radiating plate 13 is formed by winding a semicircular conductor plate having a radius r = 75 mm shown in FIG. 29D once around a 50 mm diameter cylinder whose center line Ox passes through the vertex of the semicircular arc as a generating line. . The plane conductor ground plate 50 was a copper plate of 300 mm × 300 mm and 0.2 mm in thickness. Power is supplied by a power supply cable 31 passing through a through hole 51 provided at the center of the plane conductor ground plane 50. The center conductor of the coaxial cable 31 is connected to the vertex 21 of the radiation plate 13 (FIG. 29C), and the outer conductor is connected to the plane conductor ground plate 50.

FIG. 30 shows VSWR characteristics measured by experiments. Comparing the obtained VSWR characteristic with the characteristic of the conventional example shown in FIG. 3, the band characteristic of the antenna device of the present invention in which the radiation plate is formed in a cylindrical shape has the same broadband characteristic as that of the conventional example. The value of VSWR is smaller than the value according to the prior art. That is, the VSWR characteristic is improved as compared with the conventional one shown in FIG. By making the radiation plate cylindrical and using a plane conductor ground plane in this way, the antenna height is halved, the width occupied by the radiation plate is only 1/3 of that of the conventional example, and it is excellent in space efficiency. Antenna device, and the VSWR characteristics are improved.

In the embodiment shown in FIGS. 23 to 28, the radiation plate 13 is shown as having a regular cylindrical shape, but may be formed in an elliptical cylindrical shape. As shown in FIG. 28, the two axes of the ellipse
An axis L2 intersects at right angles to x and an axis L1 orthogonal to the axis L2. The following three cases (a) L1 = L2 = 50 (cylindrical) (b) L1 = 33mm, L2 = 60mm (ie L1> L2 (C) The VSWR characteristics measured for L1 = 60 mm and L2 = 33 mm (that is, L1 <L2 elliptic cylinder) are shown by the solid line 31A, the thick line 31B, and the thin broken line 31C in FIG. 31, respectively. As is clear from the figure, there is no significant change in the VSWR characteristic even when the cylindrical radiation plate 13 is replaced by an elliptical cylinder, and therefore, the curvature of the radiation plate 13 is reduced by the axial ratio.
When L1 / L2 is in the range of about 0.5 to 1.5, it indicates that not only a cylinder but also an elliptic cylinder may be used. This applies to all the following embodiments, and also applies to both the radiation plates 13a and 13b.

In the embodiment shown in FIGS. 23 to 28, the radiation plate 13 is wound once around a cylinder and curved so that both ends are almost in contact with each other. It may be wound less than once to form a gap d between both ends as shown in FIG. In this case, the diameter D of the cylinder is D = 48 mm (a gap d between both ends to be formed is 1 m).
FIG. 33 shows the VSWR characteristics measured for the case m) and the case where D = 60 mm ( gap d = 37 mm), and the solid line 33A and the broken line 33B are shown. Also in this case, the broadband property of the antenna device is maintained. Although the VSWR deteriorates as the gap d increases, the VSWR characteristic is still superior to that of the prior art shown in FIG.

In FIG. 32, the measurement results of the VSWR characteristics in the case where d = 0 and the both ends of the radiation plate 13 are half-attached to each other and in the case where the specific contact is made very slightly (about 1 mm) apart are shown by broken lines in FIG. 33 shown in a and the solid line 33 B. As is apparent from this figure, the VSWR characteristic is hardly affected even if the both ends of the curved radiation plate 13 are in contact with each other, and therefore, it is not necessary to force both ends into contact. This is true for all other embodiments. Ninth Embodiment FIG. 35 is a diagram showing a ninth embodiment of the present invention, and shows the structure of an antenna device in a perspective view. This antenna device is similar to the cylindrical radiation plate 13 in the embodiment of FIG.
In this case, for example, a notch 41 similar to that shown in FIG. 13 is formed, and a half obtained by forming a substantially semicircular notch 41 at the center of a semicircle of a substantially semicircular conductor plate. The circular ribbon-shaped conductor plate (see FIG. 36D) is wound once around a column having a center line Ox passing through the apex of a semicircular arc as a generatrix to form the radiation plate 14. That is, this radiation plate 14
The radiation plate 13 is cut in parallel to the lower peripheral edge (semicircular arc) of the lower side apex 21 of the radiation plate 13 shown in FIG. This radiating plate 1 has an arcuate ribbon shape, as in FIG.
4 and a plane conductor ground plate 50 close to the lowermost vertex 21 of the arc.
Is provided.

The power is supplied from the coaxial cable 31 passing through the through hole 51 formed in the plane conductor ground plane 50 with the apex 21 of the radiation plate 14 as a feeding point. That is, the coaxial cable 31
Are connected to the feeding point 21 of the radiation plate 14, and the outer conductor is connected to the plane conductor ground plane 50. By providing the cutout portion 41 in the radiation plate in this way, the seventh cutout of the semicircular conductor plate having no cutout in a cylindrical shape can be obtained.
Alternatively, the space efficiency can be further improved as compared with the eighth embodiment. As described above, the antenna current of the radiating plate 14 wound once in a cylindrical shape is distributed and flows in the vicinity of the lower arc-shaped periphery, and the antenna current does not flow in the upper straight side and the center, that is, the radiation of radio waves Does not affect the operation as an antenna even if the notch 41 is formed. Therefore, the shape of the notch 41 is not limited to a semicircular shape (in an expanded state), but may be, for example, a semielliptical shape.

An experiment was conducted to confirm the performance of the antenna device. 36A, 36B, and 36C show a front view, a plan view, and a right side view of the antenna device used in the experiment, respectively, and FIG. 36D shows a developed view of the radiation plate 14.
FIG. 37A shows VSWR characteristics measured by an experiment. The radiating plate 14 as an antenna device is a semi-circular conductor plate having a radius r ₁ = 75 mm and a semi-circular notch 41 having a radius r ₂ = 55 mm concentric with the outer shape, and a semi-circular arc. It is wound once around a 50 mm diameter column whose center line Ox passes through the vertex 21 as a generating line. The plane conductor ground plane 50 is 300mm x 300
A copper plate having a thickness of 0.2 mm and a thickness of 0.2 mm was used. The power supply is a plane conductor ground plane 5
This is performed by the power supply cable 31 passing through a through hole 51 formed in the center of the zero. The center conductor of the coaxial cable 31 is connected to the apex 21 of the radiation plate 14, and the outer conductor is connected to the plane conductor ground plate 50.

When the obtained VSWR characteristic (FIG. 37A) is compared with the VSWR characteristic (FIG. 30) of the antenna device shown in FIGS. 29A to 29D having no notch 41, the notch 41 is provided on the radiation plate. It can also be seen that the broadband characteristics are equivalent to the conventional example. However, VSWR deteriorates below 5 GHz.
Compared with the characteristics according to the prior art, no deterioration is observed on the low frequency side, and the improvement of the VSWR on the wide frequency side is rather remarkable. By providing the notch 41 in the radiation plate in this way,
An antenna having a different shape can be incorporated into the cutout portion, and the antenna device is excellent in space efficiency.

By changing the area of the semicircular notch 41,
The ratio of the area of the notch 41 to the area of the radiation plate 14 without the notch 41 and the worst VS in the operating band
FIG. 37B shows the relationship with WR. When the VSWR is allowed up to 2 from this figure, the notch 41 has the area ratio of 50%.
%. This is approximately r ₂ / r ₁ = 0.7 when represented by the radius ratio r ₂ / r ₁ in FIG. 36D, indicating that a considerably large notch 41 can be formed. Tenth Embodiment FIG. 38 is a diagram showing a tenth embodiment of the present invention, and shows the structure of an antenna device in a perspective view. This antenna device differs from the ninth embodiment in FIG. 35 in that a cutout portion 41 of a radiation plate 14 is provided with a radiation element of a type different from a semicircular ribbon-shaped element. That is, a substantially semicircular cutout portion 41 is formed in a substantially semicircular conductor plate concentrically with the semicircle,
The conductor plate is wound once around a column having a center line Ox passing through a vertex 21 of the arc as a generatrix, thereby forming an arc-shaped ribbon-shaped radiation plate 14. A plane conductor ground plane 50 is provided near the apex 21 of the circular arc of the radiation plate 14. A helical antenna 62 is connected to the notch 41 of the radiation plate 14. The axis of the helical antenna 62 is substantially perpendicular to the plane conductor ground plane 50 and is located above the apex 21 of the arc. The coaxial cable 31 is passed through a through hole 51 formed in the plane conductor ground plane 50, the center conductor of the coaxial cable 31 is connected to the apex 21 of the radiating element 14, and the outer conductor is connected to the plane conductor ground plane 50, Power is supplied between the radiating plate 14 and the plane conductor ground plate 50 with the apex 21 of the radiating plate 14 as a feeding point. Power is supplied to the helical antenna 62 via the radiation plate 14.

This embodiment has a structure in which a helical antenna is incorporated as a second antenna into the antenna having the structure shown in FIG. The band of the second antenna to be incorporated is arbitrary. In particular, if an antenna having an operating band in a frequency band lower than the lowest resonance frequency of the first antenna is selected, the structure shown in FIG. 35 can be obtained by incorporating the second antenna. Of the antenna device can be made multi-resonant. Further, by selecting an antenna having a size that can be accommodated in the cutout portion 41 in FIG. 38 as the second antenna, the lowest resonance frequency can be reduced without increasing the size of the antenna.

Next, an experiment was conducted to confirm the performance of the antenna device. 39A, 39B, and 39C show a front view, a plan view, and a right side view of the antenna device used in the experiment, respectively, and FIG. 39D shows a developed view of the radiation plate 14. FIGS. 40 and 41 show VSWR characteristics measured by experiments. Here, FIG. 41 shows the frequency band of 0 to 1 GHz on the horizontal axis in FIG. 40 with the horizontal axis enlarged, and is measurement data of the same antenna. Radiating plate 14
Is a semi-circular conductor plate with a radius of 75 mm, a radius concentric with the outer shape.
A conductor plate provided with a 55 mm semicircular cutout 41 is formed by winding once around a 50 mm diameter column whose center line passes through the vertex 21 of the semicircular arc. As the second antenna element, a helical antenna 62 tuned to operate at 280 MHz is installed in the notch 41, and one end of the helical antenna is connected to the vertex 21 of the semicircle of the notch 41 of the radiation plate 14. are doing. The plane conductor ground plane 50 is 300 mm x 300 mm,
A copper plate having a thickness of 0.2 mm was used. Power is supplied by a power supply cable 31 passing through a through hole 51 provided at the center of the plane conductor ground plane 50. The center conductor of the coaxial cable 31 is connected to the apex 21 of the radiation plate 14, and the outer conductor is connected to the plane conductor ground plate 50. Comparing FIG. 40 with FIG. 37A, which is an experimental result of the ninth embodiment, it can be seen that the same band characteristic is obtained even when the helical antenna 62 is incorporated in the cutout 41. Also, it can be seen from FIG. 41 that resonance is generated even at 280 MHz by incorporating the helical antenna 62. From this measurement result, it can be seen that multi-resonance can be achieved without changing the size of the antenna device, and that the lowest resonance frequency can be further reduced.

FIGS. 42, 43 and 44 show modifications of the tenth embodiment. In these examples the cutout portion 2 each as a radiating element that is incorporated into 41 the helical antenna 62 _1, 62 2 _two meander monopoles 61 _1, 61 ₂ and resistively loaded monopole 63 of the radiation plate 14 is used. The radiating element incorporated in the notch 41 may be of another type as long as it fits in the notch 41. Further, FIGS. 42 and 43 show examples in which two radiating elements are incorporated, respectively, but the number is not limited. Power is supplied to the built-in radiating element by connecting the built-in radiating element to the radiation plate 14.

As shown in FIGS. 42 and 43, when a plurality of different radiating elements are incorporated in the cutout 41 of the radiating plate 14, if the resonance frequencies of the respective antennas are different,
Further, multi-resonance becomes possible. Further, by using a broadband antenna like the resistance-loaded monopole 63 shown in FIG. 44 and setting the resonance frequency thereof lower than that of the semicircular conductor monopole antenna composed of the radiation plate 14, the minimum resonance can be achieved without increasing the size of the antenna. The frequency can be reduced, and a wider band can be achieved. The radiating element provided in the notch 41 and the radiating plate 14 are shifted in resonance frequency, impedance, and the like to such an extent that the antenna operation does not affect each other.

[0048]

As described above, the antenna device according to the first aspect of the present invention cuts the radiation plate made of a semicircular conductor plate and provides the following, thereby improving the space efficiency while maintaining the wide band characteristics. Can be enhanced. Further, by incorporating another radiating element into this cutout, it is possible to realize an antenna device having the same size as a conventional antenna device, having more resonance, a wider band, or a lower minimum resonance frequency.

According to the second aspect of the present invention, the semicircular radiation plate is wound once in a cylindrical shape, so that the maximum occupied width can be reduced. By forming the notch in the radiation plate, it is possible to further enhance the space efficiency. An antenna having a shape and an operation band different from those of the semi-circular radiating plate is incorporated in the cutout, so that the antenna device has a small size, a wide band, and a multi-resonance as compared with a conventional antenna, or an antenna having a low minimum resonance frequency. The device can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a conventional antenna device.

FIG. 2 is a perspective view showing a simplified configuration example of the antenna device of FIG. 1;

FIG. 3 is a diagram showing VSWR characteristics of the antenna device shown in FIG. 2;

FIG. 4 is a diagram showing a configuration of an antenna on which analysis which is a basis of the present invention is performed.

5A is a diagram showing a current density distribution on a radiation plate analyzed by the configuration of FIG. 4, and FIG. 5B is a diagram showing VSWR characteristics when the radiation plate shape is changed in the configuration of FIG.

FIG. 6 is a perspective view showing a first embodiment of the present invention.

FIG. 7 is a diagram showing one mode of power supply in FIG. 6;

FIG. 8 is a diagram showing another mode of power supply in FIG. 6;

FIG. 9 is a diagram showing still another mode of power supply in FIG. 6;

10A is a front view of the antenna device of FIG. 6 used in an experiment, FIG. 10B is a plan view, and FIG. 10C is a side view.

FIG. 11 is a diagram showing measured VSWR characteristics.

FIG. 12 is a perspective view showing a second embodiment of the present invention.

FIG. 13 is a perspective view showing a third embodiment of the present invention.

FIG. 14 is a diagram showing VSWR characteristics of the antenna device of FIG.

FIG. 15 is a perspective view showing a fourth embodiment of the present invention.

FIG. 16 is a perspective view showing a fifth embodiment of the present invention.

FIG. 17 is a perspective view showing a sixth embodiment of the present invention.

18 is a diagram showing VSWR characteristics of the antenna device of FIG.

FIG. 19 is an enlarged view of a low frequency region in FIG. 18;

FIG. 20 is a view showing a modification of the embodiment shown in FIG. 16;

FIG. 21 is a view showing another modification of the embodiment shown in FIG. 16;

FIG. 22 is a view showing still another modification of the embodiment shown in FIG. 16;

FIG. 23 is a perspective view showing an example of the sixth embodiment of the present invention.

FIG. 24 is a perspective view showing another example of the sixth embodiment of the present invention.

FIG. 25 is a perspective view showing a configuration example for power supply in the present invention.

FIG. 26 is a perspective view showing another configuration example for power supply in the present invention.

FIG. 27 is a perspective view showing still another configuration example for power supply in the present invention.

FIG. 28 is a perspective view showing a seventh embodiment of the present invention.

29A is a front view of the antenna device used in the experiment of the seventh embodiment of the present invention, FIG. 29B is a plan view, FIG.
7 is a development view of the radiation plate 13.

FIG. 30 is a view showing measured VSWR characteristics of the antenna devices of FIGS. 29A to 29D.

FIG. 31 is a view showing VSWR characteristics when the axial length of the elliptical cylinder in FIG. 28 is changed.

FIG. 32 is a view for explaining the interval between both ends of a semicircular radiation plate wound in a cylindrical shape.

FIG. 33 is a diagram illustrating VSWR characteristics when the distance between both ends is changed by changing the cylindrical diameter of the semicircular radiation plate.

FIG. 34 is a view showing VSWR characteristics when both ends of a semicircular radiating plate are electrically connected and separated.

FIG. 35 is a perspective view showing an eighth embodiment of the present invention.

36A is a front view of the antenna device used in the experiment of the eighth embodiment of the present invention, FIG. 36B is a plan view, FIG.
3 is a development view of the radiation plate 14.

37A is a diagram showing measured VSWR characteristics of the antenna device of FIGS. 36A to 36D, and FIG. 37B is a diagram showing an example of the relationship between the notch area ratio and the worst VSWR in a band.

FIG. 38 is a perspective view showing a ninth embodiment of the present invention.

39A is a front view of the antenna device used in the experiment of the tenth embodiment, B is a plan view, C is a right side view, and D is a developed view of the radiation plate 14. FIG.

FIG. 40 is a diagram showing measured VSWR characteristics of the antenna devices of FIGS. 39A to 39D.

FIG. 41 is an enlarged view of the low frequency side in FIG. 40;

FIG. 42 is a view showing a modification of the tenth embodiment;

FIG. 43 is a view showing another modification of the tenth embodiment;

FIG. 44 is a view showing still another modification of the tenth embodiment;

Continuation of the front page (56) References JP-A-57-142003 (JP, A) JP-A-61-109205 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01Q 9 / 46 H01Q 9/26 H01Q 9/27

Claims (15)

(57) [Claims] 1. A first radiation plate made of a substantially semicircular conductor plate, and the first radiation plate has a substantially semicircular notch formed concentrically with the semicircle, and is formed at right angles to the radiation plate. An antenna device comprising: a plane conductor ground plane disposed to face the semi-circular arc; and a feeder line connected to the apex of the semi-circle arc of the radiation plate and the plane conductor ground plane for feeding power therebetween. 2. The antenna device according to claim 1, wherein another radiating plate having substantially the same shape as the first radiating plate is provided to intersect with each other while sharing a central axis. 3. A first radiating plate comprising a substantially semicircular conductor having a substantially semicircular notch formed concentrically; a second radiating plate comprising a substantially semicircular conductor plate; The second radiating plate has the vertexes of the respective arcs arranged opposite to each other, and the vertexes of the first and second radiating plates are used as feed points, respectively, and a feed line for feeding power therebetween. Including antenna devices. 4. The antenna device according to claim 3, wherein the antenna has substantially the same shape as the first radiating plate, the first radiating plate and the arc vertices substantially coincide with each other, and intersect with each other while sharing a central axis. The third radiating plate provided has substantially the same shape as the second radiating plate, and the second radiating plate and the arc vertexes are substantially coincident with each other, and the third radiating plate is provided so as to intersect each other while sharing a central axis. And four radiation plates. 5. The antenna device according to claim 3, wherein the second radiating plate has a notch formed substantially concentrically with the semicircle. 6. The antenna device according to claim 1, wherein at least one radiating element of a type different from the semicircular radiating plate is arranged in the cutout portion of the first radiating plate, It is connected to the plate in the vicinity of the feeding point. 7. The antenna device according to claim 6, wherein the radiating element includes any one of a meandering monopole, a resistance-loaded monopole, and a helical antenna. 8. have conductor plates of approximately semicircular one at least a radiation plate formed by being bent into a cylindrical shape, is formed to a radius of the upper Kishirube material plate r, is cylindrically curved that when the gap between both ends of <br/> on Kishirube material plate and d, d is 0.5r
Antenna apparatus characterized by upper Kishirube material plate is curved so as to satisfy the following. 9. The antenna device according to claim 8, wherein a plane conductor ground plane opposed to a vertex of a semicircular arc of said radiation plate and arranged substantially at right angles to a generatrix of said cylinder, and a vertex of said semicircular arc and said plane A power supply line connected to the conductive ground plane for supplying power therebetween. 10. The antenna device according to claim 8, wherein a center line coincides with the semicircular conductive plate, and another radiating plate having an arc-shaped periphery facing the semicircular arc of the radiating plate;
A power supply line is connected to the arc vertex of the radiating plate and the arc vertex of the another radiating plate, and feeds power therebetween. 11. The antenna device according to claim 10, wherein
The other radiation plate is formed of another semicircular conductor plate. 12. The antenna device according to claim 10, wherein
The other radiating plate is a cylindrical radiating plate formed by winding another semicircular conductor plate into a substantially cylindrical shape. 13. The antenna device according to claim 9, wherein the radiation plate has a substantially semicircular notch formed substantially concentrically with a semicircle of the conductor plate. 14. The antenna device according to claim 13,
At least one radiating element different in type from the semicircular radiating conductor is attached to the cylindrically curved conductor plate in the notch. 15. The antenna device according to claim 14,
The radiating element is at least one selected from a meandering monopole, a resistance-loaded monopole, and a helical antenna.
One antenna element.