JPH0690111A - Linearly polarized wave antenna system - Google Patents

Abstract

PURPOSE:To receive both of a horizontally polarized wave and a vertically polarized wave with one antenna by fitting two dipole antennas so that polarizing planes can be mutually orthogonal at a position in front of the terminal of a circular waveguide, which terminals are short-circuited, just for lambda/4. CONSTITUTION:Near the focal point of a paraboloid reflection mirror 10, dipole antennas 2 for horizontally and vertically polarized waves are fitted to a circular waveguide 1 so that the polarizing planes can be orthogonal. The length of an antenna element 3 outside the waveguide 1 is almost set to the 1/4 wavelength of the received or transmitted radio wave. On the other hand, a conductor-made cap-shaped reflector 11 is fitted to the head of the waveguide 1, and this reflector 11 is composed of a disk part 12, which is vertical to the waveguide 1 and provided with an outer diameter longer than the full length of the antenna 2, and a ring-shaped return part 13 almost vertically returned from this disk part to the side of the waveguide 1. A distance D between the terminal of the waveguide 1 and the antenna 2 is almost lambda/4, and a length L of the return part 13 almost set to the 1/4 wavelength of a used radio wave, namely, almost equally to the distance D. The waveguide 1 is connected to a CS converter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear polarization antenna device suitable for receiving communication satellites and the like, and more particularly to a linear polarization antenna device capable of receiving both horizontal and vertical polarizations.

[0002]

2. Description of the Related Art Conventionally, as a parabolic antenna device for SHF, as shown in JP-A-56-93402, a structure in which a primary radiator is arranged at the focal point of a reflecting mirror is well known. In the case of a linearly polarized antenna device that receives horizontally polarized waves or vertically polarized waves, a primary radiator that can receive horizontally or vertically polarized waves may be selected as the primary radiator to be combined with the parabolic reflector. Here, we consider a structure in which a dipole antenna is used as the primary radiator and is fed by a circular waveguide.

FIG. 9 shows a conventional structure in which a dipole antenna 2 is attached near the end of a circular waveguide 1 having a short-circuited end by λ / 4 (where λ: wavelength in the waveguide). In the figure,
Reference numeral 3 denotes an antenna element of a dipole antenna, which is a conductor rod, and a conductor rod portion extending from the antenna element is a coupling probe 5 protruding into the waveguide.
The pair of antenna elements 3 constituting the dipole antenna 2 are insulated and supported by the circular waveguide 1 by an insulator 6, and the length of the antenna element 3 which is outside the circular waveguide 1 is either received or transmitted. It is set near the 1/4 wavelength of the radio wave.

FIG. 10 shows a radiation pattern in the 0 ° plane (dipole antenna arrangement plane) of the dipole antenna fed by the circular waveguide shown in FIG. 9, and the radiation patterns before and after are symmetrical. When such a characteristic is used in combination with a reflecting mirror, there is a problem that the forward radiation is not used and the gain is low.

Incidentally, FIG. 9 shows one dipole antenna 2
Is provided in the circular waveguide 1, but another dipole antenna whose polarization plane is orthogonal to this dipole antenna 2 can be similarly provided in the circular waveguide 1, and the circular waveguide 1 is commonly used. It is possible to feed radio waves whose polarization planes are orthogonal to each other.

FIG. 11 is a modification of the structure shown in FIG. 9, in which the dipole antenna 2 is mounted near λ / 4 before the end of the circular waveguide 1 whose end is short-circuited, and at the end surface of the circular waveguide 1. A disc-shaped reflector 7 is provided. Other structures are the same as in FIG.

FIG. 12 shows a radiation pattern in a 0 ° plane (dipole antenna arrangement plane) of the dipole antenna with a reflector shown in FIG. 11 along a dotted line (a) and in a 90 ° plane (dipole antenna arrangement plane perpendicular to the dipole antenna arrangement plane). The radiation pattern in the plane is shown by the solid line (b). In this case, the front and rear radiation patterns are asymmetric, and the rear radiation pattern is larger. However, the beam of the radiation pattern is narrow, and the difference between the radiation patterns of the 0 ° plane and the 90 ° plane is large, and it is disliked that the gain cannot be expected even when combined with a reflector having a wide aperture angle.

[0008]

As described above, as shown in FIG.
Also, in the conventional configuration of FIG. 11, there is a problem with the radiation pattern, and it has been difficult to realize a high-gain linearly polarized antenna device by combining it with a reflector having a wide aperture angle.

In view of the above points, the present invention provides two circular dipole antennas whose polarization planes are orthogonal to each other and devises the structure of the reflector provided on the end face of the circular waveguide. An object of the present invention is to provide a linearly polarized antenna device capable of receiving both horizontal and vertical polarized waves by one unit and combining with a reflecting mirror to significantly improve the gain.

[0010]

In order to achieve the above object, the linearly polarized antenna device of the present invention has a λ / 4 (where λ is the wavelength in the waveguide) from the end of a circular waveguide whose end is short-circuited. ) Two dipole antennas are attached in the vicinity of the front side so that the planes of polarization are orthogonal to each other, and a disc portion perpendicular to the circular waveguide and a folded portion folded back from the disc portion to the circular waveguide side. A cap-shaped reflector consisting of and is arranged on the terminal side of the circular waveguide.

[0011]

In the linearly polarized antenna device of the present invention, two dipole antennas are attached in the vicinity of λ / 4 before the end of the circular waveguide whose ends are short-circuited so that the planes of polarization are orthogonal to each other. In the circular waveguide, radio waves with orthogonal polarization planes do not interfere with each other, so it is possible to share the circular waveguide to feed each dipole antenna, and use one dipole antenna for receiving horizontally polarized radio waves, for example. By using the other dipole antenna for reception of vertically polarized radio waves, it is possible to receive both horizontally and vertically polarized waves with one device. Further, by devising a reflector structure arranged on the terminal side of the circular waveguide, a disc portion perpendicular to the circular waveguide and a folded portion folded back from the disc portion to the circular waveguide side. By using a cap-shaped reflector consisting of
The backward pattern of the radiation patterns on both 0 ° planes can be widened to achieve high gain in combination with a reflector having a wide aperture angle.

[0012]

Embodiments of the linearly polarized antenna device according to the present invention will be described below with reference to the drawings.

A first embodiment of the present invention will be described with reference to FIGS. In these figures, 10 is a parabolic reflector (parabolic reflector), and a dipole antenna 2 for horizontal polarization and vertical polarization is provided near the focus of the parabolic reflector 10 as shown in FIG. Is attached to the circular waveguide 1 so that the planes of polarization are orthogonal to each other (in FIGS. 1 and 2, only the dipole antenna for horizontal polarization in the horizontal plane is shown). Here, the antenna element 3 of the conductor rod of each dipole antenna 2 is attached to and supported by the circular waveguide 1 via the insulator 6 at a position in front of the end of the circular waveguide 1 by a distance D,
The extension conductor rod portion of the antenna element 3 serves as a coupling probe 5 protruding into the waveguide. The length of the antenna element 3 extending outside the circular waveguide 1 is set to around ¼ wavelength of the radio wave to be received or transmitted. Further, a conductor cap-shaped reflector 11 is attached to the tip end (end side) of the circular waveguide 1. The cap-shaped reflector 11 is perpendicular to the circular waveguide and has a disk portion 12 having an outer diameter larger than the overall length W of the dipole antenna 2 and the circular waveguide side (reflecting mirror side) of the disk portion 12. It is composed of a ring-shaped folded-back portion 13 folded back substantially vertically.
The distance D between the end of the circular waveguide 1 and each dipole antenna 2 is about λ / 4 (where λ: wavelength in the waveguide), and the length of the folded portion 13 (inside depth) L Is set in the vicinity of a quarter wavelength of the used radio wave, that is, approximately the same as the dimension of the distance D. The circular waveguide 1 passes through the center axis of the reflecting mirror 10 and is drawn out to the rear side of the reflecting mirror, and is passed through a demultiplexer 14 to a horizontal polarization CS converter 15A and a vertical polarization CS converter 15B, respectively. Connected.
The demultiplexer has a function of separating and extracting the horizontally polarized wave and the vertically polarized wave. The circular waveguide 1 and the reflecting mirror 10
And are integrated with each other on the rear side of the reflecting mirror.

In FIG. 4, the radiation pattern in the 0 ° plane of the dipole antenna with a reflector shown in the above embodiment is shown by a dotted line (c), and the radiation pattern in the 90 ° plane is shown by a solid line (d). Is. In this case, the front and rear radiation patterns are asymmetric, and the rear (reflecting mirror side) radiation pattern is considerably larger. Moreover, the beam of the radiation pattern is extremely wide, and the difference between the radiation patterns of the 0 ° plane and the 90 ° plane is small. As a result, the gain can be significantly improved by combining with the reflecting mirror 10 having a wide aperture angle. That is, a wide range of incident radio waves reflected by the reflecting mirror 10 can be efficiently received by the dipole antenna 2 serving as a primary radiator.

Since radio waves having orthogonal polarization planes do not interfere with each other in the circular waveguide 1, the horizontally polarized radio waves received by the dipole antenna 2 arranged in the horizontal plane propagate in the circular waveguide 1. Then, through the polarization splitter 14, horizontal polarization CS
Guided to converter 15A. Similarly, the vertically polarized radio wave received by the dipole antenna 2 arranged in the vertical plane propagates in the circular waveguide 1 and is guided to the vertically polarized CS converter 15B via the polarization splitter 14.

FIG. 5 shows a second embodiment of the present invention. In this case, the conductor cap-shaped reflector 11A has a disk portion 12A perpendicular to the circular waveguide 1 and a taper shape (cross-section trapezoidal shape) from the disk portion 12A to the circular waveguide side (reflecting mirror side). And a folded-back portion 13A folded back into The distance D between the end of the circular waveguide 1 and each dipole antenna 2 is λ
/ 4 (where λ is the wavelength in the waveguide), and the depth L of the folded portion 13A is set to be approximately the same as the dimension of the distance D. The rest of the configuration is the same as that of the first embodiment described above, and the obtained characteristics are also the same.

FIG. 6 shows an antenna element 3A of a dipole antenna according to the third embodiment of the present invention. In this case, each antenna element 3A of the dipole antenna is composed of a conductor cylinder having a large diameter for widening the frequency characteristic band. The conductor cylinder extending from the antenna element has a coupling probe 5A protruding into the circular waveguide 1.
Each antenna element 3A is insulated and supported by the circular waveguide 1 by an insulator 6. The other components including the reflector 11 are the same as those in the first embodiment.

FIG. 7 shows an antenna element 3B of a dipole antenna according to the fourth embodiment of the present invention. In this case, each antenna element 3B of the dipole antenna is composed of an inverted conical conductor rod (a tip having a large diameter and a taper toward the base portion) for widening the frequency characteristic band. A conductor rod portion extending from the antenna element serves as a coupling probe 5B protruding into the circular waveguide 1, and each antenna element 3B is insulated and supported by the circular waveguide 1 by an insulator 6. The other components including the reflector 11 are the same as those in the first embodiment.

FIG. 8 shows a fifth embodiment of the present invention. In this case, the circular waveguide 1 with each dipole antenna 2 attached
A low-loss dielectric material 20 having a relative dielectric constant of more than 1 is filled in the inside. The wavelength in the circular waveguide in this case is [1 /
(Square root of relative permittivity)], it is assumed that the cutoff frequency is the same as that of the circular waveguide in the absence of the dielectric. You can This is effective in reducing blocking of the reflecting mirror 10 by the circular waveguide or the reflector. By providing the dielectric in the circular waveguide, the distance D between the end of the dielectric and the element of the dipole antenna is also shortened. The other structure is similar to that of the first embodiment.

[0020]

As described above, according to the linearly polarized wave antenna device of the present invention, two circular dipole antennas whose polarization planes are orthogonal to each other are provided and the circular waveguide end face side is provided. Since the structure of the reflector has been devised, it is possible to greatly improve the gain by combining with a reflecting mirror that can receive both horizontal and vertical polarized waves with one unit and has a large aperture angle.

[Brief description of drawings]

FIG. 1 is a plan sectional view showing an overall configuration of a first embodiment of a linearly polarized wave antenna device according to the present invention.

FIG. 2 is a plan sectional view of an essential part of the first embodiment.

FIG. 3 is a perspective view of a main part of the first embodiment.

FIG. 4 is a pattern diagram showing a radiation pattern of a dipole antenna with a reflector in the case of the first embodiment.

FIG. 5 is a plan sectional view of an essential part showing a second embodiment of the present invention.

FIG. 6 is a plan sectional view of an essential part showing a third embodiment of the present invention.

FIG. 7 is a plan sectional view of an essential part showing a fourth embodiment of the present invention.

FIG. 8 is a plan sectional view of an essential part showing a fifth embodiment of the present invention.

FIG. 9 is a plan sectional view showing a conventional dipole antenna fed by a circular waveguide.

FIG. 10 is a pattern diagram showing a radiation pattern of the dipole antenna of FIG.

FIG. 11 is a perspective view showing another conventional example to which a reflector is added.

FIG. 12 is a pattern diagram showing a radiation pattern of the dipole antenna with a reflector shown in FIG.

[Explanation of symbols]

 1 circular waveguide 2 dipole antenna 3, 3A, 3B antenna element 5, 5A, 5B coupling probe 6 insulator 10 reflecting mirror 11, 11A cap-shaped reflector 12, 12A disk portion 13, 13A folding portion

Claims (3)

[Claims] 1. A λ from the end of a circular waveguide whose end is short-circuited.
/ 4 (where λ is the wavelength in the waveguide), two dipole antennas are attached so that the planes of polarization are orthogonal to each other, and a disc portion perpendicular to the circular waveguide and the disc portion A linearly polarized antenna device, wherein a cap-shaped reflector including a folded-back portion folded back to the circular waveguide side is arranged on the terminal side of the circular waveguide. 2. The linearly polarized antenna device according to claim 1, wherein the two dipoles are arranged near a focal point of the reflecting mirror. 3. The linearly polarized wave antenna device according to claim 1, wherein the circular waveguide is filled with a dielectric having a relative dielectric constant of more than 1.