JPH0477004A - Offset antenna - Google Patents

Abstract

PURPOSE:To prevent/reduce snow deposition and to realize an offset antenna with a high communication line efficiency inexpensively by forming part of an outer circumferential ring reinforcing the surround of a main reflecting mirror to have a hollow closed cross section and providing a heater wire and a fluid in the inside of the hollow closed cross sectional area. CONSTITUTION:An electric heater wire 13 is mounted in the inside of the lower part of the circumference of a hollow outer circumferential ring 12 whose cross section is closed in a rectangular shape reinforcing the surround of a main reflecting mirror 1. Moreover, the inside of the lower circumference of the outer circumferential ring 12 is filled by a fluid such as water with ethylene glycol added thereto. Then in the case of snowfall, snow deposition is liable to grow while the outer circumferential ring 12 is used as a core and the snow core is molten with the heated electric wire 13 via the fluid 16 and soon dropped down and the snow deposition is limited to the direct snow deposition to the reflecting mirror 11. Thus, the outer circumferential ring 12 in a rage where the electric heater wire 13 is inserted and the fluid 16 is filled is efficiently heated.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates mainly to an aperture antenna used for microwave communication or radar, etc., and more specifically relates to off-cell antennas for satellite communication earth stations [and prevention of snow accumulation on antennas]. It is something.

[Prior Art] Fig. 5(a) is a front view of a conventional Offsera 1 antenna whose concept was shown in, for example, Japanese Patent Publication No. 53-31345, and Fig. 5(b) is a 011 side view. In (1)
is the main reflecting mirror obtained by cutting the paraboloid of revolution at plane P, (
2) is a sub-reflector that is part of a paraboloid of revolution.

(3) is, for example, a primary radiator of a conical horn, and the radio wave phase center of this secondary radiator (3) coincides with one of the conjugate foci of the sub-reflector ffl (2), and the second-order radiator of the sub-reflector (2) The focus of is coincident with the focus of the main reflection ffl (1).

(4) is a ladder-shaped frame that connects the sub-reflector (2) and the -order radiator (3) in a predetermined relationship, and (5) is the main reflector M
Connect (1) and frame (4) to main reflector (1) and sub-reflector! (2) is a stay that maintains a predetermined relationship; (6) is a transmission path for receiving or transmitting radio waves; (7) is an outer ring with a channel-shaped cross section that stiffens the area around the main reflecting mirror (1); Depending on the size of the main reflecting mirror (1), the outer edge shape of the main reflecting mirror (1) may be integrally molded when molded using a press or the like.

(8) is a frame that holds the main reflector (1), (9) is an AZ (azimuth) adjustment mechanism that determines the direction of received or transmitted radio waves in the horizontal plane, and (10) is the direction of received or transmitted radio waves in the vertical plane. EL (elevation) adjustment mechanism that determines the direction;
(11) is a frame to be installed on a building, steel tower, etc.

A conventional offset antenna is constructed as described above, and when considered as a receiving antenna for a satellite communications earth station, 2
Radio waves arriving from population hygiene (not shown) are transmitted through the transmission line (6)
As shown, the radio wave is sequentially reflected by the main reflecting mirror (1) and the sub-reflecting mirror R (2), and is focused on the radio wave phase center of the primary radiator (3), and reaches a receiver (not shown).

Offset antennas have no blocked part of the transmission path (6), and compared to parabolic antennas and Cassegrain antennas that inherently have blocking, there is no sidelobe deterioration or gain reduction due to blocking, and they are suitable for satellite communications and high-speed antennas as antennas with good characteristics. It is used for density communication.

The antenna is installed outdoors, and in order to reduce cross-polarization characteristic deterioration and gain reduction due to snowfall in winter, the main reflection [(1)] is set at a nearly vertical angle in order to reduce standing snow. Selecting the shape of the reflector (1).

FIG. 7(a) is a front view of an offset antenna showing another conventional example, and FIG. 7(b) is a side view.
1a) is a reflecting mirror obtained by cutting a paraboloid of revolution along plane P, and (3) is a primary radiator of, for example, a conical horn.The radio wave phase center of this -order radiator (3) is the reflection M, (la ) is consistent with the focus of

(4) is a frame that connects with the -order radiator (3) in a predetermined relationship, and (5) connects the reflector (1a) and frame (4) for reflection! (la) and the -order radiator (3) are kept in a predetermined relationship; (6) is a transmission path for receiving or transmitting radio waves.

(7) is an outer ring that stiffens the periphery of the reflector M(la), which is used when forming the reflector M(la) with a press or the like.
Although it is integrally molded as the outer edge shape of a), one reflection ff1(l
Depending on the size of a), it may be a separate part.

(8) is a frame that holds the reflector (la), (9) is an AZ (azimuth) adjustment mechanism that determines the direction of received or transmitted radio waves in the horizontal plane, and (10) is the direction of received or transmitted radio waves in the vertical plane. EL (elevation) adjustment mechanism that determines
(11) is a frame to be installed on a building, steel tower, etc.

A conventional offset antenna is configured as described above, and when considered as a receiving antenna for a satellite communication earth station, 9
Radio waves arriving from an artificial satellite (not shown) are transmitted through a transmission path (6)
Reflected by the 1st reflector (1, a) and the primary radiator (3)
The radio wave is focused on the phase center of the wave and reaches a receiver (not shown).

Offset antennas have no part where the transmission path (6) is connected, and compared to parabolic antennas and Cassegrain antennas, which inherently have blocking, there is no sidelobe deterioration or gain reduction due to blocking, and they are suitable for satellite communications as antennas with good characteristics. It is used for high-density communication.

Since the antenna is installed outdoors, in order to reduce cross-polarization characteristics deterioration and gain reduction due to snowfall in winter, the reflector (LA) is set at a nearly vertical angle during use to reduce snowfall! The shape of (la) is selected.

[Problems to be Solved by the Invention] The above-mentioned two conventional offset antennas have a much smaller amount of snow accumulation than a parabolic antenna or a Cassegrain antenna, in which snow accumulates on the entire surface of the antenna, and have less influence on one communication line.

However, on rare occasions, the communication line of the offset antenna may be momentarily interrupted.

This is the main reflection ffl (1), and as shown in Fig. 6 and Fig. @ (1) There is a tendency for snow to accrete in areas where the angle of the plane in contact with the reflector (1a) does not reach the vertical, and this snow grows from below where the angle is far from the vertical, and the snow falls downward under its own weight. This occurs because the frame (4) prevents the snow from moving, melting, and sliding down, and when this blocked snow accumulates to a certain extent and falls all at once, a sudden change in reception level and polarization plane occurs.

How important is it to eliminate snow accumulation in order to eliminate momentary interruptions in communication lines and ensure operating rates? (1).

Even if we choose the angle at which the reflection M(1, a) stands, it is impossible due to the influence of snow quality and wind direction, so in the past, ceramic-based or fluorine-based anti-snow paints were used to obtain the main reflection ffl (1), reflection # !
(Ia) or main reflection! (1), reflector (1
The method used in a) is to melt snow by running heating wires behind it.

However, the anti-snow coating is currently only effective for about two years and requires periodic repainting, and the heating wire cannot be used with the main reflector (1
), the method of attaching it to the back of the reflector M(la) is that the main reflector (1) and the reflector (1a) are thermally great heat sinks, so the main reflector M(1) and the reflector M(la) ) requires a considerable amount of electricity to effectively heat it.

These ultimately led to an increase in maintenance costs and made it difficult for a factory with an operating rate of 7 communication lines.

The present invention has been made to solve this problem, and aims to provide an offset antenna at a low cost that substantially prevents the effects of snow accumulation and has a high communication line operating rate.

[Means for solving the problem] An offset antenna according to the present invention has a main reflector (1)
Alternatively, at least a part of the outer circumferential ring that stiffens the periphery of the reflector (la) has a hollow closed cross section, and a heating wire is attached to the inside of this hollow closed cross section, and at the same time, the inside of the hollow closed cross section is filled with fluid. .

[Operation] In the present invention, by supplying electric power to the attached heating wire, a desired area filled with fluid on the main reflecting mirror or the outer edge of the reflecting mirror is heated intensively.

[Embodiment] Fig. 1(a) is a front view showing an embodiment of the present invention, Fig. 1(b) is a side view, and Fig. 2(a) is a partially enlarged view showing the attachment of a heating wire. In the figure (1) to (6).

(8) to (11) are exactly the same as the conventional device shown in FIGS. 5 and 6.

(12) is a hollow outer ring with a rectangular closed cross section that surrounds the main reflector (1), (13) is an outer ring (12)
The heating wire 9 is installed inside the lower part of the periphery and is made of a nichrome wire insulated with silicone rubber, for example.

(14) is a temperature measuring means such as a platinum resistance thermometer or a thermostat, and (15) is a control unit that adjusts the amount of electric power given to the heating wire (13) based on the output of the temperature measuring means.

(16) is a fluid filled in the lower part of the periphery of the outer ring (12), which is water to which ethylene glycol has been added, for example.

In the offset antenna configured as above,
The behavior of received waves and transmitted waves is exactly the same as in the conventional device.

During snowfall, as already explained, the snow condition is determined by the main reflector (
The snow accretion on the lower part of 1) is noticeable, especially around the periphery, here the snow tends to grow around the outer ring (12) as a core, but this core snow is transferred via the fluid (16). It melts due to the heat generated by the heating wire (13) transmitted to the outer ring (12) and immediately falls.
).

Furthermore, even if snow adhering to the lower part of the direct main reflecting mirror (1) moves downward due to its own weight or slides down, the movement of the snow is promoted since it is a heat source in the moving direction.

Considering the heat transfer from the heating wire (13) to the outer ring (12), the heat transfer coefficient and heat tolerance of the fluid (16) are much higher than that of gas (air), so the main heating wire (13) )
When inserted into the outer ring (12), the heating wire (13)
) can be made compact/71cm by increasing the watt density of the heating wire (13), and the heating range is not only the insertion part of the heating wire (13) but also the outer ring (12) of the area filled with the fluid (16). ) can be heated efficiently, and there is little effect of temperature changes on the amount of heat dissipated due to sudden snowfall or snow movement.

In other words, by heating the outer edge of the main reflector (1), especially the necessary part of the lower half, it is possible to effectively prevent and reduce snow accumulation, but the power consumption is It is far less expensive than heating the entire reflecting mirror (1), and does not require regular maintenance like anti-snow coatings, so it is particularly effective and cost effective.

In the above embodiment, the outer ring (12) is the main reflection fi.
I explained the case where it is a separate part from (1).

As shown in FIG. 2(b), the outer edge shape of the main reflecting mirror (1) may be integrally formed by curling with a press or the like, and a sealing agent such as silicone sealant (1) may be used.
It goes without saying that the same effect can be obtained by applying 7) to effectively make a part of the outer ring (12) a closed section so that the fluid (16) does not flow out.

If the heating wire (13) is a self-regulating heater whose resistance value has a negative characteristic with respect to temperature, such as a polyethylene/carbon black composite heating wire, the temperature measuring means (14) and the control section (15) are simple or unnecessary. Needless to say, it will happen.

Furthermore, the type and material of the heating wire should not be a concern, and the fluid (16) should not be a matter of type or material as long as it is fluid, such as mineral oil, and is stable with little volatility, from low temperatures to room temperature. Needless to say, the sealing agent (17) is not limited to nine types and materials such as thiocol sealant.

FIG. 3(a) is a front view showing another embodiment of the present invention, FIG. 3(b) is a side view, and FIG. 4(a) is a partially enlarged view showing a heating wire device. (la).

(3) to (6), (8) to (11) are shown in Figures 7 and 8.
This is exactly the same as the conventional device shown in the figure.

(12) is an outer circumferential ring that supplements the circumference of the reflecting mirror (1a), and is a hollow outer circumferential ring with a single circular closed cross section that has been curled with a press as the outer edge shape of the nine reflecting mirror (la).

(13) is a heating wire attached to the lower part of the periphery of the outer ring (12), and is made of, for example, a nichrome wire insulated with silicone rubber.

(14) is a temperature measuring means such as a platinum resistance thermometer or a thermostat, and (15) is a control unit that adjusts the amount of electric power given to the heating wire (13) based on the output of the temperature measuring means.

(16) is a fluid filled in the lower part of the periphery of the outer ring (12), which is water to which ethylene glycol has been added, for example.

(17) is a sealant such as silicone sealant applied to a part of the outer ring (12), which effectively prevents (16) from flowing out from the outer ring (12).
) is a closed section.

In the offset antenna configured as above,
The behavior of received waves and transmitted waves is exactly the same as in the conventional device.

During snowfall, as explained above, snow conditions can be determined using a reflector (I).
The snow accretion at the bottom of a) is noticeable, and the snow tends to grow especially around the periphery, that is, the outer ring (12), but this core snow is transferred to the outer periphery via the fluid (transducer). Since the ring (12) is melted by the heat generated by the heating wire (13) and falls immediately, snow accretion is limited to that which directly adheres to the reflecting mirror (la).

Further, even if snow attached to the lower part of the direct reflecting mirror (1a) moves in the direction F due to its own weight or slides down, the movement of the snow is promoted because there is a heat source in the moving direction.

Considering the heat transfer from the heating wire (13) to the outer ring (12), the heat transfer coefficient and heat capacity of the fluid (16) are much larger than that of gas (air), so the heating wire (13) is simply
When inserted into the outer ring (12), the heating wire (13)
) can be made compact by increasing the watt density of the heating wire (■3), and the heating range is not only the insertion part of the heating wire (■3) but also the outer ring (■2) of the area filled with the fluid (16). can be heated efficiently, and there is little effect of temperature changes on the amount of heat dissipated due to sudden snowfall or snow movement.

In other words, it is possible to effectively prevent and reduce snow accumulation by heating the outer edge of the reflector (la), especially the necessary part of the lower half, but the power consumption is lower than the reflector H. (la) It is far less expensive than heating the entire body, and does not require regular maintenance like anti-snow coatings, so it is particularly effective and cost effective.

In addition, in the above embodiment, the outer ring (12) is connected to the reflecting mirror (1
Although we have explained the case where the outer edge shape in a) is integrally formed by pressing, etc., the same effect can be obtained even if it is a separate part from the reflection M(la) as shown in Fig. 4(b). Needless to say, if the heating wire (13) is a self-regulating heater whose resistance value has a negative characteristic with respect to temperature, such as a polyethylene/carbon black composite heating wire, the temperature measuring means (14) and the control section (15) Needless to say, it will become simpler or unnecessary.

Furthermore, the type and material of the heating wire does not matter, and the type and material of the fluid (16) does not matter as long as it is fluid, such as mineral oil, and is stable with little volatility from low temperatures to room temperature. Needless to say, the sealant (17) cannot be limited to just one type or material, such as a thiocol sealant.

[Effects of the Invention] As explained above, the present invention has a main reflecting mirror of an offset antenna or a part of the outer ring that reprints around the reflecting mirror has a hollow closed cross section, and a heating wire and a fluid are provided inside the hollow closed cross section. The simple structure of adding 100% of the total amount of snow has the effect of preventing and reducing snow accretion and realizing an offset antenna with 1 communication line operating rate at a low cost.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are structural diagrams of an offset antenna showing an embodiment of the present invention, and FIGS. 2(a) and 2(b) are partially enlarged views showing the installation of a heating wire in an embodiment of the present invention. . FIGS. 3(a) and 3(b) show another embodiment of the present invention. FIGS. 4(a) and 4(b) are partially enlarged views showing the installation of heating wires in another embodiment of the present invention. Figures (a) and (b) are configuration diagrams showing a conventional offset antenna, Figure 6 is a diagram showing the state of snow accumulation, Figures 7 (a) and (b) are diagrams showing another conventional offset antenna, FIG. 8 is a diagram showing the state of snow accumulation on another offset antenna. In the figure, (1) is the main reflection fit, and (]a) is the reflector. (2) is the sub-reflector, (3) is the -order radiator, (4) is the frame, (5) is the stay, (6) is the transmission line 2, (7) is the outer ring, (8) is the skeleton, ( 9) is the AZ adjustment mechanism,
(]0> is the EL adjustment mechanism, (11) is the mount, 02)
(13) is the heating wire, (14) is the temperature measuring means, (15) is the control unit, (13) is the fluid, (17)
is a sealant. Note that in each figure, the same reference numerals indicate corresponding parts.

Claims (2)

[Claims] (1) A main reflecting mirror obtained by cutting a paraboloid of revolution with a plane, a sub-reflecting mirror that is a part of an ellipsoid of revolution whose focal point is one of the conjugate focal points of the main reflecting mirror, and an offset antenna comprising a primary radiator whose radio wave phase center is at the other conjugate focal point; An offset antenna characterized by comprising: a heating wire disposed inside the hollow closed cross section; and a fluid filled inside the hollow closed cross section. (2) A reflecting mirror obtained by cutting a paraboloid of revolution with a plane,
an offset antenna comprising a primary radiator whose radio wave phase center is the focal point of the reflector, at least a portion of which has a hollow closed cross section, an outer peripheral ring that stiffens the periphery of the main reflector, and the hollow closed cross section; An offset antenna comprising: a heating wire disposed inside the hollow closed cross section; and a fluid filled inside the hollow closed cross section.