JP3283589B2 - Planar antenna device for SNG - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar antenna for an earth station which accesses a communication satellite such as an SNG, and more particularly to a planar antenna device for an SNG which prevents a grating lobe from being generated in a geostationary satellite orbit even when an antenna beam is shaken. About.

SUMMARY OF THE INVENTION The present invention relates to a method for constructing a planar antenna device for an earth station used for satellite communication such as SNG. The antenna for the earth station is constituted by a planar array antenna, and the antenna is adapted to wind or the like. If an automatic tracking function is provided so that the antenna beam always faces the satellite even if it moves, grating lobes generally appear as the beam direction moves from the boresight of the antenna, and may satisfy the CCIR standard. Although it is not possible, to solve this, a sub-array of vertical m-elements and horizontal n-elements is configured, and when viewing the geostationary satellite orbit from the earth station, the sub-array is arranged so that grating lobes do not occur in the orbit plane direction. A planar antenna device for SNG is configured.

[0003]

2. Description of the Related Art A parabolic antenna device has been generally used as an earth station antenna device for satellite communication such as SNG.

[0004] The reason for this is that the characteristics of the earth station antenna, especially the side lobe characteristics, are strictly defined so as not to interfere with other communication satellites, and the parabolic antenna device is superior in this respect.

[0005] In the parabolic antenna device, an antenna device having a good side lobe characteristic with an opening of about 1.2 m has been already developed and put into practical use by a technique of a double reflecting mirror and an improvement in mirror surface accuracy.

However, when the satellite is automatically pointed by the parabolic antenna device, the tracking is performed mechanically based on information from a separately attached monopulse sensor.

As an example of using a planar antenna device for an earth station, it has been put to practical use in low bit rate communication such as digital data from Inmarsat.
There has been no example in which a planar antenna device has been put into practical use as an earth station antenna device that can directly access S (JCSAT, Superbird, etc.) or Intelsat.

However, as a method of designing a low side lobe type flat array antenna device, as described in the Antenna Engineering Handbook (edited by the Institute of Electronics and Communication Engineers), an example in which the aperture plane excitation distribution is a Chebyshev distribution or a Taylor distribution is used. There is.

[0009] As another technique, a technique for reducing the element arrangement interval so that the grating lobe does not appear within the maximum beam scanning range is also known.

[0010]

By the way, due to recent advances in digital modulation technology, it has been desired to realize a portable earth station which enables good communication even with a small antenna aperture and is easy to carry. .

As an antenna device for a portable earth station that satisfies such demands, a flat antenna device that can be configured to be lightweight and thin can be considered.

However, in order to apply the planar antenna device to the antenna device for the earth station, it is necessary to taper the aperture distribution in order to keep the side lobe level below a specified value. When an automatic tracking function is added so that the beam always points in the direction of the satellite even if it oscillates, the side lobe characteristics need to be below a specified level even when the antenna beam moves from the boresight direction of the antenna device.

In general, when beam scanning is performed by a planar array antenna device, grating lobes appear at a certain scanning angle. To avoid this, it is necessary to reduce the element spacing. For example, when the main beam is oscillated at ± 30 degrees, the element spacing must be about 0.6 free space wavelength.

However, in this case, due to the limited number of phase shifters and the like, when the plane array is divided into sub-arrays composed of a plurality of elements and phase control is performed by adding a phase shifter to each sub-array, The phase centers of the sub-arrays are separated by one or more free-space wavelengths, and a grating appears when beam scanning is performed.

As a result, as shown in FIG. 5, the angle is set to ± 3 degrees along the geostationary satellite orbit, and exceeds the CCIR specified value defined by the off-axis angle θ from the boresight of the antenna device, and the earth It cannot be used as an antenna device for a station.

In view of the above situation, the present invention takes into account the geosynchronous orbit of a communication satellite viewed from the antenna installation point on the earth, and considers the side lobe of the antenna apparatus in the orbit plane direction even when the beam is swung to the maximum. It is an object of the present invention to provide an SNG planar antenna device capable of reducing the level and preventing generation of a grating lobe.

[0017]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a planar array antenna device comprising a large number of radiating elements, wherein the array constituted by each radiating element is divided into a plurality of sub-arrays. The phase center of each sub-array is shifted by one radiating element with respect to the direction of the geosynchronous orbit, and is formed in a step shape in a direction perpendicular to the direction of the geosynchronous orbit. It is characterized by being arranged densely in the orbital direction and coarsely in the direction perpendicular to the direction of the stationary orbit.

According to the above configuration, the effective sub-array spacing is set densely in the direction of the geostationary orbit and coarsely in the direction perpendicular to the direction of the geostationary orbit. Taking into account the geostationary orbit of the communication satellite viewed from the point, even when the beam oscillates to the maximum, it is possible to reduce the side lobe level of the antenna device in the orbit plane direction and prevent the occurrence of grating lobe .

[0019]

FIG. 1 is a partial structural view showing an embodiment of a planar antenna device for SNG according to the present invention.

The SNG planar antenna device 1 shown in FIG.
Is constituted by a plurality of sub-arrays 2 arranged in the X direction and the Y direction so as to suppress the appearance of the side lobe level and the grating lobe in the X axis direction, and supplied via a feeder line (not shown). The transmission signal to be transmitted is phase-controlled by a phase control circuit (not shown) provided for each sub-array 2 and supplied to each sub-array 2, emitted from each of the sub-arrays 2 as a radio wave, and transmitted by each sub-array 2. When a radio wave is received, it is converted into a received signal by each of these sub-arrays 2, and this is phase-controlled by each phase control circuit and output.

Each sub-array 2 has four sub-arrays 2 in the X direction,
The antenna is composed of a total of 32 antenna elements 3 in the direction, and feed lines (not shown) for connecting these antenna elements 3, and the phase center of each sub-array 2 is in the X-axis direction. The antennas are arranged so as to be shifted by one antenna element, and are arranged by eight antenna elements in the Y-axis direction. In other words, the phase center of each sub-array is shifted by one radiating element in the X-axis direction (the direction of the geosynchronous orbit), and is formed in a step shape in the Y-axis direction perpendicular to the X-axis direction (the direction of the geosynchronous orbit). As a result, the configuration is such that the effective sub-array intervals are densely arranged in the direction of the geosynchronous orbit and coarsely arranged in the direction perpendicular to the direction of the geosynchronous orbit.

On the other hand, as shown in FIG. 2, when the communication satellite JCSAT1 is viewed from Tokyo, for example, the communication satellite JCSAT1 is viewed.
The portion ± 3 degrees from the geostationary satellite orbit of No. 1 looks almost straight as shown by the dotted line in the figure. Furthermore, communication satellite JCSAT
In the state where the polarization of the antenna is matched to the polarization of No. 1, the directivity plane in the geostationary satellite orbit direction approximately coincides with the φ = −30 degree plane.

When the beam direction is θ = 0 degrees, the directivity of the plane φ = −30 degrees is calculated by the arrangement shown in FIG. 1 (the block array is 8 blocks in the X-axis direction and 4 blocks in the Y-axis direction). Then, the table shown in FIG. 3 was obtained.

In the same arrangement, the beam is set to θ = 5 degrees, φ
When the direction was changed in the direction of = -30 degrees, when the directivity of the plane of? =-30 degrees was calculated, the table shown in FIG. 4 could be obtained.

As is clear from FIGS. 3 and 4, even when the beam is shaken with the X-axis direction overlapping the geostationary satellite orbit, no grating lobe is generated on the geostationary orbit. It can be seen that low side lobe characteristics can be obtained.

As described above, in this embodiment, considering the orbit of the geostationary satellite viewed from the earth station, the sub-arrays 2 are closely arranged in the direction of the geosynchronous orbit, and are perpendicular to the direction of the geosynchronous orbit. In the direction, the intervals between the sub-arrays 2 are coarsely arranged so that grating lobes do not appear in the direction of the geostationary satellite orbit, and that the grating lobes appear in the direction perpendicular to the direction of the geostationary satellite orbit. Allowed, all sub-arrays 2 are arranged with almost the same density as the square arrangement, so even when scanning the beam, the generation of grating lobes on the φ plane that intersects the orbital plane is suppressed, and low side lobe characteristics are achieved. And the low side lobe characteristics can be obtained without densely arranging the sub-arrays 2 having sharp directivity without performing taper excitation in the sub-arrays 2. It is possible to obtain.

Thus, it is possible to prevent the antenna gain from being reduced due to the tapered excitation.

[0028]

As described above, according to the present invention, taking into account the geosynchronous orbit of a communication satellite as viewed from the antenna installation point on the earth, even when the beam is swung to the maximum, the antenna can be oriented in the orbit plane direction. The side lobe level of the device can be reduced, and grating lobes can be prevented.

[Brief description of the drawings]

FIG. 1 is an element array configuration diagram showing one embodiment of an SNG planar antenna device according to the present invention.

FIG. 2 is a table showing the geostationary satellite orbit when viewing JCSAT1 from Tokyo.

FIG. 3 is a table showing directivity calculation values (φ = −30 degrees plane, beam θ = 0 degree direction) of the planar antenna device for SNG shown in FIG. 1;

4 is a directional calculation value (φ = −30 degrees plane, beam direction φ = −30 degrees,
It is a table | surface figure which shows (theta |

FIG. 5 shows CCIR Rec. It is a schematic diagram which shows the example of prescribed | regulated application range in geostationary satellite orbit in 524-3.

[Explanation of symbols]

 Reference Signs List 1 Planar antenna device for SNG 2 Subarray 3 Antenna element (radiating element)

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Norihiko Yazawa 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside the Japan Broadcasting Corporation Research Institute of Broadcasting (72) Inventor Fuyasu Suginoshi 1-10 Kinuta, Setagaya-ku, Tokyo No. 11 Inside Japan Broadcasting Corporation Broadcasting Research Institute (56) References JP-A-4-90608 (JP, A) JP-A-1-503669 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H01Q 3/00-3/46 H01Q 21/00-21/30

Claims (1)

(57) [Claims] In a planar array antenna device including a large number of radiating elements, an array including each radiating element is divided into a plurality of sub-arrays, and a phase center of each sub-array is set to be one with respect to a direction of a geosynchronous orbit. It is displaced by a radiating element and is formed in a step shape with respect to a direction perpendicular to the direction of the geostationary orbit, and an effective sub-array interval is densely arranged in the direction of the geostationary orbit.
A planar antenna device for SNG, wherein the antenna is roughly arranged in a direction perpendicular to the direction of the geosynchronous orbit.