JPH0486103A - Main scanning antenna for mobile station - Google Patents

Abstract

PURPOSE:To reduce man-hours for inspection and maintenance by crossing plural antenna arrays each comprising a helical antenna element whose elevating angle is less than 90 deg. at one point with each other and arranging each antenna element opposite to each antenna array alternately. CONSTITUTION:Line segments of each of antenna element 31 arranged in each of antenna arrays 211-215 provided on an antenna mount 11 are crossed with each other at one point and each of the antenna element 31 arranged at an elevating angle less than 90 deg. is directed opposite to each other alternately for each of antenna arrays 211-215. Thus, when a feeding phase is set to each antenna element 31 at first, it is not required to revise the phase and a range of an azimuth angle of 360 deg. is scanned by selecting the antenna arrays 211-215 only.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application 1] The present invention relates to a scanning antenna for a mobile station in satellite broadcasting (BS).

rPrior Art J Generally, in satellite broadcasting (BS), when radio waves are transmitted and received between a satellite and a mobile station (on the earth), the mobile station tracks the satellite.

For example, in the case of a mobile station mounted on a moving object such as a car, satellites are captured by scanning the antenna mechanically or electronically.

Regarding such antenna scanning means, the following known documents l,
2 can be seen.

Publicly known literature 1: Journal of the Institute of Electronics, Information and Communication Engineers E Vol, J71-B No, 11 pp, 1389
-1392 November 1988 "Mobile antenna system for satellite communication using a new automatic tracking method" In the case of the mechanical antenna scanning means disclosed in this document 1, the elevation angle of the antenna is set to an appropriate angle, and the inclination The antenna is rotated by a power machine to determine the elevation angle and azimuth from 0 to 380.
It corresponds to °.

A printed spiral type antenna element is used as the antenna element.

Publicly known document 2: Institute of Electronics, Information and Communication Engineers journal B-II Vol, J72-B-II No, 7pp,
323-329 July 1989 "Electronic Scanning Antenna for Automotive Satellite Communication" In the case of the electronic antenna scanning means disclosed in this document 2, thin antenna elements are arranged in a polygonal shape on a plane, and these antenna elements by electronic scanning, elevation angle 30~SO°, azimuth O~36°
It corresponds to 0°.

More specifically, 10 to 20 antenna elements are arranged in a polygon, and these antenna elements are electronically switched in the azimuth direction at intervals of lθ to 20°.

As the antenna element, a planar microstrip type antenna element is used.

``Problem to be Solved by the Invention J Since the mechanical antenna scanning means found in the known literature is mechanical, regular inspection and maintenance are essential, and therefore, when used for a long period of time, ,
Inspection and maintenance costs increase, and in depopulated areas, it becomes difficult to receive inspection and maintenance services.

Although the electronic antenna scanning means shown in Publication Document 2 does not require much inspection and maintenance as in Publication Document 1,
The number of antenna elements increases, and the switching circuit for aligning and switching the electrical phases for each direction becomes complex.

Moreover, in the case of the microstrip antenna used in Publication Document 2, the directivity is the sharpest and the gain is highest when the radiation surface is directed directly upward. ) to correspond to the satellite, the gain will be low even though multiple antenna elements are combined.

In view of these technical problems, the present invention not only allows the adoption of an electronic scanning means that requires almost no inspection or maintenance, but also simplifies the switching circuit for scanning.

It is an object of the present invention to provide a scanning antenna for a mobile station that can effectively utilize the gain of an antenna element.

1 Means for Solving the Problem J In order to achieve the intended purpose, the scanning antenna for a mobile station according to the present invention has a plurality of antennas arranged on a plurality of odd number of substantially horizontal line segments that intersect with each other at - points. Helical antenna elements are each arranged at an elevation angle of less than 90° to form a multi-row antenna array, each antenna element in the antenna array.

Each antenna array is characterized by alternately oriented in opposite directions.

1 Effect J In the case of the mobile station scanning antenna according to the present invention, first,
Once the feeding phase to each antenna element is set, there is no need to change it from now on, and the satellite can be tracked in the range of azimuths from 0 to 360 degrees by scanning simply by switching the antenna array.

Moreover, in the case of the mobile station scanning antenna according to the present invention, each antenna element is inclined, and the direction of inclination of each antenna element is opposite for each antenna array, so that near the intersection of these antenna arrays Therefore, each antenna element does not collide with each other, and high gain can be obtained.

Embodiment Embodiments of the mobile station scanning antenna according to the present invention will be described with reference to FIGS. 1 to 4.

In the figure, 11 indicates an antenna mounting body having a substantially horizontal antenna mounting surface (including a horizontal surface), 21+, 21
2.213.214, 215 indicates a plurality of rows (odd number) of antenna arrays provided on the mounting surface of the antenna mounting body 11, and 31 indicates a helical type unit antenna when configuring each antenna array 211 to 215. The antenna elements of are shown respectively.

In the above, each antenna array 211 to 215 provided on the antenna mounting body 11 includes each antenna element 3! The line segments lined up intersect with each other at one point, and the antenna elements 31 arranged at an elevation angle of less than 90 degrees (40 to 50 degrees) are arranged in alternate directions in opposite directions for each antenna array 21+ to 215. It has become.

In the above, the helical antenna element 31 is made of a publicly known or well-known element, for example, a pair of conducting wires (coils) wound spirally in opposite directions around the outer periphery of a circular tube shaft, and feeding power from the center of the pair. This is how it was done.

In the case of the scanning antenna for a mobile station according to the present invention, that is, the antenna mounting body 11 having the antenna arrays 211 to 215, - for example, it is installed as a mobile station mounted on a car (mobile body), and on the other side: It is equipped for mobile stations aboard ships, aircraft, and other moving objects, thus providing the required satellite communications! (C5) is provided for satellite broadcasting (BS), and a specific example of this is as follows.

In the case of the antenna element 31 illustrated in FIG. 4, its gain G and half-width B (dog) are expressed by the following equations (1) and (2).

G effect 15・(C/in) 2 X (nS/in) -----
-----(L)B=52/((C/in)・vT77■
])""" (2) Each symbol in Figure 4 and formulas (1) and (2) has the following meaning.

d: Coil diameter of helical antenna (mid) S: Coil winding pitch (layer weight) of helical antenna C: Length per coil winding (layer weight) (C=πd) In: Wavelength (fat layer) (1, f3GHz When λ=187.5mm)n
: Number of coil turns In the above, d-48 layer lid φ, element length -104 (L in Figures 2 and 3), S + 34.8 sn, n
*3 When λ = 187.5 m layer, the gain G and half width B of the helical antenna element 31 alone are G = 5.4, that is, 7.3 dB, and B = E16.
．． ? That is, it is approximately 87°.

On the mounting surface of the antenna mounting body 11 (outer diameter D=lli70 φ in FIGS. 2 and 3), six antenna elements 31 are installed at a time, and the elevation angle is 45°, as shown in FIGS. When arranged as shown in Fig. 3, each antenna array 21
The gain of 1 to 215 is the sum of the gain of the antenna element 31 alone and the gain of these multiple elements, and its value is about 15 dB.

At this time, the half-value angle θH of the azimuth shown in FIG. 1 is about 87°, and the half-value angle θν of the elevation angle shown in FIGS. 2 and 3 is about to
'is.

Furthermore, in FIGS. 2 and 3, each antenna element 31
The height h is ha101+gm.

As mentioned above, the half-value angle θH of the azimuth is 87°, so when the antenna arrays 211 to 215 are configured in five rows with six antenna elements 31 each as shown in the illustrated example, in the range of θ to 360°. A gain of 12 dB or more can be obtained.

In the case of the mobile station scanning antenna according to the present invention, first,
Once the feeding phase to each antenna element 31 has been set, there is no need to change it from now on; simply
A range of 360° in azimuth can be scanned by simply switching between 1 and 21 seconds.

Therefore, the scanning antenna does not require a complicated phase switching circuit.

Furthermore, in the case of the mobile station scanning antenna according to the present invention, each antenna element 31 is arranged at an angle, and each antenna array 21. Since these antenna arrays 211 to 2 are reversed every 21 seconds,
The antenna elements 31 do not collide with each other near the intersection 1s.

Therefore, in the case of the scanning antenna, coupling between the antenna arrays is also reduced compared to an antenna array in which the antenna arrays are arranged in parallel with each other.

In the illustrated example, the antenna array is arranged in five columns, but if a small gain is sufficient, the number of antenna arrays can be reduced from the illustrated example; conversely, if a larger gain is required, the number of antenna arrays can be reduced from the illustrated example. increase more than

Similarly, the number of each antenna element in the antenna array is increased or decreased as necessary.

In addition, regarding the reflector of the antenna element (see Figure 4), since this is orthogonal to the element axis and approximates the required directivity, allowance should be made to absorb the error caused by the above-mentioned tilted arrangement. It is preferable to leave it there.

Effects of the Invention J As explained above, in the scanning antenna for a mobile station according to the present invention, a plurality of rows of antenna arrays each made up of helical antenna elements having an elevation angle of less than 90° intersect with each other at one point,
Since each antenna element in these antenna arrays is alternately oriented in opposite directions for each antenna array,
In addition to being able to employ electronic scanning means that requires less inspection and maintenance, the switching circuits of these antenna arrays can also be simplified, and in addition, the antenna element f-
The gains can be effectively utilized.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of an embodiment of a scanning antenna for a mobile station according to the present invention, FIG. 2 is an arrow diagram of the nn line in FIG. An arrow diagram of the connecting m-■ line,
FIG. 4 is a schematic explanatory diagram of an antenna element according to the present invention. 11... Antenna mounting bodies 211 to 215... 31... Antenna element agent Yoshio Saito 2, 7,

Claims (1)

[Claims] A plurality of helical antenna elements are arranged at an elevation angle of less than 90 degrees on a plurality of odd number of substantially horizontal line segments that intersect with each other at one point, forming a plurality of rows of antenna arrays. A scanning antenna for a mobile station, characterized in that elements are alternately oriented in opposite directions for each antenna array.