JP2611883B2 - Mobile station antenna for satellite communication - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile station for satellite communication, and more particularly to a mobile station antenna for satellite communication capable of controlling the elevation angle of the antenna.

[0002]

2. Description of the Related Art In mobile satellite communications, it is essential to direct the main radiation direction of a mobile station antenna toward a satellite. However, conventionally, it has been difficult to realize an inexpensive mobile device due to a complicated satellite tracking mechanism. When an omni-directional antenna that radiates radio waves in all directions is used as a mobile station antenna, it does not require satellite tracking, but is a low-gain antenna. Therefore, it is desirable that the mobile station antenna for mobile satellite communication has directivity only in the satellite direction. For example, when a higher-order mode-excited microstrip antenna or helical antenna is used, a radiation directivity called a conical beam that radiates radio waves toward the satellite can be realized as shown in FIG. it can.

[0003]

However, since the elevation angle range of the satellite actually changes due to a change in the position of the mobile station, etc.,
With a cone beam antenna having a fixed elevation angle, it is difficult to satisfy a certain level of gain over all elevation ranges, and it has been desired to control the main radiation direction of the antenna in the elevation direction.

[0004] It is an object of the present invention to make it possible to easily change the antenna directivity in the elevation direction by using an antenna having a conical beam in combination with an antenna of a mobile station for mobile satellite communication. The purpose is to do.

[0005]

SUMMARY OF THE INVENTION A mobile station antenna for satellite communication according to the present invention comprises a plurality of circular microstrip conductors formed at equal intervals on a plurality of concentric circles, respectively. It comprises a plurality of circular microstrip antenna elements forming an angular conical beam directivity, and a switch for selecting and exciting one of the circular microstrip antenna elements.

As described above, in the antenna having the conical beam characteristic, the control of the radiation pattern of the antenna in the elevation direction, which was impossible with the prior art, can be easily realized, and the satellite can be tracked in a wide elevation angle range. An antenna having a higher gain than a directional antenna can be obtained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a basic configuration diagram of an antenna according to the present invention. A phase shifter 3 is inserted in each of the N radiating elements 1 in series, and these radiating elements 1 are connected to the power distributor 4 through the respective phase shifters 3. What is indicated by the dotted line in FIG.
The radiation directivity of each of the radiating elements 1 to #N is in the form of a conical beam having different elevation angles from each other. The amplitude of power supply to each radiating element 1 is changed by the power divider 4 and the phase is shifted. By changing the phase in the phaser 3 and giving an appropriate amplitude difference and phase difference between these cone beam characteristics and appropriately exciting the N radiating elements 1, for example, the solid line cone beam directivity in FIG. 2 is synthesized. be able to.

Here, the radiating element 1 having a conical beam also means a radiating element having unidirectionality. In FIG. 3, the power distribution ratio to each radiating element 1, that is, the amplitude control is set to 1 or 0, and 1 is set to 1 for only one radiating element 1. That is, as shown in FIG. 3, the N radiating elements 1 are directly connected to the switch circuits 2, respectively. FIG.
2 shows the radiation directivity of the radiating elements 1 from # 1 to #N. # 1
The # 1 to #N radiating elements 1 have main radiation directions in different elevation angles as radiation directivities as shown in the drawing. In the configuration shown in FIG. 3, the radiation directivity of the antenna is changed by sequentially switching to one radiating element corresponding to the satellite elevation angle in the switch circuit 2 in accordance with the fluctuation range of the satellite elevation angle, and the optimum cone as shown by a solid line, for example. Switch to radiating element 1 with beam. In this case, since only one radiating element 1 is fed, there is no need to consider the phase, and the phase shifter 3 is omitted.

FIGS. 5 and 6 show a configuration of an embodiment of a radiating element that can be used in the present invention. The figure shows a configuration in which microstrip antennas having different excitation modes are vertically stacked. A dielectric layer 12 is formed on a grounding conductor substrate 11, a circular strip conductor 13 is formed on the dielectric layer 12, a dielectric layer 14 is formed on the circular strip conductor 13, and a dielectric layer 14 is formed on the dielectric layer 14. A circular strip conductor 15 is formed. The center lines of the ground conductor substrate 11 and the strip conductors 13 and 15 are located on the same straight line. The diameter of the strip conductor 15 is smaller than the diameter of the strip conductor 13, one conical beam antenna element 16 is formed by the substrate 11 and the strip conductor 13, and one conical beam antenna element 17 is formed by the strip conductors 13 and 15. Have been. That is, the strip conductor 13 acts as a ground plate for the strip conductor 15. Further, the antenna feed circuit can be formed on the same dielectric layer constituting the element,
Power can also be supplied through

In this embodiment, a conical beam antenna element 17 having unidirectionality and an antenna element 16 having a conical beam
The two antenna elements having different radiation directivities are switched and used. As the antenna elements 16 and 17, when using a circular microstrip antenna for exciting the TM _31, TM ₁₁ modes, respectively, each of the radiation directivity with respect to the dielectric layer of the dielectric constant 1 is as shown in FIG. In the figure, the directivity of the circular microstrip antenna element 17 as shown by the solid line is excited in TM ₁₁ mode, a directional circular microstrip antenna element 16 as indicated by a dotted line is excited TM ₃₁ mode. Therefore, by the case of the high satellite elevation angle by the position of the mobile station is the TM ₁₁ mode of the antenna element 17, in the case of low satellite elevation selecting the antenna element 16 of the TM ₃₁ mode switch 2, high gain over a wide elevation range Can be realized.

When the excitation is performed by changing the amplitude ratio and the phase difference, the directivity of the antenna having the conical beam can be controlled in the same manner. For example, the radiation directivity when the same configuration as that shown in FIGS. 8 and 9 are shown in FIGS. This example is TM ₁₁ ,
It shows the radiation directivity when the amplitude ratio of the excitation of the two circular microstrip antenna elements 17 and 16 excited in the TM ₃₁ mode is changed, and the amplitude ratio of each mode (TM ₃₁ mode to TM ₁₁ mode) (Excitation amplitude ratio) is 0.5 and 0.1. By changing the amplitude ratio, the main radiation direction can be shifted from the zenith direction to the low elevation angle direction.

FIG. 10 shows a configuration example in which conical beam antenna elements are arranged on the same plane. Grounding conductor board 11
A dielectric layer 12 is formed thereon, and eight circular microstrip conductors 21 and 22 are formed on the dielectric layer 12 at equal intervals on two concentric circles. The eight strip conductors 21 and the substrate 11 constitute a conical beam microstrip antenna element, and the eight strip conductors 22 and the substrate 11 similarly constitute a conical beam microstrip antenna element. The elevation angle direction can be changed by switching these two conical beam microstrip antenna elements.

[0013]

As described above, according to the present invention, it is possible to easily change the radiation directivity of the antenna having the conical beam directivity in the elevation direction of the antenna in the mobile station for satellite communication, and the wide elevation angle range. Satellite tracking is possible with
In addition, an antenna having a higher gain than an omnidirectional antenna can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing the principle of the present invention.

FIG. 2 is a view for explaining radiation directivity of the configuration of FIG. 1;

FIG. 3 is a configuration diagram illustrating one embodiment of the present invention using a switch.

FIG. 4 is a diagram for explaining radiation directivity of the configuration of FIG. 3;

FIG. 5 is a perspective view showing an embodiment of a radiating element which can be used in the present invention, in which microstrip antenna elements are arranged vertically.

FIG. 6 is a sectional view of FIG. 5;

FIG. 7 is a diagram showing radiation directivities produced by circular microstrip antenna elements excited by TM ₁₁ and TM ₃₁ ;

FIG. 8 is a radiation directivity diagram showing an example in which the excitation direction is controlled to change the radiation direction in the elevation direction.

FIG. 9 is a view showing another example of FIG. 8;

FIG. 10 is a perspective view showing another example of a radiating element that can be used in the present invention, in which microstrip antenna elements are arranged on a plane.

FIG. 11 is a view showing a conical beam.

Continued on the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location H01Q 21/20 H01Q 21/20 21/29 21/29

Claims (1)

(57) [Claims] 1. A plurality of circular microstrip antennas each having a plurality of circular microstrip conductors formed at equal intervals on a plurality of concentric circles and forming conical beam directivity characteristics having the same axis and different apex angles. And a switch for selecting and exciting one of these circular microstrip antenna elements.