JPH04347911A - Mobile station antenna for satellite communication - Google Patents

Abstract

PURPOSE:To control the elevation angle direction of a beam having a conical directional pattern. CONSTITUTION:A dielectric layer 12 having the same diameter as a circular ground conductor substrate 11 is formed on this substrate 11, and a circular strip conductor 13 whose diameter is shorter than that of the dielectric layer 12 is formed on this layer 12, and a dielectric layer 14 having the same diameter as the dielectric layer 12 is formed on the strip conductor 13, and a circular strip conductor 15 whose diameter is smaller than that of the strip conductor 13 is formed on the dielectric layer 14. The substrate 11 and the strip conductor 13 constitute a conical beam antenna element 16, and strip conductors 13 and 15 constitute a conical beam antenna element 17. Antenna elements 16 and 17 are excited in TM31 and TM11 modes respectively, and a switch is switched to use the antenna element 17 for a high satellite elevation angle and use the antenna element 16 for a low satellite elevation angle.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile station antenna for satellite communication, which is used in a mobile station for satellite communication, and more particularly to a mobile station antenna for satellite communication that can control the elevation angle of the antenna pointing direction.

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 the satellite. However, in the past, the satellite tracking mechanism was complicated, making it difficult to realize an inexpensive mobile device. When an omnidirectional antenna that radiates radio waves in all directions is used as a mobile station antenna, satellite tracking becomes unnecessary, but the antenna has low gain. Therefore, it is desirable that a mobile station antenna for mobile satellite communication has directivity only in the direction of the satellite. For example, when using a high-order mode excitation microstrip antenna or helical antenna, it is possible to achieve a radiation directivity called a cone beam that emits radio waves in the direction of the satellite, as shown in Figure 11, and a simple and low-cost mobile device can be configured. can.

0003

[Problem to be solved by the invention] However, in reality, the elevation angle range of the satellite changes due to changes in the position of the mobile station, etc.
With a conical beam antenna having a fixed elevation angle, it is difficult to satisfy a gain above a certain level for all elevation angle ranges, and it has been desired to control the main radiation direction of the antenna in the elevation angle direction.

[0004] An object of the present invention is to easily change the antenna directivity in the elevation direction by using a combination of antennas having conical beams in the antenna of a mobile station for mobile satellite communication. The purpose is to

[0005]

[Means for Solving the Problems] According to the present invention, a plurality of strip antenna elements each having a conical beam as a directivity are arranged on the same plane or above and below, and the amplitude and phase of the feeding signal to these strip antenna elements is adjusted. The elevation direction of the conical beam is controlled by changing the . This amplitude change may be turned on and off to turn on only one strip antenna element.

[0006] In this way, in an antenna with conical beam characteristics, antenna radiation directivity control in the elevation angle direction, which was impossible with conventional techniques, can be easily realized, satellite tracking is possible in a wide elevation angle range, and moreover, it is possible to An antenna with higher gain can be obtained compared to a directional antenna.

[0007]

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

[0008] Here, the radiation element 1 having a conical beam also means a radiation element having unidirectionality. In FIG. 3, the power distribution ratio to each radiating element 1, that is, amplitude control, is set to 1 or 0, and is set to 1 only for one radiating element 1. That is, as shown in FIG. 3, the N radiating elements 1 are each directly connected to the switch circuit 2. Figure 4
shows the radiation directivity of the radiating elements 1 from #1 to #N. #1
As shown in the figure, the radiating elements 1 from #N have main radiation directions in different elevation angle directions as radiation directivity. 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 according to the variation range of the satellite elevation angle, so that the radiation directivity of the antenna is changed, for example, to create an optimal cone as shown in the solid line. Switch to the radiating element 1 with the beam. In this case, since only one radiating element 1 is supplied with power, there is no need to consider the phase, and the phase shifter 3 is omitted.

FIGS. 5 and 6 show the configuration of an embodiment of a radiating element that can be used in the present invention. The figure shows a structure in which microstrip antennas with different excitation modes are stacked one above the other. A dielectric layer 12 is formed on the 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 grounding 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, the substrate 11 and the strip conductor 13 constitute one conical beam antenna element 16, and the strip conductors 13 and 15 constitute one conical beam antenna element 17. has been done. In other words, the strip conductor 13 acts as a grounding plate for the strip conductor 15. The antenna feeding circuit can also be created on the same dielectric layer that constitutes the element, or
It can also be powered through.

This embodiment includes a conical beam antenna element 17 having unidirectionality and an antenna element 16 having a conical beam.
Antenna elements with two different radiation directivities are switched and used. When circular microstrip antennas that excite the TM31 and TM11 modes, respectively, are used as the antenna elements 16 and 17, their respective radiation directivities with respect to a dielectric layer with a relative permittivity of 1 are as shown in FIG. In the figure, the solid line indicates the directivity of the circular microstrip antenna element 17 excited in the TM11 mode, and the dotted line indicates the directivity of the circular microstrip antenna element 16 excited in the TM31 mode. Therefore,
Depending on the location of the mobile station, if the satellite elevation angle is high, the antenna element 17 is in TM11 mode, and if the satellite elevation angle is low, the antenna element 17 is in TM11 mode.
By selecting the 31-mode antenna element 16 with the switch 2, an antenna having high gain over a wide elevation angle range can be realized.

[0011] When exciting by changing the amplitude ratio and phase difference, the directivity of an antenna with a conical beam can be controlled in the same way. For example, the radiation directivity when using the same configuration as shown in Figs. are shown in FIGS. 8 and 9. This example is TM11
, represents the radiation directivity when changing the amplitude ratio of excitation of two circular microstrip antenna elements 17 and 16 excited in TM31 mode, and the amplitude ratio of each mode (excitation of TM31 mode with respect to TM11 mode) These are calculated values when the amplitude ratio) is set to 0.5 and 0.1. By changing the amplitude ratio, the main radiation direction can be shifted from the zenith direction to a low elevation angle direction.

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

[0013]

As explained above, according to the present invention, it is possible to easily change the radiation directivity in the directivity elevation angle direction of an antenna with a conical beam directional characteristic in a mobile station for satellite communication, and to provide a wide elevation angle range. This makes it possible to track satellites, and provides an antenna with higher gain than omnidirectional antennas.

[Brief explanation of drawings]

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

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

FIG. 3 is a configuration diagram showing 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 of an embodiment of a radiating element that can be used in the present invention, which is configured by vertically arranging microstrip antenna elements.

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

FIG. 7 is a diagram showing radiation directivities created by circular microstrip antenna elements excited by TM11 and TM31.

FIG. 8 is a radiation directivity diagram showing an example in which the radiation direction in the elevation angle direction is changed by controlling the excitation amplitude.

FIG. 9 is a diagram showing another example of FIG. 8.

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

FIG. 11 is a diagram showing a conical beam.

Claims (2)

[Claims] Claim 1: A plurality of strip antenna elements having conical beam characteristics are arranged on the same plane or above and below,
A mobile station antenna for satellite communication, comprising means for controlling the directivity in the elevation direction by controlling the amplitude and phase of power feeding to the plurality of strip antenna elements. 2. A mobile station antenna for satellite communication, wherein the amplitude of power feeding to the plurality of strip antenna elements is controlled by using a switch, and only one strip antenna element is turned on by turning on/off the power feeding.