Mobile apparatus with plurality of antennas having different directivities

• US 6,297,780 B1
• Filed: 04/21/1999
• Issued: 10/02/2001
• Est. Priority Date: 04/23/1998
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Kirisawa, Akihiro
• Primary Examiner(s): Ho, Tan
• Assistant Examiner(s): Alemu, Ephrem
• Application Number:
  US09/295,388
• Time in Patent Office: 895 Days
• Field of Search: 343/895, 343/757, 343/824, 343/703, 343/702, 343/876, 343/853, 343/844, 455/62, 455/78, 455/80, 455/82, 455/83, 455/575, 455/562, 455/65, 455/101, 455/277, 455/115, 455/129, 455/121, 455/123, 375/267, 342/372, 342/368, 342/359
• US Class Current: 343/703
• CPC Class Codes: H01Q 1/362 for broadside radiating helical antennas
• CPC Class Codes: H01Q 11/08 Helical antennas
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• CPC Class Codes: H04B 7/0602 using antenna switching H04B7/0686 takes precedence; antenna beam directivity switching H01Q3/24

Abstract

In a mobile apparatus for communication with a satellite, a plurality of antennas having different directivities from each other are provided. A selector circuit is connected between a transmitter circuit and the antennas to select and connect one of the antennas to the transmitter circuit. A control section controls the selector circuit in accordance with a reflected power detected from one of the antennas.

Claims

1. A mobile apparatus for communication with a satellite comprising:

a transmitter circuit;

a plurality of antennas having different elevation angle directivities from each other;

a selector circuit connected between said transmitter circuit and said antennas, for selecting and connecting one of said antennas to said transmitter circuit; and

a control section, connected to said selector circuit, for controlling said selector circuit in accordance with a reflected power detected from said connected one of said antennas.

2. The apparatus as set forth in claim 1, wherein, when the reflected power detected from said one of said antennas is not smaller than a predetermined value, said control section controls said selector circuit to select another of said antennas.

3. The apparatus as set forth in claim 1, wherein, when all the reflected powers from said antennas are not smaller than a predetermined value, said control section controls said selector circuit to select one of said antennas having the smallest reflected power.

4. The apparatus as set forth in claim 1, wherein said control section comprises:

a directional coupler, connected between said transmitter circuit and said selector circuit, for taking out the reflected power from the connected one of said antennas, said directional coupler passing a transmitting signal from said transmitter circuit to said selector circuit;

a detecting diode, connected to said directional coupler, for receiving the reflected power from said one of said antennas; and

a control circuit, connected to said detecting diode, for comparing the reflected power from the connected one of said antennas with a predetermined value and controlling said selector circuit to select and connect to a different one of said plurality in accordance with whether or not the reflected power from said connected one of said antennas is smaller than said predetermined value.

5. The apparatus as set forth in claim 4, wherein, when all reflected powers from said antennas are not smaller than said predetermined value, said control circuit controls said selector circuit to select one of said antennas having the smallest reflected power.

6. The apparatus as set forth in claim 1, wherein said control section comprises:

a circulator, connected between said transmitter circuit and said selector circuit, for taking out the reflected power from said connected one of said antennas, said circulator passing a transmitting signal from said transmitter circuit to said selector circuit;

a detecting diode, connected to said circulator, for receiving the reflected power from said connected one of said antennas; and

a control circuit, connected to said detecting diode, for comparing the reflected power from said connected one of said antennas with a predetermined value and controlling said selector circuit to connect to a different one of said antennas in accordance with whether or not the reflected power from said connected one of said antennas is smaller than said predetermined value.

7. The apparatus as set forth in claim 6, wherein, when all reflected powers from said antennas are not smaller than said predetermined value, said control circuit controls said selector circuit to select one of said antennas having the smallest reflected power.

9. The apparatus as set forth in claim 1, further comprising:

a duplexer connected between said transmitter circuit and said selector circuit; and

a receiver circuit connected to said duplexer,

said duplexer connecting said transmitter circuit to said selector circuit in a transmitting mode and connecting said receiver circuit to said selector circuit in a receiving mode.

8. A mobile apparatus for communication with a satellite comprising:

a transmitter circuit;

a plurality of antennas having different elevation angle directivities from each other;

a selector circuit connected between said transmitter circuit and said antennas, for selecting and connecting one of said antennas to said transmitter circuit; and

a control section, connected to said selector circuit, for controlling said selector circuit in accordance with a reflected power detected from said connected one of said antennas, wherein said plurality of antennas comprise;

a single cylindrical element; and

a plurality of helical conductors wound on said cylindrical element, each of said helical conductors performing as one of said antennas,

each of said helical conductors having different pitches from each other.

10. A mobile apparatus comprising:

a transmitter circuit;

a plurality of antennas having different elevation angle directivities from each other;

a selector circuit, connected between said transmitter circuit and said antennas, for selecting and connecting said antennas to said transmitter circuit;

a directional coupler, connected between said transmitter circuit and said selector circuit, for passing a transmitting signal from said transmitter circuit to said selector circuit and taking out a reflected power from said connected one of said antennas;

a control section, connected between said directional coupler and said selector circuit, for controlling said selector circuit in accordance with the reflected power from said connected one of said antennas.

11. A mobile apparatus comprising:

a transmitter circuit;

a plurality of antennas having different elevation angle directivities from each other;

a selector circuit, connected between said transmitter circuit and said antennas, for selecting one of the said antennas and connecting said one of said antennas to said transmitter circuit;

a circulator, connected between said transmitter circuit and said selector circuit, for passing a transmitting signal from said transmitter circuit to said selector circuit and taking out a reflected power from said one said antennas; and

a control section, connected between said circulator and said selector circuit, for controlling said selector circuit in accordance with the reflected power from said one of said antennas.