ANTENNA SYSTEM WITH REDUCED MULTIPATH RECEPTION

• US 20160064809A1
• Filed: 08/26/2014
• Published: 03/03/2016
• Est. Priority Date: 08/26/2014
• Status: Active Grant

• Current Assignee: Topcon Positioning Systems Incorporated (Topcon Corporation)
• Original Assignee: Topcon Positioning Systems Incorporated (Topcon Corporation)
• Inventors: Astakhov, Andrey Vitalievich, Tatarnikov, Dmitry Vitalievich
• Granted Patent: US 9,590,311 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/36 relating to the receiver frond end
• CPC Class Codes: H01Q 11/08 Helical antennas
• CPC Class Codes: H01Q 3/446 the radiating element being at the centre of one or more rings of auxiliary elements

Abstract

An antenna system with a sharp difference in directional pattern is intended for receiving GNSS signals. The antenna system includes at least two antenna elements located above a high-impedance capacitive ground plane, and a combining network. Antenna elements are spaced apart in vertical direction. The combining network provides subtraction of the signal reflected from the ground, the arrangement of antenna elements above the high-impedance capacitive ground plane making such subtraction efficient.

Claims

1. An antenna system designed for operating with circularly-polarized signals having a vertical axis relative to which amplitude directional pattern is symmetrical and a plane perpendicular to the vertical axis such that the antenna system has a right-hand circular polarization upward from the perpendicular plane, the antenna system comprising:

a high impedance capacitive ground plane (HICGP);

two or more antenna elements; and

a combining network connected to the antenna elements;

wherein the antenna elements are located above the HICGP and are separated along the vertical axis; and

wherein the combining network subtracts signals coming from downward of the HICGP plane to produce an output signal.

2. The antenna system of claim 1, wherein the ground plane is flat and includes a plurality of conducting pins.

3. The antenna system of claim 2, wherein a length of the conducting pins is 0.25λ

-0.35λ

.

4. The antenna system of claim 3, wherein the conducting pins are galvanically coupled to the flat ground plane and are perpendicular to it.

5. The antenna system of claim 4, wherein the pins are located along concentric circles.

6. The antenna system of claim 5, wherein the conducting pins located at the same radius are connected one to another by a conducting ring which is parallel to the ground plane and offset from it.

7. The antenna system of claim 1, wherein antenna elements are quadrifilar cylindrical helical antennas, each of which has a diameter no greater than 0.3λ

and a maximum Down/Up ratio in a nadir direction for each element is about −

12-−

15 dB.

8. The antenna system of claim 1, wherein a lower element is an antenna receiving right hand circular polarized (RHCP) signals and having maximum Down/Up ratio in the nadir direction about −

12-−

15 dB.

9. The antenna system of claim 1, wherein HICGP is spherical.

10. The antenna system of claim 9, wherein the one of the two antenna elements is a ring-shaped array of radiators located outside the impedance capacitive ground plane,

wherein the one of the antenna elements is located near its surface.

11. The antenna system of claim 10, wherein the ring shaped array is an plurality of radiators which are located on an imaginary ring surface-perpendicular to the vertical axis of the antenna system, and wherein a center of the imaginary ring surface is on the vertical axis.

12. The antenna system of claim 11, wherein the radiators of the ring-shaped array are excited with an equal amplitude signal with a linear phase progression such that a right hand circular polarized (RHCP) field would be excited in the vertical axis direction.

13. The antenna system of claim 10, wherein the HICGP is a part of a spherical HICGP, and its extension is a flat HICGP.