Antenna system with reduced multipath reception
First Claim
1. An antenna system for operating with circularly-polarized signals, the antenna system 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);
first and second antenna elements; and
a combining network connected to the first and second antenna elements;
wherein the first and second antenna elements are located above the HICGP and are separated along the vertical axis by a gap; and
wherein the combining network subtracts signals received by the first element from signals received by the second element to produce an output signal representing the circularly-polarized signals received only from an upper hemisphere.
1 Assignment
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Accused Products
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.
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Citations
19 Claims
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1. An antenna system for operating with circularly-polarized signals, the antenna system 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:
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a high impedance capacitive ground plane (HICGP); first and second antenna elements; and a combining network connected to the first and second antenna elements; wherein the first and second antenna elements are located above the HICGP and are separated along the vertical axis by a gap; and wherein the combining network subtracts signals received by the first element from signals received by the second element to produce an output signal representing the circularly-polarized signals received only from an upper hemisphere. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An antenna system 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:
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a ground plane; first and second antenna elements above the ground plane; and a combining network connected to the first and second antenna elements; wherein the first and second antenna elements are separated by a gap along the vertical axis, wherein the combining network subtracts signals received by the first element from signals received by the second element to produce an output signal, and wherein the ground plane is flat and includes a plurality of conducting pins. - View Dependent Claims (10, 11, 12, 13)
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14. An antenna system 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:
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a high impedance capacitive ground plane (HICGP); first and second antenna elements above the HICGP; and a combining network connected to the first and second antenna elements; wherein the first and second antenna elements are arranged along the vertical axis, wherein the combining network subtracts signals received by the first element from signals received by the second element to produce an output signal, and wherein the first and second antenna elements are quadrifilar cylindrical helical antenna elements, 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. - View Dependent Claims (15)
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16. An antenna system 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:
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a high impedance capacitive ground plane (HICGP); first and second antenna elements above the HICGP; and a combining network connected to the first and second antenna elements; wherein the first and second antenna elements are arranged along the vertical axis, wherein the combining network subtracts signals received by the first element from signals received by the second element to produce an output signal, and wherein a lower element of the first and second elements is an antenna element receiving right hand circular polarized (RHCP) signals and having maximum Down/Up ratio in the nadir direction about −
12-−
15 dB. - View Dependent Claims (17, 18, 19)
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Specification