METHOD OF DESIGNING WEIGHT VECTORS FOR A DUAL BEAM ANTENNA WITH ORTHOGONAL POLARIZATIONS

• US 20120212372A1
• Filed: 03/04/2010
• Published: 08/23/2012
• Est. Priority Date: 10/28/2009
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Petersson, Sven Oscar, Johannisson, Bjorn Gunnar
• Granted Patent: US 8,994,588 B2
• Time in Patent Office: Days
• US Class Current: 342/373
• CPC Class Codes: H01Q 21/08 the units being spaced along or adjacent to a rectilinear path waveguide fed H01Q21/0037
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H04B 7/043 using best eigenmode, e.g. beam forming or beam steering
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

The present invention relates to a method of generating two beams, having orthogonal polarizations, covering a selected area using an antenna (20) comprising multiple dual-polarized array elements (11). Each dual-polarized array element having a first phase centre (18) associated with a first polarization and a second phase centre (18) associated with a second polarization. The method comprises: designing a first weight matrix having a first non-zero weight vector for the first polarization and a second non-zero weight vector for the second polarization, calculating a second weight matrix based on the weight vectors of the first weight matrix, and applying the first and second weight matrix to the dual-polarized array elements to generate a second beam covering the selected area.

Claims

1. A method of generating two beams, having orthogonal polarizations, covering a selected area using an antenna comprising at least three dual-polarized array elements, each dual-polarized array element having a first phase centre associated with a first polarization and a second phase centre associated with a second polarization, orthogonal to said first polarization, the first and second phase centres of said dual-polarized array elements arranged in a first direction and symmetrically distributed across a two dimensional antenna surface in relation to a symmetry line, perpendicular to said first direction, each beam is generated by feeding said multiple dual-polarized array elements, said method comprising:

designing a first weight matrix having a first non-zero weight vector for the first polarization and a second non-zero weight vector for the second polarization;

applying the first weight matrix to said dual-polarized array elements to generate a first beam covering the selected area;

calculating a second weight matrix based on the weight vectors of the first weight matrix; and

applying the second weight matrix to said dual-polarized array elements to generate a second beam covering the selected area.

2. The method according to claim 1, wherein said step of calculating the elements in the second weight matrix comprises calculating elements in the second weight matrix by:

mirroring each element of the first weight vector in a real axis and mirroring each element of the second weight vector in a imaginary axis;

row reversing the calculated elements; and

column reversing the calculated row reversed elements.

3. The method according to claim 1, wherein the first weight matrix W₁^T is defined as:

4. The method according to claim 1, further comprising arranging said first and second phase centres of said dual-polarized array elements on a straight line.

5. The method according to claim 1, further comprising arranging each dual-polarized array element to have a first feeding point associated with the first polarization and a second feeding point associated with the second polarization, whereby each beam is generated by feeding said first and second feeding points.

6. The method according to claim 1, further comprising selecting each dual-polarized array element to have an arbitrary configuration provided the first and second phase centres are arranged in the first direction and symmetrically in relation to the symmetry line.

7. The method according to claim 1, further comprising selecting all dual-polarized array elements to be identical.

8. The method according to claim 7, further comprising dividing each dual-polarized array element into two antenna elements having identical antenna power patterns with orthogonal polarization.

9. The method according to claim 1, further comprising performing polarization rotation of both beams by applying a polarization rotation matrix Φ

to the first and second weight matrices, said polarization rotation matrix defined as;

10. The method according to claim 1, wherein a separation between the first phase centres, and a separation between the second phase centres, is identical, said method further comprising performing spatial beam steering for both beams by applying a spatial beam steering matrix Ψ

to the first and second weight matrices, wherein said beam steering matrix is designed as a linear phase shift over the antenna defined as;

11. An antenna configured to generate two beams, having orthogonal polarizations, covering a selected area, said antenna comprising at least three dual-polarized array elements, each dual-polarized array element having a first phase centre associated with a first polarization and a second phase centre associated with a second polarization, orthogonal to said first polarization, the first and second phase centres of said dual-polarized array elements arranged in a first direction and symmetrically distributed across a two dimensional antenna surface in relation to a symmetry line, perpendicular to said first direction, each beam generated by feeding said multiple dual-polarized array elements, said antenna further configured to be controlled by a method as defined in claim 1. $