Phased array wireless power delivery optmization
A method of setting phases of a multitude of transmit elements of a phased array includes, in part, setting a phase of a first transmit element to N different values during each of N different time intervals, transmitting an electromagnetic signal from the first transmit element at each of the N time intervals, measuring a power of the electromagnetic signal at a receiving unit during each of the N time intervals, and selecting coefficients of a basis function such that a difference between a power value computed by the basis function and the measured power value associated with each of the N phases is smaller than a threshold value. The threshold value is optionally defined by a minimum of the sum of squares of the difference between a power value computed by the basis function and the power value for each of the N phases.
1. A method of setting phases of a plurality of transmit elements of a phased array, the method comprising:
setting a phase of a first transmit element to N different values during each of N different time intervals, wherein N is an integer greater than one;
transmitting an electromagnetic signal from the first transmit element at each of the N time intervals;
measuring a power of the electromagnetic signal at a receiving unit during each of the N time intervals;
applying the measured powers to a basis function; and
selecting coefficients of the basis function such that a difference between a power value computed by the basis function and the measured power value associated with each of the N phases is smaller than a threshold value, wherein a measured power of the electromagnetic signal transmitted by the first transmit element is defined by the phase Ø of the first transmit element, and a static phase offset φ of the first transmit element.
2. The method of claim 1 wherein said threshold value is defined by a minimum of the sum of squares of the difference between a power value computed by the basis function and the power value for each of the N phases.
3. The method of claim 2 further comprising:
determining a phase of the first transmit element using the selected coefficient and the basis function.
4. The method of claim 3 further comprising:
transmitting an electromagnetic signal from the first transmit element in accordance with the determined phase.
5. The method of claim 2 wherein said basis function is a periodic basis function.
6. A method of setting phases of a phased array comprising K transmit elements, wherein K is an integer, the method comprising:
setting phases of M transmit elements to M different values during each of N different time intervals, wherein M and N are integers greater than 2;
transmitting electromagnetic signals from the M transmit elements at each of the N time intervals;
measuring a power of the electromagnetic signals at a receiving unit during each of the N time intervals;
applying the measured powers to a basis function for each of the M transmit elements; and
selecting coefficients of each of the basis functions such that a difference between N power values computed by the basis functions and the N measured power values associated with the N×M phases is smaller than a threshold value, wherein a measured power of the electromagnetic signal transmitted by a first one of the M transmit elements is defined by a phase Ø of the first transmit element, and a static phase offset φ of the first transmit element.
7. The method of claim 6 wherein said M is smaller than said K.
8. The method of claim 6 wherein said threshold value is defined by a minimum of the sum of squares between the N power values computed by the basis functions and the N measured power values associated with the N×M phases.
9. The method of claim 6 further comprising:
determining a phase of each of the M transmit elements using the selected coefficients and the basis function associated with the transmit element.
10. The method of claim 9 further comprising:
transmitting an electromagnetic signal from each of the M transmit elements in accordance with the phase determined for the transmit element.
11. The method of claim 9 wherein each said basis function is a periodic basis function.
12. A phased array comprising a plurality of transmit elements and a controller configured to:
set a phase of a first transmit element to N different phases during each of N different time intervals;
cause an electromagnetic signal to be transmitted from the first transmit element at each of the N time intervals;
receive a measurement of a power of the electromagnetic signal from a remote receiving unit during each of the N time intervals;
applying the measured powers to a basis function; and
select coefficients of the basis function such that a difference between a power value computed by the basis function and the received power value measurement associated with each of the N phases is smaller than a threshold value wherein a measured power of the electromagnetic signal transmitted by the first transmit element is defined by the phase Ø of the first transmit element, and a static phase offset φ of the first transmit element.
13. The phased array of claim 12 wherein said threshold value is defined by a minimum of the sum of squares of the difference between a power value computed by the basis function and the received power value measurement at each of the N phases.
14. The phased array of claim 13 wherein said controller is further configured to:
determine a phase of the first transmit element using the selected coefficients and the basis function.
15. The phased array of claim 13 wherein said controller is further configured to:
cause an electromagnetic signal to be transmitted from the first transmit element in accordance with the determined phase.
16. A phased array comprising K transmit elements, K being an integer, and a controller configured to:
set phases of M transmit elements to M different phases during each of N different time intervals, wherein M an N are integers greater than 2;
cause electromagnetic signals to be transmitted from the M transmit elements at each of the N time intervals;
receive a measure of power of the electromagnetic signals from a remote receiving unit during each of the N time intervals;
applying the measured powers to a basis function for each of the M transmit elements; and
select coefficients of each of M basis functions such that a difference between N power values computed by the M basis functions and the N received power value measurements associated with the N×M phases is smaller than a threshold value, wherein a measured power of the electromagnetic signal transmitted by a first one of the M transmit elements is defined by a phase Ø of the first transmit element, and a static phase offset φ of the first transmit element.
17. The phased array of claim 16 wherein said M is smaller than said K.
18. The phased array of claim 16 wherein said threshold value is defined by a minimum of the sum of squares between N power values computed by the basis functions and N power values measured associated with the N×M phases.
19. The phased array of claim 16 wherein said controller is further configured to:
determine a phase of each of the M transmit elements using the selected coefficients and the basis function associated with the transmit element.
20. The phased array of claim 17 wherein said controller is further configured to:
cause transmission of an electromagnetic signal from each of the M transmit elements in accordance with the phase determined for the transmit element.
21. The method of claim 1 wherein the power of the electromagnetic signal transmitted by the first transmit element to the receiving unit is defined as:
P
(
∅
)
=
a
0
+
cos
(
π
(
∅
+
φ
)
180
)
wherein a 0 represents the background power level from other antenna elements, Ø represents the phase of the first transmit element, and φ is the static phase offset corresponding to the first transmit element.