System and method for isolating an individual radiation pattern of a given radiator in the presence of other radiators

1. A method for determining a far-field pattern of an antenna within a composite radiator, comprising:

performing a near-field scan of the composite radiator;

computing a first plurality of coefficients corresponding to the near-field scan;

computing a first far-field pattern corresponding to the first plurality of coefficients;

computing a phase adjustment corresponding to a translation from a scan origin to a point within the antenna;

computing a second far-field pattern corresponding to the first far-field pattern and the phase adjustment, the second far-field pattern having a second plurality of coefficients;

reducing the second plurality of coefficients to a third plurality of coefficients, wherein a quantity of the third plurality of coefficients corresponds to a minimum sphere that is centered at the point within the antenna and substantially exclusively encompasses the antenna; and

computing a third far-field pattern corresponding to the third plurality of coefficients.

2. A system for determining a far-field radiation pattern of

an antenna included within a composite radiator, comprising:

a scan probe;

a two-axis position control system; and

a host computer coupled to the two-axis position control system, the host computer having a non-transitory computer readable medium encoded with a program for measuring a near-field radiating pattern according to a spherical scan at an angular sample spacing; computing a first plurality of coefficients corresponding to the near-field pattern; computing a phase adjustment corresponding to a translation from an origin corresponding to the spherical scan to a point within the antenna; computing a second plurality of coefficients, wherein the second plurality of coefficients corresponds to a far field pattern and the phase adjustment; reducing the second plurality of coefficients according to a minimum sphere substantially exclusively encompassing the antenna; computing a third plurality of coefficients corresponding to the reduced second plurality of coefficients; and computing the far-field radiation pattern based on the third plurality of coefficients.

3. The system of claim 2 , wherein the antenna is coupled to a signal source, and the scan probe is coupled to a receiver.

4. The system of claim 2 , wherein the program for measuring the near-field pattern comprises a program for computing the angular sample spacing based on a diameter of a first minimum sphere encompassing the composite radiator and having a center at the origin.

5. The system of claim 4 , wherein computing the angular sample spacing includes computing a first quantity corresponding to a smallest maximum spherical modal order necessary to sample a contour of a composite radiator far-field pattern.

6. The system of claim 5 , wherein computing the second plurality of coefficients quantity includes computing a quantity of the second plurality of coefficients corresponding to a second sphere that encompasses the composite radiator, wherein the second sphere has a center that is located within the antenna.

7. The system of claim 5 , wherein computing a second plurality of coefficients includes computing a plurality of far field coefficients corresponding to the first plurality of coefficients, and adding the phase adjustment to the far field coefficients.

8. The system of claim 7 , wherein the far field coefficients include vector spherical harmonic coefficients.

9. The system of claim 2 , wherein the two axis position control system comprises:

a turntable connected to a turntable controller; and

a gantry connected to a gantry controller.

10. The system of claim 2 , wherein the composite radiator comprises a roof of a car.

11. The system of claim 2 , wherein the composite radiator comprises a phased-array antenna.

12. A method for determining a far-field pattern of an antenna within a composite radiator, comprising:

performing a near-field scan of the composite radiator, wherein the near-field scan has a range length greater than one half a diameter of a first minimum sphere that encompasses the composite radiator and has a first center at an origin defined by a crossing point of a pair of scan coordinate axes;

computing a first far-field pattern corresponding to the near-field scan, the first far-field pattern having a first plurality of coefficients corresponding to a sampling on a second minimum sphere encompassing the composite radiator and having a center within the antenna;

computing a phase adjustment corresponding to a translation from the origin to a center of a third minimum sphere, wherein the center of the third minimum sphere is located within the antenna, and wherein the third minimum sphere substantially exclusively encompasses a radiating portion of the antenna;

computing a second far-field pattern that includes the phase adjustment, the second far-field pattern having a second plurality of coefficients;

selecting a third plurality of coefficients from the second plurality of coefficients, wherein a quantity of the third plurality corresponds to a diameter of the third minimum sphere; and

computing a third far-field pattern based on the third plurality of coefficients.

13. The method of claim 12 , wherein the near-field scan has a sample spacing corresponding to a diameter of the first minimum sphere.

14. The method of claim 13 , wherein the sample spacing is in part based on the diameter of the first minimum sphere and a wavelength of interest.

15. A non-transitory computer readable medium encoded with a program for determining a far-field pattern of an antenna within a composite radiator, the program comprising instructions for:

measuring a near-field radiating pattern according to a spherical scan at an angular sample spacing;

computing a first plurality of coefficients corresponding to the near-field pattern;

computing a phase adjustment corresponding to a translation from an origin corresponding to the spherical scan to a point within the antenna;

computing a second plurality of coefficients, wherein the second plurality of coefficients correspond to a far field pattern and the phase adjustment;

reducing the second plurality of coefficients according to a minimum sphere substantially exclusively encompassing the antenna;

computing a third plurality of coefficients corresponding to the reduced second plurality of coefficients; and

computing the far-field pattern based on the third plurality of coefficients transitory and non-transitory.

16. The computer readable medium of claim 15 , wherein the angular sample spacing corresponds to a first sphere that encompasses the composite radiator, wherein the first sphere has a center that is located at the origin.

17. The computer readable medium of claim 16 , wherein a quantity of the second plurality of coefficients corresponds to a second sphere that encompasses the composite radiator, wherein the second sphere has a center that is located within the antenna.

18. The computer readable medium of claim 17 , wherein computing a second plurality of coefficients comprises computing a plurality of far field coefficients corresponding to the first plurality of coefficients, and adding the phase adjustment to the far field coefficients.

19. The computer readable medium of claim 18 , wherein the far field coefficients include vector spherical harmonic coefficients.

20. The computer readable medium of claim 19 , wherein the spherical modal coefficients are a function of polarization, azimuth angle, and polar angle.