Spherical wave rotation in spherical near-field antenna measurements

The rotation of spherical waves in spherical near-field antenna measurement is discussed. Considering the many difficult but interesting features of the rotation coefficients, an efficient rotation scheme is derived. The main feature of the proposed scheme is to ignore the calculation of the very small coefficients outside the ellipse. Therefore, not only will the underflow problem be eliminated but much computation time will be saved as well. An example is presented which shows the feasibility of the proposed method.<>