Modeling of antenna radiation field based on uniformly distributed dipoles

Target electromagnetic scattering is related to radar observed antenna in the near field, and a modeling method for antenna radiation field is developed based on dipole models. The dipole models include electric and magnetic dipoles whose position is uniformly distributed on the antenna radiation aperture. Through coordinate transformation of dipole radiation field and spherical wave expansion (SWE) of antenna radiation field, a linear matrix equation is found between the dipole parameters and the SWE coefficients of antenna radiation field. The least square estimation for dipole parameters is obtained based on an algorithm of singular value decomposition. The experiments for three types of antennas, including an horn, slotted wave guide, and patch array, are executed to verify the modeling accuracy of dipoles. The equivalent dipole models with a modeling error less than 1% for the three antennas is achieved, respectively. Also, the accuracy of predicting the radiation field of antennas at any observation distance using the equivalent dipole models is evaluated. The results demonstrates that the effectiveness of modeling antenna radiation field based on uniformly distributed dipoles.