Model analysis on radiation fields of wire antenna in free space

The method of matrix moment adopting piecewise sinusoidal basis functions is used to get the current of wire antenna.With the aid of the radiation field expression of piecewise sinusoidal current,the total radiation field of the antenna is obtained through linear superimposition of contribution fields of every piecewise current.The spherical wave expansion is introduced into antenna radiation modal analysis.In addition,numerical integration is adopted to get the spherical wave coefficients of antenna radiation field.Using the proposed method,the mode coefficients of dipole,circular loop antenna and helical antenna is obtained,which validates the feasibility of the method.