Abstract: This paper investigates a new moment method for calculating the electrical characteristics of teh Normal Mode Helical Antenna(NMHA). The piecewise-straight segments are used to model the NMHA. The NMHA can be analyzed by the Moment Method with the Composite basis functions and the Composite testing functions. The rank of the impedance matrix can be reduced by using this method. Thereofre, the CPU time and the memory storage are significantly reduced in solving the matrix equation. The current distributions and radiation patterns of teh NMHA obtained by this method are compared with the NEC results, indicating that the two agree fairly well.

Key words: moment method, composite basis function, normal mode helical antenna(NMHA)