FDTD design of bifilar and quadrifilar truncated spherical helical antennas

The radiation characteristics of bifilar and quadrifilar truncated spherica l helix antennas are analyzed using the FDTD method. Special attention is p aid to the generation of a circularly polarized wave over a wide region abo ve the antenna. By introducing the multiarm structure and changing the feed ing geometry, the proposed antennas are capable of providing a symmetric, c ircularly polarized, broad-beam radiation pattern, as well as a conical rad iation pattern. (C) 2001 John Wiley & Sons, Inc.