Broadband quadrifilar helix antenna with compact feeding network

Conventional self-phasing method is difficult to achieve excellent impedance matching and circularly polarized (CP) radiation simultaneously over a wide band in quadrifilar helix antenna (QHA) designs. This is because the lowest points of return loss and axial ratio cannot match. Although QHA with additional feeding network can solve the problem above, the size is too large to be used in handset applications. In this paper, we proposed a QHA attached a compact feeding network on its bottom end to achieve balanced power division and quadrature phasing in a wide bandwidth. QHA with the proposed feeding network could achieve broadband CP radiation. Moreover, the configuration is compact and very suitable for GPS/CNSS portable mobile handset applications.