Broadband Square Annular Planar Monopoles

This paper describes a vertical square planar monopole with a square concentric slot and a shifted feed location for broadband applications. The impedance and radiation characteristics of the proposed monopoles are experimentally studied, as a function of antenna dimensions and feed location. The proposed monopoles are shown to yield impedance bandwidth ratios of >1:1 for VSWR = 2:1, which fulfill most of the demands of EMC applications. Within the broad bandwidths, acceptable monopole-like radiation patterns are also observed.