Circular annular planar monopoles with EM coupling

A circular annular planar monopole with electromagnetic coupling shows broadband properties. The planar radiator is electromagnetically coupled with a probe-fed strip, between which the medium is a thin dielectric sheet. The parametrical effects on the bandwidth are examined experimentally. The measurements have demonstrated that the proposed monopoles have the merit of broad impedance bandwidths in the order of 100% for VSWR ¼ 2:1 and 4:1 for VSWR ¼ 3:1 and acceptable radiation patterns across the bandwidths.