Planar trapezoidal and pentagonal monopoles with impedance bandwidths in excess of 10:1

A planar disc monopole antenna has been developed for the Japanese TV band (90-770 MHz) in 1991. A model for determining the input impedance of a circular disc monopole has been proposed in 1993. In 1998, a simple formula for predicting the frequency corresponding to the lower edge of the bandwidth was proposed. The planar monopole may be realised by replacing the cylindrical element of a conventional monopole with a planar element.