Ultra-wideband monopole antenna with lumped elements

This paper presents a resistively and inductively loaded ultra-wideband monopole antenna with a top loaded disk. The proposed structure consists of a circular disk top load and the metal cylindrical arm. Lumped resistors and inductors are loaded. The ultra-wide bandwidth can be achieved by the resistive load. The disk top-load and inductive load enable this antenna have a small and compact size (about 1/15 wavelength at 20MHz). The proposed antenna has an ultra-wideband impedance bandwidth from 20MHz to 4GHz (S11<;-6dB) and an omnidirectional radiation pattern. This antenna is a promising candidate for broadband passive direction finding and observation systems.