I. Introduction
Conventional research efforts on ultrawideband (UWB) antennas have been concentrated on impulse radiating antennas (IRAs) mainly for RADAR applications [1]. Recent allocation of the frequency spectrum from 3.1 GHz to 10.6 GHz by Federal Communications Commission [2] for use in commercial wireless communication has sparked renewed interest in UWB antenna research from a somewhat different perspective. Small physical size, low unit manufacturing cost, and possibility of integration into the system board of the host device are some of the desirable features for UWB communication antennas in addition to satisfactory electrical performances.