Frequency- and Time-Domain Characterizations of Ultrawideband Tapered Loop Antennas

A novel ultrawideband (UWB) antenna that consists of a tapered loop radiator and a coplanar waveguide-to-coplanar stripline (CPW-to-CPS) transition is investigated in both frequency- and time-domain. Contrary to the conventional monopole/dipole-like UWB antennas, this tapered loop antenna has predominately magnetic near fields and hence the coupling due to nearby dielectric objects is less significant. The antenna possesses a wide impedance bandwidth from 3.1 to 10.6 GHz under the |S₁₁| < -10 dB criterion, and shows similar radiation patterns and 3.3-7 dBi antenna gain in its operating band. The time-domain characteristic of the transmitting/receiving antenna system is described by antenna transfer function. The propagation channel considering reflection effect is represented as the sum of the contributions of different multipath components. The calculated time-domain pulse response of the UWB antenna-channel system is validated by measurement. Results indicate that the proposed antenna with broad bandwidth and low pulse distortion is a good candidate for UWB applications.