Abstract
A novel compact and ultrawide-band (UWB) antenna is presented in this paper. The basis for achieving such an UWB operation is through proper magnetic coupling of two adjacent sectorial loop antennas in a symmetrical arrangement. A large number of coupled sectorial loop antennas (CSLA) with different geometrical parameters are fabricated and their measured responses are used to experimentally optimize the geometrical parameters of the antenna for achieving the maximum bandwidth. Through this optimization process an antenna with a VSWR of lower than 2.2 (S/sub 11/<-8.5 dB) across an 8.5:1 frequency range is designed. The maximum dimension of this antenna is smaller than 0.37/spl lambda//sub 0/ at the lowest frequency of operation and provides an excellent polarization purity. Furthermore, the antenna exhibits a relatively consistent radiation pattern. Modified versions of the CSLA are also designed to reduce the overall metallic surface and weight of the antenna while maintaining its wide-band characteristics. This allows modifying its dimensions to design low frequency light-weight UWB antennas.
I. INTRODUCTION
Afew decades after the early investigations on ultrawide-band (UWB) wireless systems, they have found a wide range of applications including ground penetrating radars, high data rate short range wireless local area networks, communication systems for military, and UWB short pulse radars for automotive and robotics applications to name a few [1]. Such systems require antennas that are able to operate across a very large bandwidth with consistent polarization and radiation patterns parameters over the entire band. A number of techniques have been developed in past to design antennas with wide-band impedance matched characteristics. Traveling wave antennas and antennas with topologies that are invariant by rotation are inherently wide-band and have been extensively used [2]–[4].
V. CONCLUSION
A novel UWB CSLA is designed and is shown to have a 8.5:1 impedance bandwidth. The antenna has consistent radiation parameters over a 4.5:1 frequency range with excellent polarization purity over the entire 8.5:1 frequency range. Modified versions of this antenna, with reduced metallic surfaces and similar radiation parameters, were also designed, fabricated, and measured. Furthermore, the time domain impulse-response measurement results show that the antenna does not significantly distort the temporal response of a signal whose spectral content does not fall outside the operating band of antenna.
