UWB Switched-Beam Array Antenna Employing UWB Butler Matrix
Yu-Chuan Su, Marek E. Bialkowski, Feng-Chi E. Tsai, Kai-Hong Cheng
Antenna International Workshop on Technology: Small Antennas and Novel Metamaterials, 2008. iWAT 2008.
4-6 March 2008
199 - 202
Recent years have seen a growing interest in ultra-wideband (UWB)echnologies, which aim at overcoming problems associated with a heavy utilization of radio spectrum by current wireless communication standards. To tackle this problem, the US-FCC  has allocated a spectrum of 3.1 to 10.6 GHz for use of narrow pulse signal transmission. The wideband spectrum and the low power spectral density used in this transmission scheme introduce very little interference to the currently existing narrowband systems. However, the shortfall of UWB is a small operating range. The range and performance can be enhanced by employing array antennas with an electronically steered beam. When such array antennas are equipped with a suitable beam-forming algorithm they are named smart antennas. One example of a simple smart antenna scheme is a switched-beam scheme that employs a Butler matrix . This has been demonstrated for narrowband systems. The Butler matrix type beam-forming network is constituted by quadrature couplers and phase shifters. The extension of this smart antenna concept to UWB applications requires both antennas and a beam-forming network to operate over UW frequency band. In recent years, a lot of successful research has been reported with respect to UWB antennas. Examples include UWB planar monopoles ,  and UWB tapered slot antennas (TSA) . Considerably less successful has been the area of UWB beam-forming networks. In this paper, we show that the design of a UWB Butler matrix can be accomplished using couplers and phase shifters in microstrip/slot technology , . As a result of the proposed approach, we present the design of a 4-element switched-beam array antenna operating between 3.1 and 10.6 GHz.
Back to References