Experimental Study on 2-Element UWB Array Antenna using Leaf-Shaped Bowtie Element

Recently, Ultra-wideband (UWB) communication systems have attracted considerable attention. Since the FCC granted permission for unlicensed use of the bandwidth of 3.1 to 10.6 GHz [1], many UWB antennas have been reported [2]– [4]. These antennas have omnidirectional radiation patterns and low directivity, approximately 0–3 dBi. The disadvantage of using omnidirectional antennas is the performance degradation caused by adjacent walls or metals. If unidirectional UWB antennas are used, the degradation on the antenna performance due to omnidirectionality can be avoided. In addition, higher speed and lower power consumption communication system can be realized because of the directivity. Therefore, the development of UWB antenna having unidirectional radiation characteristics and highdirectivity is highly desirable. The authors have recently proposed a unidirectional UWB antenna using leaf-shaped bowtie elements and a reflector [5]. The gains of this antenna are 5.2–8.2 dBi in the frequency range of 4.2– 10.2 GHz. In this paper, we propose a 2-element UWB array antenna using leaf-shaped bowtie elements and a reflector, which has unidirectional radiation characteristics and higher-directivity. In addition, the effects of arraying elements are investigated by comparing a 1-element leaf-shaped bowtie antenna with the proposed 2-element array antenna. Furthermore, the waveform distortions caused by this antenna are evaluated by calculating cross-correlation coefficient between source and received pulses.