This article proposes a miniaturized quarter-circular-slot UWB (QCS-UWB) antenna using field-pattern analysis of the circular-slot UWB prototype antenna. The prototype antenna operates on a series of multi-pole radiation based on TEn modes, and has a completely symmetrical and approximate symmetrical planes along the vertical and the horizontal lines, respectively, on the antenna.

Using the symmetrical planes we designed and fabricated the miniaturized UWB antenna on RF-60A substrate with thickness of 0.64 mm, relative dielectric constant 6.15 and loss tangent=0.0025.

Even though the proposed antenna has only the quarter part of the prototype antenna it maintains UWB antenna characteristics. The measured gain of the miniaturized antenna from 3.0 GHz to 12.0 GHz is within -0.1 dBi ~ 1.6 dBi, which is comparable to the prototype antenna’s gain, -2.7 dBi ~ 3.1 dBi.

INTRODUCTION

To meet the growing demands for various communication services there have been rapid developments of wireless technology. These same services have exhausted many frequency resources thereby requiring the technologies for wireless communication to be improved further in order to satisfy the higher resolution and higher data rate requirements.

For these reasons, Ultra-wideband (UWB) systems have recently drawn considerable attention [1]. Since many UWB systems could be used for short distance, indoor and/or handheld applications, the need for miniaturized antennas has increased. However, most UWB antennas with good performance (i.e. frequency-independent characteristics) have inherently large physical dimensions [2]-[5].

Recently, some studies on miniaturized UWB antennas using a symmetrical plane have been reported [6]-[9]. They all achieved half-sized UWB antennas compared to their original antennas based on well-known antennas of monopole and/or dipole types. However they show only experimental results without any explanation for the operating principle, analysis for electromagnetic field distributions or methodology for miniaturization of the presented antennas.