Wideband Planar Folded Dipole Antenna With Self-balanced Impedance Property

A planar folded dipole antenna that exhibits wideband characteristics is proposed. The antenna has simple planar construction without a ground plane and is easy to be assembled. Parameter values are adjusted in order to obtain wideband properties and compactness by using an electromagnetic simulator based on the method of moments. An experimental result centered at 1.7 GHz for 50 $\Omega$ impedance matching shows that the antenna has bandwidth over 55% $({\rm VSWR} \leq 2)$. The gains of the antenna are almost constant (2 dBi) in this frequency band and the radiation patterns are very similar to those of a normal dipole antenna. It is also shown that the antenna has a self-balanced impedance property in this frequency band.

I. Introduction

With THE recent progress and rapid increase in radio communication systems, wideband wireless systems are being put into actual use; examples are an ultrawideband system [1], [2] and digital terrestrial television [3], [4]. This emphasizes the importance of designing high performance antennas for small mobile terminals. A key demand is wideband and compact antennas [5], [6].