A Dual-band-rejected Design for a Cross Semielliptic Monopole Antenna

In this article the use of cross monopole antennas is discussed. These antennas are known for their wide impedance bandwidth and good omni-directional radiation pattern.

A novel dual-band-rejected design for cross semi-elliptic monopole antenna is proposed and experimentally studied. The proposed antenna consists of an ultra-wideband cross semi-elliptic monopole antenna and H-shaped slots, thereby producing dual-band-rejected characteristics and maintaining omni-direction radiation. This technique is suitable for creating multi-wideband antenna or ultra-wideband (UWB) antenna with dual-rejected band. Details of the results for the proposed antenna are presented and discussed.

1. INTRODUCTION

Since the advent of UWB technology, planar monopole antennas have been the subject of renewed interest in recent years [1–4]. Although planar monopole antennas can be obtained with very wide impedance bandwidth (fit to be used with wideband communications by varying the antenna elements), they have non-omnidirectional radiation at higher frequency. For this reason, studies of cross monopole antenna or of other shapes have been made [5–11]. In addition, several articles had been devoted to the study of band-rejected operation for planar monopole antenna [12–15]. This is because wideband systems normally overlap several narrowband wireless technologies leading to the need for wideband devices to provide filtering in those bands which may cause interference between narrowband and wideband systems. Alternatively, the use of antennas with band-rejected operation can relieve the requirements for the filtering electronics within the wideband devices. However, one-band-rejected operation is insufficient for modern or future wireless communication. Thus, multi-wideband antennas or those with dual (or even above)-band-rejected operation, and good omni-direction radiation have become an important concern.