Design of novel super wide band antennas close to the small antenna limitation theory

摘要

The fundamental bandwidth limitation theory of small antennas and their applications to Super Wide Band (SWB) antenna designs are investigated in this paper. Firstly, a circular patch antenna with a substrate of permittivity (εr = 3) and patch metallization thickness of 0.5 mm is designed. Thereafter, the same antenna is designed with increased patch height (26.5 mm). The antennas are designed to achieve a super wide bandwidth with a bandwidth ratio ranging from 27∶1 to as high as 31∶1. The operating frequency bands of antenna with 0.5 mm height are from 1.8 to 50 GHz whereas with increased antenna height, the operating frequency ranges from 1.6 to 50 GHz. A reduction in antenna electrical size and improvement in impedance bandwidth is obtained here by using the spherical volume of the antenna efficiently. A further investigation with respect to classical Chu and Mclean theories depicts that the proposed antenna electrical size almost touches the Mclean and gets very close to the Chu fundamental limit curves.