The Efficiency-Fractional Bandwidth Product (EB) of Small Dielectric Loaded Antennas and the System EB

Ichirou IDA  Takatoshi SEKIZAWA  Hiroyuki YOSHIMURA  Koichi ITO  

Publication
IEICE TRANSACTIONS on Communications   Vol.E84-B   No.9   pp.2498-2506
Publication Date: 2001/09/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Innovation in Antennas and Propagation for Expanding Radio Systems)
Category: Mobile Antennas
Keyword: 
electrically small dielectric loaded antennas,  efficiency-fractional bandwidth product (EB),  system EB,  antenna impedance measurement,  Wheeler cap method,  

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Summary: 
The efficiency-fractional bandwidth product (EB), which is expressed as a ratio of the radiation resistance to the absolute value of the input reactance of an antenna, is used as a performance criterion for small dielectric loaded monopole antennas (DLMAs). The dependence of the EB on the permittivity of the dielectric loading (i.e., the electrical volume) is experimentally and numerically investigated for the first time in antenna research. As a result, it is found that the EBs of the some DLMAs are enhanced over a bare monopole antenna and an EB characteristic curve has a maximum point. This result suggests the presence of the optimum electrical volume for the dielectric loading in order to obtain the best EB performance. A general reason for the existence of the peak value is also explained using a mathematical deduction. Finally the system EB, which is an efficiency-fractional bandwidth product of the DLMA with a practical matching circuit, is defined and its dependence on the relative permittivity is illustrated. Consequently, the existence of the peak value is also confirmed for the system EBs. In addition, it is demonstrated that the enhancement of the system EB is mainly due to the enhancement in the efficiency of the antenna system.