Small Antennas: Downsizing Techniques and Its Index Factor

Hiroyuki ARAI

IEICE TRANSACTIONS on Communications   Vol.E88-B    No.5    pp.1801-1808
Publication Date: 2005/05/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.5.1801
Print ISSN: 0916-8516
Type of Manuscript: Special Section INVITED PAPER (Special Section on Recent Progress in Antennas and Propagation Researches--Selected Papers Translated from the IEICE Transactions on Communications (Japanese Edition)--)
small antenna,  matching circuit,  electrical volume,  radiation efficiency,  Wheeler method,  

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In this paper, we present the classification of small antennas based on statistical data. The three categories of downsizing methods are loading a matching circuit, changing the current path, and using dielectric/magnetic materials. These categories are explained using several examples. In this paper, we show that the miminum Q value as a fundamental limit defined by an infinitesimal dipole is effective for determining the index factor of small antennas. Radiation efficiency measurements for small antennas are also discussed.