ABSTRACT: Antenna radiation efficiency is one of the essential antenna parameters to be taken into account for optimum wireless system performance. Several radiation efficiency measurement methods have been thoroughly described in the literature. Many of them, such as directivity/gain and radiometric methods are known for having reduced accuracy and significant complexity. Some are time consuming and require specialized laboratory equipment, such as calorimetric method that requires the use of high power sources and thermal insulation boxes. Other measurement methods are known to be easy to implement, nevertheless they can become very costly if the structure of the antenna is complex, as in the case of the resistance comparison method. Most of the known antenna radiation efficiency measurement methods are valid in a relatively narrow bandwidth and are dependent on the antenna circuit model (in general, most antennas can be modeled by series or parallel resonant circuit models). Therefore they are not very suitable for radiation efficiency measurement in wide frequency ranges, such as UWB because the UWB frequency range expands to several octaves where serial and parallel resonant circuit antenna models are interlaced along the frequency band. Among the known narrowband measurement techniques the Wheeler cap method has become the standard because of its repeatability and simplicity of implementation. However, it assumes a pure series RLC equivalent circuit antenna model which is purely resonant, and so in principle this kind of method is not well suited for UWB antennas. This is why several authors proposed modifications of the Wheeler cap method, intending to increase its measurement accuracy or measurement bandwidth. Johnston-Geissler method is based on Wheeler principle but has no need of assumption on the antenna equivalent circuit model. This makes it particularly interesting for application in wide frequency ranges. The work presented in this talk discusses the applicability of Johnston-Geissler measurement method in very large bandwith, especially in UWB.

 

SPEAKER: Pavel Miškovský was born in Příbram, Czech Republic in 1979. He received his engineering degrees from École Nationale Supérieure des Télécommunications (ENST), France, and from Czech Technical University (CTU), Czech Republic in 2003 and 2004. In 2004-2005 he was granted by the Centre Tecnològic de Telecomunicacions de Catalunya (CTTC) Ph.D. fellowship. He received his Ph.D. degree in Electrical Engineering from Technical University of Catalonia (UPC), Spain in 2010. Since 2006 he is a Research Assistant at CTTC where he is involved in national and industry-funded projects. His research interests include, UWB and reconfigurable antennas and antenna characterization and measurement methods.