Review of the ECONAM project activities in the area of electromagnetic characterization of metamaterials C. R. Simovski 1 , S.A. Tretyakov 1 , A. Sihvola 1 1 Department of Radio Science and Engineering, Helsinki University of Technology (TKK), Finland, e-mail: csimovsk@cc.hut.fi, sergei.tretyakov@tkk.fi, ari.sihvola@tkk.fi, fax: +358-9-451-2152. Abstract  In this overview we present the main activities of the FP7 Coordination Support Action ECONAM, devoted to development, testing, and dissemination of methods and tools for electromagnetic characterisation and metrology of nanostructured composite materials. 1 INTRODUCTION Usually, the basic properties of conventional dielectrics and magnetic materials are described by their permittivity and permeability. There are no means for the direct measurement of electromagnetic parameters, which are for this reason dependent on the model used for their extraction. Approaches to measurements of even these fundamental electromagnetic characteristics of materials vary dramatically for electromagnetic waves of different frequencies, e.g. radio waves and light, and require specialised measurement techniques. These difficulties are dramatically escalated in electromagnetic characterisation and metrology of nanostructured materials with complex geometries of unit cells. For example, a device can operate at the wavelength of 500-600 nm, the structural periodicity is 50-100 nm, and the particle sizes are of the order of 30-70 nm. Such structures can still be described in terms of effective parameters (permittivity and permeability) of an equivalent homogeneous medium. However, the conventional models based on quasi-static homogenisation procedures normally applied at the atomic level are not applicable here, and the resulting effective phenomenological parameters (like permittivity and permeability) have different physical meaning as compared with conventional materials. The ECONAM project (http://econam.metamorphose-vi.org/) is a Coordinating and Support Action funded by the European Commission within the FP7 Programme. The main project objective is to consolidate efforts and bring coordination in the European work towards development, testing, and dissemination of methods and tools for electromagnetic characterisation and metrology of nano-structured composite materials. The main novel characterisation approaches are focused on intrinsically interrelated developments and harmonisation of the material phenomenological models, standardisation of characteristic parameters and measurement techniques for evaluating the specified parameters. The coordinator of the Project is Prof. A. Sihvola, and its scientific coordinator is Prof. C. Simovski. The project started in May 2008, and its duration is 3 years. In this overview we present the main activities of this project, including the special ECONAM session organized at the 3 rd International Congress on Advanced Electromagnetic Materials in Microwaves and Optics, London, UK, Aug 30th-Sept 4th, 2009. 2 EXPERT CONSULTATIVE GROUPS AND THEIR ACTIVITIES The main activities of the ECONAM project are carried out by two expert consultative groups specializing on the following aspects of the problem: Characterization Theory and Modeling (chaired by F. Bilotti), and Measurement Techniques and Standards (chaired by A. Schuchinsky). 2.1 Characterization Theory and Modeling During the first year of the project this group of experts produced several overview and recommendation documents available at the ECONAM web site (http://econam.metamorphose- vi.org/activities/expert-group-on-the-theory-and- modelling). The group started its activities by identifying the physical requirements for physically well defined effective material parameters. The following requirements have been identified. Physically sound (local) material parameters * are independent of the spatial distribution of fields excited in the material sample, * are independent of the geometrical size and shape of the sample, * satisfy the causality requirement (Kramers- Kronig relations), * satisfy the passivity requirement (II law of thermodynamics). The first two requirements are difficult to satisfy for many nano-structured samples, mainly because   ,((( 24