The modeling of a GTEM cell which consists of a tapered rectangular waveguide loaded with an eccentric sloping plate conductor is discussed. The fields of the cross section of the uniform structure are derived by transverse resonance diffraction. The local modes approach is applied to the study of the longitudinal field distribution. Results show the structure to be actually overmoded rather than quasi-TEM. Numerical results agree with those in the literature, where available. The treatment is highly accurate and requires no more computer power than that of a desktop computer.

In this paper a medium-high performance wireless sensor node based on low-cost Micro Electro-Mechanical Systems (MEMS) accelerometers for Structural Health Monitoring (SHM) applications is proposed. The objective of the work is the estimation of the performances of the low cost MEMS system for SHM with a possible application on a pervasive permanent monitoring of buildings in seismic prone regions often affected by earthquakes. The work aims at improving the sensing technology involved in the dynamic identification and SHM, with the intent to reduce the overall cost of acquisition's system and to make faster the tests procedure. Preliminary experimental tests performed to compare the performance of the proposed system with those of a typical high-performance and expensive wired system, are presented and discussed.

In this paper, we present the analysis of periodic arrays on cylindrical surfaces using open-ended waveguide radiators loaded with radomes and frequency selective surfaces (FSS). The multilayer structure can be used to obtain a filtering behavior by properly choosing the radomes and the size of the FSS apertures. The effect of the gradual cutoff properties of the cylindrical waves is also addressed and the design of a number of filtering structures including one or two FSS is presented.

A simple, drawable, and efficient equivalent circuit is proposed to represent a discontinuity/junction with N ports. The circuit is based on N transmission lines connected to the sides of a polygon with N side. N( N-1)/2 susceptances are placed on the sides and on the inner diagonals of the polygon. The circuit modularity permits to identify the N( N+1)/2 electrical parameters in a simple way. In fact, the lengths of the N transmission lines are obtained solving a system of N polynomial equations and the N( N-1)/2 susceptances are obtained solving a simple linear equation system. The proposed circuit is used to evaluate the equivalent circuit of some directional couplers in the horizontal plane and of a 3-D six-port coupler acting on the horizontal and vertical planes.

In this work, a simple and efficient circuit modelling of metamaterial structures, providing a compact circuit able to describe accurately the device over a large bandwidth of operation is proposed. The equivalent circuit model is obtained by the identification process of the load in terms of shunt branches constituted by reactive elements that can be both positive and negative. The circuit model is validated by analysing the Split Ring Resonator (SRR) structure. The presence of negative elements in the non-Foster load are transformed to positive reactive elements by converting the load from shunt to series. Unlike the T or Π circuit models, using this approach a circuit model can be constructed directly from the scattering parameters and valid for any circuit topologies.