A. G. Schuchinsky

Passive intermodulation on microstrip lines

The theory of passive intermodulation generation on printed transmission lines has been proposed. The new model for a terminated section of the transmission line with distributed nonlinear resistance has been developed and verified against the published experimental data. The closed form relation between the macroscopic nonlinear resistance and microscopic nonlinear surface resistivity of strip conductors has been obtained for microstrip lines. Effects of microstrip line width, length and matching on passive intermodulation generation have been studied in detail.

Voltage Controlled Intertwined Spiral Arrays for Reconfigurable Metasurfaces

Reconfigurable bistate metasurfaces composed of interwoven spiral arrays with embedded pin diodes are proposed for single and dual polarisation operation. The switching capability is enabled by pin diodes that change the array response between transmission and reflection modes at the specified frequencies. The spiral conductors forming the metasurface also supply the dc bias for controlling pin diodes, thus avoiding the need of additional bias circuitry that can cause parasitic interference and affect the metasurface response. The simulation results show that proposed active metasurfaces exhibit good isolation between transmission and reflection states, while retaining excellent angular and polarisation stability with the large fractional bandwidth (FBW) inherent to the original passive arrays.

Studies on passive intermodulation phenomena in printed and layered transmission lines

This paper reports on the recent developments into the investigation of passive intermodulation products (PIMs) in PCB based printed and layered transmission lines. Based on the results of earlier experiments, potential sources of PIM generation are examined, and a new semi-phenomenological model of PIM production mechanisms is discussed. The proposed model assumes non-local nature of PIM sources stochastically distributed along the path of high power microwave transmission. A consistent interpretation of the PIM measurements of printed circuits is proposed and further experiments are discussed.

Characterization of metamaterials made of stacked layers of dogbone conductor pairs

The metamaterials composed of planar arrays of tightly coupled dogbone-shaped conductors have recently attracted considerable interest owing to their potential of supporting backward wave propagation [1]-[3]. The detailed study of the plane wave interaction with a layer of dogbone pairs has been performed in [3], [4] along with the eigenwave analysis of an infinite stack of array layers. In particular, it has been found that such metamaterial may exhibit negative effective refractive index near the transmission resonances.

Reconfigurable metasurface comprised of dogbone shaped conductor pairs

A reconfigurable metasurface (MS) composed of a periodic array of dogbone shaped conductor pairs and embedded varactor diodes is analyzed with the aid of a qualitative analytical model and simulated numerically. It is demonstrated that electric and magnetic type resonances are independently controlled by applying bias to specific subsets of varactor diodes. The predictions of the analytical model are confirmed by full-wave numerical simulations and demonstrate tunability of the MS resonance response in a broad frequency range.

Gaussian pulse mixing by stacked semiconductor layers

The nonlinear scattering of two Gaussian pulses with different central frequencies incident at slant angles on the periodic stack of binary semiconductor layers has been modelled in the self-consistent problem formulation taking into account the dynamics of charges. The effects of the pump pulse length and central frequencies, and the stack physical and geometrical parameters on the properties of the emitted combinatorial frequency waveforms are analysed and discussed.

Wave channelling in 2-D anisotropic lattice metamaterials with tunable L-C parameters

The generic conditions of wave channelling on planar 2-D periodic lattices of reactive elements have been established. It was shown that the properties of the channelled waves are invariant to the physical arrangements of the unit cells with the same characteristic parameter X=(-Y 2 /Y 1)1/2. This allows for the channel direction and wave handedness to be tuned by varying only capacitance of the constituent L-C circuits. It was demonstrated that backward type waves experience stronger attenuation on imperfect lattices than forward type waves regardless of the specific type of constituent lattice admittances.

Development of micro-structured metamaterials for innovative antenna layouts

In this paper, we present the joint activities developed in the frame of the FP6 European Network of Excellence METAMORPHOSE in the field of new micro-structured materials for antenna applications. One of the key scientific goals of the research efforts developed within this network is to design innovative micro-structured materials to improve the performances of conventional radiators. Miniaturization, multi- functionality, reduced interference with electronic circuitry, are some of the main challenges in the design of antennas for the next generation of electronic transceivers in the microwave frequency range. The employment of different classes of metamaterials in innovative antenna layouts has been demonstrated to be effective to reach most of the desired goals. The theoretical, numerical and experimental efforts carried out by the leading European institutions working in this field, in fact, show how metamaterial antennas with unusual features are ready to push the innovation in the antenna research. The collaborative dimension of this research is described in this paper, as well as the related scientific achievements.

Wave Channelling in Higher Order Anisotropic Tunable Meshes with Capacitive Control

An analytical and numerical analyses of three types of the mesh unit cell configurations comprised of double series, double parallel and mixed parallel and series L-C circuits as the arms of a periodic grid have been performed. The results of detailed study show that control of frequency selective wave channeling and the type of channeled wave (forward or backward) on the mesh can be achieved by varying capacitance only. These findings are of particular importance for implementation of tunable meshes for beam steering and phase compensation applications

Surface plasmons in layered semiconductor-dielectric structures

Eigenwaves in a parallel plate waveguide loaded with a tangentially magnetised semiconductor layer sandwiched between two dissimilar dielectric layers are analysed. The dispersion equation (DE) is factorised in order to separate dynamic and plasmonic type waves. Then asymptotic solutions of the factorised DE are obtained in closed form for the plasmonic type eigenwaves and used as initial approximations for the numerical solution. The simulated dispersion characteristics, field and Poynting vector distributions show that the parameters of the dielectric layers surrounding the semiconductor layer may qualitatively alter the fundamental properties of the surface magnetoplasmons.