Physical Review B

http://ieeexplore.ieee.org/iel5/5/31325/01456922.pdf

An introduction to optical waveguides

In this paper, an overview of near field UHF RFID is presented. This technology recently received attention because of its possible use for item-level tagging where LF/HF RFID has traditionally been used. We review the relevant literature, discuss basic theory of near and far field antenna coupling in application to RFID, and present some experimental measurements.

An Overview of Near Field UHF RFID

We demonstrate that a structured light intensity pattern can be produced at the output of a multi-mode optical fiber by shaping the wavefront of the input beam with a spatial light modulator. We also find the useful property that, as in the case for free space propagation, output intensities can be easily superimposed by taking the argument of the complex superposition of corresponding phase-only holograms. An analytical expression is derived relating output intensities ratios to hologram weights in the superposition.

Hologram transmission through multi-mode optical fibers

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Piezoelectricity An Introduction to the Theory and Applications of Electromechanical Phenomena in Crystals

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. >

Rigorous analysis of the GTEM cell

Microwave microscopy has recently attracted intensive effort, owing to its capability to provide quantitative information about the local composition and the electromagnetic response of a sample. Nonetheless, the interpretation of microwave images remains a challenge as the electromagnetic waves interact with the sample and the surrounding in a multitude of ways following different paths: microwave images are a convolution of all contributions. In this work we show that examining the time evolution of the electromagnetic waves allows us to disentangle each contribution, providing images with striking quality and unexplored scenarios for near-field microscopy.

Disentangling time in a near-field approach to scanning probe microscopy.

Guided, hybrid propagation in a slotline at microwave and millimeter-wave frequencies is discussed. The analysis is carried out rigorously in the space domain, involving the variational solution of a singular integral equation for an E, field tangential to the slot. Data are obtained for field distributions, dispersion, and characteristic impedance, and are compared with data available in the literature. Results are reported on power lost by the propagation mode in the conductors and in the dielectric substrate. The analysis highlights the onset of leakage into a sufficiently thick substrate due to the excitation of a TM (transverse magnetic) surface wave. This sets a high-frequency limit for lossless operation. >

Hybrid modes, substrate leakage, and losses of slotline at millimeter-wave frequencies

Inductive posts of finite dimensions are currently employed for the precise realization of millimeter-wave filters in waveguides. Although this structure constitutes a classical problem, no true wideband equivalent circuit seems to be available, that is, with elements dependent only on post geometry and, at the same time, capable of describing higher-order mode interaction. The availability of such an equivalent circuit is prerequisite for efficient CAD. A rigorous wideband model, including near-neighbor interaction, that is suitable for accurate filter synthesis and CAD by means of a desk-top computer is developed. Three applications to the design of multipost filters are presented with practical results in excellent agreement with computer predictions. Computation times are such that the analysis can be effected in real time. >

Accurate full-band equivalent circuits of inductive posts in rectangular waveguide

In this work we describe the application of a dual-channel scanning probe microscope performing simultaneously Scanning Tunneling Microscopy (STM) and wide-band Near Field Scanning Microwave Microscopy (wide-band SMM) - developed by ourselves- to a graphene flake. In our system we introduce a conversion in Time-Domain to discriminate the desired information, achieving high quality microwave images with nanometric resolution. The graphene sample is deposited on a substrate of SiO 2 with an additional deposition of gold (a contact finger). The preliminary measurements seem to show evidence of localized change of impedance near the edge of the flake.

Tullio Rozzi

Papers

Rigorous analysis of the GTEM cell

Disentangling time in a near-field approach to scanning probe microscopy.

Hybrid modes, substrate leakage, and losses of slotline at millimeter-wave frequencies

Accurate full-band equivalent circuits of inductive posts in rectangular waveguide

Broadband Scanning Microwave Microscopy investigation of graphene