Design Study of a Miniaturized Multi-layered Antenna-in-package for 2.4 GHZ Wireless Communication

This paper proposes a novel miniaturization technique to enhance the radiation properties of small multi-layer patch antenna used in packaged circuits. The multilayered antenna design is composed of three layers with different shapes. An enhancement on the radiation properties has been obtained by optimizing the geometry of the radiated element and the parasitic conductor of the middle layer. The whole design has been implemented on the FR4 substrate with dielectric constant of 4.4, thickness of 1.6 mm and Copper thickness of 5 μm. The first layer is a driven element while second and the third layer are parasitic patch elements. The optimized multilayer antenna has a very small size of 12×6×5 mm^3. Considering the small size of the antenna, a detailed study of the parameter affecting the radiation has been considered to force the antenna to operate at 2.4 GHz band. Miniaturization techniques based on the current distribution have been also taken into account to shift down the resonant frequency and reduces more and more the antenna size at the designed operating frequency. The miniaturized antenna maintains performant radiation characteristics in terms of reflexion coefficient, bandwidth and directivity. All developed antennas are simulated using the commercial Electromagnetic CST Microwave Studio software. Achieved results demonstrate a good performance with low cost and compact size.

Multiband Multi-Standard LNA with CPW Transmission Line Inductor

LNA is one very essential bloc in the RF receiver. Due to the growth of the standard evolution, this component must handle several frequency bands with the best performances. This chapter presents a wide band LNA design for IEEE802.16 standard with the CMOS 0.35µm technology. In this LNA, we use a CPW transmission line to design the inductive degeneration inductor of 0.38nH. This circuit has a S21 of 12dB, a noise figure less than 3dB and an input/output reflexion coefficient less than -10dB between 2 and 6GHz. The CPW line presents a characteristic impedance of 120O, an inductance of 0.38nH, a capacitance of few fF and a resistance less than 2O on the desired frequency band.

Hydraulic and diffusional permeabilities of isolated outer medullary descending vasa recta from the rat

Water permeates many microvessel walls via a pathway shared with small hydrophilic solutes and also via an exclusive water pathway. In outer medullary descending vasa recta (OMDVR), the relationship between diffusional permeabilities to water and sodium indicates the existence of an exclusive water pathway and suggests that of a shared pathway. We investigated the latter possibility by estimating hydraulic permeability (Lp) and diffusional permeability to [3H]raffinose (P(raf)) in isolated, perfused OMDVR. The product of hydraulic permeability and osmotic reflexion coefficient of albumin (Lp sigma a) was 1.56 +/- 0.19 x 10(-6) cm.s-1.mmHg-1 (n = 28), calculated from transmural volume fluxes induced by perfusate-to-bath differences in albumin oncotic pressure (delta IIa). P(raf) in the same vessels was 40.1 +/- 7.5 x 10(-5) cm/s when delta IIa was zero. In separate experiments, sigma a was at least 0.89 +/- 0.10 (n = 17). Lp sigma a correlates with P(raf), indicating that OMDVR contain a shared pathway for convection driven by delta IIa and for diffusion of small hydrophilic solutes.

Nonlinear variations of the reflexion coefficient for lower-hybrid heating

The effect of the ponderomotive depression of the plasma density on the power reflexion coefficient is calculated in the first space harmonic approximation. Numerical results demonstrate a considerable growth of the reflexion coefficient when increasing the RF power. Exceptionally, the reflexion coefficient can be almost invariable up to high RF power densities (≃ 10kW cm-2), if the unperturbed plasma density gradient is high (≳ 5 × 1012 cm-4). The relation of the present theory to experiments is discussed.

The electrical resistivity of gold films

We present measurements of the d.c. electrical resistance of three classes of pure epitaxial gold films in the thickness range 30 to 900 nm. The combination of diverse morphological techniques with temperature-dependent data from 2 to 300 K enables us to apply a new theory based on those of Mayadas and Shatzkes for grain-boundary scattering, and of Soffer for surface scattering. Gold, evaporated and annealed on mica substrates, produced (111) films which gave a mean microscopic surface roughness to Fermi wavelength ratio, r, of 0.05 and a grain-boundary reflexion coefficient, Rg, of 0.45. On KBr substrates, samples, prepared similarly, formed two distinct types of (100) film. Use of reflexion high energy electron diffraction and electron microscopy showed that the grain structure of these types of film differed; however, both gave an r of 0.1. An R g of 0.10 was determined for one type but remained unknown for the other. Our results show how previous workers, often relying on the validity of Fuchs’s theory and the misapplication thereof, have failed to present convincing evidence for specular surface scattering. We demonstrate the necessity for, experimentally, morphological observations and measurements over a wide temperature range, and, theoretically, the use of a method that combines the effects of both grain-boundary and angular-dependent surface scattering.

Relaxation and Backscattering of Light Ions in a Semi-Infinite Medium

Relaxation and backscattering of light ions of moderate energy ( ≲ 1 keV) in solid walls are investigated applying the normal Boltzmann equation to a semi-infinite medium, thereby satisfying the exact boundary conditions at the wall surface. Since momentum and energy relax on different scales, Boltzmann's equation is solved in a two scale procedure, treating momentum and energy relaxation separately. Matching the two regions self-consistently yields the ion distribution function and with that macroscopic quantities, e.g. the range distribution and the spectral reflexion coefficient. The application of the method is demonstrated for a simple test model with constant nuclear scattering cross section and no electronic losses.

Wave reflexion from beaches

The usual way of posing the problem for the reflexion of wave trains from beaches seems inevitably to imply perfect reflexion. Energy considerations show that wave absorption must be associated with the degradation of mechanical energy either through wave breaking or viscous effects. Some experiments reported here showed substantial wave absorption in the absence of any breaking.We describe some theoretical and experimental work aimed at assessing the role played by friction at the bottom in determining the reflexion coefficient of a beach. The results suggest that, if the parameter (νω3)½½gα2 is not too small, bottom friction can be a significant factor in the absorption process for waves on beaches. Here ν represents the kinematic viscosity (or perhaps an ‘eddy’ viscosity) of the fluid, ω is the frequency of the motions, α is the slope of the beach and g is the acceleration due to gravity.