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We have studied the effects of concentration of cobalt and sintering temperature on the complex relative permittivity and permeability of Mg[Fe.sub.1.98][O.sub.4] ferrite ceramics. All samples were doped with 3wt% [Bi.sub.2][O.sub.3] to improve the sintering properties of the [Mg.sub.1-x][Co.sub.x][Fe.sub.1.98][O.sub.4] ceramics and thus attain a low dielectric loss tangent. X-ray diffraction data indicated that the ferrite samples all have a single-phase spinel structure and that there was no reaction between the ferrite and [Bi.sub.2][O.sub.3]. In terms of microstructure development and grain growth, the effect of [Bi.sub.2][O.sub.3] is much more pronounced than that of Co. At a given concentration of Co, the magnetic properties can be fairly explained by a magnetic circuit model. The relationship between static permeability and the concentration of Co can be understood by using the single-ion model combined with the local uniaxial anisotropic model. Among the samples we prepared, [Mg.sub.0.96] [Co.sub.0.04][Fe.sub.1.98][O.sub.4] sintered at 1000[degrees]C for 2 h has almost equal real permeability and permittivity--both approximately 10--as well as sufficiently low dielectric and magnetic loss tangent over a range 3 to 30 MHz [the high- frequency (HF) band]. These properties that should be useful for miniaturization of HF antennas. Index Terms--Magnetodielectric, Mg-Co ferrite, permeability, permittivity.

Composites based on ferrite powders [Ni.sub.0.95-x][Zn.sub.x] [Co.sub.0.05][Fe.sub.1.90][Mn.sub.0.02][O.sub.4] with x = 0-0.25, with a volume concentration of 50%, were fabricated and characterized. Dielectric and magnetic properties of the composites were measured over 0.01-16.5 GHz. The permeability of the composites at low frequency increases from ~4.18 to ~7.85 as the contribution of Zn is increased from x = 0 to x = 0.25, while the permittivity remains almost unchanged with x. The composites based on the ferrite powders with Zn of x = 0.10-0.25 have almost equal values of [epsilon]' and [mu]' at low frequency (< 30 MHz). With the low magnetic and dielectric loss tangent, these materials are useful to the design of miniaturized antennas over 2-30 MHz.

We present a wide-band experimental characterization of an on-chip shunt inductor and capacitor (LC) interconnect. (A previous paper by the authors considered the series LC case). In order to capture the effects of parasitic parameters on the wide-band transmission and reflection characteristics of shunt LC interconnects, we propose a generalized frequency-independent circuit model for fast-running simulations. The model is accurate to above its second resonant frequency, with low average simulation errors for both reflection and transmission coefficients compared to the measured two-port S parameters over the frequency range of 1 to 14 GHz. Index Terms--Circuit model, first and second resonance frequencies, on-chip shunt LC interconnect, S parameter, wideband.

Comprehensive experimental results on the coupling effects between two on-chip symmetric and asymmetric neighboring inductors on GaAs substrates are presented in this paper. These pairs of inductors are fabricated with the same track width, turn number, and spacing. Based on the S parameters measured using de-embedding technique, we show the effects of edge distance between these two neighboring inductors on the return and transfer losses, and self-resonance frequency. Certain ways to reduce the transfer loss are explored. Index Terms--Coupling, inductance, on-chip neighboring inductors, Q factor, return and transfer losses.

The coaxial air-line method is used to investigate the dependence of the permittivity of single-walled and multiwalled carbon nanotube composites on frequency and concentration. The results have shown that scaling law based on the percolation theory has described the frequency dependence of measured permittivity in carbon nanotube composites.

The dipole resonance of long high-conducting fibers embedded in an inhomogeneous composite sheet is studied. No effect due to inhomogeneity of the environment is observed.

The resonant frequency of long conductive fibers embedded in an anisotropic composite as a function of layer thickness is studied both numerically and experimentally and is discussed in terms of the equivalent permittivity of the layer. A simple empirical exponential law is suggested to fit the thickness dependence of the equivalent permittivity. The law involves a critical thickness value, below which the layer can no longer be treated as a bulk material for a fiber of given length and thickness. The critical thickness is retrieved from numerical data for different permittivity values of isotropic and anisotropic layers and for different fiber length. [ABSTRACT FROM AUTHOR]

In our previous study, we have obtained the effective propagation vector of composite material with aligned spheroidal inclusions. Such composite material is found to be effectively anisotropic. It is necessary to retrieve the effective permittivity tensor to have a better understanding of the electromagnetic properties of such anisotropic material. Extraction of the effective permittivity tensor from the obtained effective wave number is considered in this paper. The problem is regarded as an inverse problem and is solved using the well-developed differential evolution strategy. [ABSTRACT FROM AUTHOR]

The effective properties of fiber composite materials are considered in this paper. A simple semi-analytic-numerical method, based on the configurational average technique, the method of moment and the Monte Carlo method, is proposed to obtain the effective properties of a general thin composite slab. Analytical results for composite materials with low concentration of spherical inclusions agree well with that by the Maxwell-Garnett (M-G) theory, while the numerical results of fiber composite slab agree well with experimental results. [ABSTRACT FROM AUTHOR]

Describes the correct formulations of the field iterative method (FIM) for two-dimensional large aperture open-ended cavity. Use of FIM for both parallel and perpendicular polarization; Consistency of findings with the Kirchoff's approximation; Agreement of results with the method of moments, particularly for small angles of incidence.

Comprehensive experimental results on the coupling effects between two on-chip symmetric and asymmetric neighboring inductors on GaAs substrates are presented in this paper. These pairs of inductors are fabricated with the same track width, turn number, and spacing. Based on the S parameters measured using de-embedding technique, we show the effects of edge distance between these two neighboring inductors on the return and transfer losses, and self-resonance frequency. Certain ways to reduce the transfer loss are explored. [ABSTRACT FROM AUTHOR]