Serhend Arvas

Shielded Dual-Mode Microstrip Resonator Measurement of Uniaxial Anisotropy

An improved technique to measure uniaxial anisotropy in planar substrates is described. This technique builds on previous work performed with stripline. The improved approach offers substantially larger bandwidth, lower error, and ease of measurement. An almost complete automation of the entire calibration and measurement extraction process is described. It is also demonstrated that the horizontal (parallel to substrate surface) dielectric constant is less than the vertical dielectric constant for glass fiber weave reinforced substrates for the purposes of microstrip and stripline design. This directly conflicts with bulk measurements of dielectric constant and is believed due to microstrip horizontal electric field concentrating in the substrate surface. This is supported by measurements of a homogeneously ceramic loaded substrate showing the expected relationship. Effects of electromagnetic analysis accuracy, metal roughness, metal thickness, and edge profile (due to etching) are found to be important.

Spiral inductor model extraction: A survey of the field

Equivalent circuit model extraction of spiral inductors is an active area of research. Uses of equivalent circuit extraction range from simply providing insight to a designer, to allowing for automated design optimization. Over the years, many equivalent circuit topologies have been proposed for modeling spiral inductors. A history of the development of such topologies is presented. The extraction of one such topology is demonstrated.

Wideband information in MOM obtained from narrowband data

When solving radiation and/or scattering problems, the Method of Moments can give wideband information by using a Model Based Parameter Estimation technique for the expansion coefficients. The parameters are obtained by computing the values of expansion coefficients and their frequency derivatives at a fixed center frequency. This requires computing the moment matrix and its frequency derivatives. The technique is illustrated for a thin wire scatterer. Piecewise sinusoids are used as expansion functions and point matching is used for testing. The moment matrix and its derivatives can then be computed analytically. Computed results show that depending on the number of derivatives used, accurate results, including resonances, can be obtained over an octave of bandwidth.

Microwave heating of heavy oil and bitumen

A theoretical study is presented for the feasibility of a microwave heating device that will raise the temperature of heavy oil and bitumen reservoir. The device is enclosed in a radome which is surrounded by a perforated metal pipe. Outside the pipe is occupied by a mixture of heavy oil and calcite. Various dielectric properties are assumed for the radome and the calcite region. Analytical and numerical results are presented for the temperature rise around the pipe.

Low power analog baseband circuits in 0.18μm CMOS for MICS and Body Area Network receivers

Design, implementation and measurement of low power CMOS analog baseband stages used in a Medical Implant Communication Service and Body Area Network receivers are presented. The analog stages presented in this work include an operational transconductance amplifier, a 5th order tunable active elliptic filter and a limiting amplifier. The designs are implemented in IBM 0.18 m RF CMOS process using a 1-V reduced supply voltage.

Yield analysis of a stripline Wilkinson power divider using Monte Carlo samples of interpolated full wave simulation data using Sonnet

The use of Monte Carlo samples of interpolated data from a linearly spaced grid of electromagnetic simulation data for yield analysis is investigated. The motivation for this approach stems from a desire to have accurate yield metrics without the need to fabricate a large number of circuits or run a large number of full wave simulations. A means to estimate circuit yield values with relatively little computational effort is presented. A Wilkinson power divider designed with Sonnets electromagnetic simulation engine, em, is provided as a simple example.

Spurious results of EFIE and CFIE applied to dielectric/optical waveguides

It is proven that the surface Electric Field Integral Equation (EFIE) has a non-unique solution when applied to a dielectric waveguide of arbitrary cross section. The Method of Moments (MOM) is used to numerically solve the EFIE applied to an optical fiber of arbitrary cross section. The fiber is assumed to consist of a dielectric core of arbitrary cross section surrounded by an infinite dielectric cladding. The numerical results for a circular fiber verify the existence of spurious results. On the other hand, no spurious results were observed when the surface Combined Field Integral Equation (CFIE) was used to solve the problem of an optical fiber of arbitrary cross section. However, it can be proven that spurious results may exist when CFIE is applied to a fiber with hollow core. The core may have one or more air tubes. Numerical results verified this claim when CFIE is applied to a circular coaxial dielectric waveguide that consists of a circular core with one or two circular air holes.

Project based graduate antenna courses

In this paper, examples of student projects illustrate the level that antenna design education can be taken through the use of software and hardware tools. Through project based courses, s complete design experience can be provided that includes the development of analytical models in addition to the use of software modeling tools, construction and validation by measurements.

Scattering from and transmission through a 2D chiral radome of arbitrary cross section

A simple moment method technique is used to solve the problem of electromagnetic scattering from, and transmission through a two dimensional chiral radome of arbitrary cross section. The radome is a cylindrical shell of arbitrary cross section and arbitrary thickness, with its axis coinciding with the z-axis. It is excited by either a plane wave (TM or TE) in the receiving case, and by an electric or magnetic line current inside the radome for the transmitting case. In solving the problem, the equivalence principle is used to replace the radome by four equivalent surface currents placed on the inner and outer surfaces of the radome. A pulse expansion, point matching technique is used in MOM. To validate the numerical results, they are compared with the exact (eigenfunction series) results for the circular cross section. A very good agreement is observed. As a second check on our results for arbitrary cross sections, we let the chirality admittance to be zero, and observed that the results reduce to the ordinary dielectric radome case.