Mohammed R. Abdul-Gaffoor

Uncertainty analysis of the transmission-type measurement of Q-factor

The transmission-type measurement of the Q-factor of a microwave resonator is analyzed with a goal of establishing uncertainty limits on the unloaded Q-factor. The three major sources of systematic errors which are discussed are: the instrumentation inaccuracy, the inequality of the input and output coupling coefficient, and the effect of coupling losses. It is shown that, for tightly coupled resonators, the uncertainty of the transmission-type method is significantly increased.

Temperature dependence of composite microwave cavities

Composite microwave resonant cavities contain several regions of different dielectric materials. The variation of the resonant frequency with temperature is described in terms of a linear model. One part of the frequency variation is caused by the physical expansion of material parts, and the other by the change in the relative dielectric constant. The frequency sensitivity coefficients for both types of variation are obtained with the use of a computer code for numerical analysis of the electromagnetic field inside bodies of revolution.

Capacity based MIMO antenna design

A Multi Element Antenna (MEA) is an array of antennas that can be driven independently so as to, among other things, mitigate adverse and variable propagation environment effects. MEAs are employed routinely by Multiple Input Multiple Output (MIMO) wireless systems and their effective radiation pattern is controlled by smart algorithms. As such, optimal MEA design cannot rely on traditional specifications like gain alone. This article outlines a Capacity based MEA design approach.