Free-space measurement of bi-axial anisotropic materials
This paper presents an extension of the free-space method for measurement of bi-axial anisotropic material at microwave frequencies. In this method, four complex transverse constitutive parameters are directly computed from the reflection and transmission coefficients of a planar sample in free space for a normally incident plane wave with two polarizations. By using the measured amplitudes of the reflection and transmission coefficients of a planar sample at six incident angles with two polarizations, two complex longitudinal constitutive parameters are obtained by finding the solution to minimize the properly designed objective function under the suitable judging criterion. The numerical trials are carried out for a high-loss material by joining random errors to simulate the real measurement condition, which verifies the validity of this method.
A free-space method for measurement of dielectric constants and loss tangents at microwave frequencies
For measurements of dielectric properties of planar slabs of ceramic and composite materials, the authors have developed a free-space measurement system in the frequency range of 14.5-17.5 GHz. The key components of the measurement system are a pair of spot-focusing horn lens antennas, a network analyzer, and a computer. Because of the far-field focusing ability of horn lens antennas, the free-space measurements can be made at microwave frequencies in a relatively compact and simple measurement setup. The time-domain gating feature of the network analyzer and the thru, reflect, and line calibration technique were used to eliminate the effects of undesirable multiple reflections. The dielectric constants and loss tangents were measured for standard materials such as fused quartz, Teflon, and polyvinylchloride (PVC). Dielectric properties for Teflon and PVC were also measured in a waveguide medium for purposes of comparison with the free-space method. >
History of Amateurism in Men's Intercollegiate Athletics: The Continuance of a 19th-Century Anachronism in America
Claiming that American intercollegiate athletics are amateur at the end of the 20th century is an anachronism, for colleges in the 19th century took on professional characteristics. The upper-class British concept of amateurism did not work effectively in a more egalitarian and achievement-oriented American society. Hypocrisy resulted when colleges claimed amateurism while accepting such professional practices as hiring professional coaches, allowing athletes to play summer baseball for money, and paying athletes through grants-in-aid. Attempts to preserve amateurism, such as the Graham Plan in the 1930s and the Sanity Code in the 1940s and 1950s, yielded to the professional spirit. Thus, while Americans had generally rejected the upper-class British social hierarchy that fostered amateurism, they retained the name amateur, continuing the hypocrisy that had begun in the previous century.