Resonance systems of millimeter wave oscillators
An analysis of open resonators specially designed for millimeter wave sources which are characterized by high frequency stability is presented. The obtained numerical results and experimental data have been used to improve the characteristics of oscillating systems formed by a two-mirror resonator with metal rod inside. To proceed the preselection of modes in the given frequency region the flat mirror of a conventional Fabri-Perot hemispherical open resonator have been replaced by a specially constructed mirror with a stepwise cross-section. The further tune axial mode filtration and the complete transverse modes suppression have been achieved by the insertion of a metal rectangular rod into the resonant cavity. The determining of parameters of the stepwise mirror and the rod is based on a detail theoretical investigation of the problem of wave scattering from these structures. Experimental results are in good agreement with numerical data. The designed open resonators can be used for generation of electromagnetic waves in the frequency region from 30 to 150 GHz. 1. The analysis of electromagnetic fields in open quasi-optical resonators has been extensively investigated because of its importance for solid-state sources design and for measurement problems in the millimeter wave band (Kotserzhinsky et al (1)). An introduction of GaAs and InP active elements into high Q circuits led to the development of millimeter wave oscillators characterized by rather high output power (about 100 mWt) and by a high frequency stability. The quality of a signal depends on the Q-factor of a circuit used in oscillators.
Open resonators with inhomogeneities
An analysis of electromagnetic properties of an Open Resonator (OR) with perfectly conducting cylindrical inhomogeneities is presented. The inhomogeneities of three types were studied. In the first case the conducting thin circular cylinder with a longitudinal slot is considered. This cavity-backed aperture possess the resonance features. It is shown that such cylindrical screen may be used in order to control the OR properties. The case of the conducting cylinders with rectangular and circular cross-section are considered too. It is shown that the inhomogeneity of small cross-sectional wave dimensions can both be imperceptible for the OR-field and efficiently scatter it, depending on location of the inhomogeneity in the OR. The theoretical analysis and experimental results are presented. The stationary wave model of the OR field is used in the theoretical analysis of scattering from cylindrical inhomogeneities. The generator of the cylindrical obstacles is parallel to the H vector of the incident field. The experiments were carried out in the millimeter wave band with the OR having spherical and flat mirrors. The numerical results are in a good agreement with the experimental data.
Hutcheson's Moral Sense Theory Reconsidered
There is no more central feature of Francis Hutcheson's moral philosophy than his theory of the moral sense. In the past this sense or faculty was widely understood to be a distinctive and independent sense devoted to the apprehension of moral qualities, but William Frankena has in recent years challenged this traditional view of Hutcheson's theory, and offered in its place an emotivist interpretation. Without question Frankena's study was of the first importance, in that it seems to have overturned the much too simplistic traditional view of the moral sense. Unfortunately, however, Frankena's own interpretation of the moral sense is as inadequate and misleading as the view he overturns, for he concludes that the moral sense is not at all a cognitive faculty, that it does not, that is, apprehend moral qualities, but, rather, is a faculty that enables and motivates us to feel, express, and evoke moral emotions. The moral sense, he argues, is “the source of the feelings involved” in moral approbation or disapprobation, and this approbation is “wholly non-cognitive, very much as it is on Ayer's more recent [emotivist] view … This, I shall show, is much too narrow a view; Hutcheson did not limit the moral sense to a single function, nor did he — lacking as he did twentieth-century perspectives — find it either necessary or desirable to assume that the domains of the cognitive and the emotive (or affective) were mutually exclusive.