The paper describes preliminary examinations on establishing usefulness criteria of foundry tooling materials in the microwave heating technology. Presented are measurement results of permittivity and loss tangent that determine behaviour of the materials in electromagnetic field. The measurements were carried-out in a waveguide resonant cavity that permits precise determination the above-mentioned parameters by perturbation technique. Examined were five different materials designed for use in foundry tooling. Determined was the loss factor that permits evaluating usefulness of materials in microwave heating technology. It was demonstrated that the selected plastics meet the basic criterion that is transparency for electromagnetic radiation.Keywords: microwaves, permittivity, loss tangent, loss factor, foundry tooling W pracy podjęto wstępne badania nad ustaleniem kryteriów oceny przydatności materiałów do budowy oprzyrządowania odlewniczego, przewidzianego do zastosowania w technologii nagrzewania mikrofalowego. Przedstawiono wyniki pomiarów przenikalności elektrycznej oraz tangensa kąta stratności, które określają zachowanie materiałów w polu elektromagnetycznym. Pomiary przeprowadzono na stanowisku falowodowej wnęki rezonansowej, która umożliwia precyzyjne wyznaczenie metodą perturbacyjną wymienionych parametrów. Badaniom poddano pięć różnych materiałów przewidzianych do zastosowania w budowie oprzyrządowania odlewniczego. Określono współczynnik stratności, który pozwala, na ocenę przydatności materiałów w technologii nagrzewania mikrofalowego. Wykazano, że wybrane tworzywa sztuczne spełniają podstawowe kryterium, jakim jest transparentność dla promieniowania elektromagnetycznego.
Presented are characteristics of new (or described in the literature but not in detail) symmetric and asymmetric coupled-line structures which are of utility in the design of quasi-ideal multilayer microstrip and coplanar directional couplers as well as other coupled-line passive components for monolithic and hybrid integrated circuits. In several designs of tightly and weakly coupled multistrip lines the coupling coeflcient can be achieved in a large range of values, enabling at the same time their quasi-ideal realisation for a given dielectric stratipcation of the structure. This proper@ allows designing high-per$ormance multisection coupledline passive circuits, which are very sensitive to how much the coupling coeflcients for individual coupled-line sections d@er@om the values determined by the circuit synthesis methods.The investigated structures have been used in the design and practical realisation of the following integrated circuits: single-and multisection coupled-line directional couplers, filters, phase shiflers, and power dividers, as well as coupled-line compensated baluns, non-reflective multiple p i n d i d attenuators /DPDT switches, compact, multidimensional Butler matrices, and broadband in-phase antenna array feeding networks. We include the design data and experimental results for most of the circuits we describe.The paper presents the results of the authors' research into the properties and applications of new microstrip and coplanar lines @om the period ofpast few years. Some of the most recent results (not yetpublished) are also presented.
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