Dielectric resonators

Boriskina, S.V., Nosich, A.I., 1999, Radiation and absorption losses of the whispering-gallery-mode dielectric resonators excited by a dielectric waveguide, IEEE Trans. Microwave Theory Tech. 47 224-231. 

Glisson, A.W., Kajfez, D., and James, J., 1983, Evaluation of modes in dielectric resonators using a surface integral-equation formulation, IEEE Trans. Microwave Theory Tech. 31(12) 1023-1029. 

For bulk dielectrics, a dielectric resonator can be formed by a cylindrically shaped piece of dielectric material. Dielectric thin films are more difficult to investigate, in particular when the loss tangent is very small. Planar resonator techniques as well as specially designed dielectric resonators can be used to examine their properties. For high-temperature superconductors both dielectric resonators and planar resonators represent an ideal tool to examine their surface impedance values. 

Dielectric resonators - In general, a dielectric resonator consists of one (sometimes more than one) piece(s) of dielectric material characterized by its relative permittivity er = Re e ... 

Table 5.2 Modes in cylindrically shaped dielectric resonators.

Figure 5.7 Material measurement configuration employing TEonp dielectric resonator modes. The sample under investigation is depicted in red.

Planar resonators - Equation (5.11) is not only valid for dielectric resonators. Any other type of electromagnetic resonator employing dielectric parts, like metal ceramic coaxial-type resonators (e.g. used as filters in mobile phones) and microstrip or coplanar resonators (used in microwave integrated circuits) have a Q-contribution due to dielectric losses. For the latter type of resonator the dielectric losses are negligible in comparison to metallic losses, unless high temperature superconducting metallization layers are applied. 

D. Kajfez and P. Guillon, Dielectric resonators, Artech House Inc., 1986. 

The discussion so far has been concerned with dielectrics in steady electric fields more commonly they are in fields that change with time, usually sinusoidally. This is clearly the case for capacitors in most ordinary circuit applications, but there are less obvious instances. For example, because electromagnetic waves have an electric field component it would be the case for dielectric resonators in microwave devices and also for fight passing through a transparent material. Fortunately, no matter how the field may vary with time, the variation can be... 

The solution to providing stable filters and oscillators in the past lay in bulky coaxial and cavity resonators fabricated from the temperature-stable metal alloy Invar. The dielectric resonator (DR) offers a means of miniaturizing the device. 

Dielectric resonators are extensively used in mobile communications technology. As far as selectivity and temperature drift are concerned the requirements for hand-held units are far less demanding than for those used in the base stations, and for the more general filter applications. For example, for... 

Fig. 5.38 Microwave ceramic components (a) metallized ceramic engine block for 40 MHz pass band filter at 1.4 GHz (b) 11.75 GHz oscillator incorporating ceramic dielectric resonator together with various resonator pucks.

Figure 5.38 shows a microwave oscillator built on to a ceramic substrate and incorporating a dielectric resonator. 

Describe the essentials of the design principles of a dielectric resonator (DR) and the advantages offered over cavity resonators. 

Hakki, B.W. and Coleman, P.D. (1960) A dielectric resonator method of measuring inductive capacities in the millimeter range, I.R.E. Trans. Microwave Theory Tech. 8, 402-10. 

Like all dielectric resonances, the silicate bands are strong for small particles (x < 1). In the transition region x 1, the band shape changes rapidly as a function of particle size, while for much smaller particles, the band shape is independent of particle size (the Rayleigh limit). The observed shape of the 10 pm silicate band is therefore sensitive to the presence of particles of sizes a 2 pm, while the 18 pm band is sensitive to particles twice that size. In short, larger particles will produce flatter silicate features with decreasing feature-to-continuum ratios [( 9.7 j.m - Fq)/Fq, e.g. van Boekel etal. 2005]. 

From a general point of view a dielectric resonator is a transparent body of certain shape consisting of a substance with a high refractive index n, usually surrounded by air. Such a structure has the ability to confine light inside, e.g. utilized in any kinds of optical fibers or waveguides. To explain this phenomenon in terms of classical electrod5Uiamics, and any similar problem respectively, it is necessary to solve the tree-dimensional wave... 

For a dielectric material in dielectric resonator (DR) applications, the wavelength of the standing wave equals the diameter D of the DR, and the velocity = c/ej , the wavelength in dielectrics, is conversely proportional... 

When a dielectric resonator is coupled with microwave circuits, the dielectric material responds to the frequency. The frequency selectivity of the microwave device depends on the loss quality of the materials. The selectivity Q ) of the dielectric materials is defined as the ratio of/ to A/, and the Q approximates the reciprocals of the loss factor (tan 5). The loss in DR (l/2 ) is the sum of the loss of dielectric materials (I/Qm). surface conduction HQ, and radiation loss (1/2,) ... 

Perhaps the most important elements in THz systems are sources and detectors. Sources are vaguely classified into two categories pulsed broadband and continuous narrowband. The most common approaches for generating broadband THz pulses are photoconductive antenna and optical rectification, while voltage controlled oscillators or dielectric resonators are the two widely used sources for generating low power narrowband continuous THz waves [5]. 

A comparison of the 77-factors of the ground state obtained from absorption and PL measurements with those obtained from ESR, dielectric resonance absorption is shown in Table 8.20. 

Having determined the fundamental properties of higher order FDTD algorithms, a set of more complicated problems will be studied in this section. These include the analysis of microstrip, cavity-backed or dielectric resonator antennas with different polarizations, fractal arrays, and metamaterial-loaded structures. 

Dielectric resonator antennas (DRAs) constitute an important family of radiation devices, since they exhibit sufficient directivity and gain, while their small size enables the handling of multipath signals [19—22]. 

K. W. Leung and H. K. Ng, The slot-coupled hemispherical dielectric resonator antenna with a parasitic patch Applications to the circularly polarized antenna and wide-band antenna, IEEE Trans. Antennas Propag., vol. 53, no. 5, pp. 1762—1769, May 2005. doi 10.1109/TAP.2005.846731... 

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