Variation of wave impedance of shielded suspended dielectric guide

A shielded suspended dielectric guide is a dielectric rectangular slab enclosed by regular metallic side walls from all the sides. This type of structure is used in dual mode phase shifter where the size of the normal rectangular wave guide is reduced at the ends, where a dielectric material is embeded in ferrite core. Hence impedance variation of a phase shifter at its transition may be easily calculated using shielded suspended dielectric guide which is a prime parameter for optimum efficiency of wave launching.     

Shielded rectangular dielectric wave guides for millimeter wave integrated circuits

The dispersion characteristics of Insulated non-radiative dielectric guides are computed using mode matching technique. From the dispersion characteristics the dielectric loss conductor loss and wave impedances are derived. Effect of metallic walls on trapped insulated image guide are also discussed. The dimensions of Insulated non radiative dielectric guide are same as that of rectangular metallic wave guide at ka band.     

Non-radiative phenomenon in couple dielectric guide

The solutions of electromagnetic field equations for non-radiative coupled dielectric guides are derived using mode matching technique. Dispersion curves are plotted for various dielectric materials and dimensional parameters. The non-radiative phenomenon in the coupled dielectric guide has been discussed in detail. The hybrid directional couplers in the above configuration have been theoretically designed by computing the normalized propagation constants. The superiority of such directional couplers is discussed.     

On the resonant scattering at guide dielectric windows

The effect of output wave resonant scattering at vacuum window of a microwave device caused by high-quality dielectric window eigenmodes excitation is studied. These negative resonant effects can seriously influence the device operation. The numerical calculation results are confirmed by a model experiment.     

Strip dielectric wave guide antenna-for the measurement of dielectric constant of low-loss materials

The value of dielectric constant are the most important parameters in material science technology. In micro-wave and millimeter wave circuits using dielectric materials the values of this parameters should be known accurately. It is observed that the number of methods are reported in litrature, however these methods impose difficulties in experimentation and are not very accurate. In this paper a novel approach to the measurement of the dielectric constant of low loss materials at micro-wave and millimeter wave frequencies has been discussed. In this method by using antenna theory, a metallic strip dielectric guide is taken in to constideration and band reject phenomenon of dielectric antenna is used. Frequency response of an antenna in band reject mode is a function of the dimensional parameters, such as the metallic strip period, the profile of the metallic strip and the dielectric constant of the material used. Hence if one measure the frequency responce of the antenna in band reject mode, the dielectric constant of the material is determined provided all other parameters are known. This method gives a direct measure of dielectric constant and is quite accurate as computer techniques are used for evaluating the dielectric constant. This method verified experimentally also.     

Metal wave-guide to dielectric image guide transition using exponential taper

A unique metal wave guide to dielectric image guide transition has been developed using exponential taper in dielectric wave guide. The propagation characteristics have been computed theoretically and taper impedance for the different cross-sections have been evaluated, so as to match it with the metal wave guide for efficient mode conversion. Transmission loss and return loss for triangular and exponentail taper with frequency for same dimensional parameters have been measured.     

Measurement of quality factor of the coupled nonradiative dielectric guide

The dispersion characteristics of non radiative coupled dielectric guide have been computed using mode matching technique. From dispersion characteristics the conductor and dielectric losses have been evaluated and thus knowing the total losses, the quality factor of the coupled non radiative dielectric guide is evaluated in Ka band.     

Image guide couplers with dielectric coupling elements and radiation reduction

Directional couplers in image guide technique for millimeter-wave circuits are discussed, and steps to improve their properties are demonstrated. The simple two-line-9 dB coupler with periodical coupling is compared to a design with an intermediate dielectric coupling element to reduce the frequency dependence. Radiation from the waveguide bends can be reduced significantly by inserting absorber materials at critical points. Experimental results for a-3 dB coupler are also given.     

Analysis of the propagation properties in an inverted strip dielectric guide

In this paper the conditions are derived which the three lowest modes satisfy respectively in an inverted strip dielectric guide (ISDG). The method of optimal design is dealt with for five parameters selected by the Orthogonal Array Table (OAT), which affect the propagation properties including the single-mode bandwidth, the external field divergence, the conductor and the dielectric losses. Many sets of parameters are presented, for which the ISDG s have optimal propagation properties.     

Synthesis of gaussian beam excited rectangular dielectric guide modes by ray theory

In the present paper, ray analysis of the wave propagation has been used to evaluate the excitation of a linear dielectric guide by a gaussian beam. The paper begins by determining the Green's function of the structure and also evaluates the excitation by gaussian beam therefrom, following Falsen and Shin [1].     

Dispersion characteristics of broadside coupled dielectric image guide at millimeter wave frequencies

Dispersion characteristics and wave impedance for the even and odd modes of the broad side coupled dielectric image guides are computed by using mode matching techniques. Dispersion curves for broadside image guide are plotted for various dielectric materials and dimensional parameters as a function of frequency. Normalized electric field for dominant electric field component E of TM even and odd modes for various half spacings between two dielectric slabs of broadside coupled image guide have been plotted. Polysterene ( r=2.56) and Stycast ( r=3.4) have been used as dielectric materials in fabricating broadside coupled image guide. This broadside coupled dielectric guide is very convenient as compared to the other dielectric guides. Since in case of broadside coupled image guide the dielectric slab can be bonded to the side metallic walls using some low loss adhesive material, while in other coupled dielectric guides the dielectric slab have to be supported by some low dielectric constant material (Eccofoam with r=1.02) to maintain the proper distance of side metallic walls from the dielectric slab. Since this structure is symmetrical, this configuration can be analysed in terms of even and odd mode phase velocities. The difference in these even and off mode phase velocities can be used to determine the coupling between coupled dielectric slab. Various couplers in this configuration can be realised.     

Shielded planar write head

Field calculation with a finite-element method was performed for optimization of the shielded planar head composed of a tapered pole in both down and cross track directions and a wrap-around shield. Especially, effect of the taper angle of the main pole and the gap length and the height of the shield on head field was investigated to obtain a strong head field with a sharp distribution. In order to explore potential of the planar head, comparison with a conventional head with a normal main pole with a short throat was made and feasibility of 1 Tbit/in² recording with patterned media was discussed in terms of magnetization reversals of aimed track and thermal stability of magnetization on adjacent tracks.     

A unique method for reducing losses of bends in dielectric optical wave guide

The dielectric optical wave guide is finding growing attention at millimeter wave frequencies. However the dielectric optical waveguide radiates at bends and thus transmission loss increases. These radiations are in the outword direction of bends. This output radiation at output bends arises due to change in phase velocities of the propagating wave at the centre of the dielectric guide and the phase velocity at the outer surface of the dielectric guide. A unique methiod is suggested to avoid these radiation losses.Experimental results are also shown at microwave frequencies.     

Dynamics of a dielectric droplet suspended in a magnetic fluid in electric and magnetic fields

The behavior of a microdrop of dielectric liquid suspended in a magnetic fluid and exposed to the action of electric and magnetic fields is studied experimentally. With increasing electric field, the deformation of droplets into oblate ellipsoid, toroid and curved toroid was observed. At the further increase in the electric field, the bursting of droplets was also revealed. The electrorotation of deformed droplets was observed and investigated. The influence of an additional magnetic field on the droplet dynamics was studied. The main features of the droplet dynamics were interpreted and theoretically examined.     

Shielded point charges and multipoles

Complex electric potentials and energy relations for shielded point charges and point multipoles of any arbitrary orders are derived. It is demonstrated that both the complex electric potentials of shielded point multipoles and their interaction energies can be expressed through derivatives of the Green’s complex function. As an example, relations for the complex potentials of point multipoles of all orders in a half-plane are presented. It is indicated that the mathematical apparatus of shielded point multipoles can be used, in particular, for successive refinement of estimates of the shielded conductor capacitance. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 81–87, December, 2007.     

Effect of metallic side walls on field distribution of generalized, single and coupled dielectric wave guide

The effect of metallic side walls on the field distribution of generalized single and coupled dielectric guide has been theoretically computed for even and odd modes using mode matching technique in E^Ymn configuration. It is concluded that the field E^Ymn is not symmetrical due to presence of side walls.     

Shielded distribution approximation for a wall-bounded classical fluid

We investigate lower order distribution functions in classical fluids in the presence of large-scale inhomogeneities, in particular those imposed by wall contacts. The consequences of the effective shielding of a wall by the nearest particle of the set being considered are determined in the context of two distribution function hierarchies, kinematic and dynamic in origin. The effects of both flat and spherical, hard and soft walls are considered, as well as those of curved and double walls. A few correction sequences to the basic shielding approximation are discussed.Supported in part by the Department of Energy under contract DE-AC02-76 ERO 3077.     

5T有源屏蔽式超导磁体结构设计

介绍了为兰州Penning离子阱项目专门设计的5T有源屏蔽式超导磁体。 为达到物理设计要求的场均匀度, 超导磁体有3层共计6个线包组成。 同时为了确保线圈绕制的定位精度和在强磁场下的稳定性, 绕制骨架采用三筒体结构, 模拟计算表明线圈的绝缘和固定结构能够达到强磁场下的电气和机械性能要求。 对5T有源屏蔽式超导磁体结构设计材料选择以及线圈的绕制工艺进行了详细的论述。 A 5T actively shielded superconducting magnet was designed for Lanzhou Penning Trap project. In order to achieve homogeneity of physical requirements, superconducting magnet was made up of six coils, which were wound on framework of three layers. Meanwhile, three framework structure can ensure the precision of coil winding and the mechanical stability under intense magnetic field. The results of simulation show that the insulation and fixed structure of the coil can satisfy the electrical and mechanical requirements under intense magnetic field. At last, properties of the used materials and coil fabrication have been presented.