Abstract—A four-pole elliptic function compact bandpass filter is designed by using interdigital hairpin resonator and step-impedance hairpin resonator. The miniaturized band-pass filter is also implemented using highpermittivitydielectricsubstrate. The full- wave simulator IE3D is used to design the compact hairpin resonator, and to calculate the coupling coefficient of the basic coupling strictures. The responses of the fabricated filters using Al 2 O 3 (ε r = 9.7, Q ×
The geometric configuration of the proposed ground plane slot resonator is shown in Fig. 1. The structure consists of a 50 Ω microstrip line on the top layer and a rectangular slot is etched in the ground plane of substrate. Two metallic plates forming a parallel plate capacitor is soldered with the ground plane across the ground slot. The low loss dielectric material could be placed between two metallic plates to increase the loading capacitance. The maximum electric field in the slot is at the centre of the slot; where parallel plates are soldered.
Abstract A novel type of integrated dielectric antenna is presented, which is suitable for low-loss integrated transceiver front-ends in the upper microwave or millimeter wave frequency ranges. The proposed antenna comprises a dielectrichighpermittivitysubstrate acting as grounded slab waveguide and a simple planar lens on top for beam focusing. The guided wave is gradually transformed to free space by a curved ground plane for end-fire radiation from the substrate edge. Apart from high radiation efficiency due to very low conductor losses, the use of a standard substrate material also simplifies manufacturing and allows accommodating MMICs or bias circuitry at minimum cost. Simulation and measurement results are presented for a scaled prototype in X-band. Simulation studies were also conducted at millimeter-wave frequencies, where the low-loss advantage is even more evident. Having dimensions of 10 mm × 18 mm, an example design provides a gain of 15 dBi at 60 GHz and a radiation efficiency of more than 80 % if a Duroid ® 6010LM
scheme is described to increase the operation bandwidth of antenna for wideband applications. The proposed antenna has compact dimension of 29 mm ×26 mm with a height of 1 mm and implemented on F4 Epoxy substrate with dielectricpermittivity of 4.4. The proposed antenna was simulated using Ansoft High frequency structure simulator (HFSS) electromagnetic simulator. The return losses of designed UWB antenna are good at 1.6 GHz, 4.1 GHz and 8.4 GHz which are < -10 dB and the antenna is useful for L, C and X bands applications respectively.
Abstract—A circular microstrip patch antenna design is proposed for applications that require suppression of surface waves and lateral waves. The proposed design is composed of a circular patch loaded with a single shorting pin on a grounded inhomogeneous dielectricsubstrate with a desired eﬀective permittivity. The modal equation for the normalized resonance frequency of this design is solved numerically. Simulated and measured radiation patterns show that a good reduction of surface waves and lateral waves is achieved. A comparison between the present work and an alternative design in the literature is presented in this paper. The proposed design could ﬁnd applications in large patch antenna arrays where mutual coupling needs to be eliminated and in high-precision global positioning system receivers where multipath interfering signals associated with low-angle reﬂection aﬀect position accuracy.
Modern communication systems are getting way to complicated, which ne- cessitates the use of simultaneous high gain and compact antenna systems. Due to its high gain and planar nature, patch antennas are very suitable for use in the devices requiring GSM applications  . Plastic is a low dielectric permit- tivity substrate whereas barium titanate possesses very highpermittivity which is also ferroelectric in nature. In this paper, the resonance and radiation perfor- mance of patch antennas loaded with plastic and barium titanate substrates at GSM 1800 MHz band have been explicated. The organization of the paper is as follows: antenna geometry and structure has been described first; in the subse- quent section, simulation and measurement results of the antennas have been shown; and in the final section, conclusion and scopes for future research with these sorts of antennas have been predicted. It is seen that the simulated and measured results of both the antennas are in good agreement with each other.
In amplified use of hybrid, monolithic microwave and millimeter wave circuits the choice of transmission line is coplanar waveguide (CPW). It is the most striking alternative to conventional used microstrip line and stripline due to its uniplanar geometry. It consist of a centre strip with two ground planes located in the same plane [1-2] i.e., on the same surface of dielectric slab as shown in Figure.1. The ground plane being on the same surface lends itself to easy mounting of circuit elements and active devices; Drilling of holes or slots through the substrate is not needed [3-6]. CPW structures are commonly used in high-speed circuits and interconnect. It offers several advantages over microstrip which are summarized in Table 1. The use of CPW in the design of circuit components and transmission lines is not yet widespread. One reason for this is due to the lack of analytical data pertaining to the characteristics of CPW [7-8].
Abstract—An electrodeless measurement technique of complex dielectricpermittivity of high-K dielectric ﬁlms is described. The technique is based on a quasi-optic Fabry-Perot resonator and modiﬁed for investigation of two-layer dielectric structures — substrate/K-ﬁlm. This procedure is destined to be used for providing a simple intermediate control of parameters of high-K ﬁlms before the following technological process. Regimes of measurements providing the most sensitive conditions for deﬁnition of ﬁlm parameters are considered. The proposed method is tested on two-layer structures with well- known parameters and is used for characterization of ferroelectric (Ba,Sr)TiO 3 ﬁlms in the millimeter
Recently, several methods have been used to optimize patch antennas with varying success, such as using a dielectricsubstrate of highpermittivity , Defected Microstrip Structure (DMS) , Defected Ground Structure (DGS) at the ground plane  or a combination of them, and various existing optimization algorithms such as particle swarm optimization (PSO)  and genetic algorithm [5–7]. The latter is one of the global optimization algorithms that have been used widely in the past by antenna designers for the optimization of the patch shape and size in order to achieve better overall performance of the antenna.
As mentioned above, almost all the MAs exhibit very thin vertical sizes, and the basic units of MAs also have very compact sizes compared to the operating wavelengths. However, for some speciﬁc applications (for examples, integrating into compact antennas/array or microwave integrated circuits for the purpose of reducing the coupling between adjacent elements), one needs ultra-compact embedding media so that they can be considered as fully homogenized media and will not induce side eﬀects in the whole system. Quite recently, two works are reported to achieve ultra-compact MAs by using a substrate of highdielectric constant  and a two-layer design . The former one uses a substrate with relative permittivity r = 100 which is of high-cost and diﬃcult to be fabricated in practical. Most importantly,
A Microstrip antenna is attractive candidate in the variety of commercial scale application such as mobile and spacecraft application due to their numerous advantages such as low cost, light weight and easily printed onto circuit board. However Microstrip antennas suffer from low bandwidth characteristics .Many efforts have been devoted to bandwidth widening techniques of Microstrip antennas, including the use of impedance matching , multiple resonators , and a thick substrate . The simplest technique to overcome the size problem is to incorporate highdielectric constant substrate which is very expensive so it is not suitable in many applications . The other technique using short circuit  or a short pin  has also been proposed. Much attention is focused to improve the bandwidth of short-circuited patch antennas [8-10].18.5% impedance bandwidth was obtained using thick foam as substrate .Two stacked short circuited patch were used to obtain impedance bandwidth of 30% .Using an L-probe feed substrate the impedance bandwidth obtained was more than 39% .Thus stacked and L-probe feed both increase the complexity of the antenna. In case of using highdielectricsubstrate the inductance introduced by coaxial probe will increase the height of foam which in turn limits the bandwidth improvement of the antenna. The U-slot cut on the patch proposed  can be used to cancel the inductance.
Organic molecules and liquid crystals (LC) are well es- tablished materials for photonic and non-linear optical device applications because of their optical non linearity and very rapid optical response . In a mixture of LC and dichroic dye the action of an electric field influences the collective orientation of the LC molecules and that of the dye molecules. This phenomenon is called Guest-host interaction. Dyes have been widely used as guest addi- tives in optical materials to develop novel optoelectronic devices. Again it is well established that the presence of dye molecules in the liquid crystal host influences many properties of the pure liquid crystals. The Effect of dye on dielectric properties of liquid crystals has been inves- tigated earlier by some groups [2,3]. The change in nonlinear refractive index and birefringence of dye doped nematic mixture has been investigated by A. Jafari et al.. It has also experimentally proved that doping a small amount of dye decreases the required threshold of molecular reorientation further in LC materials . Temperature dependence of direction reorientation of dye doped nematic liquid crystal has been studied by Esteves et al. . Voigot et al. have studied emission of circularly polarized light in dye based chiral nematic liquid crystals . Thermal non-linearity of dye doped nematic liquid crystals have been reported by Henninot et al. , while photovoltaic effect in liquid crystal cells containing dyes have been studied by Sato et al. . Mustafa Okutan et al. have studies refractive index dis-
Dielectric resonator antennas (DRAs) were first discovered in 1983 by Long et. al., and since then they have been widely studied . There have been several works reported in literature to improve various parameters (impedance bandwidth, axial ratio bandwidth, gain etc.) of DRAs [2-20]. Their inherent features of high radiation efficiency & ease of excitation, compactness, and ability to obtain radiation patterns using different excitation modes offer much to an antenna application . Furthermore, the shape of a DRA can be custom, resulting in favorable operating modes or polarizations. Also, the DRAs supporting circular polarizations have been studied and can be found in the literature. Traditionally, circular polarization is achieved using quadrature couplers and elaborate feed systems which can also be done with DRAs as well [3, 4].
Dielectric resonator methods constitute one of the most useful techniques for the measurement of electromagnetic material properties in the microwave frequency range. Several geometric confi- gurations are used for this purpose and, in the present paper, we consider the case of a dielectric rod enclosed in a cylindrical metallic enclosure. To carry out dielectric measurements in this sys- tem it is necessary to know the highest permittivity constant value for which the resonance condi- tion still can be attained into the cavity. Using an approach based on magnetic and electric Hert- zian potentials we have derived the set of TE and TM modes for the relevant geometry described and, then we have calculated the valid dielectricpermittivity constant range of measurements for low-loss materials in a cylindrical cavity using a simple resonance frequency condition. Finally, we present a simple application of this method in order to determine the dielectricpermittivity con- stant of heavy oil with 11 API.
Dielectric losses of BFN ceramic were measured as a function of temperature up to 300 ◦C at various frequency ranges from 100 kHz to 1MHz, as shown on Fig. 6.Values of loss tangent (tan δ) at room temperature of our ceramics was in the range of 0.1 to 1.2 . The increase of losses with temperature reflects the conducting character of the sample (paraelectric phase). Fig.7 shows dielectricpermittivity variations as function of the frequency and for different measuring temperatures. One can observe that the permittivity increases with increasing temperature and the occurrence at high of the frequency, of an anomaly accompanied by a maximum of the permittivity; this maximum shifts to higher frequencies with increasing temperature. Table 3 gathers the observed permittivity values. The existence of such anomaly, at high frequency values, may be attributed to the occurrence of a resonance phenomenon; to our knowledge, existence of such anomaly has not been reported in the literature. Dielectric behavior of the samples was also studied with the help of the modified Uchino’s law:
nano-particles show that ε '' and tg δ significantly reduced. At introduction in the composites aluminum na- no-particles isolated clusters is formed alongside with the semiconductor particles. Aluminum nano-particles— conductive clusters randomly distributed in the PE matrix. Increasing Al content in the composite leads to an in- crease in the number of nano-particles per cross section of the composite, which is equivalent to the proportion of Al in the total thickness of the composite—sample. Closed each other through-thickness sample clusters can be considered as active resistance connected between the electrodes. Since they have high compared with PE+ xvol.%TlInSe 2 composites conductivity, it can be assumed that the resistance of the composite will be mainly
Negative refraction in the left-hand materials (LHMs) with negative permittivity and negative permeability simultaneously has attracted much attention for their exotic electromagnetic (EM) properties [1–7]. Due to the fact that natural materials with both negative permittivity and negative permeability have not been available, the conventional LHMs have focused on the combination of subwavelength metallic structures to achieve negative parameters at the same time by electric and magnetic resonances, and thus a negative refractive index [2–6]. For instance, the combination of split ring resonators (SRRs) and metallic wires is widely adopted [2–4]. In this case, the SRRs provide the negative effective permeability based on magnetic resonance which depends on its detailed geometry, while the metallic wires provide the negative effective permittivity when the frequency below the plasmon frequency. However, these artificial materials mainly gain their negative parameters from the structures rather than from their intrinsic properties directly. It should be a big challenge to realize them in optical frequency due to much complicated nano-farication technique. So it will be very interesting and significant to realize nonmetallic LHMs using the intrinsic properties of the materials.
The oxidation of secondary alcohol was investigated to compare the polymer substrate supported reagent with a commercially available cross-linked polymeric reagent. The reagent supported on anion exchange resin was found to be more efficient in the oxidation reaction. The reagent is very easily separated from the reaction mixture and can be manually removed from the reaction mixture, which remains clear during and after the reaction. The kinetics of oxidation of secondary alcohol with chromic acid supported on anion exchange resins like Duolite A-101[Cl - ] and Ambersep 900[ OH ] in 1,4-dioxane has been studied. The reaction is found to be of zero order each in concentration of alcohol and oxidant. The stoichiometric coefficient of the reaction has been found to be 2:1. The oxidation products have been isolated and characterized by their derivatives, UV and FT-IR spectral studies. The effect of substituent’s on the rate of oxidation and activation parameters for the overall reactions has been computed from Arrhenius plot.
There have been numerous approaches to model electromagnetic (EM) backscatter from rough surfaces and from horizontally stratiﬁed media, but these typically involve assumptions that limit the overall solutions to the point that the phenomena being modeled are not physically realizable. Lord Rayleigh  developed the perturbation method to study the reﬂection of acoustic waves from a sinusoidal surface and this was ﬁrst extended to electromagnetic waves by Rice . Rice considered static 2D rough surfaces that could be expressed as a Fourier Series with the series coeﬃcients as random variables. The analysis was completed to second order for scatter from a perfectly conducting surface and a horizontally- polarized wave on a rough dielectric surface. Wait  considered reﬂection of a vertically-polarized EM wave from a 2D periodic surface using the Leontovich boundary conditions and derived results to second order. Barrick [4, 5] was interested in radar propagation across the ocean and considered the wave as being guided by a rough, conductive surface. The scattered ﬁeld was limited to the component traveling away from the surface and multiple scattering was not included in the analysis. These results were extended to all spectral orders of scattering by Rosich and Wait . Rodriguez and Kim  developed a uniﬁed perturbation expansion that reduced to Rice’s results when the same assumptions are made, but the second order cross sections deteriorate as incidence angle or surface height increases. Perturbation methods are one of the most common approaches for modeling backscatter from rough surfaces. However they are only valid when the amplitude of surface roughness is much smaller than the radar wavelength and some implementations of the technique assume plane wave incidence.