Layers Of Dielectric Substrate Research Articles

Effects of dielectric substrate properties for optical phenomena in a nanoscale ridge aperture

In this paper, we show that the increase in power throughput is dependent on the thickness and the relative permittivity of the dielectric substrate in the aperture-on-dielectric-substrate configuration. We also show that, similar to a metal nanoparticle, an increase in the medium dielectric constant results in a red-shift in the plasmon resonance of a nanoscale ridge aperture. These results, which are verified by a numerical analysis, provide a new understanding of the phenomenon of surface-plasmon-enhanced transmission. We demonstrate that the red-shifted wavelength and dielectric properties can compensate for the optical loss due to plasmon red-shift. In addition, the dielectric substrate layer behaves like a Fabry–Pérot optical resonator, resulting in coherent constructive interference. The simulation results show that the |E|2 intensity of the triangular aperture is ∼200% greater when this dielectric effect and red-shift resonance are considered.

2.45 GHz and 5.8 GHz Compact Dual-Band Circularly Polarized Patch Antenna

A dual-band circularly polarized stacked microstrip antenna for ISM Bands (2.45 GHz & 5.8 GHz) applications is designed and implemented. By stacking two different corner-truncated square patches in a dielectric substrate layer, the microstrip antenna for dual-frequency circular polarization (CP) can be achieved with –11.5 dB and –12.8 dB measured return loss for 2.45 GHz and 5.8 GHz. Semicircular grooves are cut at the four sides of the low frequency patch to achieve compact design by ∼ 12% size reduction. Details of the obtained dual-band CP performances are presented and discussed. This antenna is a promising candidate to be installed for a smart antenna system, cognitive radio, radar application in the future.

Broadband Planar Antenna Combining Monopole Element with Electromagnetic Bandgap

New structure of broadband planar antenna, combining monopole elements with electromagnetic bandgap (EBG) structures, is proposed. The antenna has a simple single layer structure and unique beam pattern. Antenna is fabricated on a surface of a single layer dielectric substrate and back side of the substrate is covered with metal layer. At the center of the substrate, an inverted L monopole strip is fabricated and on both sides of this monopole, EBG unit cells are placed. By tuning monopole length and EBG bandgap frequency, the monopole resonates even if metal layer exists close to the monopole radiator. Three types of EBG, one dimensional (1D), square two dimensional (2D) and hexagonal 2D, are tested. By combining monopole strip with hexagonal 2D-EBG, the bandwidth of prototype antenna, whose return loss is less than 10dB, is 840MHz in 5GHz band. To control beam patterns of antenna, parasitic elements are placed close to the monopole radiator and EBGs. These parasitic elements work as directors of quasi Yagi-Uda antenna and radiation gain at lower tilt angles is improved.

Waveguide to microstrip line transition and power divider

A novel waveguide to microstrip line transition and power divider with a planar structure is presented. The transition and power divider is designed on both sides of a single layer dielectric substrate, and can be used as a feed of an array antenna with a waveguide feed structure or as a complete integration of waveguide components with active components such as MMIC. Experimental results are shown and compared with simulations; it is shown that good return and insertion loss characteristics are obtained for the K-band.

Compact CPW-fed Sierpinski fractal monopole antenna

A novel compact and uniplanar CPW-fed Sierpinski fractal monopole antenna is presented. A fractal radiating element represents the fourth iteration of the Sierpinski gasket with scale factor δ=1.5. The antenna is printed on a single layer dielectric substrate and fed by 50 Ω CPW transmission line. The multiband operation of the planar fractal structure is confirmed experimentally.

A reciprocity approach for calculating radiation patterns of arbitrarily shaped microstrip antennas mounted on circularly cylindrical platforms

The paper presents a convenient and efficient approach, based on the reciprocity theorem, for calculating the radiation patterns of arbitrarily shaped microstrip antennas with dielectric substrate and superstrate layers mounted on circularly cylindrical platforms. A detailed theoretical development followed by examples with numerical and graphical results illustrate the versatility of the technique. The reciprocity approach presented is very flexible and may be used in conjunction with any of the commonly employed computational electromagnetics modeling approaches such as the method of moments, finite-element methods, and finite-difference time-domain techniques.

Characteristics of cylindrical multiconductor transmission lines above a perfectly conducting ground plane - Summary

The non-planar microstrip lines are becoming increasingly popular due to its wide range of applications which require circuits to conform to curved surfaces such as those of aircraft, missiles, probes, etc. The non-planar microstrip line studied here consists of a finite number of infinitesimally thin perfectly conducting strips, placed either between a dielectric substrate and an overly, or on top of two layers of dielectric substrate. The whole structure is then placed on the tip of a perfectly conducting wedge as shown in Fig. 1. The quasi-TEM characteristics of this geometry are rigorously derived, based on the technique presented in [1,2]. The first part of this analysis is to determine the capacitance matrix for the multiconductor line. Once the capacitance matrix is obtained, other parameters such as the phase velocities, the characteristics impedances, and the coupling between the conductors are readily obtained from the capacitance matrix [3]. The derivation starts with solving Laplace's equation for the potentials in the free space region and in each of the dielectric regions. The potentials are expressed in terms of Fourier series with unknown expansion coefficients for each regions. The expressions for the potentials are constructed such that the continuity of the tangential components of the electric field across the dielectric interfaces are automatically enforced. The remaining boundary conditions are applied by enforcing the potential to have constant voltages on the conducting strips and satisfying the jump discontinuity in the normal derivative of the potential across the dielectric interfaces. The equations obtained are then solved using Galerkin's method to find the expansion coefficients [2]. The expressions for the charge distributions on the strips and the capacitance matrix are then obtained. The transmission line considered for analysis consists of two cylindrical layers of dielectric material, the substrate and the overlay. The substrate is defined by permittivity e r2 and radius a 2 . The overlay is defined by permittivity e r1 and radius a 1 . The conducting strips are placed either on the interface between the substrate and the overlay or on top of the overlay as shown in Fig. 1. The arc width of the strips is given by (β i - α i ), where i = 1, 2,...,S and S is the total number of strips not counting the ground plane. The dielectric layers are placed on top a perfectly conducting wedge of angle γ

Characteristics of a helical tape antenna embedded in a multilayer dielectric coated cylinder

The dispersion relation and radiation characteristics of a tape helix with two layers of dielectric substrates and one layer of dielectric superstrate is derived and analyzed. The derivation is based on the hybrid mode field expressions in cylindrical coordinates with unknown expansion coefficients. The application of the appropriate boundary conditions and the point matching technique is used to determine the expansion coefficients. It is assumed that the tape current has only one component along the length of the tape for small values of tape width. The dispersion relation is obtained based on an approximate representation of the current on a narrow tape helix. The k-β diagram is then obtained from the solution of the complex dispersion relation. The radiation patterns of the first and second propagating modes, for a finite number of turns of the tape helix, are presented for different geometrical and electrical parameters.

Quasi-Static Characteristics of a Two-Conductor Multi-Layer Microstrip Transmission Line with Dielectric Overlay and a Notch between the Strips

Different methods for controlling the coupling between a two-conductor microstrip transmission line are investigated in this paper. The transmission line consists of two thin perfectly conducting strips with a rectangular notch between the strips, two layers of dielectric substrate, and a dielectric overlay. The formulation and solution technique are based on the equivalence principle, a free space Green's function, and the method of moments. It has been found that the coupling between the conducting lines can be reduced significantly if dielectric material between the lines is removed. Further reduction in coupling is observed when the relative permittivity of the upper substrate layer is made smaller than that of the lower substrate. Coupling can be maximized if the notch is filled with dielectric material having large relative permittivity compared to that of the substrates. If the strips are covered with a dielectric overlay (or superstrate), the coupling will be substantially increased. Moreover, wit...

New bandwidth extension technique for conformal microstrip antennas

A broadband microstrip patch concept is presented. Fed using electromagnetic coupling, but over a single layer of dielectric substrate, this simple mechanical structure permits antenna applications in structurally and thermally severe environments. One S-band application is presented for such elementary patch and for a cylindrical ‘belt’ microstrip antenna of omnidirectional pattern built around this elementary principle.

An Accurate Determination of Dielectric Loss Effect in Monolithic Microwave Integrated Circuits Including Microstrip and Coupled Microstrip Lines

For the first time, by a rigorous analysis, the performance of MIC planar transmission lines with Iossy substrates can be studied accurately. The generaf structural shape chosen for the analysis includes infinitely thin metallic strips embedded within the layers of homogeneous dielectric substrates. The rigor of the analysis was guaranteed by the assumption of the propagation of an electromagnetic hybrid wave (i.e., TE+TM) along tbe planar transmission lines. An efficient computation was, however, achieved by implementing the spectral domain approach as the basis for the analysis. To test the analysis, phase constants, characteristic impedances, and attenuations, due to dielectric losses, were computed for microstrip and coupled microstrip lines. The results obtained were compared with those given previously by the spectral domain analysis in which dielectric losses were not included directly [1]. The comparison showed an excellent agreement between the two theories for low-loss substrates. However, for Iossy substrates the present method is more accurate.

Suspended Slot Line Using Double Layer Dielectric

This paper presents a rigorous analysis of a) slot line on a double layer dielectric substrate, and b) slot line sandwiched between two dielectric substrates. The structure is assumed to be suspended inside a conducting enclosure of arbitrary dimensions. The dielectric substrates are assumed to be isotropic and homogeneous and are of arbitrary thickness and relative permittivity. The conducting enclosure and the zero thickness metallization on the substrate, are assumed to have infinite conductivity. The effect of shielding on the dispersion, characteristic impedance, and the effective dielectric constant are illustrated. These results should find application in the design and fabrication of MIC components and subsystems.

Analysis of a circular microstrip disk antenna with a thick dielectric substrate

The problem of a circular microstrip disk excited by a probe is solved using rigorous analysis. The disk is assumed to have zero thickness, and the current on the probe is taken to be uniform. Using vector Hankel transforms the problem is formulated in terms of vector dual-integral equations, from which the unknown current can be solved for. Due to the singular nature of the current distribution arising from probe excitation, the direct application of Galerkin's basis function expansion method gives a slowly convergent result. Therefore the singular part of the current is removed since the singularity is known a priori. The unknown current to be solved for is then regular and tenable to Galerkin's method of analysis. It is shown that this analysis agrees with the single-mode approximation when the dielectric substrate layer is thin, and that it deviates from the single-mode approximation when the substrate layer is thick. Excellent agreement of both the computed real and imaginary parts of the input impedance with experimental data is noted. The radiation patterns and the current distributions on the disk are also-presented.