Extremely compact harmonic tuning circuits for class-F amplifiers are realized using composite right-/left-handed (CRLH) transmission line stubs. The proposed circuits take up only a small fraction of the amplifier circuit area and yet are capable of treating four harmonics up to the 5th with a single stub or double stub configuration. This has become possible by using the negative order resonance modes of the CRLH TL, allowing for flexible and simultaneous control of many harmonics by engineering the dispersion relation of the stub line. The CRLH harmonic tuning stubs for 2-GHz amplifiers were realized using surface mounting chip capacitors, whereas the stub for 4-GHz amplifiers was fabricated based fully on microstrip-line technology. The fabricated 2-GHz and 4-GHz GaN HEMT class-F amplifiers exhibited peak drain efficiency and peak PAE of more than 83% and 74%, respectively.

Electrophoretic deposition (EPD) usingpolydimethylsiloxane(PDMS)-based organic-inorganic hybrid materials as binders can be used to prepare alumina-binder composites on metal substrates. Herein, we investigated the deposition mechanism of PDMS-based polymers. The composition and porosity of EPD composites can be controlled by adjusting the EPD condition, and shape of alumina particles.

This paper describes a novel composite right-/left-handed (CRLH) transmission line (TL) stub resonator for X-band low phase-noise oscillator application. The bandpass filter type resonator composed only of microstrip components exhibits unloaded-Q exceeding that of microstrip-line resonators by engineering the dispersion relation for the CRLH TL. Two different types of stub resonator using identical and non-identical unit-cells are compared. Although the latter type was found to be superior to the former in terms of spurious frequency responses and the circuit size, care was taken to prevent the parasitic inductances distributed in the interdigital capacitors from impeding the Q-factor control capability of the resonator. The stub resonator thus optimized was applied to an 8.8-GHz SiGe HBT oscillator, which achieved a phase-noise of -134dBc/Hz at 1-MHz offset despite the modest dielectric loss tangent of the PCB laminate used as the substrate of the circuit.

Novel design approaches for microwave active circuits using composite right-/left-handed (CRLH) transmission line (TL) stubs are presented. We show that, by modifying the dispersion diagram of the CRLH TL stub, the frequency band or the harmonic tuning capability can be enhanced in such a way that it would have been difficult or impractical if done using conventional micro-strip line stubs. The frequency response of the CRLH TL stub can be controlled almost arbitrarily while at the same time reducing the stub length significantly, because the dispersion curve in the left-handed region and in the right-handed region is controlled independently. As a proof of concept, a triple-band rectifier, single-band and dual-band harmonic tuning circuits for class-F amplifiers are demonstrated.

A compact composite right/left-handed transmission-line (CRLH TL) stub resonator is presented. The bandpass frequency of the resonator and the adjacent transmission-zeros are determined by the negative order resonance modes of the stub line. We demonstrate that these resonance frequencies can be arbitrarily controlled by using non-identical, unbalanced unit cells, leading to enhanced loaded-Q as well as unloaded-Q. We show that despite the presence of lumped element loss the unloaded-Q is enhanced by a factor of 2 compared to that of microstrip line as a result of nearly-zero group velocity. As a consequence, the loaded-Q can be increased without incurring significant insertion loss as in the case of conventional stub resonators on the same substrate. The physical mechanisms of the distinct features are discussed based on an equivalent dispersion diagram, a concept introduced to model general one-port CRLH TL used as a stub line.

A transmission ellipsometric method without an aperture was recently developed to characterize the electro-optic (EO) performance of EO polymers. The method permits much simpler optical setup compared to the reflection method, and allows easy performance of the incident angle dependence measurements using a conventional glass substrate and uncollimated beam. This paper shows the usefulness of this method for a simple and reliable evaluation of the EO coefficient both for organic and inorganic EO materials, as well as analysis for uniaxial anisotropic materials.

Phase-nonreciprocal ε-negative and CRLH metamaterials are analyzed using a new approach in which field analysis and transmission line model are combined. The examined one-dimensional nonreciprocal metamaterials are composed of a ferrite-embedded microstrip line periodically loaded with shunt stubs. In the present approach, the phase constant nonreciprocity is analytically estimated and formulated under the assumption of operating frequency far above the ferromagnetic resonant frequency. The present approach gives a good explanation to the phenomenon in terms of ferromagnetic properties of the ferrite and asymmetric geometry of the metamaterial structure, showing a good agreement with numerical simulations and experiment.

Metamaterials are generally defined as a class of artificial effective media which macroscopically exhibit extraordinary electromagnetic properties that may not be found in nature, and are composed of periodically structured dielectric, or magnetic, or metallic materials. This paper reviews recently developed electromagnetic modeling methods of metamatericals and their inherent basic ideas, with a focus on full wave numerical techniques. Methods described in this paper are the Method of Moments (MoM) and the Finite Difference Time Domain (FDTD) Method for scattering problems excited by an incident plane wave and a single nonperiodic source, and the Finite Element Method (FEM), the Finite Difference Frequency Domain (FDFD) method and the FDTD method for band diagram calculations.

The metallic waveguide is one of many effective media for millimeter- and submillimeter-waves because of the advantage of its low-loss nature. This paper describes the fabrication method of PTFE-filled waveguide components with the use of the SR (synchrotron radiation) direct etching process of PTFE, sputter deposition of metal, and electroplating. PTFE is known as a difficult material to process with high precision. However, it has been reported that PTFE microstructures can be fabricated by the direct exposure to SR. First, an iris-coupled waveguide BPF with 5-stage Chebyshev response is designed and fabricated for the Q-band. It is demonstrated that the present process is applicable for the fabrication of the practical components inclusive of narrow patterns. Then, a cruciform 3 dB coupler with air-filled posts is designed and fabricated for the Q-band. Directivity and matched state of the coupler can be realized by “holes” in the dielectric material. The measurement results are also shown.

We present a review of several types of microwave antennas made of metamaterials, including the resonant electrically small antennas, metamaterial-substrate patch antennas, metamaterial flat-lens antennas, and Luneburg lens antennas. In particular, we propose a new type of conformal antennas using anisotropic zero-index metamaterials, which have high gains and low sidelobes. Numerical simulations and experimental results show that metamaterials have unique properties to design new antennas with high performance.

Beam steering of leaky wave radiation from a nonreciprocal composite right/left handed transmission line with a ferrite substrate is proposed. The nonreciprocal phase constants of the line were tuned by changing the applied DC magnetic field normal to the ferrite substrate. In the numerical simulation and the experiment, the nonreciprocal phase characteristics and leaky wave radiation are investigated for the ferrite substrate with the magnetization not only in the saturated region, but also in the unsaturated region. The numerical simulation results are in good agreement with the measurement. It is confirmed that the beam directions of the obliquely unidirectional leaky wave radiation for two different power directions are continuously tunable.

A novel structure for a composite right/left-handed (CRLH) corrugated waveguide in the millimeter-wave band is proposed. The CRLH waveguide is composed of a rectangular waveguide with tilted corrugations on its bottom broad wall. By operating above and below the cutoff frequency of the dominant mode of the rectangular waveguide, the CRLH waveguide provides, respectively, an inherent series inductance and shunt capacitance, and an inherent shunt inductance. Moreover, the tilted corrugations provide a series inductance and a series capacitance, which can support CRLH propagation. A frequency-scanning antenna using this CRLH waveguide is also studied numerically and experimentally. The results demonstrate that the antenna can provide backward-to-forward beam scanning, including the broadside direction. A scanning angle from -9.9 to +2.2 is achieved within a 1.8-GHz frequency range in the 60-GHz band.

The characteristics of a left-handed traveling-wave transistor, which is formulated as two composite right- and left-handed (CRLH) transmission lines with both passive and active couplings, are discussed for generating unattenuated waves having left-handedness. The design criteria for convective instability are described, together with results of numerical calculations that solve the transmission equation for the device.

The characteristics of two-stage composite right- and left-handed (CRLH) transmission lines are discussed. The dispersion relationship of both balanced and unbalanced two-stage CRLH lines is described, together with numerical calculations that demonstrate their potential.

Transmission line metamaterials on coplanar waveguide with series-capacitive and shunt-inductive distributed loading in periodical intervals are characterized using our developed fullwave self-calibrated method of moments. Firstly, the two effective per-unit-length transmission parameters, i.e., complex propagation constant and characteristic impedance, are numerically extracted. The results provide a straightforward insight into the forward- and backward-wave propagation characteristics in several distinctive bands, including the left- and right-handed stopbands and passbands. In particular, it is demonstrated that in the whole left-handed passband, the propagation constant has purely negative phase constant while the characteristic impedance has only positive real quantity. Next, varied left- and right-handed passbands are studied in terms of lower/higher cut-off frequencies based on ideal equivalent circuit model and practical distributed CPW elements, respectively. Of particular importance, the left-handed and right-handed passbands find to be able to be directly connected with a seamless bandgap under the condition that normalized inductance and capacitance of loaded CPW inductive and capacitive elements become exactly the same with each other. Finally, the 9-cell metamaterial circuits on CPW with actual 50 Ω feed lines are designed and implemented for experimental validation on the derived per-unit-length parameters.

Eye tracking is a useful tool for accurately mapping where and for how long an individual learner looks at a video/image, in order to obtain immediate information regarding the distribution of a learner's attention among the elements of a video/image. This paper describes a quantitative investigation into the effect of voice navigation in web-based learning materials.

Basic microwave properties of magnetic photonic (MPC) and degenerate band edge (DBE) crystals are investigated mathematically and experimentally. Two dimensional and three dimensional models are considered demonstrating the very high sensitivity and field growth associated with these crystals. A major part of the paper deals with the development of realistic anisotropic periodic structures using a combination of layers constructed from thin film frequency selective surfaces, alumina, titanate and calcium vanadium garnet (CVG) materials. Measurements for antenna applications demonstrate and validate the theoretical performance of the MPC and DBE crystals. The latter part of the paper will present an exciting and promising development relating to microwave circuit applications. Specifically, a novel dual-line printed circuit is presented to emulate propagation in anisotropic media. As such, the MPC and DBE phenomena can be realized using very simple printed circuits (coupled lines). Lastly, physically small printed antennas and arrays based on the coupled transmission lines are presented.

The paper presents a method for testing transport of composite contacts materials under electrical arc conditions at high currents and for polarized electrodes. Tests and the discussion of results were carried out for silver-metal, silver-metal oxide and silver-tungsten carbide contact materials. Additionally, tungsten electrode was used as the second contact which was either cathode or anode. Spectrometric analysis of arc erosion components transported onto the second electrode and into the surroundings was carried out.

In order to improve the antenna gain, a composite right/left-handed (CRLH) leaky-wave (LW) antenna composed of symmetrical unit cells with short stubs terminated by vertical vias is designed. The use of symmetrical unit cells suppresses the cross-polarization of radiation to less than 23 dB. By comparing the measured radiation characteristics to that of a conventional CRLH LW antenna without short stub in the X-band, it is shown that the presented CRLH LW antenna with 51 unit cells offers a narrower beam and the antenna gain improves 4.1, 2.2 and 3.1 dB in the backward, broadside and forward directions of radiation, respectively.

Frequency-variation method (FVM), reported in [1], was further studied for simultaneously measuring the both complex permittivity and complex permeability by intentionally changing the test frequency to obtain different reflections. An enhanced coaxial-probe-based in-situ measurement system has been established. The spectral domain full-wave model is derived to take place of the quasi-static one. A novel coaxial probe is designed so that the one-port calibration could be performed with Agilent-supplied precise cal-kit instead of the liquid standard. Criterions for a right order of the interpolation polynomial used to approximate the frequency-dependent EM parameters; measures to reduce the residual mismatch errors and random error in reflection measurements and to suppress the ambiguities in solving the transcendent equation system were experimentally studied to resolve the problems and improve the accuracy in dispersive absorbing materials' test. Several typical dispersive absorbing coatings have been tested via FVM. The good comparison between the measured results and reference ones validate the feasibility of the proposed improved technique.