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Mobile and wireless communications are playing an irreplaceable role in our daily life. 5G is highly expected and can be considered as the convergence of mobile and wireless communications. This topic becomes one of the hottest research topics recently, and papers on this topic have been paid much attention. Table I lists the top ten papers published in the IEEE Transactions on Microwave Theory and Techniques (TMTT) in 2019 with the highest numbers of Full Text View since published. Seven papers are about millimeter-waves (mm-waves), and because mm-waves multiple-input–multiple-output (MIMO) will be adopted globally, the 24.25–27.5-GHz band and 27–29.5-GHz bands are now approved worldwide as the standard 5G communication bands. The most popular paper is published by Asbeck et al. [item 1) in the Appendix] for mm-wave power amplifiers.

In this paper, the feasibility of inkjet printing of circuit and microwave structures on paper-based substrates is investigated for the first time in the implementation of a complete low-cost wireless platform for sensors. First, the system-level design of the module including the amplifier characterization were carried out to ensure optimum performance of the sensor modules in the UHF bands used in RF identification communication. These results were then used to design two different antenna structures, which are printed on paper along with their respective circuit layouts using inket-printing technology. Different techniques were investigated for the assembly of circuit components on the silver printed layouts. Finally, wireless link measurements on the assembled prototypes verified the good performance on the wireless and sensing sides.

Multiwalled carbon nanotubes (MWNTs) are characterized at X-, Ku-, Ka-, and Q-bands by rectangular waveguide measurements. The scattering parameters (S-parameters) of thin MWNT papers containing a large ensemble of randomly oriented nanotubes are measured by a vector network analyzer from 8 to 50 GHz. A rigorous extraction algorithm has been developed to compute the effective complex permittivity ( epsiv = epsiv'- jepsiv") and permeability ( mu = mu' - jmu") of the nanotube papers from the measured -parameters. The extracted effective medium parameters are verified by finite-element simulations using Ansoft's High Frequency Structure Simulator (HFSS). The uncertainties for this characterization method are analyzed. The systematic uncertainties are found larger at lower frequencies than at higher frequencies. The extracted conductivity of the nanotube papers is in the range of 810-1500 S/m and the dielectric constant is from 250 to 700. The extracted complex permittivity can be fitted with the Drude-Lorentz model for the 8-50-GHz frequency range. The effective medium theory is then applied to remove the impact of air in the nanotube paper.

In this paper, inkjet-printed UHF and microwave circuits fabricated on paper substrates are investigated for the first time as an approach that aims for a system-level solution for fast and ultra-low-cost mass production. First, the RF characteristics of the paper substrate are studied by using the microstrip ring resonator in order to characterize the relative permittivity (epsivr) and loss tangent (tan delta) of the substrate at the UHF band for the first time reported. A UHF RFID tag module is then developed with the inkjet-printing technology, proving this approach could function as an enabling technology for much simpler and faster fabrication on/in paper. Simulation and well-agreed measurement results, which show very good agreement, verify a good performance of the tag module. In addition, the possibility of multilayer RF structures on a paper substrate is explored, and a multilayer patch resonator bandpass filter demonstrates the feasibility of ultra-low-cost 3-D paper-on-paper RF/wireless structures.

A solution to the nonlinear problem of drying of a sheet material is presented, which combines basic thermodynamic properties with the field equations. Some results are given in a numerical simulation. >

In this paper a brief survey of research and development on latching ferrite quadnrpole-field devices in China is presented. Initially, theoretical analyses and some general roles for these kinds of devices are given. Some practical construction techniques and experimental results are also presented. Finally, many practical devices are described (e.g. reciprocal phase shifters with fast switching polarizations, reciprocal phase shifters with transverse magnetization, duplex phase shifters). In general, latching ferrite quadrupole-field devices have many advantages, among them simplicity, ruggedness, and rapid switching.

Using the conservation of complex power technique (CCPT), this paper presents a solution to the problem of EM scattering at the junction of a parallel-plate waveguide and an N-furcated parallel-plate waveguide with arbitrarily spaced thick septa. Although this junction can be regarded as an (N + 1)-port configuration, the problem is formulated so that it is viewed mathematically as a generalized 2-port. This leads to very simple expressions for the scattering parameters of the junction. Convergent numerical results are presented for bifurcated, trifurcated, and 4-furcated structures, and the effects of varying the thickness of the septa are investigated. The formulation is directly applicable to N-furcated rectangular waveguide junctions having TE/sub n0/ excitation, with application in the design of E-plane filters.

Numerical solutions are presented for the characteristic impedance of various line structures derived from the slab line, which allow the calculation also of the even and odd impedance of coupled slab lines. Some approximated formulas are also derived, which match the numerical results with good precision for a large range of geometrical dimensions of the structures. The results presented here are compared with some formulas and numerical results available from previous technical papers.

A dynamic bridge-measurement technique has been developed to characterize the time evolution of millimeter-wave fields in a plasma-controlled semiconductor waveguide. The time resolution of this technique is about 2 ns.

A new horn-shaped waveguide hyperthermia applicator, operating in the range 300-1000 MHz, has been designed. The applicator is filled with deionized water acting as both a dielectric and a cooling fluid. Pretiminary tests indicate that proper heating can be achieved at frequencies of about 340,440, 560, and 690 MHz, A very low level of enviromental pollution was observed. Thermodosimetry has been carried ont on two young femate sheep. Measurements in vivo have been carried out using up to 5 temperature sensors in different positions. The results indicate the occurrence of different temperature trends if the water is maintained at 15, 23, 30, and 35°C.

A technique for the plasma simulation using a two-dimensional strip medium is developed. The experimental results for, X-band rectangular waveguide and cavity filled with the strip simulated plasma are in good agreement witi the theoretical results and thus validate the simulation.

A new type of applicator with a convergent lens for localized microwave hyperthermia is developed. A lens applicator of direct contact type was designed to conduct actual and progressive experiments with phantoms of simulated fat and muscle tissues heated at 2450 MHz. The experimental results showed that the heating power penetration depth increased 40 percent with this applicator as compared to a simple rectangular waveguide applicator with the same size aperture that had generally been used for microwave hyperthermia. Our applicator had a concave-shaped aperture and was designed to contact well with the heating medium whose shape was cylindrical like a human body.

This short paper describes a proposed structure of a broad-band electrooptical modulator and an application of existing microstrip analysis programs to determine dimensions of the structure for a broad-band property. Results of numerical computations indicate that it is possible to obtain a broad-band modulator by using LiNbO/sub 3/ or LiTaO/sub 3/.

The WR15 thermal noise standard that is used as the national reference standard of noise power in the frequency range from 56 to 64 GHz is described in this short paper. The source forms a basis for both the noise-power comparison service and noise-figure service offered by the National Bureau of Standards in this frequency range.

This short paper describes a practical design and performance of 60-90-GHz broad-band mixers. Conversion loss was less than 11 dB in the 60-90-GHz region, and the conversion-loss deviation could be less than about 1 dB throughout the 30-GHz band with fixed circuit parameters. In this design, a new construction technique, using a wave absorber in place of a filter in the IF circuit, was employed.

The dispersion characteristics of the dominant and higher order modes in unilateral finlines on uniaxially anisotropic substrates have been obtained. The solution has been obtained by applying the equivalent transmission-line concept in the spectral domain and by using Galerkin's method. Numerical results for the propagation constant as a function of the slot-width ratio and frequency are presented.

Design curves for --3-dB branchline couplers that include compensation for the junction discontinuities are presented. The curves are obtained by including an accurate model of a stripline T-junction in an optimization program.

An analytical approximate method to determine the admittance of a general coaxial-waveguide junction is presented. The accuracy of the method is verified experimentally for the case of rectangular waveguide.

An exact solution of the capacitance matrix of circular rods located inside a grounded rectangle is presented. The capacitances were determined by solving the integral equation for the charge densities on the conductors using the Green function. The results are compared to E. G. Cristal's [1] data. Examples of the computing capacitance matrix for some unsymmetrical configurations are given.

A four-diode X-band Gunn diode combiner is described, and the performance characteristics are presented for combining efficiency, tuning range, pushing fire, frequency drift, external Q, and FM noise.

Noise parameters of an isolator and those of a receiver with an isolator at the input are reviewed. Some comments on recently published results are offered.

From a consideration of the properties near the edge of a flat finite-thickness strip and an elliptic cross-section strip, it is shown that the divergence that arises in the perturbation method near a sharp edge can be handled by halting the loss calculation at a definite distance just short of the strip edge. This distance can be expressed in terms of the radius of curvature at the tip for a rounded edge, and in terms of the strip thickness for a flat edge.

This short paper describes a novel method for temperature compensation of TE/sub 011/-mode circular-waveguide cavities. Implementation and experimental results on a single cavity are presented.

A simple, quick, and accurate method employing a magic-T interferometer for the measurement of electric susceptibility in gases is presented in this short paper. The electric susceptibility of five substances in a gaseous state has been measured satisfactorily as a function of pressure at room temperature with the help of this setup.

This paper provides additional dispersion data on slotlines not available in the literature to date. In particular, data are presented on wide slots etched on an electrically thin substrate of low-dielectric constant. The range of parameters covered in this paper are 0.006

This paper investigates the repeatability of measurements of the reflection coefficient Gamma of highly reflecting devices with changes in the RF connector joint. The changes in the connector joint are due to disconnecting and reconnecting the connector pair. It is shown that many of the measurement discrepancies observed in practice can be explained with a simple connector model. The paper shows that the sensitivity of measuring RF connector changes can be increased by using highly reflecting loads. The changes in Gamma due to changes in resistance or reactance can be four times greater for highly reflecting devices (|Gamma| /spl ap/ 1)than for nonreflecting devices (|Gamma| /spl ap/ 0). Experiments on two devices with 14-mm connectors are described in order to compare them with theory. The basic principles described in this paper should be beneficial to connector designers who need to observe small changes in connector parameters and to the work of calibration standards designers, where small connector imperfections are a major part of their measurement uncertainty.

This paper addresses semiconductor isolators of the field displacement effect type. The semiconductor is modelized by its surface impedance tensor. This description allows an extension of the well-known spectral domain method to the analysis of the semiconductor isolators. Different configurations are studied and numerical results are given. The finline isolator with InSb is shown to be the best choice-indeed, insertion loss is less than 3 dB/cm and isolation is greater than 18 dB/cm. Experimental results supporting these calculations will be published in a following paper.

The Q factor of an open-circuited resonator is influenced by dielectric, conductor, and radiation losses. This short paper discusses these losses and shows that insight into the radiation loss can be obtained by an extension to the analysis given by Lewirt. This shows that the radiation loss is a maximum for the dominant mode and that provided the permittivity is not less than 9.0 the radiation losses are at a minimum for the second mode. It is suggested that these results may be applied to the design of filters based on dielectric resonators. The application of the results to stripline resonators in which the dielectric extends past the termination of the upper conducting strip is more difficult, and it is suggested that experimental work is required to investigate postulated improvements. Finally, some of the radiation patterns of the open-circuited dielectric resonators, obtained in this paper, show interesting directional properties which may be applied to the design of antenna systems.

The cutoff frequency of the first higher order mode in a rectangular stripline is determined by two disparate techniques and compared to published results. Results from a novel experiment verify the cutoff frequency predictions. Furthermore, a nomenclature scheme for uniquely identifying rectangular stripline modes is offered.

This paper introduces a novel compact ultra-lightweight multiband RF energy harvester fabricated on a paper substrate. The proposed rectenna is designed to operate in all recently released LTE bands (range 0.79-0.96 GHz; 1.71-2.17 GHz; and 2.5-2.69 GHz). High compactness and ease of integration between antenna and rectifier are achieved by using a topology of nested annular slots. The proposed rectifier features an RF-to-dc conversion efficiency in the range of 5%-16% for an available input power of -20 dBm in all bands of interest, which increases up to 11%-30% at -15 dBm. The rectenna has been finally tested both in laboratory and in realistic scenarios featuring a superior performance to other state-of-the-art RF harvesters on flexible substrates.

This paper describes a concept for an efficient design of finline tapers that is especially useful in cases when certain quantities have heen prescribed with respect to reflection loss and bandwidth. Since abrupt discontinuities are neglected, the analysis is applicable to smooth finline tapers only. Various contour functions are investigated for the taper optimization. Experimental results for optimized tapers confirm the design theory.

We present in this paper, the electromagnetic parameters of free and shielded dielectric spherical resonators for their utilization in the millimeter-wave frequency band.