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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.

The 38 papers in this special issue are expanded versions of papers presented at the 2012 International Microwave Symposium. held on June 17-22, 2012, in Montreal, QC, Canada.

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. >

This paper presents a supply modulated $X$ -band 12-W peak power transmitter that maintains an average efficiency greater than 50% for various shapes of amplitude-modulated pulses. The main power amplifier is a two-stage GaN-on-SiC MMIC with a peak efficiency of 65%, while the pulse envelope modulator is a 95% efficient hybrid 3-b power DAC implemented with GaN-on-Si transistor switches. Envelope shaping of a pulsed waveform results in improved spectral confinement of greater than 15 dB for the first sideband compared with constant-envelope pulses, with over 20 points improvement in total efficiency. The combination of supply modulation and digital predistortion is shown to result in high composite (total) efficiency of over 55%, with simultaneous high dynamic range and with flexible digitally programmable pulse shaping.

Most of the studies concerning microwave oscillators have so far been based on the Van der Pol oscillator model. However, this model is too simple to obtain good agreement between observation and theory. Our previous paper proposed a new mathematical model which describes the loading characteristics of oscillators more accurately than the Van der Pol model does. In this paper, we have investigated injection-locked microwave oscillators using the mathematical model to find out the relation between the loading and injection-locking characteristics.

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.

This short paper presents a design procedure for the widely used three-port waveguide circulator that has a partial height ferrite post in the junction region. Design formulas and curves are derived for two configurations of partial height circulators: one has a short circuit at one end of the ferrite post, while the other has dielectric spacers at both ends. The design method was used to build two circulators for operation at 38 GHz and 60 GHz, respectively. Excellent agreement between theory and experiment was obtained in predicting the center frequency and required matching structure of these devices.

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.

The fertility of microwave-irradiated fruit flies was investigated in an experiment conductedat 40 GHz and at a low power level to avoid thermal effects. In a series of six experiments with 82910 flies, the fertifity of irradiated flies and of their first and second filial generation was determined. No radiation effect was found. This result is contrary to previously pnblished data.

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/.

This short paper aims to recognize the correct decomposition for the total odd-mode capacitance of the coupled microstriplines and present an improved expression for the gap capacitances. The used procedure utilizes the results which were obtained earlier by the conformal mapping techniques.

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 electromagnetic boundary value problem of two waveguides coupled by an aperture or an aperture in a waveguide radiating into free space may be described by an integral equation. An analytical solution to this integral equation cannot be readily found due to the complexity of the kernel. However, extremely useful results may be obtained if the method of moments is employed to reduce the integral equation to a matrix equation which can be solved by known methods. In this short paper, series and shunt slots in a rectangular waveguide are analyzed using this technique.

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 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 proposes an application of the boundary-element method to two-dimensional electromagnetic field problems. By this method, calculations can be performed using far fewer nodes than by the finite-element method, and unbounded field problems are easily treated without special additional consideration. In addition, the results obtained have fairly good accuracy. In this paper, analyzing procedures of electromagnetic field problems by the boundary-element method, under special conditions, are proposed and several examples are investigated.

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.

In many practical planar circuitries, the circuit pattern can be divided into several segments which themselves have simpler shapes such as rectangles. The segmentation method proposed in this short paper is a method in which the characteristics of a planar circuit are computed by combining those of the segmented elements. It features a relatively short computer time required. The principle and computer algorithm are described. Finally, as an example, the application of the proposed method to the trial-and-error optimum design of a ladder-type 3-dB hybrid is described.

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.

In recent MIC techniques, double-sided MIC has been studied because its advantages in propagation characteristics are greater than that conventional MIC's. A coupled microstrip slotline is one of them. Its application to various circuit elements has often been discussed. But the coupled microstrip slotline is essentially three-dimensional structure, so the analysis demands a rigorous three-dimensional treatment. Also, the recent high-speed pulse technique demands analysis in the time domain. The present paper treats a directional coupler using the coupled microstrip slotline in three-dimensional space and time. The results of the directional coupler analysis is presented with the complicated time variation of the three-dimensional electromagnetic field. So, the mechanism of the directional coupling phenomena that is produced by the propagation characteristics of the even and odd modes is presented in the time domain, In particular, the instantaneous diagram of the Poynting vector details the energy flow in the transient process. For the analysis of the characteristics of the complex microwave device, these results present the utilities of the various field distributions that are obtained by the three-dimensional vector analysis in the time domain.

In this paper, we present a method for analyzing finline structures with finite metallization thickness. The method is based on a hybrid mode formulation but it by-passes the lengthy process of formulating the determinantal equation for the unknown propagation constant. Some numerical results are presented to show the effect of the metallization thickness for unilateral and bilateral finlines.

Workers engaged in the operation of RF industrial devices are exposed to electromagnetic radiation in the near-field zone that is characterized by high spatial and temporal gradients. The present paper is concerned with measurement methods and data analyses which allow the evaluation of the electromagnetic field exposure of tbe operator together with the SAR induced by near-field exposure accounting for the spatial and temporal variations. These methods are applied to the theoretical dosimetry of the occupational exposure to RF radiation emitted by 27.12-MHz plastic sealers. The data obtained are compared with those deducible through a conventional wide-band isotropic field meter.

This paper extends some results for waveguide irises to obtain accurate design formulas for the design of circular waveguide irises in coupled-resonator rectangular waveguide filters. Experimental results confirm the improved accuracy of the new design formulas. The new approach has been successfully applied to the design of a 12-GHz waveguide filter in WR90 waveguide for satellite transponder studies. Improved accuracy in the iris design enabled the filter to meet stringent group delay specifications.

This short paper describes the determination of couplings within a system of coupled cavities by measuring frequencies at which the phase of the input reflection coefficient is either 0/spl deg/ or 180/spl deg/. A high degree of accuracy may be achieved and corrections can be made for finite cavity Q.

In this paper, we deal with the microstrip gap that should be analyzed in three-dimensional space. The time variations of the electric field at each surface of the stripline having a finite metallization thickness are analyzed. Our method of analysis is based on both an equivalent circuit of Maxwell's equations and Bergeron's method. The former has advantages in the vector analysis by using all electromagnetic components. The latter has advantages in the time-domain analysis of the field. Therefore, our method can analyze field variations in three-dimensional space and time. We present the time variation of the instantaneous electric-field distributions below the strip, at the side of the strip, and at the gap end surface. These results show how the steady-state field distribution grows in the gap.

Research has shown that the determination of absorbed microwave energy as well as the control of environmental parameters are important in relating biological-effect data to, radiation protection. This short paper describes the development of an environmentally controlled waveguide irradiation facility for the exposure of small animals to 2450-MHz CW microwave energy. Integral dose rate is determined without perturbing the microwave field interacting with the irradiated animal.

The relocation of weather satellite facsimile downlinks from VHF into S-band has generated a requirement for reliable, low-cost microwave receiving equipment. This paper explores many of the design tradeoffs encountered in developing one such receiver system.

This short paper presents a general computer analysis of gradually tapered waveguide with arbitrarily shaped cross sectious. The technique combines coupled-mode theory with numerical methods for solving the uniform waveguide problem. The coupling coefficients are computed by using eigenvalues and eigenfunctions obtained numerically. The mode amplitudes are obtained either by numerical solution of a set of differential equations or from a closed-form solution. The applicability of this technique is illustrated by the analysis and measurement of two transitions. It is shown that theoretical prediction of coupled-mode amplitudes is reliable for gradual tapers where the flare angle is small. For large flare angles, more rigorous coupled-mode theory has to be employed.

The near field of uninsulated dipole antenna in a dissipative dielectric medium is important in microwave hyperthermia and geophysical applications. In this paper, the electric field near an insulated dipole has been calculated by the direct numerical evaluation of a surface integral over the insulation. The computed results are compared with those previously obtained by an approximate numerical calculation.

Radial-line stubs have been found to work better than low-impedance rectangular stubs when an accurate localization of a zero-point impedance is needed. In this paper, microstrip radial-line stubs are analyzed using a planar circuit technique and characterized for design purposes. Experiments performed on various structures are in excellent agreement with the theory and confirm the suitability of such a structure as an altenative to a conventional straight stub.