Microwave Circuits Based on Negative Refractive Index Material Structures

The paper presents the fundamentals of composite right/left-handed (CRLH)transmission lines and materials,and proposes an accurate circuit model of these structures for the design of practical applications.Three novel applications of CRLH meta-structures,developed at UCLA,are demonstrated:an arbitrary coupling-level backward-wave coupler,a zero th order resonator and a distributed planar negative lens

A waveguide type power divider/combiner of double-ladder multiple-port structure

We propose a waveguide type microwave power divider/combiner of double ladder multiport structure which is advantageous for its very low insertion loss and high power capability. Analysis based on equivalent circuits give the design formula for perfect power dividing/combining. Numerical analysis gives optimal design parameters for broadband characteristics both of the divider and of the combiner. Analyses of power flows in the divider structure and isolation characteristic are given. Operation characteristics of divider-combiner system and the effect of phase deviation in combiner input signals on the combining efficiency are also discussed. Experiments showed good performances in accordance with the theory: the -0.5 dB relative bandwidths of four-, eight-, and twelve-way deciders were as large as 0.5, 0.38, and 0.38 respectively. For four- and eight-way divider-combiner systems, relative bandwidths were 0.22 and 0.13, respectively both with insertion loss of less than 0.1 d

A Wideband Microwave Power Divider/Combiner with Multiple-Port Double-Ladder Structure

We propose a new microwave power divider/combiner with multiple-port doubleladder structure for use in high power solid-state power amplifiers. Numerical and experimental analysis were carried out at X-band, and the results of the divider/combiner indicated low insertion loss and wide band characteristics in good accordance with the theory

Zero Poynting vector E∥H Beltrami field cylindrical cavity resonators

In this paper, we present novel cylindrical cavity resonators accommodating spatially and temporally zero Poynting vector Beltrami standing waves with the parallel electric and magnetic fields (E∥H). We introduce the special boundary conditions, i.e., longitudinal electromagnetic conductor (LEMC) on which zero longitudinal electromagnetic components are enforced and circumferential electromagnetic conductor (CEMC) on which zero circumference electromagnetic components are enforced in an axisymmetric waveguide system, and show that the zero Poynting vector E∥H Beltrami standing wave is generated as a superposition of dual degenerated axisymmetric TM and TE standing waves in a cylindrical resonator using the LEMC and CEMC boundary conditions. We present physical implementation methods of the LEMC and CEMC boundary conditions composed of the circumferentially arranged corrugations and the concentrically aligned cylindrical thin fins, respectively. In addition, we numerically demonstrate the Beltrami standing field generation and reveal its peculiar electromagnetic properties: the spatially and temporally E∥H with zero Poynting vector distribution, identical electric and magnetic energy density distributions, and zero local reactive energy flow

Quarter-wavelength E‖H Beltrami cavity resonators

In this paper, we present the design and implementation methods of quarter-wavelength resonators accommodating Beltrami standing waves with parallel electric and magnetic (E‖H) fields. The resonator is bounded by the quarter-wavelength longitudinal electromagnetic conductor (LEMC), the circumferential electromagnetic conductor (CMEC), and the radial electromagnetic conductor (REMC). The LEMC, CEMC, and REMC boundaries are artificially implemented by the circumferentially aligned corrugation, concentrically aligned circular fins, and axisymmetrically aligned radial fins, respectively. The coupling control methods by introducing slots in the CEMC and REMC with the external TM01 and TE01 circular waveguides are presented. We design the quarter-wavelength resonators with the implemented LEMC, CEMC, and REMC boundaries with controlled external couplings and numerically demonstrate their E‖H properties, which confirms the validity of the proposed design method

Traveling-wave microwave power divider composed of reflectionless dividing units

We propose a new waveguide type traveling-wave microwave power divider that is adequate for high power applications. The divider is composed of multiple stages of reflectionless dividing units, each having two output ports. Design formulas for reflectionless equal-power dividing are first derived. Structural parameters for wideband design of two- to six-stage dividers are then obtained by means of numerical analyses based on an equivalent circuit. Comparison of experiments at X-band shows good qualitative agreement with the analyses. Typical measured bandwidth for relative divided powers deviation of less than ±0.5 dB was 2.7 GHz, and that for -20 dB return loss was more than 3.2 GHz for the four-stage (eight-way) divider. The divider presented here has excellent features; the bandwidth for equal-power dividing decreases very little and the bandwidth for low return loss increases with increasing number of the dividing stages. It also has advantages of low insertion loss and flexibility over the number of the dividing stage

Microwave analog of Stern-Gerlach effects using nonuniform chiral metamaterials

This study observes microwave beam splitting dependent on circular polarizations through nonuniform chiral metamaterials. Nonuniform chiral metamaterials with a gradation in refractive index are constructed using chiral meta-atoms that exhibit optical activities at microwave frequencies. Microwave scattering far-field patterns by the nonuniform chiral metamaterials demonstrate a deflection of microwaves, which transmit in a direction perpendicular to the refractive index gradient. Furthermore, circularly polarized microwaves with opposite “spins of light” go their separate ways in the nonuniform chiral metamaterials. This phenomenon is an optical analog of the Stern-Gerlach effects for electrons

Smart Agriculture IoT Education Course in enPiT-everi (Education Network for Practical Information Technologies - Evolving and Empowering Regional Industries)

In Japan, expectations for the utilization of IT such as AI (Artificial Intelligence) and IoT (Internet of Things) are becoming greater and greater to address the shortage of working population due to the declining birthrate and aging population, and the depopulation of rural areas. There is a serious shortage of IT human resources, especially in rural areas, and I believe that IT human resource development is an urgent task to promote the super-smart society, Society 5.0, which is being promoted by the government. Thus, in order to promote business efficiency and productivity improvement, the utilization of IT in companies will become even more important[1]. Then, five universities, mainly in Kyushu and Chugoku regions, have been selected by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) for the enPiT-Pro project, and will collaborate to provide systematic and practical IT education programs to working people from local companies, with the aim of fostering advanced IT human resources. In this paper, we report on a class of the enPIT-everi program, the Agricultural IoT Education course.The 2021 International Conference on Artificial Life and Robotics (ICAROB 2021), January 21-24, 2021, Higashi-Hiroshima (オンライン開催に変更

Videofluoroscopy-guided balloon dilatation for treatment of severe pharyngeal dysphagia

Balloon dilatation is a widely accepted technique in the management of esophageal and other types of gastrointestinal strictures, but it is rarely used for the treatment of pharyngeal dysphagia. Therefore, the aim of our prospective study was to evaluate the use of videofluoroscopy-guided balloon dilatation (VGBD) for the treatment of severe pharyngeal dysphagia. The study included 32 stroke patients who had been diagnosed with oral and/or pharyngeal dysphagia. All patients underwent dilatation of the esophageal inlet using a balloon catheter under videofluoroscopic guidance during one or more sessions. Following esophageal dilatation, manual feeding was provided twice weekly. VGBD was effective in 10 out of 32 patients; however, the remaining 22 patients were unable to attempt oral food consumption because aspiration was not completely resolved on videofluoroscopy. According to this case series, VGBD may provide treatment for patients with severe pharyngeal dysphagia, who have not consumed food orally for a long period of tim