The generation and reduction reaction of magnesium plasma were studied using a cylindrical transverse magnetic-mode applicator in magnetic and electric field modes. By heating Mg powder using the magnetic field mode, plasma was generated with the evaporation of Mg and stably sustained. When the Mg plasma sample was introduced into the reaction zone and exposed to microwave and lamp heating, a reduction reaction of scandium oxide also occurred. The results of this study provide prospects for the development of a larger microwave refining system.

This paper theoretically presents that a terahertz (THz) oscillator using a resonant tunneling diode (RTD) and a rectangular cavity, which has previously been proposed, can radiate high output power by the impedance matching between RTD and load through metal-insulator-metal (MIM) capacitors. Based on an established equivalent-circuit model, an equation for output power has been deduced. By changing MIM capacitors, a matching point can be derived for various sizes of rectangular-cavity resonator. Simulation results show that high output power is possible by long cavity. For example, a high output power of 5 mW is expected at 1 THz.

In this paper, we applied cavity resonator wireless power transfer (CR WPT) to an enclosed space with scatterers and revealed that high transfer efficiency at line-of-sight (LOS) and non-line-of-sight (NLOS) position in the power transmitter can be achieved by this method. In addition, we propose a method for limiting the wireless power transfer space utilizing metal mesh and show its effectiveness by experiment. First, we confirm that the constructed experimental model is working as a cavity resonator by theoretical formula and electromagnetic field analysis. Next, we calculate the maximum power transfer efficiency using a model including a plurality of scatterers by installing a power receiver at LOS and NLOS positions in the power transmitter, and it was confirmed that transfer efficiency of 30% or more could be expected even at the NLOS position. Then, we measured the frequency characteristics of a model in which one surface of the outer wall was replaced with a metal mesh, and it was clarified that the characteristics hardly changed in the power transfer frequency band. Finally, we confirmed that simultaneous communication can be performed with driving of the battery-less sensor by CR WPT, and clarify effectiveness of the proposed method.

A 100 GHz grooved circular empty cavity is proposed for the low loss dielectric substrate measurements by the cut-off circular waveguide method in W band. The influence of the excitation holes for the coaxial cable with a small loop are revealed by an FEM based 3D electromagnetic simulator. And also, the diameter of the excitation hole is determined based on the calculated results and the manufacturing accuracy. Then, two kinds of four 100 GHz grooved circular empty cavities are fabricated. Comparative experiments of the cavities with the different excitation holes validate the simulated results. Moreover, the complex permittivity of a PTFE plate is measured using the fabricated four cavities by the cut-off circular waveguide method around 84 GHz. The measured results agree within measurement error about 0.5% for εr and 5% for tanδ. Also, these results accord with results measured by the Whispering-Gallery mode resonator method in 85–110 GHz band. It verifies that the proposed 100 GHz cavity for the cut-off waveguide method is useful for the complex permittivity measurement of low loss dielectric substrates in W band.

A design of the tunable superconducting power filter is described. The filter consists of superconducting microwave cavities with a mechanical tuning method. The electromagnetic simulations using niobium cavity suggested that there were conditions where the resonator with high-unloaded Q can realize a fractional center frequency change of more than 10% by using a Nb rod moving in the cavity. The simulations approximated the resonant frequency dependence of the rod moved by a cryogenic actuator in the tunable cavity experiment. In addition, the simulation of the power handling capability showed a feasibility of the value more than 50 dBW.

An ultra-deep polymer cavity structure exposed using deep X-ray lithography is used as a template for metal electroforming to produce a 24-GHz cavity resonator. The metal cavity is 1.8 mm deep and has impressive structure, including extremely vertical and smooth sidewalls, resulting in low conductor loss. The measured resonator has an unloaded quality factor of above 1800 at a resonant frequency of 23.89 GHz.

In this paper, we present a numerical analysis for resonant characteristics of the TM010 mode of a cylindrical cavity containing a dielectric rod and a conductive layer on its metal walls. This analysis uses the mode matching method for calculation. Error in complex permittivity of a loaded dielectric rod measured using a layered cavity is evaluated as a function of thickness and layered conductor conductivity. A thick layered cavity is necessary for precise measurement of material properties using the cavity resonator method at microwave and millimeter-wave frequencies.

In this paper, we calculated resonant frequency and unloaded Q-factor for the TM0i0 resonant mode excited in a cylindrical cavity composed of walls with finite conductivity and with a dielectric rod loaded coaxially along the central axis. Formulation for the calculation is made using the mode-matching method. Convergence of the calculation is checked. Values calculated by the present method for various combinations of dimensions, permittivity, and conductivity of the inner-components of cavity are compared with those calculated by a conventional method formulated using loss-less electromagnetic fields of cavity. Although the difference between the values calculated by those two methods is usually small, it is found that the difference increases as permittivity of dielectric rod increases and becomes about 10-6 in reciprocal of unloaded Q-factor of the loaded cavity in a presented case.

To measure temperature dependent complex permittivity of dielectric materials, a rectangular cavity resonator with a heating system has been developed. In the experiment, microwave power with the frequency of 2.45 GHz is applied to heat the dielectric material. In order to reduce the error of the complex permittivity of dielectric material obtained from the perturbation method, an electromagnetic (EM) field simulator is applied which uses the Transmission Line Modeling (TLM) method. The uniformity of the temperature is also discussed by the use of heat transfer equation which applies the results of TLM simulation. It is found from the results that the accurate temperature dependence of complex permittivity of the material can be obtained by the method presented here.

A stabilized local oscillator is one of the key components for any radar system, especially for a Doppler radar in detecting slowly moving targets. Based on hybrid semiconductor/superconductor circuitry, the HTS local oscillator produces stable, low noise performance superior to that achieved with conventional technology. The device combines a high Q HTS sapphire cavity resonator (f=5.6 GHz) with a C-band low noise GsAs HEMT amplifier. The phase noise of the oscillator, measured by a HP 3048A noise measurement system, is -134 dBc/Hz at 10 kHz offset at 77 K.

This paper describes a nondestructive measurement method for complex permittivity of dielectric plates at 2 GHz, using a cylindrical cavity resonator. The resonator is divided into two parts at the center. Two dielectric plates are symmetrically loaded around the center of the cavity. These plates have high permittivity of 45. A dielectric plate specimen is clamped with these halves. The values of relative permittivity ε and loss tangent tanδ of the specimen are obtained from the resonant frequency and unloaded Q-value of TE011 mode. Measured results of various materials are compared with those values obtained at 3 and 10 GHz by other cavity resonator method. An edge effect is taken into account by a reference method, using measurement data of a sapphire plate. The errors of the present method are smaller than 1% and 2-310-5 for ε and tanδ, respectively.

A radial line slot antenna (RLSA) is a high gain and high efficiency planar antenna proposed for DBS subscribers. Spirally arrayed slots are excited by a cylindrical wave with the rotational symmetry. In a small sized antenna where large slot coupling is adopted, aperture efficiency reduction due to rotational asymmetry associated with a spiral arrangement of the slots becomes notable. Authors proposed a RLSA with a concentric slot arrangement excited by a rotating mode in order to enhance the rotational symmetry. This is the first report of the normal operation of a rotating mode RLSA fed by a cavity resonator. The experiments confirm the basic operation of this novel antenna; the gain of 27.8dBi and the efficiency of 68% is measured at 11.85GHz for the RLSA with 0.24mφ.

This paper describes the method of applying the integral form of Maxwell's equations to the transmission-line network used in the spatial network method for the modeling of curved conductor surfaces. The techniques of dealing with the transmission-line network near cylindrical conductor surface are explained in detail. To compare exact solutions with computed values, a cylindrical cavity resonator is analysed. The resonant frequencies and unloaded Q's for the computed three modes are obtained with the error of about 1%. Moreover, applying this treatment to the waveguide with magnetron anodeshape cross section, a cutoff-constant is computed successfully. It is found that the treatment proposed in this paper can be used as the method for modeling of curved conductor surface in the spatial network method. It is also considered that this treatment can be extend to TLM method.

This paper describes a nondestructive measurement method for complex permittivity of dielectric material at pseudo microwave frequencies. The resonator used in this study has a cylindrical cavity filled with a sapphire material of a well known complex permittivity. The resonator is divided into two parts at the center. A dielectric substrate specimen is clamped with these halves. Relative permittivity εand loss tangent tan δ of the specimen are obtained at 3 GHz using the TE011 resonance mode. The accuracy of the present method is evaluated through the comparison of the measured values by the new method with those at around 10 GHz by the conventional empty cavity resonator method. The errors of measurements are smaller than 1% and 1105 for εand tan δ, respectively.