Parallel line feeder (PLF) consisting of a two-wire transmission line operating in the MHz band has been proposed as a wide-coverage short-distance wireless charging. In the MHz band, a PLF of several meters suffers from standing wave effect, resulting in fluctuation in power transfer efficiency accordingly to the receiver's position. This paper studies a modified version of the system, where the PLF is divided into individually compensated segments to mitigate the standing wave effect. Modelling the PLF as a lossy transmission line, this paper theoretically shows that if the segments' lengths are properly determined, it is able to improve and stabilize the efficiency for all positions. Experimental results at 27.12 MHz confirm the theoretical analysis and show that a fairly high efficiency of 70% can be achieved.

A planar electromagnetic field stirrer with periodically arranged metal patterns and diode switches is proposed for improving uneven heating of a heated object placed in a microwave oven. The reflection phase of the proposed stirrer changes by switching the states of diodes mounted on the stirrer and the electromagnetic field in the microwave oven is stirred. The temperature distribution of a heated object located in a microwave oven was simulated and measured using the stirrer in order to evaluate the improving effect of the uneven heating. As the result, the heated parts of the objects were changed with the diode states and the improving effect of the uneven heating was experimentally indicated.

This paper presents a novel circuit for impedance matching to a load moving along a transmission line. This system is called FERMAT: Far-End Reactor MATching. The FERMAT consists of a power transmission line and a variable reactor at its far-end. The proposed system moves standing-wave antinodes to the position of the vehicle in motion. Therefore, the moving vehicle can be fed well at any position on the line. As a theoretical result, we derive adjustable matching conditions in FERMAT. We verified that the experimental result well agrees with the theory.

A plane coupler has been developed for a two-dimensional (2D) wireless power transmission. This coupler can construct a continuous wireless power transmission system for mobile devices due to its small, light characteristics. This coupler has two elements connected with a 2D waveguide sheet, and coupling capacitances between the elements and the sheet decrease the coupler size by reducing their resonance frequencies. A propagation loss of -10.0 dB is obtained using the small 0.025-λ2 coupler. Continuous operation of the mobile device is demonstrated by applying wireless power transmission to the 2D waveguide sheet with the small plane coupler.

In this paper, a contactless measurement technique of passive intermodulation (PIM) using a coaxial tube excited with standing waves is proposed. The principle of the proposed method is described using a two-port network model with the lumped resistances representing the losses of a specimen and test equipment. To show its validity, a test using nickel wires producing high PIM is carried out, and its PIM-dependency on DUT-position in the coaxial tube is simulated using the FDTD method. The simulated result shows a good agreement to the experiment. Through the examination, it is found that the power consumption by the PIM source in a specimen is essential in PIM production, and sensitive PIM detection does not require good matching condition. Finally, the relation between PIM-source size and generated PIM level is also examined. The result shows that at least 18 dB-PIM reduction is obtained by PIM source size in a half-wavelength conductive wire.

The data dispersion of the measurement of electromagnetic disturbance above 1 GHz is mainly affected by site imperfections (expressed by the site voltage standing wave ratio (SVSWR)). To confirm the relationship between site imperfections and the measured field strength, we measured the SVSWR and the field strength radiated from the equipment under test (EUT) by changing the area covered by the RF absorber on the metal ground plane. From the results, we found that the data dispersion of measured field strength can be estimated from the measured SVSWR, and therefore, we can determine the measurement uncertainty of the measured field strength at the test site.

In the research field of microwave radar, a range finding method based on standing wave is known to be effective for measuring short distances. In this paper, we focus our attention on audible sound and fundamentally examine the distance estimation method in which acoustical standing wave is used.

The electric fields inside and outside a car must be carefully determined when designing a wireless communication system to be employed in the car. This paper introduces an effective simulation method and a precise measurement method of electric field distributions in a cabin of a simplified scale car model. A 1/3 car model is employed for ease of measurement. The scaled frequency of 2859 MHz, 3 times 953 MHz, is employed. The use of a moment method simulator utilizing the multilevel fast multipole method allows calculations to be performed on a personal computer. In order to judge the accuracy of simulation results, convergence of simulation output in accordance with segment size (triangle edge length) changes is ensured. Simulation loads in the case of metallic body only and a metallic body with window glass are also shown. In the measurements, an optical electric field probe is employed so as to minimize the disturbances that would otherwise be caused by metallic feed cable; precise measurement results are obtained. Comparisons of measured and simulated results demonstrate very good agreement which confirms the accuracy of the calculated results. 3-dimensional electric field distributions in the car model are shown and 3-dimensional standing wave shapes are clarified. Moreover, calculated and measured radiation patterns of the car model are shown so the total electric field distributions around a car are clarified.

Various types of radars have been developed and used until now--such as Pulse, FM-CW, and Spread Spectrum. Additionally, we have proposed another type of radar which measures distances by using standing wave. We have named it as "Standing Wave Radar." It has a shorter minimum detectable range and higher accuracy compared to other types. However, the radar can not measure distances down to zero meters like other types of radars. Minimum detectable range of the standing wave radar depends on a usable frequency range. A wider frequency range is required if we need to measure shorter distances. Consequently, we propose a new method for measuring distances down to zero meters without expanding the frequency range. We use an analytic signal, which is a complex sinusoidal signal. The signal is obtained by observing the standing wave with multiple detectors. We calculate distances by Fourier transform of the analytic signal. Moreover, we verify the validity of our method by simulations based on numerical calculation. The results show that it is possible to measure distances down to zero meters. In our method, measurement errors are caused by deviations of position and gain of the detectors. They are around 10cm at the largest if the gain deviations are up to 1% and the position deviations are up to 6% of the spacing between the detectors. Prevalent radars still have a common defect that they can not measure distances from zero to several meters. We expect that the defect will be eliminated by putting our method into practical use.

In this study, the frequency and spatial properties of undesired electromagnetic radiation distribution around a simple printed circuit board (PCB) model, which only has the mismatching printed line (PL) and ground, are estimated. Finite difference time domain (FDTD) modeling is developed for the analysis space, which is 500 400 51 mm3 in size, around the PCB. As the driving clock pulse has a very wide frequency bandwidth, ranging from kHz to GHz, basic and precise investigation of the noise emission mechanism from the basic model is performed. The results of the magnetic field Hx on the PCB as determined by FDTD simulation, and those of the experiment, driven by a clock pulse, agree well. The results show that although this approach is basic and simple, it becomes clear that the frequency and spatial characteristics of the electric and magnetic field near the PCB are influenced by the wavelength of the frequency and appling the driving clock pulse, and the low-frequency component of the electromagnetic distribution around the PCB is larger than the high-frequency components. It is suggested that the low-frequency noise problem should be carefully considered.

A method for estimating complex permittivity of a material using a rectangular waveguide with a flange is presented by the finite difference time domain (FDTD) method. An advantage of the present method is that it is not necessary to vary the material structure in order to insert it into the waveguide. Therefore estimation errors related to the dimensions of the material are almost negligible. In this case, fluoridated rubber is chosen as the low-loss material. The comparison of the complex permittivity of the material determined by the present method with FDTD and the conventional waveguide method at 10 GHz is performed. It was confirmed that the present method is effective for estimating the complex permittivity under the condition that the length of the flange is about 50 mm (1.7λ) square.