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This paper proposes to transform microwaves for snow melting, which slightly leaking from the slotted waveguide, into electric power using a wireless power transmission technique for effective use. A combination of left-handed and right-handed waveguides is a method to melt snow evenly over a large area using microwaves. The left-handed waveguide, however, has large loss because of stubs. In order to evaluate the effect of the left-handed waveguide’s loss, this paper analyzed the wireless power transmission efficiency when the left-handed waveguide with a slot was set as the power transmission part, and a dipole array was placed above the left-handed waveguide as a power reception unit. The wireless power transfer efficiency was calculated using kQ product from S-parameters that were obtained by using the method of moments. The results clarified that the sum of the maximum efficiencies of the arrayed dipoles could be made larger than the maximum efficiency of one dipole.

In this research, a waveguide-type composite right/left-handed (CRLH)transmission line (TL)composed of metallic cylinder-pairs is applied to a leaky-wave antenna. The leaky-wave antenna operating in microwave region is fabricated and its radiation characteristics are measured. The measured results show that the fabricated antenna can steer a beam according to input frequency, and the beam-steering operation are achieved in the angular range from +60° to +120°.

A waveguide-type leaky wave antenna with periodical slots is proposed. The beam can be scanned at a single frequency by switching diodes connected to the slots. A combination of the slots is excited selectively so as to make a beam to a desired direction. By changing the combination the beam can be scanned discretely from 60 deg. to 120 deg. Measured radiation patterns agree with theoretical predictions. The diode loss is comparatively small.

A left-handed material with a simple structure is proposed. The metamaterial is composed of metal strips on both sides of periodic dielectric substrates. The metal strips have both an electric property and a magnetic property. By putting the strips alternately on both sides, a double negative region can be obtained. The dispersion relations and the transmission characteristics are confirmed experimentally. Moreover the propagation characteristics of modes in a composite right/left-handed (CRLH) material are shown.

Recently, various wireless applications have hugely become popular. Especially, mobile terminals such as mobile phones are actively developed. In developments of mobile terminals, miniaturization and frequency multiband of antennas are very important issues. However, there are no rational design strategy in small antenna designs. So, antenna developments depends on electromagnetic simulators or capability of engineer. And many cut-and-try processes are necessary for achieving desired characteristic. This makes many problems such as prolongation of developments. Then, now, automatic design techniques of antenna using genetic algorithm (GA) are paid attention. In this paper, the new design strategy for miniaturization of antennas is proposed by operation of chromosome-length in GA. Proposed design technique provides a minimum area necessary for keeping characteristics of a antenna. And, efficient miniaturization of a antenna and removing many undesirable conductors in a design ares are possible. Removing undesirable conductors provides lower-cost designing of antennas. The new design method can become rational design strategy for antennas miniaturization.

In this paper, a radio frequency to direct current (RF-DC) conversion circuit composed of chip devices is proposed. This circuit has high conversion efficiency as high as the previously proposed circuit, and the circuit size does not depend on the operating frequency.

A Rectifying Antenna (Rectenna) is one of the most important components for a wireless power transmission. It has been developed for many applications such as Space Solar Power System (SSPS), Radio Frequency IDentification (RF-ID), and electric vehicle etc. The Rectenna consisting of RF-DC conversion circuits and receiving antennas needs to be designed for high conversion efficiency to achieve efficient power transmission. In this paper, we investigated the RF-DC conversion circuits by the theoretical analysis. And, we propose the theoretical formula for calculating the output DC voltage in giving the input voltage. The result that is calculated by the formula agreed with the simulator's result, so, we confirmed the validity of the formula we derived. The theory and the formula we derived are useful in order to know the basic operation of the RF-DC conversion circuit, and to design the circuit efficiently.

A Rectifying Antenna (Rectenna) is one of the most important components for a wireless power transmission. It has been developed for many applications such as Space Solar Power System (SSPS), and Radio Frequency Identification (RFID) etc. The Rectenna consisting of RF-DC conversion circuits and receiving antennas needs to be designed for high conversion efficiency to achieve efficient power transmission. In this paper, we try to design the mw-Class RF-DC conversion circuit using full-wave rectification.

A rectenna is one of the most important components for a wireless power transmission. It has been developed for many applications such as Space Solar Power System (SSPS), and RFID etc. The rectenna consisting of RF-DC conversion circuits and receiving antennas needs to be designed for high conversion efficiency to achieve efficient power transmission. In this paper, the extended FDTD method is proposed as a method for calculating the RF-DC conversion circuit, and the availability of this method is confirmed. Furthermore, the output power from the circuit including the radiation power is investigated.

粗い管及び滑かな管内の乱流に就てその速度変化が同一の方則に従てゐることを見出し、これを基として粗滑両管内の速度分布の異る所以は單に両管内の最大速度の異れる点に存することを示し両管に共通なる速度分布の実驗式を求めた。且粗い管内の最大速度は滑かな管内の最大速度そのものと粗度に関する項とより成ることを見出し、これより平均速度、抵抗等を與へる式を求めた。実驗値としてはNikuradseの報告を取りこれと比較して上記の諸式が実驗値とよく一致することを確め、粗い管内の流れにおける粘性と粗度との影響をある程度明かにすることが出耒た。

亂流に関するPrandtlの變動の假説を用ひて滑かなる管内の混合距離、管内の速度、速度變化交換量等の間の理論的関係式(6)(7)(8)(9)を求め、Nikuradseの實驗値より混合距離を表はす實驗式(10)を見出し、これより管内の速度、速度變化、交換量等を表はす式(11)(13)(19)(19α)(20)を得た。これ等の諸式はレイノルド數が100×103以上なる場合には實驗値とよく一致する。尚上記の理論的関係式を用ひて管内の速度分布を與へるPrandtlの一般式(1).ポテンシャル式(2)及びKarmanの理論式(3)を調べこれ等の式より求めた速度變化、混合距離及び交換量の値が實驗値と甚しく相違する事を示した。

滑かなる管内の乱流に於てレーノルド数が100×103以上なる場合の速度分布その他に就ては既に本誌に述べた。更にこれを擴張してレーノルド数の小なる場合にも適用し得る速度分布式を求め、これより理論的に速度変化、混合距離、平均速度及び抵抗を與へる式を算出して実驗値と比較した。