Shigeji Nogi

Efficiency and harmonics generation in microwave to DC conversion circuits of half-wave and full-wave rectifier types

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. we try to design the mw-Class RF-DC conversion circuit using half-and full-wave rectification. The measured conversion efficiencies is 59.3 % and 65.3 % athalf- and full-wave type, respectively. And the full-wave type has lower 2nd harmonic reflection coefficient.

The design of mW-class compact size rectenna using sharp directional antenna

This paper proposes the compact size rectenna using the open ended diamond antenna which is radiation pattern of sharp. This antenna which is fabricated at the planer has same dimension as the patch antenna. In addition, this antennas half beamwidth is more narrow than the patch antenna. To realize the compact size rectenna, the dimension of the rectification circuit is smaller than the antenna. So the rectification circuit is constructed of the chip device has the 59.5% of conversion efficiency and the dimension of this circuit has 10mm × 10mm at 5.8GHz. The rectenna array which is composed of 2 elements is fabricated, and confirm operating. As a result, the output voltage is 117mV at 0.6m, and 69mV at 1.0m.

Efficient antenna miniaturization technique by cut off of chromosome-length in genetic algorithm

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.

An efficient LE-FDTD method for the analysis of the active integrated circuit and antenna mounted non-linear devices

The trend of microwave circuits has been toward highly integrated systems. Most design tools for designing microwave circuits mounted the linear or the nonlinear devices adopt the fundamental circuit theory using the S matrix on the frequency domain. The harmonic balance method is also used to correspond to the nonlinear circuit. Therefore, the effect of the electromagnetic field, for example, a mutual coupling between sub-circuits through the space is almost disregarded. To calculate these circuits included its surrounding electromagnetic field, the finite difference time domain method combined with the equivalent circuit simulation had been presented as the lumped element FDTD (LE-FDTD) method. In general, even if an analytical target is a linear circuit, the FDTD method requires very long analytical time. In this paper, we propose an efficient LE-FDTD method to reduce the analytical time. We investigate its efficiency to compare with the conventional LE-FDTD method or measurements, consequently, it is confirmed that the proposal method requires only at analytical time of 1/10 compared with the conventional method. We also show that the proposal method is able to analyze characteristics of the active integrated antenna (AIA) which are practicably impossible to analyze by using the conventional method.

Acoustic lens using sonic crystal for energy-transmission application

We design and characterize a two-dimensional sonic crystal (SC) to manipulate the propagation of acoustic waves by numerical simulation based on the finite-difference time-domain (FDTD) method and by ultrasonic measurement. Two types of SC for an acoustic lens effect are studied. One is a homogeneous periodic structure exhibiting negative refraction, and the other has a hetero-structure. Negative refraction behavior in the simulation is good agreement with the experiment in the frequency range around 1.2MHz. We also observe a lens effect for far-field wave in the hetero-structured SC. These results indicate that a novel energy-transmission/harvesting device can be designed using SCs.

A novel extended FDTD method for the analysis of the active integrated circuit and antenna mounted non- linear devices

The trend of microwave circuits has been toward highly integrated systems. Most design tools for circuits are based on the fundamental circuit theory using the S-matrix combined with the harmonic-balance method. Consequently, the electromagnetic effect is ignored or approximated at best. Therefore, the extended finite-difference time-domain (FDTD) method combined with the equivalent circuit simulation had been presented. However, it takes very long times to analyze any circuits. In this paper, we propose a novel extended FDTD method to reduce calculation resources. We investigate its efficiency to compare with the conventional extended FDTD method or measurements, consequently, it is confirmed that the proposal method is required calculation resources less than 10% compared with the conventional method. We also show that the proposal method is able to analyze characteristics of the active integrated antenna(AIA) which are practicably impossible to analyze by using the conventional method.

Hyper NRD guide oscillator with Gunn diodes mounted in the dielectric strip

Hyper NRD guide oscillators mounted with a single and multiple Gunn diodes have been investigated. The operating mode of the hyper NRD guide can be lower order by optimizing the structure of the guide. The Gunn diodes were arranged in the dielectric strip of the guide. In experiments at X-band, the oscillation frequencies could be varied by a movable shorting plane for the single diode case and an almost perfect power combining was obtained for the double diode case.

Bent patch antenna for polarization diversity antenna

For the next generation wireless data transmission system, a high-speed and the high-capacity system is required. For such a system, an adaptive antenna array, the polarization diversity technique or the sector antenna will be used. This paper presents the characteristics of a bent patch antenna on a rooftop shaped ground plane which obtains the same beam width in the E- and H-plane for an antenna element composing a sector polarization diversity antenna.