Minoru Sanagi

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 /spl plusmn/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 stages. >

The design of mw-class RF-DC conversion circuit using the full-wave rectification

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.

Efficient design approach of mW-class RF-DC conversion rectenna circuits by FDTD analysis

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.

The Fundamental Design Approach of The RF-DC Conversion Circuit for Optimizing Its Characteristics

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 simulators 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.

Design of RF-DC conversion circuit composed of chip devices

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.

Development of high efficiency rectification circuit for mW-class rectenna

For applications of the microwave power transmission technology, it is necessary to realize high efficiency rectennas or rectification circuits. Especially, RF-IDs or ubiquitous power sources demand high RF-DC conversion efficiency for below mW microwave inputs. However, almost all past rectennas or rectification circuits were designed for over 100mW rectifying and the RF-DC conversion efficiencies were less than 20% at 1mW microwave input. In this paper, we investigate rectification circuits for developing mW-class rectennas. Discussing diode mount structures in order to increase the efficiency below 10mW microwave input, we succeeded in developing a rectification circuit whose efficiency is 62.8% for a 10mW microwave input. We also find that approximately 30% of the input microwave power is consumed by the diode in the rectification circuit.

Axially symmetric Fabry-Perot power combiner with active devices mounted on both the mirrors

We investigate an axially symmetrical Fabry-Perot power combiner with many more active devices operating in axially symmetric TEM/sub 01n/ mode, which has an excellent feature of uniform device-field coupling required for high power combining efficiency. By numerical calculation using the boundary element method, it was shown that high combining efficiency can be obtained when a circular groove of larger radius is installed on either the plane mirror or the concave mirror. In experiments at X-band, almost perfect power combining of twenty or twenty-four Gunn diode oscillators mounted on both of the mirrors was achieved.

An optical waveguide bend with enhanced curvature and the optimization of its structure

Abstract We have investigated a waveguide bend having enhanced curvature with reduced loss. The waveguide width is made wider toward the inner side of the bend. The numerical analysis, by means of the beam propagation method, showed that the loss of the proposed bend is lower than that of an abrupt bend or a smooth bend of constant curvature. For a typical waveguide, we have optimized the structure of the bend and achieved one order of loss reduction in comparison with an abrupt bend of the same angle.

Transmission line coupled active microstrip antennas for phased arrays

An effective transmission line coupling network for spatial power combining and beam scanning purposes is reported. The harmful effect of radiative coupling is eliminated using a modified version of this network for peripheral elements. A technique to control the inter-element phase differences of planar arrays was also developed. Experiments on 1/spl times/4 and 2/spl times/2 oscillator arrays using the proposed coupling network agrees well with the theory.

Traveling-wave power divider with coplanar waveguide probes inserted into rectangular waveguide

A new traveling-wave power divider with coplanar waveguide probes is investigated. The divider is constructed by connecting successively the dividing units which consist of coplanar waveguide probe-pairs inserted into a rectangular waveguide and the thin narrow section. From experiments on fourand six-way dividers, wideband characteristics comparable to a divider with coaxial probes is demonstrated.