Goh Fukuda

The S-band GaN-based high power amplifier and rectenna for space energy transfer applications

Gallium nitride (GaN) is one of the most significant elements to achieve effective use of energy in space not only for communications but also for power transmissions. This is because that GaN has the features such as high efficiency, high breakdown voltage, and harsh environment robustness and it is expected to fit the requirements for space use. Using GaN, the flexibilities for future missions in terms of size, weight, and power consumption etc. will be improved significantly. In this research, as a high power and high efficiency device, use of a GaN device was tried in a high power FET amplifier and in a single shunt rectifier diode. Circuits operating at S-band were designed, produced, and evaluated experimentally with the DC-RF conversion of 63.3% in the power amplifier and with the RF-DC one of 35.5% in the rectifier diode. A wireless power transmission (WPT) experiment using HPA and rectenna was conducted. As a result, it was confirmed that a battery could be charged up to 133.7 Ws in about 1500 s (25 min) by the DC power generated by the rectifier, where the EIRP was 57.2 dBm, the rectifier input power was 32.5 dBm, and the distance between a power transmitter and the receiver was 1.2 m.

Wide power range operable 3-stage S-band microwave rectifier with automatic selector based on input power level

This research proposes a wide power range operable 3-stage microwave rectifier for microwave wireless power transfer systems. The proposed rectifier is fabricated and measured at S-band. The proposed rectifier system consists of three rectifiers which has different operational range. Also, the system automatically selects the appropriate rectifier based on input power level. The rectifiers utilize HEMT instead of conventional schottky diodes for future integration into MMIC of wireless communication system. We have confirmed the system has over 30dB range of input power with efficiency of over 25%. The concept of the system is effective for future microwave wireless power transfer system.

The C-band MPT rectifierusing a HEMT without bonding-wire connection for a space health monitoring system

This paper demonstrates fundamental evaluation results of a C-band rectifier using GaAs high-electron mobility transistor (HEMT) for microwave power transfer (MPT) inside of future reusable rockets. Rectifiers which utilize HEMT MMICs with hot-via interconnection structure are feasible solution to integrate with conventional wireless communication MMICs or sensor tags for low cost, light weight, and small components for space health monitoring system. Simulation of large signal S-parameters, measurement of rectification efficiency are conducted as a fundamental evaluation. Maximum rectification efficiency of 51.3 % at 5.1 GHz while the load resistance is 350 Ω is obtained from the measurement.

Experimental Demonstration of Coexistence of Microwave Wireless Communication and Power Transfer Technologies for Battery-Free Sensor Network Systems

This paper describes experimental demonstrations of a wireless power transfer system equipped with a microwave band communication function. Battery charging using the system is described to evaluate the possibility of the coexistence of both wireless power transfer and communication functions in the C-band. A battery-free wireless sensor network system is demonstrated, and a high-power rectifier for the system is also designed and evaluated in the S-band. We have confirmed that microwave wireless power transfer can coexist with communication function.

GaN HEMT based rectifier for spacecraft health monitoring system using microwave wireless power transfer

High power operable and miniaturized rectifier is one of the most important issues for spacecraft health monitoring system. This is because the flexibility of location, number, and power consumption regarding sensor tag is indispensable for reliable health monitoring. Previous single rectifiers focusing on schottky diode are unsuitable since operating at high power and considering integrated MMIC sensor tags are quite difficult. This research proposes GaN HEMT based rectifier for these issues due to its excellent properties such as structurally-preferable for MMIC, and suitable for high power operation. Design and evaluation of GaN HEMT based rectifier and an experiment using the rectifier and a thermal sensor with microwave wireless power transfer has been conducted. The proposed rectifier can be operated with 47 dBm input RF signal.

7/8-GHz band 2×2 circular patch active integrated array antenna for solar sail applications

This paper describes a basic characteristic of a 7/8-GHz band circular stacked patch active integrated array antenna (AIAA) unit for solar sail embedding application. The proposed AIAA unit mainly consists of a 2×2 stacked circular patch array, two low noise amplifiers (LNAs) and two power amplifiers (PAs). The array has stacked structure for dual band operation. Moreover, the stacked patch array has orthogonal feed structure for better isolation characteristics between transmitter and receiver ports. Radiation patterns and S-parameters are evaluated by 3-D electromagnetic field simulation and measurement.

Cryogenic GaAs high gain and low-noise amplifier module for radio astronomy

A small size low noise amplifier (LNA) module operating at 10GHz capable of a cryogenic cooling for radio astronomy is presented. The LNA has been fabricated using a 0.15μm gate length GaAs-based pseudomorphic high electron mobility transistor (pHEMT) monolithic microwave integrated circuit (MMIC) technology. This MMIC amplifier is a single chip consisting of three-stages was assembled in a module with a size of 38mm × 20mm. Using cryogenic equipments, the module was cooled down to a cryogenic temperature of 113 K, where the LNA achieved a high gain of 32.6dB with a noise temperature of 71K (noise figure of 0.96 dB) at 10 GHz. The result obtained prove that the LNA presented is a suitable candidate for radio astronomy.