Shigeo Kawasaki

In this paper, we evaluate system feasibility of the wireless sensor network system powerd by the microwave power transmission (MPT) technology inside a prototype spacecraft named RVT. 2.4-GHz band and 5.8-GHz band is used for the wireless communication and the MPT. Two experiments, power balance evaluation and multi-sensor operation evaluation was carried out. Desirable energy balance between income and consumption in a sensor node was achieved. Moreover, as the multi-sensor evaluation, mutli-sensor capabilities were also achieved.

In this paper, we propose a novel wireless sensor network system which is compatible with microwave power transmission (MPT) system. For the coexistence between the wireless communication and the MPT, frequency division operation as well as time division operation is deveioped. 920 MHz band and 5.8 GHz band is used for the wireless communication and the MPT. The firmware was developed for the time division operation. As a fundamental evaluation, packet error rate, received signal strength indicatior, and rectifier output DC power of less than 1 %, -35.0dBm, and 145 mW is measured under the condition of distance between antennas and output RF power of 80cm and 42.0 dBm.

Retrodirective Arrays have a characteristic to transmit a received signal back toward the interrogator without prior knowledge. In this paper, mixer type retrodirective HIC (Hybrid Integrated Circuit) which has better performance related to conversion gain is presented. And for the compact design, we also present about diplexer and planar cross-over structure. This retrodirective arrays can be used for satellite communications which of 7.1GHz for uplink and 8.4GHz for downlink. The details of trial manufacture are shown below.

A typical reusable vehicle test (RVT) rocket is wired with a vast array of sensors. While converting these sensors from wired implementations to wireless simplifies the cost and lowers aircraft weight, it introduces design challenges such as power requirements and wireless transmission conflict control. This paper introduces a communication algorithm operating in the 2.4GHz and 920Mhz bands, that allows for multiple nodes to achieve both conflict free wireless communication, and wireless power transfer.

We are developing Dielectric Micro Calorimeter (DMC) that could achieve E/ΔE〜1000 with megapixel in principle in the future. In order to measure X-ray energy, DMC uses dielectric pixels with temperature-dependent permittivity as thermometer that form LC resonators in GHz band. The signals can be read out easily with frequency multiplexing. Up to now, experiment by our group have shown that SrTiO_3 has temperature dependent permittivity below 2 K and that LC resonators using SrTiO_3 has Q>1000 at 360 mK. X-ray irradiation test with pixel DMC is under preparation. Development status and future plan of the DMC are in this paper.