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The Forefront of Space Science

Transmitting Information about the Universe via a Small Circuit Space Communications by the Cutting-Edge Radio-wave Engineering Technology
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A small antenna is required in radio-wave communication engineering, as well as the integrated circuit above. As MMIC has a thin structure, a planar antenna suitable for it is frequently used. Recently, a prototype transceiver with antenna was fabricated, that uses an Active Integrated Antenna (AIA) combining these devices. Since the design of such a multi-functional electronic circuit with antenna is complex, however, we need a computer-aided design (CAD) tool for the antenna/circuit design. In this way, we are also advancing R&D of a design tool in addition to design methodology. Figure 3 shows a prototype of a compact antenna-equipped transmitter AIA, which was manufactured with the design tool and a 40W-class, 32-element AIA array using the transmitter AIA. We successfully made it smaller and lighter, while maintaining multi-functionality and high power. Our final target is the world’s smallest transceiver with antenna at a size of tens millimeter square.

In order to build an ultra-high-speed wireless communication energy network system, we need an electronic phase control and an integrated array antenna using semiconductor element, or AIPAA. An “array antennaEis one that is made of many small regularly aligned antennas and functions in the same way as large parabola antenna shown in Fig. 1. An AIPAA is one that merges an AIA with an Active Phased Array Antenna (APAA). Since we can steer its antenna beam electronically, high-speed beam control becomes possible compared to the mechanical-drive type antenna. Accordingly, it is possible to communicate with and transmit energy to many communication points and fast-moving objects.

One unique aspect to our research is that it enables simultaneous transmission of information/communication and energy/power using a single radio-wave frequency. To demonstrate this function, we conducted an experiment to transmit electrical power and information to a robot or a rover used on the lunar surface and/or in a disaster area. Figure 4 is a snapshot of the experiment. The power transmitter is an AIA array with a total output of 120W. A wheel-driven rover positioned about 3m away was equipped with a detector array with an antenna (or rectenna), which converts the propagated wireless electric power to direct current. By installing a simple tracking function onto the power transmitter, we succeeded in wireless power transmission to the rover that was moving forward/back and left/right. MMIC is literally a “little giantEbecause this small power transmitter drives a large system. We are also planning to perform an experiment to communicate with a high-speed moving object while transmitting electric power to it.


Figure 4
Figure 4. Wireless energy transmission experiment to the rover (conducted in cooperation with the Institute for Unmanned Space Experiment Free Flyer, the Research Institute for Sustainable Humanosphere of Kyoto University, et al.)

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