Wireless communications technology using microwaves has been making our daily lives very convenient. Smartphones are the most successful example. These were made possible by the development of various microwave devices, such as compact-sized filters and high-efficiency power amplifiers. We are studying metamaterials that can be used to make devices more compact and functional. We are also researching wireless power-transfer technology as a future microwave application. Our research activities are aimed at making future lives more comfortable by developing microwave communication devices.