New Insights into Radio Wave Energy Harvesting across Wide Geographical Ranges Harnessing Medium‐Wave Radio Broadcasting Infrastructure

Abstract

This study conducts field experiments using the radio‐wave energy harvester of hoop‐shaped radio (HOOPRA) to elucidate the relationship between the distance from the medium‐wave (MW) radio broadcasting station and the resonance voltage as an index of harvested energy. Accordingly, a numerical equation that describes the relationship between the distance and voltage with a strong correlation coefficient of R2 > 0.996 is derived. HOOPRA can illuminate ultrabright white, green, and red light‐emitting diodes (LEDs) within a 5 km radius of the public Nihon Hoso Kyokai JOFG (927 kHz, 5 kW) in Fukui, thereby serving as a valuable energy source for the 150 000 residents (60 000 households) in this region. The public JOAK (594 kHz, 300 kW) and JOAB (693 kHz, 500 kW) are examined for similar field experiments in the Kanto region. The results reveal that HOOPRA can illuminate ultrabright white, green, and red LEDs within a radius of 30 km and ultrabright red LEDs within a radius of 50 km from JOAB, which will benefit the 23 million residents (1.1 million households) in this region. Overall, the results provide novel insights for developing ultrawide‐area wireless energy‐transfer technology by leveraging the global infrastructure of MW radio broadcasting.