Value chain · CLM-1138
In plain terms
A 1994 Japanese test sent five kilowatts from a three-metre dish to an eleven-square-metre rectenna 42 metres away and caught about three-quarters of the beam; what came out as DC is not stated.
The claim as recorded
In 1994 Kyoto University, Kobe University and Kansai Electric built a ground-to-ground link in which "5 kW of magnetron-generated microwave energy at 2.45 GHz was fed to a 3-m parabolic antenna" and transmitted to a 3.2 x 3.54 m "rectenna array (2,304 elements) located 42 m away. The beam efficiency was about 74%".
Evidence behind this: T2-review restatement of Shinohara and Matsumoto 1998 [81], not held; "beam efficiency" is not defined in the review.
Scope and limits
NO DC OUTPUT AND NO RF-TO-DC FIGURE; the 74 per cent is collection, not conversion, and its definition is assumed. Primary not held.
What it assumes
"Beam efficiency" is the fraction of transmitted power falling on the rectenna, the beam collection efficiency of the review's Table 3 (PDF 6, table text is an image; render reading).
Where it comes from
PDF 8 / printed 236: "In 1994, Kyoto University, Kobe University, and Kansai Electric Corporation jointly developed the Ground-to-Ground Microwave Power Transmission (MPT) system [81]" (normalised); "Here, 5 kW of magnetron-generated microwave energy at 2.45 GHz was fed to a 3-m parabolic antenna" (normalised); "The parabola then transmitted the power to a 3.2 m" (normalised) x 3.54 m. PDF 9 / printed 237: "rectenna array (2,304 elements) located 42 m away. The beam efficiency was about 74%" (R1). Recomputed: 3.2 x 3.54 = 11.3 m2; 11.3 m2 / 2,304 = 49 cm2 per element, a 7.0 cm (0.57 lambda) pitch at 2.45 GHz; 5 kW x 0.74 = 3.7 kW onto the array.
Basis: kW RF; GHz; m; m2; element count; per cent beam efficiency
Cite this
energyaperture.com/c/clm-1138
CLM-1138, Energy Aperture, as of 2021-01.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-269
- CLM-1134The field's own 2021 scorecard: the two records were both set in 1975 (30-35 kW across about a mile, and 54 per cent DC in to DC out at...CLM-1135Modern power beaming, by the review's dating, starts in 1963 with a radar tube, a horn five and a half metres away and a single vacuum-tube...CLM-1136The famous 1964 helicopter hung fifteen metres up for ten hours on beamed microwaves, rectified by four and a half thousand diodes; then...CLM-1137In 1987 a Canadian model plane with a four-and-a-half-metre wingspan flew for twenty minutes at 150 metres on nothing but a microwave beam...CLM-1139A 1995 Japanese blimp carrying a three-by-three-metre rectenna flew for four minutes at fifty metres on ten kilowatts of microwaves from...CLM-1141In 2002 a metre-wide rectenna moved along an exhibition floor in Houston, tracked by a self-steering 5.8 GHz beam, converting 82 per cent...CLM-1142In 2015 Mitsubishi Heavy sent ten kilowatts of microwaves half a kilometre along a Kobe pier to an eight-by-eight-metre receiver, enough to...CLM-1143Japan's flagship 2015 ground test: a solid-state GaN array of about one and a half square metres sent 1.8 kilowatts 55 metres and 335 watts...More on the source page.