Value chain · CLM-1134
In plain terms
The 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 short range), and in the 45 years since, nobody listed has reported more than about a kilowatt of DC delivered, or more than about a fifth of the wall-plug power coming out as DC.
The claim as recorded
The NRL group's 2021 review catalogues microwave power beaming demonstrations from 1963 to 2020 in a chart (Fig. 2, receiver output power against distance, [7], [8], [13]-[28]) and a historical narrative, and states two records: "W. Brown's 1975 Goldstone demonstration [22] remains the highest-power result to date, delivering 35 kW at 1.55 km", and "His other experiment of the same year [13] demonstrated the highest DC-to-DC power beaming efficiency result to date, delivering 495 W at 54% total system efficiency", the latter broken down as "68.87" +/- 1.0 per cent DC-to-RF and "78.67" +/- 1.1 per cent RF-to-DC; between them and 2020 the review lists Raytheon 1963 (100 W, 15 per cent, 5.5 m), the 1964 helicopter (10 hr at 15.2 m), SHARP 1987 (150 W at 150 m), the 1994 Kyoto ground link (5 kW, 42 m, about 74 per cent beam efficiency), ETHER 1995 (10 kW to an airship at 50 m), KERI (2.3 kW to 1.02 kW, 44 per cent, 50 m), the 2002 World Space Congress rectenna (82 per cent RF-to-DC at 5.8 GHz), Maui-Hawaii 2008 (148 km, beam collection under 0.001 per cent), MHI 2015 (10 kW sent over 500 m), METI 2015 (1.8 kW to about 335 W over 55 m), the 2019 drone (about 60 W at 10 m), Wuhan 2019-2020 (10 GHz at 100 m, 19.5 per cent; 35 GHz about 1 kW at 300 m, 9.89 per cent), Chengdu 2014 and 2020 (14.2 and 18.5 per cent at 4.5 and 10 m) and PRAM-FX 2020 (8.4 W RF in orbit, the maximum to date and preliminary); every microwave demonstration after 1975 it lists with a DC figure delivered under 1.1 kW of DC, and none states a wall-plug-to-DC efficiency above the Chinese 19.5 per cent (KERI's 44 per cent is from transmitter power, CLM-1140).
Evidence behind this: T2-peer-reviewed invited review by the NRL group; the demonstration figures are the review's restatements of primaries it cites, three of them private communications, none held here.
Scope and limits
GOLDSTONE IS STATED THREE WAYS ACROSS THE GROUP'S TWO PAPERS - 35 kW at 1.55 km (PDF 2, from a 2003 lecture [22]) and 30 kW at 1.54 km at 2.388 GHz (PDF 7, from the 1975 JPL and Raytheon reports [71], [72]) in this review, and 34 kW at 1.55 km at 2.39 GHz in the 2022 paper (SRC-270 PDF 11 / printed 38, CLM-1129); the register's CLM-1097 carries 30 kW over 1.6 km from Brown's 1977 report; recorded, not repaired, primaries not held. No table exists; the chart's values are crop readings on log axes. Three demonstrations rest on private communications ([86], [110], [113]). The review is by the group that then set the 1.6 kW X-band result (SRC-270), and its "records" framing is theirs.
What it assumes
The review's figures are its sources' figures; the chart's reference numbers identify the demonstrations as the reference list on PDF 25-27 names them.
Where it comes from
PDF 2 / printed 230: "Fig. 2 provides an illustration of selected power beaming demonstrations to date [7], [8], [13]" (normalised); "W. Brown's 1975 Goldstone demonstration [22] remains the highest-power result to date, delivering 35 kW at 1.55 km" (normalised); "His other experiment of the same year [13] demonstrated the highest DC-to-DC power beaming efficiency result to date, delivering 495 W at 54% total system efficiency" (read at the render; the text layer drops the line-end hyphen of DC-to-DC); Fig. 2 (crop read): microwave points [13] about 500 W at 1.7 m, [14] 10 W at 6 m, [15] 13 W at 11 m, [16] 90 W at 10 m, [17] 200 W at 18 m, [18] 340 W at 55 m, [19] 500 W at 60 m, [20] 150 W at 150 m, [21] 80 W at 1,500 m, [22] 35,000 W at 1,550 m; optical [7], [8], [23]-[28] between 1.5 W and 1 kW out to 1 km. PDF 7 / printed 235: "The breakdown of the 54.18" +/- "0.94% overall efficiency is 68.87" +/- "1.0% for the DC-to-RF conversion and 78.67" +/- "1.1% for the RF-to-DC conversion [69], [70]" (raw; R1; raw; normalised); "The operating frequency was 2.446 GHz, and the rectenna array's output DC power level was 495 W" (normalised); "to this day stands as the highest power beaming end-to-end efficiency" (R1); "microwave energy at 2.388 GHz was sent over a 1.54-km distance of the Mojave Desert to an awaiting 26.8-m2 rectenna array" (normalised); "The rectenna array, designed by W. Brown at Raytheon, outputted 30 kW of DC power [71], [72]" (normalised). The per-demonstration figures and their pages are in CLM-1135 to CLM-1146, each span probed at its page. PDF 19 / printed 247 (Section VI-A) on PRAM-FX: "The maximum RF power achieved to date is 8.4 W" with an efficiency of about 8 per cent, stated as preliminary. Recomputed: 0.6887 x 0.7867 = 0.5418; 30 kW / 26.8 m2 = 1.12 kW/m2.
Basis: year; GHz; m; W or kW sent and received; per cent as each source defines it
Cite this
energyaperture.com/c/clm-1134
CLM-1134, 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-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-1138A 1994 Japanese test sent five kilowatts from a three-metre dish to an eleven-square-metre rectenna 42 metres away and caught about...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.