Value chain · CLM-1452
In plain terms
By our rough arithmetic, the beam of the UK's full-size reference design would carry about a million times more power than the power-beaming tests checked here that have a stated power: a Chinese ground test in 2022 that sent about 2 kilowatts across 55 metres, and two figures of about a kilowatt reported in the press in 2026, one for a Japanese satellite that is planned and not shown to have flown (a Japanese space agency researcher's 2025 lecture shows the same plan) and one for another Chinese ground test. At the design's peak beam strength, such a test could cover less than ten square metres, against tens of square kilometres for the design, so none of these tests comes close to the full-size beam that the worry about disturbing the upper atmosphere concerns. No output power is stated in the documents held here for a third test, a US Air Force flight test that nothing held shows has launched.
The claim as recorded
For the UK reference design (a 6.7 km by 13 km elliptical rectenna of 68.4 km2, about 2 GW delivered to the grid, and a maximum beam intensity of around 240 W/m2 at the rectenna centre), the microwave beam would carry between about 2 GW (the grid output, which comes after conversion losses) and about 3.4 GW (the electricity the UK Phase 1 study's satellites generate on board, before any transmission loss), by our arithmetic. Of the demonstrations checked here (Xidian University's ground tests and the OHISAMA and Arachne flight projects), the one power a held source reports as achieved, 2,081 W transmitted over 55 m in Xidian's 2022 ground test, is about six orders of magnitude lower (the design's beam would be 9.6e5 to 1.6e6 times larger). For the three checked for 2025-2026 (CLM-1451), the press reported in 2026 about 1 kW for Japan's planned OHISAMA satellite, which a JAXA researcher's October 2025 lecture also plots as the plan, and 1,180 W for another Xidian ground test, which give the same order (1.7e6 to 3.4e6 times), while the AFRL documents held state no output power for the US Air Force Research Laboratory's Arachne. At the design's centre maximum, 2,081 W could cover at most about 9 m2, against 68.4 km2, so on total power and beam area none of the tests checked here with a stated power comes close to the full-scale beam that the ionospheric self-focusing question concerns, at any altitude.
Evidence behind this: T0-calculation: the stated values (the bounds, the ratios and the area bound) are arithmetic performed here on held figures, and CALC-001 carries the footprint. The inputs the result rests on are the UK design figures, T4 (SRC-023, SRC-024), and the Xidian test, T2 (SRC-113); the Arachne null is T3 (SRC-198). The OHISAMA plan in a JAXA lecture (SRC-764) and the two press figures (CLM-1451) are T5 and corroborate only: without them the result is unchanged.
Scope and limits
The knowledge base's estimate from one design's published figures, not a figure any cited source states; read it as a scale comparison, not a precise figure. It compares total power and beam area, not local intensity: by the same arithmetic, taking the 87.3 per cent beam collection efficiency as the share of the transmitted power that reached the rectenna, the 2022 Xidian test put a mean of about 86 W/m2 on its 5.2 m rectenna (2,081 W x 0.873 / 21.2 m2; SRC-113 PDF p5, p6, p9 and p10), about a third of the design's centre maximum, over 55 m on the ground, so a small test can reach an intensity of the same order over about 20 square metres. The same UK summary gives 245 W/m2 received on PDF p15 (CLM-0003); using it in place of 240 W/m2 changes no result. The press figures come from two reports that are not held (CLM-1451), so they corroborate the scale and are not the basis of the result. The OHISAMA figure is a plan, and nothing held shows that OHISAMA or Arachne has flown (CLM-1451). Arachne's output power is stated in none of the AFRL documents held, so it should not be assumed to be kilowatt-scale. Three demonstrations for 2025-2026 were checked; no search has established the full set, so this is not a statement about every test. Older ground tests reached more power: Brown's 1977 report gives a total DC output of 30 kW over 1.6 km for the 1975 JPL test at Goldstone (CLM-1097, CLM-1134), at 82 per cent conversion. So about 37 kW of microwave power reached its rectenna, about five orders of magnitude below the design's beam (2e9 / 3.66e4 = 5.5e4). The power sent was higher, and the test report does not state it; a 1975 press account that only about 12 per cent of the transmitter's power was intercepted (CLM-1306) would put it near 0.3 MW, about four orders below the design's beam. At 240 W/m2, 37 kW could cover about 150 m2 and 0.3 MW about 1,300 m2, against 6.84e7 m2 for the design (CALC-141).
What it assumes
A total-power and beam-area comparison, not a beam-propagation or local-intensity calculation. The 3.4 GW is the on-board generation the UK Phase 1 study (2020) gives for its satellites, applied to the reference design of its 2021 summary, which delivers the same 2 GW to the grid and itself gives over 3 GW generated on the satellite (SRC-023 PDF p14). The demonstration figures are transmitted or radiated power at the source; the design's bounds hold for its beam both as sent and as received, so the ratios compare like with like. Whether the reported 1,180 W was sent or received is not settled (CLM-1451); either reading leaves the order unchanged.
Where it comes from
This is the project's own working, shown in full:
Our order-of-magnitude arithmetic, with units carried; CALC-141 sets out the working in full, with the source and tier of each input. Lower bound: the design delivers about 2 GW into the grid (SRC-023 PDF p15; also PDF p14), after conversion losses, so the beam carries more than 2 GW. Upper bound: the UK Phase 1 study's satellites generate around 3.4 GW of electricity on board and produce around 2 GW to the grid (SRC-024 PDF p10, as CLM-0001), so the beam, which comes after conversion to microwaves, carries less than 3.4 GW. Footprint: pi x 3.35 km x 6.5 km = 68.4 km2 = 6.84e7 m2 (CALC-001), from the 6.7 km by 13 km rectenna (SRC-023 PDF p15 and p17). Centre maximum: around 240 W/m2 (SRC-023 PDF p17). Xidian: SRC-113 PDF p10 (printed p99), Table 3, in paraphrase: Xi'an (2022), 55 m, 2081 W transmitted, beam collection efficiency 87.3 per cent, DC-DC efficiency 15.05 per cent; the same page dates the test to June 2022 (as CLM-0520). Ratios: 2e9 / 2,081 = 9.61e5 and 3.4e9 / 2,081 = 1.63e6 (log10 5.98 to 6.21). Reported figures (CLM-1451; neither press report is held): 2e9 / 1,180 = 1.69e6 and 3.4e9 / 1,000 = 3.40e6 (log10 6.23 to 6.53). SRC-764 PDF p20 (JAXA lecture slides, 2025-10-28): a log-scale chart of power against distance plots the OHISAMA project as a plan at about 1 kW of radiated power. SRC-198: neither AFRL fact sheet states an output power for Arachne (as CLM-1451). Area bound: a beam carrying a power P cannot hold an intensity I over more than P / I of area, so at 240 W/m2, 2,081 / 240 = 8.7 m2, 1,180 / 240 = 4.9 m2 and 1,000 / 240 = 4.2 m2, against 6.84e7 m2 (6.84e7 / 8.7 = 7.9e6). The looser upper bound that applies the centre maximum over the whole rectenna, 240 x 6.84e7 = 1.64e10 W, about 16 GW, sits above the 3.4 GW generated on board, so it is not used.
Basis: watts, W/m2 and m2, order-of-magnitude only
Related records
- Answers question
- QST-002 not published in this release
- Supersedes
- CLM-0556 not published in this release
Cite this
energyaperture.com/c/clm-1452
CLM-1452, Energy Aperture, as of 2026-10.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-023
- CLM-0002The summary report says the beam is strongest at the middle of the receiving site, at about 240 watts per square metre, and argues that...CLM-0003The report gives the receiving site as an ellipse roughly 7 km by 13 km, and states a beam strength of 245 watts per square metre.CLM-0005A second figure of 29 watts per square metre appears in the same report, but it measures electricity produced per unit of land, not beam...CLM-0006None of the five main studies mentions the international radio-frequency exposure limits, or any safety standard, or a restricted area...CLM-1436A UK study says that one space solar power system would typically deliver about 2 gigawatts to the grid, and it compares this with the...CLM-1441Documents give the size of the CASSIOPeiA satellite design as anything from 1 to 2 km across. For a full-size version delivering 2...CLM-1442A 2021 study for the UK government shows one design, CASSIOPeiA, as about 1.7 km across and 2,000 tonnes, sending 2 gigawatts to the grid...CLM-1443The 2021 study for the UK government says the leading designs need no new materials, but that building them at a sensible cost needs two...More on the source page.
- Also from SRC-024
- CLM-0001The UK government's own feasibility study describes a system beaming microwaves at about 230 watts per square metre onto the ground.CLM-0006None of the five main studies mentions the international radio-frequency exposure limits, or any safety standard, or a restricted area...CLM-0007The UK study's own experts expect the beam to interfere with electronics in its path, and think it unlikely to have much effect outside the...CLM-0235A 2020 UK study rated the UK behind other countries in many technologies for a solar power satellite. For three key ones, large mirrors...CLM-0714The 2021 UK study by Frazer-Nash Consultancy proposed that the satellite fly itself to its final orbit, using its own solar panels to run...CLM-1436A UK study says that one space solar power system would typically deliver about 2 gigawatts to the grid, and it compares this with the...CLM-1441Documents give the size of the CASSIOPeiA satellite design as anything from 1 to 2 km across. For a full-size version delivering 2...CLM-1472The designer of the UK's CASSIOPeiA satellite says it has no moving parts and is built from many small identical pieces, so when pieces...More on the source page.