Value chain · CLM-1129
In plain terms
The authors say the 1975 record still stands at twenty times their power, that the custom diodes which set it no longer exist, and that going bigger needs three things nobody has yet built for this job: many small combined transmitters instead of one big tube, a tougher diode, and the electronics to feed a rectenna into a grid.
The claim as recorded
NRL 2022 places itself as "the first demonstration exceeding 1 km in range and 1 kW in received power at a frequency >2.5 GHz", with the prior record "W. Brown's 2.39-GHz demonstration of 34 kW received at 1.55 km" (cited to a 2003 Acta Astronautica lecture), and states what scaling needs: spatially combined sources, because "unitary microwave power sources in the >10 kW range are typically pulsed. Continuous sources at >10 kW are rare, expensive, and difficult to maintain" and AESA-style combining of "numerous smaller microwave sources" is "A more realistic alternative"; higher-power-handling diodes, because Brown's demonstration (its reference 41) used custom S-band Schottky diodes for high power handling and high efficiency, a technology the paper says no longer exists, and so, with GaN nano-Schottky results from Teledyne showing "major improvements in breakdown voltage" over the MA4E1317 that "If productized" could set records "at frequencies >10 GHz"; and power management, since "considerable work is needed to integrate rectennas into general purpose microgrids" including "the need to present an optimal resistive load at the rectenna output".
Evidence behind this: T2-peer-reviewed authors' positioning against prior art and their recommendations; the prior-art figure is theirs from a 2003 secondary source, the recommendations are judgement, and the GaN diode result is a communication from K. Shinohara at Teledyne Scientific, not a publication.
Scope and limits
THE PRIOR-ART FIGURE IS 34 kW AT 1.55 km AT 2.39 GHz FROM A 2003 LECTURE; THE REGISTER'S GOLDSTONE DATUM FROM BROWN'S 1977 REPORT (CLM-1097) IS 30 kW OVER 1.6 km AT 2.45 GHz - two statements of one demonstration from two sources, both recorded, neither chosen here. The GaN diode "results" are a communication from K. Shinohara at Teledyne Scientific with one figure (Fig. 28), not a published measurement; the "no longer exists" statement about Brown's diodes is the authors' and is consistent with CLM-1097's custom-Raytheon-diode history but not independently checked. Recommendations are judgement, not results, and are for terrestrial beaming; the paper's only space remark is that space-to-earth WPT is the field's eventual motivation (PDF 1).
What it assumes
"Brown's" demonstration at 2.39 GHz is the 1975 JPL Goldstone RXCV test (SRC-270 does not name Goldstone; the register's Goldstone rows do).
Where it comes from
PDF 2 / printed 29: the paper describes itself as the first demonstration exceeding 1 km in range and 1 kW in received power at a frequency above 2.5 GHz (R1). PDF 11 / printed 38: the highest recorded result, the paper says, is W. Brown's 2.39 GHz demonstration of 34 kW received at 1.55 km (normalised); the authors state that their 9.7 and 10.5 GHz demonstrations exceed all other prior microwave results in transmission distance (normalised); Fig. 27 (render) plots received power against distance with [41] at about 34 kW near 1.5 km and this work's peak near 1.6 kW at 1 km. PDF 12 / printed 39: unitary microwave power sources in the >10 kW range are typically pulsed, the paper says, and continuous sources at >10 kW are rare, expensive and difficult to maintain (R1); the more realistic alternative it offers is to spatially combine the power from numerous smaller microwave sources, as in active electronically scanned arrays (AESAs) (normalised); Brown's demonstration (its reference 41) used custom S-band Schottky diodes for high power handling and high efficiency, a technology the paper says no longer exists, and so (R2); recent GaN nano-Schottky diode results from Teledyne Scientific Company, its reference [52] (R2), show "major improvements in breakdown voltage" and, "If productized", could in the authors' words lead to records in rectenna output power at frequencies >10 GHz (normalised); considerable work is needed, the paper says, to integrate rectennas into general purpose microgrids (normalised); including the need to present an optimal resistive load at the rectenna output (normalised). PDF 14: [41] is R. M. Dickinson's first Bill Brown lecture on the state of the art of wireless power transmission technology, Acta Astronautica vol. 53 no. 4 pp. 561-570, 2003 (R1); [52] is a communication from K. Shinohara, Teledyne Scientific, Thousand Oaks, CA, USA (R1). Recomputed: 34 / 1.6 = 21 times the power; 1.55 km against 1.046 km.
Basis: kW; km; GHz; V breakdown
Cite this
energyaperture.com/c/clm-1129
CLM-1129, Energy Aperture, as of 2022-01.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-270
- CLM-1122About twenty thousand postage-stamp-sized antenna-plus-diode cells, each with an off-the-shelf microwave diode, wired into tiles, then...CLM-1123A five-metre dish and a 100 kW radar-type pulsed tube a kilometre away, bounced partly off the ground on purpose to get more power onto the...CLM-1124One panel the size of a sheet of paper turned about seven-tenths of the microwave power landing on it into DC, and did best at about three...CLM-1125Four square metres of receiver turned 73 per cent of the microwave power arriving at it into 1.65 kW of DC, measured a kilometre from the...CLM-1126They deliberately fried each of the four panels with ever-stronger pulses. A bare panel gave up at 672 watts out; clamping its voltage with...CLM-1127As flown, under two per cent of the microwave power fed to the dish came out of the receiver as electricity, because the beam had to be...CLM-1128A second test used a big radar dish in Massachusetts to light up a strip of LEDs on a tower over a kilometre away, with about a kilowatt...CLM-1130A quick way to size a ground-to-ground beam: at the distance where the dish stops focusing, the cone holding half the power is about twice...More on the source page.