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The article jumps between multiple experiments (some laser some microwave), but if you're interested in the the recent 10 GHz microwave experiment the authors w

by mNovak 4y ago

The article jumps between multiple experiments (some laser some microwave), but if you're interested in the the recent 10 GHz microwave experiment the authors were a part of (and which was on the HN frontpage recently) -- 1.6kW delivered over 1km -- the details were published in [1]. Very relevant datapoint: the transmitter source was 100kW, fed into a 5.4m dish. The receiver array was 2x2m. The end to end efficiency, which this article pointedly avoids, is on the order of 1-2%, over 1km. [1] https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9662403 https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=966...

exmadscientist 4y ago
The laser system shown in the top photo is similar in efficiency. And, trust me, the engineers are very aware of it. It's also frighteningly expensive, with a large number of exotic things. (Source: I work with the guy who designed a big chunk of the receiver circuitry, among other things.)
walrus01 4y ago
100kW turning into 1.6kW is just gross, go buy ten 380W STC rated 72 cell monocrystalline Si photovoltaic panels, a really good charge controller and 10kWh of good quality battery storage instead.
teleforce 4y ago
Forget about about wireless power transfer efficiency, the normal wireless power amplifier (PA) efficiency for cellular wireless applications (or any wireless systems) is probably just around 10 - 20%. This inefficiency is terrible not only because the use of modern linear wireless power amplifier but also due to other factors. For starter, there is a significant distance of wired connection between PA and the antenna that resides on the tower (yes wireless PA still need wires to function). This distance create delay effect on the signal and suddenly this unaccounted impedance mismatched (because delay is phase), and changing phase results in totally different impedance on the Smith Chart even for exactly the same signal amplitude. Secondly, wideband signal impedance matching (tens to few hundreds of MHz that are now the norm rather the exception) is impossible to do in analog domain as practiced by the industry and putting anything and everything not working as the mythical "memory effect". Can't wait until the climate change people get into the matter and realize that about half of the wireless systems power budget is due to the inefficiency of the freaking PA and all hell breaks loose.

by mNovak 4y ago

exmadscientist 4y ago

The laser system shown in the top photo is similar in efficiency. And, trust me, the engineers are very aware of it. It's also frighteningly expensive, with a large number of exotic things. (Source: I work with the guy who designed a big chunk of the receiver circuitry, among other things.)

walrus01 4y ago

100kW turning into 1.6kW is just gross, go buy ten 380W STC rated 72 cell monocrystalline Si photovoltaic panels, a really good charge controller and 10kWh of good quality battery storage instead.

teleforce 4y ago

Forget about about wireless power transfer efficiency, the normal wireless power amplifier (PA) efficiency for cellular wireless applications (or any wireless systems) is probably just around 10 - 20%. This inefficiency is terrible not only because the use of modern linear wireless power amplifier but also due to other factors. For starter, there is a significant distance of wired connection between PA and the antenna that resides on the tower (yes wireless PA still need wires to function). This distance create delay effect on the signal and suddenly this unaccounted impedance mismatched (because delay is phase), and changing phase results in totally different impedance on the Smith Chart even for exactly the same signal amplitude. Secondly, wideband signal impedance matching (tens to few hundreds of MHz that are now the norm rather the exception) is impossible to do in analog domain as practiced by the industry and putting anything and everything not working as the mythical "memory effect". Can't wait until the climate change people get into the matter and realize that about half of the wireless systems power budget is due to the inefficiency of the freaking PA and all hell breaks loose.