Whilst 60% is efficient and it's an excellent figure don't be fooled by the hype. I reckon what they've said in the the video is outrageous in that much of it i

Whilst 60% is efficient and it's an excellent figure don't be fooled by the hype. I reckon what they've said in the the video is outrageous in that much of it is deceptive and misleading in the extreme. Let's briefly look at some of the issues: 1. We need to carefully look at where that efficiency happens and then examine every place where loss of energy can occur, especially those that aren't stated. Let's take a brief look at some of the more obvious ones: 2. Conversion of energy into power suitable for generating microwaves at the transmitter. On earth, and assuming direct connection from the power grid, we need to consider losses in the power transformers and power supply or switching power supply, these days efficiency can be very high perhaps even 90% or more. As this equipment will be used primarily for military use, it would likely couple with diesel motor/generators suitable for use in the field, if so then I'd be surprised if the combo was more than 35% efficient at best (someone who knows up-to-date specs on these units correct me if necessary). If the unit is ultimately used in space then the conversion efficiency of its solar panels must be taken into account. As far as I'm aware no solar cell has ever reached 60% or over—even the best GaAs ones (from memory, this 60% figure would exceed theoretical 'quantum efficiency' figures). 3. Assuming no other loss at the power supply end (such as offline batteries, which are a distinct possibility in the field in military use) then we have to take the efficiency of microwave sources into account. I've not up-to-date figures on the latest 10GHz generators so I'd be guessing these figures, suffice to say that until recently generating microwaves was comparatively inefficient (unless magnetrons are used and they have messy and inconvenient HV power requirements). 4. Next comes the waveguides, antenna horn and focusing unit and the antenna (these, if optimized, could be quite efficient). 5. Now comes the path loss between transmitter and receiver. Exactly what that is remains to be seen. I've worked with microwaves and I can assure you that it is dead easy for the antennas be slightly off alignment and you receive almost no signal. For this scheme to work efficiently there would have to be some kind of efficient control system (servo/feedback, etc.) that keeps the TX and RX antennas in precise alignment. Moreover, at 10GHz a storm or a heavy rainfall downpour could kill the circuit altogether (I've actually seen this happen to the extent that only over a path of a half dozens or so miles that not only the fade margin, normally >30dB, on microwave links was exceeded but also the signals fell so low that the circuit was actually lost. Moreover, for reliability, two microwave links were run in parallel and both circuits failed for some 5 or 6 minutes until the rain cleared). 5a. Now the killer bit: as mentioned, commercial microwave links have huge fade margins to protect against variations in atmospherics and objects—planes etc., blocking the way. These links have what is known as AGC—Automatic Gain Control—to keep signals level. That cannot apply in power transmission; in practice, even a temporary path loss of 6 - 12dB (which could easily be expected) would essentially be catastrophic, that is effectively kill all received power at the receiver (they'd want to have pretty good battery backup and often in military operations that's not always possible, extra weight etc.)! 6. Now comes the horror bit (this could also apply to the generation of the microwaves at the transmission end). That is, the rectification of microwaves at the receiving end will generate considerable RF hash and noise. To be efficient, the diodes rectifying the incoming RF would have to have an f(t) of well in excess of that frequency and heaven help anyone operating a microwave receiver within many miles of the receiver (radio astronomers for instance). As the rectification diodes have to be near or on the antenna for efficiency, screening them to stop them radiating locally generated crap everywhere would be a near impossibility—remember your Fourier lessons, you're chopping sine waves up to get DC and that means harmonics—the more efficient the process the more noise generated! Any attempt to filter the hash and noise generated by the diodes would further reduce efficiency. This is the sort of scenario that spectrum managers and planners have nightmares about. Whilst this isn't quite the same, here's an example that illustrates what can happen. I had an Amateur Radio friend who used to do moonbounce on 432MHz and he'd often complain to me that various LED lights (i.e.: diodes) in his neighbors' possession would interfere with his incoming reception to the point where on occasions he'd have to abort the exercise. Now keep this in mind, he raised this matter with me over 10 years ago when LED lighting was far less common that it is today. Face the facts, much of this pronouncement is little more than spin. Likely the principle reason the video was made was to keep their funding masters happy. Little of it will fool the technical cognoscenti. Also keep in mind that all 'niceties' are off during military conflicts, interference to services other than to the military's own communications equipment would likely be irrelevant (as we saw in WWII, the military was the principal user of spectrum, what it wanted it got). As for a permanent space port 'broadcasting' power to earth the idea is ludicrous—that is, until thousands of questions about likely problems have been asked and that genuine engineering solutions for them are actually found. Seems to me their PR department has taken a leaf from the wordbook used by social media and politicians—that's the one that redefines the word 'fact'!