Coming up this week on Ham Talk Live!, Paul Jaffe, KJ4IKI from the U.S. Naval Research Laboratory will take your questions about his research on collecting solar energy in space and beaming it back to Earth. Tune in to hear how his ham radio experience is helping with energy research. Tune into Ham Talk Live! Thursday night at 9 pm EDT (Friday 0100Z) by going to hamtalklive.com. When the audio player indicates LIVE, just hit the play button! If you miss the show live, you can listen on demand anytime also at hamtalklive.com; or a podcast version is on nearly all podcast sites a few minutes after the live show is over. Some sites include Apple Podcasts, Stitcher, Google Play, SoundCloud, and iHeart Podcasts; and it's also available on YouTube. A replay is also broadcast on WTWW 5085 AM on Saturday nights at approximately 6:30 pm Eastern. Be sure to CALL in with your questions and comments by calling 859-982-7373 live during the call-in segment of the show. You can also tweet your questions before or during the show to @HamTalkLive.
Paul's work is an extension of his 2013 Ph.D. thesis on a 'stacked' modular solar cell to microwave converters, which I 'first' described, and dubbed an 'aperture engine', published in 1998. IOW the idea has a long provenance going back. Efficiencies are additionally afforded by fractal and transparent antennas in that mix, which resulted in patents (for example, 10,014,586, 10,483,649 ; filed 2008). Here's a diagram from that patent; claims include converting layers, RF transmission layers also: Of course, microwave transmission of power from space, as an idea, dates back almost 50 years , this is a more efficient method of doing so. The problem with microwave transmission is that you still need collecting area on the ground, and having a higher power density from a microwave transmission, than from straight solar cell collection in the same area, is not a viable tradeoff--YET . IOW you still need area on the ground--why not just let that area be solar cells? The meter favoring using that area for microwave power collection is, at present, a contrived one. The very issues that are problematic for 'solar'--nightime, clouds, etc, are still shared to some degree with a microwave collection. Also, on the ground, the down conversion back to DC is not efficient yet. That's not to say that Paul's efforts aren't useful--there's been enough delay fostering this approach and all steps are positive. This is a great step in the right direction. You can find more info on this by looking up 'PRAM'. It's a good analogy to ask 'why didn't we have electric cars'? Well,because work with magnets and new battery technologies took the meter in their favor, after almost 100 years of combustion engine dominance. The same may happen in 20 years for microwave transmission of power from space. 73 Chip W1YW
$1,000,000 a pound to get it in orbit , kinda makes more sense to build out solar power plants down on earth , very happy with my solar-powered ham home ( over 42 megawatt-hours in 3.5 years and 30 TONS of carbon not burned. ) what we don't want to see is top-down control of resources and energy ( big dirty corporate profit-driven power plants ) it is much better to have personal systems that can work together grid or no grid.... such as sunny island type inverter setups...then you don't need the power company anymore.... https://www.solarelectricsupply.com...nverter-off-grid-solar-battery-backup-systems
Thing, is solar panels are wayyy more efficient in orbit, 11-21% efficiency on earth and the solar panels are 80% efficiency on the ISS the last I heard. Not to mention each panel we manufacture uses mined quartz and coal to manufacture. If we use solar panels we'd better squeeze all the efficiency we can out of them if its CO2 that you worry about. Maybe if we actually go ahead with that comet miner we can assemble and smelt them in orbit and save some monies, who knows.
What I've always wondered about: how on earth (pun intended) are you going to compensate for the path loss?? Path loss increases with frequency, so lets assume were going to use 1Ghz as our microware transport frequency and the panels are flying at a geostationary height of 36,000 km above earth. The path loss will then be 203dB!!. That requires some hefty antenna arrays to make up for that loss!
The present tests are LEO. Not geostationary. The platform is able to change orbits, and track the ground from roughly 360+ kms up.. There is --no inverse square path loss-- if you capture the full TX beam at ground station. Narrow TX beam; wide ground based capture area. I suspect they are envisioning a far future battlefield, trickle powering remote battle drones via LEO power sat delivery, as an alternative or backup to solar. For us civvies, solar makes the most sense in my lifetime, anyway
Has anyone read "Sunstroke" by David Kagan? Its from 1993. Solar satellite, microwave downlink, control is lost and the downlink starts frying everything in its path!
That won't happen, because the power density per square foot, on th ground, is not too high. Sunstroke , with sunlight, is a far more dangerous outcome.
But that would be far from practical. A LEO system does indeed need to be tracked. But that would give us only a short period of usage, unless many very large scale receiver arrays are to be built around the globe. And the moment you go geostationary, the receiving array will be very very large.
No one brought up 'geostationary'. You just assumed it. You should look up the subject of this thread: 'PRAM'. The space vehicle is designed for low orbit and orbital manueverability AND change. Yes, it can TRACK from low orbit. It's not ballistic.That's what makes it 'practical' for military applications. 73 Chip W1YW
