7 minutes ago, martin-w said:

No... a receiver. Why a power transmitter? they wouldn't be transmitting anything. 

I mean would they each need a dedicated transmitter with tracking capabilities to transmit the power to them.

12 minutes ago, martin-w said:

Just as an example, island to island in an archipelago

I misunderstood your reference to "stretches of ocean".

14 minutes ago, martin-w said:

The researchers hope that although microwave-powered rocket propulsion is still in its early stages, it could someday become a superior way to launch rockets into orbit given the high onboard-fuel demands of conventional propulsion techniques.

I know and I'm hoping it will be possible. I am wondering why "the efficiencies of the power transfer through the beam" were only 4 per cent. I can't imagine how much microwave power would be needed to send a rocket into orbit but, at least, the researchers seem confident that it can be done.

1 minute ago, dmwalker said:

I mean would they each need a dedicated transmitter with tracking capabilities to transmit the power to them.

 

Oh right, I would think so, for multiple drones. They would if they were a distance apart. I'm thinking a super light micro drone swarm might just need a single, wide beam. The power requirements for a micro drone would be small. The Black Hornet micro drone used by the military fits easily in the palm of the hand.

 

 

 

36 minutes ago, martin-w said:

Here's a handy calculator to measure distance to the horizon. From 3000m the distance would be 195.6km:

http://www.ringbell.co.uk/info/hdist.htm 

11 minutes ago, dmwalker said:

I am wondering why "the efficiencies of the power transfer through the beam" were only 4 per cent.

 

I think it was just an unoptimized proof of concept, to see if it could be done, rather than fines tuning for optimum efficiency. 

 

18 minutes ago, dmwalker said:

I can't imagine how much microwave power would be needed to send a rocket into orbit but, at least, the researchers seem confident that it can be done.

 

They might be thinking microwave thermal propulsion though. As per the illustration I posted.

 

https://parkinresearch.com/microwave-thermal-rockets/

Propellant is on the spacecraft and heated by the beam from the ground. 

24 minutes ago, martin-w said:

I think it was just an unoptimized proof of concept, to see if it could be done, rather than fines tuning for optimum efficiency.

This was building on the experience from a previous attempt which achieved an efficiency of 0.1%.

“We used a sophisticated beam-tracking system to ensure that the drone received as much of the microwave power as possible,” said Kohei Shimamura, lead author. “Moreover, to further increase the transmission efficiency, we carefully tuned the phase of the microwaves using an analogue phase shifter that was synchronised with GPS units.”

1 hour ago, dmwalker said:

This was building on the experience from a previous attempt which achieved an efficiency of 0.1%.

 

Apparently only 30% of the beam was captured by the drone and only 40% of that was converted to electricity.

Edited October 6, 20232 yr by martin-w

22 hours ago, martin-w said:

Why is it necessary for a topic to stay slap bang on topic? Some of the most interesting conversations drift into other areas.

The simple solution is to spawn a new thread and provide a link in the original thread.

24 minutes ago, n4gix said:

The simple solution is to spawn a new thread and provide a link in the original thread.

Agree!  It also is good for anyone new joining the conversation to not be confused because the topic isn't being followed!

55 minutes ago, n4gix said:

The simple solution is to spawn a new thread and provide a link in the original thread.

 

I didn't ask for a solution or object to staying on topic. I just asked why. Which was answered.

On the forum I moderated for years topics evolving caused no issues at all and resulted in interesting conversations. But if "bang on topic" is required here, so be it.

 

So, the way things are going, we'll be using microwaves to make things fly and lasers to shoot them down. The circle of technology will be complete.

Seems CALTECH have already done it. Prototype solar space module, tested in space and power beamed to the ground.

Hovering quad copter demo too.