Reflection of Radio Waves by a Mirror-like surface

[EnergyInMotion]

Hey guys, I'm new to the physicsforums. I wanted to share some videos I made and see if anyone was interested or wanted to discuss what they see.

In this video I show in a manner in which is VERY easy to see, that a reflective surface will reflect not just light but also radio waves (and most likely anything in the electromagnetic spectrum)
I use a modified powercast RF testing stick, a powercast RF transmitter (powerspot) and some cardboard and reflective paper. Check it out!
Radio Waves & Reflection - Youtube video


I also wanted to share this other video which is fairly related, where I literally draw a functional antenna on a piece of paper with a Circuit Scribe pen and it captures nearby radiowaves, converts it to DC electricity (with a powercast RF->DC chip), and powers and LED. Video is shown in real time as it happens!
Drawing a functional wireless power antenna - Youtube Video

Let me know what you think !

 

[berkeman]

Does that Circuit Scribe Pen use conductive ink?

 

[hutchphd]

If it works that looks great! If you can stack two layers under the modules you could make "circuit boards". Anybody else seen these close up?

 

[berkeman]

a powercast RF transmitter (powerspot)

What frequency and power are transmitted by the powerspot? Since you are also an amateur radio operator, you know that we need to stay within licensed bands and power limits. Looks like a useful tool, as long as it is licensed or operating in the microwave oven band.

(Aside -- have you been on any transmitter hunts as part of your amateur radio experience? They can be pretty fun and challenging!)

 

[EnergyInMotion]

Does that Circuit Scribe Pen use conductive ink?

Yes, that's exactly how it works!

What frequency and power are transmitted by the powerspot? Since you are also an amateur radio operator, you know that we need to stay within licensed bands and power limits. Looks like a useful tool, as long as it is licensed or operating in the microwave oven band.

(Aside -- have you been on any transmitter hunts as part of your amateur radio experience? They can be pretty fun and challenging!)

915Mhz, 3Watts EIRP. From what I understand you don't necessarily need a license to use it as they acquired FCC certifications and it is marketed to consumers. There's one product I see that so far that "charges" off of it, which is some sort of Nintendo Switch Handheld controller grips.

I read about the transmitter hunts but I have not participated. In fact, I purchased some radios and messed around with listening, but never once have actually made a transmission! I'm about as "amateur" as it comes for actual Amateur Radio activities.

I was at one point attempting to set up a radio-based IRC channel, but never finished with it. I think that would be really cool to try.

 

[EnergyInMotion]

If it works that looks great! If you can stack two layers under the modules you could make "circuit boards". Anybody else seen these close up?

The hard part is somehow getting actual components to sit on the paper that you draw on. But it could be possible to make layers and somehow get them to go vertical to another layer to interconnect things. I did try, and almost succeeded, to actually glue circuit components in place and have a functional, paper-based hand drawn circuit that would not be broken if I picked it up or moved it.

 

[berkeman]

I read about the transmitter hunts but I have not participated. In fact, I purchased some radios and messed around with listening, but never once have actually made a transmission! I'm about as "amateur" as it comes for actual Amateur Radio activities.

Do a Google search for Weekly HAM Net in your area. You can listen to a few of them, and then practice checking in. Weekly Nets are how we practice good radio protocol.

KI6EGL

 

[hutchphd]

The hard part is somehow getting actual components to sit on the paper that you draw on. But it could be possible to make layers and somehow get them to go vertical to another layer to interconnect things. I did try, and almost succeeded, to actually glue circuit components in place and have a functional, paper-based hand drawn circuit that would not be broken if I picked it up or moved it.

Seems like it could be a good educational toy if done well. Fun, if it could be made reliable.

 

[EnergyInMotion]

Seems like it could be a good educational toy if done well. Fun, if it could be made reliable.

Yep that's actually what they market it as! They have little circuit boards that you push down on your circuit drawing and it makes things happen. They made easy to use components that are compatible with circuit drawings from their pen. I'm not sure why they only market it to kids though, as it can be fun and useful for prototyping for adults also, similar to a breadboard in a way.

 

[berkeman]

915Mhz, 3Watts EIRP. From what I understand you don't necessarily need a license to use it as they acquired FCC certifications and it is marketed to consumers.

Cool. What's the FCC ID off of the label? Thanks.

 

[EnergyInMotion]

Cool. What's the FCC ID off of the label? Thanks.

https://fcc.report/FCC-ID/YESTX91503

 

[Klystron]

Yes, that's exactly how it works! ...

I read about the transmitter hunts but I have not participated. In fact, I purchased some radios and messed around with listening, but never once have actually made a transmission!

Radio receivers and subsequent signal processing interest me as much as transmitters. Receivers require less power and allow the operator to scan for signal. Brilliant that most antennae both transmit and receive.

 

[sophiecentaur]

Brilliant that most antennae both transmit and receive.

There's the principle of Reciprocity, which says that the emf at the receiver end has the same ratio to the input current at the transmitter, whichever way round they're connected (that's sort of how I remember it) so the link can work both ways. However, many receiving antennae will not handle the powers of the transmitter (many would just melt).
An interesting anecdote, based on my connection with BBC World Service transmitting sites is that many of the technicians on site are / were Radio Hams. They told me that the massive Curtain Arrays, used for transmitting to overseas sites, work as fantastic receiving antennae. That's when broadcasting schedules allow, of course (Against all H and S rules too). 200kW going out of a nearby array would obvs fry a receiver, connected to another array, whatever design frequency bands of the two antennae.