308

50ohm goes brrrrrr (sh.itjust.works)

submitted 1 week ago by einfach_orangensaft@sh.itjust.works to c/science_memes@mander.xyz

16 comments fedilink hide all child comments

all 17 comments

sorted by: hot top controversial new old

[-] JackbyDev@programming.dev 2 points 5 days ago

My reaction while reading this.

Heathcliff in a ham helmet

[-] marcos@lemmy.world 35 points 1 week ago

Just to point out, because it's bothering me way more than it should...

But the electric and magnetic peaks align with each other's valleys, not with each other's peaks.

[-] FishFace@piefed.social 10 points 6 days ago

If two waves of the same frequency align with each others' valleys, they align with each others' peaks. Do you mean they should be aligned peak to valley? I don't know how you're deciding which direction of the axes is positive and which is negative though.

[-] ChaoticNeutralCzech@feddit.org 4 points 5 days ago* (last edited 5 days ago)

No, they fucking shouldn't

https://en.wikipedia.org/wiki/Maxwell%27s_equations#Vacuum_equations,_electromagnetic_waves_and_speed_of_light

Edit: neither of us are right, EM waves in vacuum do travel in phase but in conductors, there is a phase difference between 0° (very high resistance) and 45° (superconductor). So yeah, EM waves can "tell" they're in a dummy load.

[-] mexicancartel@lemmy.dbzer0.com 1 points 4 days ago* (last edited 4 days ago)

Well it's wrong. I suppose you are thinking so because Maxwell's equations shows B depending on (∆E/∆t)[i cant write \partial symbol], BUT remember LHS is not B but is curl(B) so derivative acts on both sides. So they are in phase and not 90° out of phase. So the peaks should align, atleast in free space

[-] captainlezbian@lemmy.world 2 points 5 days ago

Yeah, because it's not pulsing in intensity, it's pulsing between which kind of energy it's being

[-] tate@lemmy.sdf.org 0 points 5 days ago

You're describing circular polarization. It's not the only way.

[-] Techlos@lemmy.dbzer0.com 0 points 5 days ago

Maybe it's showing polarization superpositions of the E-field?

[-] Remember_the_tooth@lemmy.world 16 points 1 week ago

I get the reference to the original meme. I don't understand the EM spectrum component, though.

[-] deranger@sh.itjust.works 34 points 1 week ago* (last edited 1 week ago)

They wish they were in an antenna and going out as radio waves, but instead they’re in a dummy load and not going anywhere. 50ohm is a common antenna impedance.

[-] Remember_the_tooth@lemmy.world 14 points 1 week ago

Thanks. That puts me on the right track.

https://www.onallbands.com/ham-radio-101-dummy-loads-smart-idea/

[-] hedgehogging_the_bed@lemmy.world 9 points 1 week ago

Had to go get my radio-tech spouse. His reply "Oh, that's the dumb name for a terminator...."

Apparently "dummy load" isn't what they call them in the USAF

[-] einfach_orangensaft@sh.itjust.works 6 points 6 days ago

i might be wrong here but i think a dummy load is different from a terminator, they both 50 ohm, but a terminator is more like a connector cap, while a dummy load is designed to dissipate heat and can often take many watts of power over extended time without starting glow

[-] Eranziel@lemmy.world 1 points 6 days ago

That's my understanding as well. I've seen dummy loads used when testing transmitters at power so that nothing gets too hot. They usually have a big aluminum heat sink.