[needs corrections] Rectifying a Bunch of Videos

I nearly commented on YouTube and said its a Dipole antenna not a monopole as a monopole is connected to earth or an earth reference but didn't want to get into a war. :) So I went looking through my collection of routers schematics to see if any had a 25 ohm impedance matching network or a 50 ohm but ended up looking deep into IC schematics and reading data sheets. I found most of them used the chassis as a ground plane and that's the confusing bit. If its a ground plane then its a dipole but the chassis is connected to mains earth making it a monopole. Short of measuring the antenna's I'm at a loss so thought it would be less savage to ask in here. Mehdi is always right but I had to ask. Cheers All

No worries here, thanks for the video. Pretty sure first guy was talking about the wire.

Dylan

I would reserve judgement until I hear from Kurzgesat too. But in the comments there are a good number comments from well educated people like CGP Grey and SmarterEveryDay supporting Kurzgesat too. It is easy to ignore the amount of effort one put into making a video. I think both sides need to sit down and talk about this.

ElectroBOOM [Mehdi Sadaghdar]

I think CB is right to be angry that, once found out, Kurz was not doing real science videos but in fact just animating and paraphrasing pop science stuff already published elsewhere, they told CB to hold off while they worked on their own self-righteous video explaining the integrity of their "fact checking" and that sometimes they make mistakes and acting as if they really care about researching subjects in-depth and just, by mistake, got it wrong. The point is that their videos aren't really based on much research and they are deceptive about their process in the public eye in order to save face. I mean, you are of course free to have your preferences but, wow... Instead of supporting a real science channel like Physics Girl you stand by this guy?

I did, I initially believed the guy was badly treated by Kurzgesat, but after releasing his email communications, Kurzgesat is not to blame more than he is with his video. Check the emails CB provided in his description and people's comments

ElectroBOOM [Mehdi Sadaghdar]

Mehdi, Maybe you should check out this video about Kurzgesat and unethical behavior and reconsider recommending him. <a href="https://www.youtube.com/watch?v=v8nNPQssUH0" rel="nofollow noopener" target="_blank">https://www.youtube.com/watch?v=v8nNPQssUH0</a> Honestly, I always found his stuff to be sort off putting in a sanctimonious and oversimplified sort of way. It's sort of depressing for me to watch youtubers just recommend other youtubers for promotional reasons without any real scrutiny towards how they communicate and the pattern of their behavior. Integrity matters.

Awh, ☹ AvE didn't get a shout out. I found your channel because of that channel.

Steve LoGiudice

True!

ElectroBOOM [Mehdi Sadaghdar]

But the reflectors are connected, not necessarily to earth ground, but the circuit ground or the shield of the coax cable. If you look at the image below, all reflectors behind or in front of the transmitter dipole antenna are connected to the same rod which is the circuit ground which also most of the times happens to be the earth ground, <a href="https://upload.wikimedia.org/wikipedia/commons/d/d3/UHF_TV_Antenna_001.JPG" rel="nofollow noopener" target="_blank">https://upload.wikimedia.org/wikipedia/commons/d/d3/UHF_TV_Antenna_001.JPG</a>

ElectroBOOM [Mehdi Sadaghdar]

I agree that the measurement is not super accurate, but the current reading is in the ballpark. Considering how easily I burn my hand and leave burn marks by just sitting close to the coil, the current is pretty significant. I I burn skin with no arcs, but by just holding the metal wire, and my skin gets very hot and burns. [edit] after more discussion, my reading might be more off than I thought, I'll redo the test with a better setup. Thanks for reviewing!

ElectroBOOM [Mehdi Sadaghdar]

Regarding the loop, you see the measurement before and after I connected my body. The loop remained the same in both cases so if fields were passing through it, they would have the same effect in either case. Never the less, the setup has some good errors in it but the result is not far off. [edit] see my comment below, I will redo the test and update the video. Thanks for peer review everyone!

ElectroBOOM [Mehdi Sadaghdar]

I don't think it's necessary for a dish in a dish antenna to be grounded. If I'm not mistaken, it will work similar to e.g. the reflector element in a Yagi. However the dish does need to have the right shape and distance from the active element.

Daniel

The transformer video is from Brazil (huehue) and the guy seems to be explaining the trick (I didn't bother to search for the original video). That is why he doesn't care about hiding the wire.

likewise

Kenneth Carlile

100 mA from just sitting nearby? And you believe it?!? Obviously your measurement method is totally wrong.

Are you aware of the fact that your scope can display ampers if you set it that way? And you can use any value of resistor, still can get correct current readout. If you used 10 or even 100 ohms, you could get a much higher usable frequency limit, and your wavefrom would be much cleaner.

8:06 You are still not the friend of magnetic calculations and correct probing. The loop you formed from the ground lead of your probe has about 0.1 uH inductance. At 1 MHz XL=0.6 Ohm, therefore it introduce about 2 dB error, but at higher freq. it is much worse, this is why you couldn't even trigger to it correctly. After getting such a huge number of lessions from Lewin, Belcher, Feynmann, one coud expect you start to care about high frequency magnetics and metrology, but this is the disappointing truth: you are done with learning. 9:16 Are you serious? Do you really think that a floating metal surface wouldn't reflect EM waves?!?

Nice content. Also, Arduino is easy, lots of examples in the documentation and the C api is very easy to work with.

arduino is easy, give it a try :)

Kostas Karanatsis

Great content, thank you!

mikenco

I tried. I shouldn't have.

Great content as always. Thank you!

People who mislead for profit and power have no regard for the effects it has on our children, society, and future. This is why I am proud to support anyone fighting against ignorance and deception. Science isn't an opinion.

Raz0rf0x

I expected him to burn himself on his tea at the start &gt;.&gt;