You are one of the greatest human beings who has ever lived.

What an elegant explanation of near and far field impedance!

Not the nervous fumbling around and pinched-ball voice from the EEVblog. How beneficial!

At my work I had a set of 3 + 3 near field probes and an accompanying termination / 20 dB amplifier. But I made some of my H field probes using a gapped ferrite ring for some special situations. Since my retirement, I have built a few more to restore my lost abilities. But where I’m going with this introduction is that recently I bought an Aim I-prober model 520. And that is amazing! It is intended for H-field and for following very small traces. Not cheap, but for me worth every penny.

Very clear and logical explaination about these 2 types of probes. As for all of your electronic basics videos a big THANKS and thumbs up as your videos help a lot in understanding *why* you have to do things the way they have to be done. Not just *that* one should do it this way. Thanks for sharing your knowledge on RF!

Nice job, it is a topic not usually addressed in these forums because of its' inherent complexities, yet you broke it down nicely and I think folks at all levels are able to take something away. You are definitely one of the top KZfaqr's in this subject mattes, keep up the good work and thanks for taking the time to share your knowledge, it is most definitely appreciated. 73

As always, the best explanation I have ever heard. I have always been confused about free space impedance equals 377 ohms. OH... I get it after 50 years in the business. Thank you!!'

Thank you for another wonderful video and the time to share articles and references..

Very nicely explained!! Looking forward to watching more videos from you.

Really informative video! Thank you for the clear and concise explanation.

We always learn nice things on this chanel that we do not see elsewhere. Nice Video

Man, what a clean explanation, kudos!

Thank you Alan for another great class. Recently I ventured to assemble and search a little more about the magnetic loop antennas for use in my humble apartment ham radio station. The main problem I try to work around, is the excess of of QRM coming from the failure to proper grounding of my station. Recently built some magnetic probes and using a SDR dongle connected to HDSDR able to locate some sources of noise generation. Unfortunately I found that a lot of equipment in my country do not have an efficient control of EMI emission and therefore hinders much the practice of SWL. But how to persist is a positive feature in our hobby, still sniffing more noise sources and trying to eliminate them through changes in noise generating equipment. Thanks again for sharing. P.S: I'm sorry for my rusty English 73 PU2SRZ

Great, Great, Great video. Thanks a million for sharing your valuable experience with us.

Beautifully explained. Thank-you very much.

Thanks for sharing the wonderful video tutorial and The technical content was precise and apt to the point.

Thanks for this wonderful video .... it clear all my doubts regarding E and H field antennas...

Very helpful and informative, thanks for putting this together! :)

Thanks again for another informative video.

My favorite channel!

Pleasure watching this insight! Brilliant

Awesome video Alan. Learned a great deal, Thanks

When is "RF for dummies" coming out? You have a the uncanny ability to extract the perfect amount of information out of complex topics. Thanks again!

Great. (really great, can not be better) And that's for all of your videos. So, hope you make another couple of hundred videos about whatever technical stuff. 30 years ago I could not have imagined someone is going to explain all this stuff.... ((well, do not move your tablet, sometimes you do, that's all))

Hi expert, I have watched many valuable videos what have been made out by you. It's really a good way to share your knowledge and skills with engineers who really interested. There is no such platform & nice man to share those matters in China. I hope I can be a such guy to do that.

Reading others' comments it seems you've been commended graciously already, but I want to add my little thanks to the list. Liked and subscribed!

3 basically free probes I find very effective: 1. Simply cutting a small diameter coax cable flush and insulating the cut end with a thin layer of glue works very well for isolating noise down to individual trace level. 2. Same as 1 but allow the center conductor to stick out a bit. This would be similar to the E-field prob in this video. 3. Using small coax again, simply make a tiny loop from the center conductor back to the shield, and insulate. This very small loop is again handy for isolating noise to trace level (or close). If you are not seeing much of anything, do the common things to lower your noise floor: Turn on the preamp (if you analyzer has one), or use an external low noise amp, remove attenuation, reduce resolution bandwidth, reduce span if you want to increase the sweep rate.

Thank you for the video and the notes, very interesting.

Thanks again for this great explanation. Would be also interesting to see how you solve such electrical- or magnetic Field issues on the board.

gracias por la gran aportacion de sus videos . con mis mejores deseos este bien ud, mister

Thanks heaps for the super informative video! Also Dave from EEVblog has a good "follow up" video on H & E field probes

Simply brilliant! Thank you..

Great, thanks for sharing.

great explanation

Another great video, thanks.

Thank you, you are a great teacher

Great explanation!!! way to go!! Thank you!!

Good stuff, I am now smarter than before! 😁

Great Video again , very informative...

Hi Alan, Thank you for making and sharing the videos. Regarding ~1:20 I believe these loops are not really "shielded". Across the gap at the top, you should have the same voltage difference (hence e-field) as for the feed of a loop made of a single conductor of the same size. I recently did a 3D EM simulation that also shows this. I can share screenshots if you like. I believe the coax shield is only kept in place to prevent cable waves on the feeding line. But this can be further analyzed.

Those nicely insulated ones would make a nice addition to my test bench. Nice bit of information, it brought back memories of using a home made sniffer probe to track down offending noise in mobile radio installations before fancy noise reduction circuits. I am giving away my age. Hi Hi. 73 Leo. k1zek.

this was very helpful thank you

Great demo thanks

Thanks so much! Interesting as usual

w2aew...I dont know if u read this. But Im depending on you so much these days. I am preparing for a interview and after watching your teachings, im confident ill crack the interview

amazing review, ty

Well explained video.

Excellent always..

I've been around electronics for quite a while, but I never knew the real relationship between the electric field and the magnetic field. This honestly blew my mind.

Im developing a product , that is why i watch this , especially back to basics parts :)

Amazing info

Really, really useful explanation. I've just purchased some probes and now realise that they don't do what I thought!! However, I can use them correctly, abeit, not for what they were bought

Thanks Alan.

Very good video!!!

Très intéressant ... merci !

Great video as always. I might try making a shielded loop using some RG-174 coax with a split shield at the far side of the loop (single turn).

Thanks for this video....

Thank you!

...yes I definitely learned a lot from this video. :)

I took me a while to get it but this may help others. What you need to do is thread the loop on the direction of the magnetic field.

So cool，thank you very much

Your handwriting is amazing.

how beautifully insane this concepts become at milimeter wave frequencies.....

I'd be interested to learn about the use cases and potential traps for using an LNA with nearfield probes too. Another terrific episode, Alan! I learn a LOT of stuff from you and your videos tend to hit just the right subject at just the right time for me. I can't tell you enough how much I appreciate your outstanding work and effective teaching style.

Nice vid!

Thanks Alan. That was quite useful... but it would have been nice to also see perhaps just a simple circuit that you could have demonstrated the sensitivity of these probes. Just a simple oscillator maybe with some different resistors that you could change out to show the current sensitivity and maybe another to show the voltage sensitivity. What are the frequency responses of these types of probes?

Thanks!

Many have a hard time with electric vs. magnetic fields. Both thumbs up.

great, thanks

How can this be used to test the quality of shielding on coax cable used in HF ham radio stations ?

Thanks for the great explanation! Very educational! I would like to ask one question regarding detected harmonics: Are those harmonics can be translated in RF (if there is some RF module fitted in) chain and transmitted to an antenna, potentially causing RF interference? Thanks in advance for answering.

Nice video, thanks for making it. I see that Beehive and Tekbox both offer wideband amplifiers to complement their probes. Do you recommend such an amplifier for the EMI probes? Are the received levels often so low that you need one if your spectrum analyzer doesn't have a builtin one? Or is there another reason for using one?

Learned a lot! 73

thanks

Such a great video, thanks for the demo. Just one question, do you purchase any amplifier with the yellow probes? I'm trying to measure the transients on a SIC-MOSFET and the measurement is getting coupled with some noise, so I want to find a good place (less noisy) in the design to perform the measurement. Thanks in advance!

wow, man, I got a long way to go. thank you. this is another hole in the pocket soon. got my huntron last year, few months ago got my PRC 2000 and polar toneohms 950 a few weeks ago. when is this bleeding is going to stop.

here on the board lot of components are surface mounted and in each component the electrons are moving in different manner and the movement depends on component operation hence we see E and H field

Thanks Alan for the very interesting video. In principle, is it possible to measure the energy radiated from the circuit by measuring both E and H at the same point (as ExH is proportional to energy, Poynting vector )? Did you use the FFT mode in the scope to measure the frequencies?

I don't know why there are someone who do not like such videos??? And vote dislike...? Thank you for your time and effort 73 de LZ1MOB

Interesting topic, would have liked a bit more info on what kinds of problems these fields cause and of course how to resolve such problems. Something I can Google I suppose ;) As always well done and thanks! As always - making us think and grow ;)

Fantastic as usual. Do these probes need an amplifier to get the most out of them?

I never knew that these things existed! They certainly are a handy tool but for me, I would rather connect those probes to a signal tracer... I only work with audio equipment and finding noisy resistors, well there's no better way to find them than using a probe like that. I have been planning to try using a head from a cassette deck but I haven't got around to it yet...

Best explanations. Thank you. For EMI testing, it is mainly for far field. It would be interesting to see the correlation between near field probing vs real EMI testing. Is there any way to build a far field (home) setup for pre-compliance testing?

Does this mean that whenever a receiver gets a signal inside the near field distance, it's really picking up reflections?

Excellent teaching video. Can you add some comments or technically explain the reactance area of the near field "inside" a large solenoid antenna. (say 60 cm in diameter). It is the area where E and H fields are unpredictable. I am looking to find an answer but I can't.

Any good way to measure the frequency of 32.768kHz crystals with a E-field probe.?

Wow! This was such a great video!! One thing that wasn't clear to me is how do you connect the probes to your MDO? I saw that Beehive doesn't sell a cable with a BNC ending. Do you use the "BNC probe adapter 0309-0006" and connect it to the scope with a BNC male-male cable? What would you recommend? Thanks!

Hi! Great video. I want to recreate this type of measurement. I could find the probes, but not the cable you used. Could you provide a link where to get the connector cable? Thanks!

I just use a sniffer with a metal Tip and metal ground then I just try to match my cascade analysis in the chain when I debug. Do you not like that style sniffer or are you strictly trying to catch fields ?

Do they work on Mixed Signal Oscilloscope? Also the yellow one, Does that comes with all accessories like cables and all??

How can I measure high frequency magnetic field with Beehive Electronics 100B EMC Probe?

Is it possible to use an ordinary o'scope to do the sniffing? Maybe even a spectrum analyzer?

Does this technique of investigation requires same oscilloscope than yours ?( will a ordinary oscilloscope or a spectrum analyser will do the job ?) thank you

Nice video. Where'd you get that plot of impedance vs FF distance? I thought it's always 377 Ohm, irrespective of how close you are to circuit impedance. A GTEM cell can go to DC, and if you place the field probe within the septum, the impedance (E/H) is still 377, even though the septum Z0=50 Ohm, all the way down to essentially DC. I thought E/H would be 50 Ohm, but after hours of researching, it's always 377. Maybe this only applies to within a TEM line.

Great Video Thanks you might have an answer for me. I am interested in building Loop antennas for HF band. Do you want the XL and XC to equal 377 ohms of Z radiating coil loop IE for 10 watt W=I^2*Z and W= E^/Z where Z=377 Ohms....I=(10/377)^.5=0.162 A......E=(10*377)^.5= 61.4 V RMS I assume.????? the input coil will have to match the the input loop of 50 ohms to the output loop 377/50 7.45 to 1 transformer primary to secondary ratio ???? so input coil Z= 50 I=10/50)^2= 0.442 A.... E=(10*50)^.5=22.56 V...input Z voltage=22.56 V output Z voltage= 61.4 V ratio of 2.72 why does this ratio not match. 2.72 ^2= 7.4 close to ratio 7.45 So transformer impedance is also square law???? people on you tube are saying they are getting several thousand volts across an RF coil with only 100 W input Why???? if you could help me figure this out. ????? thanks N7RBC

hi regarding the self made probe at 2:17, how do i design the size of the loop and number of loop? does the size of loop will afffect the sensitivity to different frequency like antenna ? hope to hear from you soon!

The near field probes are often used effectively to detect emissions from PCB assemblies. Would these probes be as effective to detect the sources of emission in Power Electronic equipment of > 50 KVA rating, like a UPS or a VFD?

Now...is there any way to get an idea of the far field based on near field measurements? If so, video please :-)

Ok Alan, you put me over the top (much to the chagrin of my wallet); been watching a set of probes for quite some time on eBay that are made by "Tekbox" in Vietnam and comparing them to the Beehive set. Guess I gotta make up my mind, although my homebrew sniffer loops have served me quite well with "big" PCBs and circuits. 73 - Dino KL0S

Re making your own H probe, could you use thin coax instead of bare wire to implement E shielding? Or maybe a foil wrapper around the coil :-) A little Faraday cage...