High Frequency Spectrum Analysis - Page 1
Forum section: electronics / projects

author: pedake
author_rank: Contributor
timestamp: September 23, 2015, 07:35:06 pm
content: I am still getting used to this Forum thing. I am posting below question again. posted to another section before. is that OK?SPECIAL QUESTIONI have a big bunch of Gunn oscillators here. Soviet made. Really interesting. Withreflectorsresonators and everything. I would like to get them running (well. I did) and set them to certain frequencies. but I have no clue on how to measure their spectrum without spending 50'000 dollars. Some of them have been calibrated to Lambda = 7 mm (~42 Ghz, if I roughed it right). I also have a detector (A gunn with a big amp and some filtering) that can detect a whole frequency rage (I am still going through the documentation - in Russian... bah)Now - how do I look at 42 Ghz? any ideas?PS:For your viewing pleasure, two of the parts on the little PCB and some pictures:http://www.trzrus.narod.ru/sourse/kt626.pdf(PNP, 45 W)http://www.chipfind.ru/datasheet/pdf/kwazar/kr140ud18.pdf(OpAmp)and pictures attachedFor anyone interested in what a Gunn diode is:https://en.wikipedia.org/wiki/Gunn_diode

author: daqq
author_rank: Super Contributor
timestamp: September 23, 2015, 08:34:32 pm
content: QuoteTo the best of my knowledge nothing of the shelf works in those areas - for ~10 GHz you could use an LNB from a satellite receiver. You might scavenge some gear in that area of ebay though - downconverters, or these:http://www.ebay.com/itm/HP-R532A-26-40-GHz-Absorption-Wavemeter-Ka-Band-Nice-/380408769716?hash=item5892212cb4with a power meter should be able to give you some info. Or you could hack one together theoretically -https://en.wikipedia.org/wiki/Absorption_wavemeter, with enough knowledge of microwave black magic.

author: rfeecs
author_rank: Frequent Contributor
timestamp: September 23, 2015, 09:24:37 pm
content: This one covers the band, 33GHz - 50GHz:http://www.ebay.com/itm/like/131601339345?ul_noapp=true&chn=ps&lpid=82There are multiple ones of this model number on ebay.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 23, 2015, 09:50:36 pm
content: Might be worth reading about how these things were done historically, e.g. J.C. Bose:https://www.cv.nrao.edu/~demerson/bose/bose.htmlIf nothing else, you need some sort of detector for that radiation. It could even be a radar absorbent material heating a thermocouple. Then you need some means of tuning it, such as a micrometer and resonator. If you are using a TEM resonant mode (such as in a coaxial resonator of OD << lambda), then when the resonator length is (2N+1)/4 wavelengths long, you will see a null in the response.Tim

author: LaserSteve
author_rank: Super Contributor
timestamp: September 23, 2015, 09:52:23 pm
content: You may be able to adapt the interferometer technique in this book:http://www.n5dux.com/ham/files/pdf/The%20Gunnplexer%20Cookbook.pdf[/urlHowever you will need an exceptional detector diode assembly to do so.Steve

author: pedake
author_rank: Contributor
timestamp: September 23, 2015, 10:39:32 pm
content: wow. thanks for the input!This Forum thing seems to work quite well :-)I will look into it :-)Unfortunately I'll be traveling again.. so no hardware for a few days. But I'll have my slow MTU (Main Thinking Unit) with meSome background info:There is a thing called "Bioelectromagnetics" (there other names for it). Sounds a little like microwave black magic (daqq) when you read it and a lot of voodoo-like stuff goes around.But there are lots of studies in Soviet literature showing (unspecific) effects of high frequency electromagnetic exposure on organisms. and they did LOTS of studies. Lots of cell interaction, intercell "communication", etc.I know a guy who was, apparently, a leading figure behind large studies in former Soviet Russia - yes.. they had dozens of thousands of human "patients" "treated" in the 70s and 80s. He is in his 70s now. But he swears this all has a series of effects, positive and some negative.A friend picked this up for a very large series of publications she is looking into... But she did not know where to start. So I am trying to help as much as I can. I got these "heads" (see pictures) - I think 2'000 of these - from their an stock from Russia and I am trying to give a few thoughts on how to do the setup. Of course I am not actually supposed to do anything for it...BUT: now I got the electronics bug and I want to make things right from the beginning:nice little board, well designed setup for the experiments, (cheap) microcontroller controlled experiments with some data logging (mostly error logging) and easy readouts.academia is horribly slow and ineffective. People play ping pong all day and watch cat clips. And most research(ers) are really one-dimensional. A renowned crack in biophysics (which she is) will not know what Ohm means (which she quite possibly doesn't).I am only now getting into it... but let's see how much of it I can actually do myself. Very excited about this :-)