Blog about RF and Microwave stuff - Page 1
Forum section: electronics / general

author: x18
author_rank: Contributor
timestamp: November 19, 2010, 08:41:42 am
content: Hi Dave.Perhaps you could create a blog about discrete RF and Microwave circuits, with things like microstrip lines, impedance matching with microstrip lines, s-parameter, rf power measurement circuits and so on.I'm a student and I really want to get into the real RF world. At present I just built a 2.45 GHz 1W power amplifier for my job at university and I just can say that there is no field in electronics in which theory and practice differ more. It's very hard to get into it because there are many things, that cannot be considered like standard, low frequency electronic stuff.So if you know something about RF please make a blog about how you started learning it and the things I mentioned before, or others. Perhaps you have also some literature to advise?Greetings from Germany.x18

author: Simon
author_rank: Unknown
timestamp: November 19, 2010, 01:30:27 pm
content: that certainly is a very practical subject, one that I'm sure you could never end talking about. I'd be very interested to hear tips and tricks on higher frequency design, luckily I've not gone that far yet but I'd wonder, do I need to start watching my layout at 50 MHz ?

author: blackdog
author_rank: Frequent Contributor
timestamp: November 19, 2010, 01:36:59 pm
content: Hi, x18Take a look at this site:http://www.rfcafe.com/Have fun!Bram

author: Time
author_rank: Frequent Contributor
timestamp: November 19, 2010, 04:34:50 pm
content: I kind of recall Dave mention hes not an RF guy. Or maybe he is and it was some other similar topic he said that about. Antennas maybe?

author: jahonen
author_rank: Super Contributor
timestamp: November 19, 2010, 05:46:56 pm
content: Quote from: Simon on November 19, 2010, 01:30:27 pmAssuming you mean digital circuits, then first thing to the wisdom is to realize that it is the edge rate what makes things more challenging, not the frequency. If you can get one edge cleanly from point A to point B, then it becomes completely irrelevant how many edges per time unit you send (frequency)Regards,Janne

author: Neilm
author_rank: Super Contributor
timestamp: November 19, 2010, 06:34:32 pm
content: I did once get into a talk with an RF engineer.He loved to point out that anything less than 1GHz was DC.My response was any voltage less than 1kV was low.It is all in the perspective.Neil

author: Time
author_rank: Frequent Contributor
timestamp: November 19, 2010, 06:42:44 pm
content: Anything less than 1 MHz is DC and anything less than 1 kV is low voltage for me as a pulsed power engineer

author: johnmx
author_rank: Frequent Contributor
timestamp: November 20, 2010, 11:29:34 pm
content: Quote from: Time on November 19, 2010, 06:42:44 pmSince I'm able to generate data @ 40 Gbps and optical pulses with a repetition rate of 320 GHz and view them with a 640 GHz bandwidth oscilloscope, anything less than 10GHz is DC for me as an Optical Communications Engineer

author: Hypernova
author_rank: Unknown
timestamp: November 21, 2010, 11:21:56 am
content: Signal frequency dick measuring: Only on the EEVblog

author: x18
author_rank: Contributor
timestamp: November 21, 2010, 01:01:12 pm
content: Quote from: johnmx on November 20, 2010, 11:29:34 pmI thought LeCroy is the market leader with their 45GHz scopes. What scopes are you talking about? Are there special scopes for the optical stuff?

author: Zero999
author_rank: Super Contributor
timestamp: November 21, 2010, 01:23:59 pm
content: I can smell BS somewhere.With regard to the high/low voltage/frequency it depends on the context and the circuit. If you're talking about what voltages create problems with arcing over insulation, high voltage is >1kV, if it's electrical shock hazard it's <60VDC or 30VAC, if it's a digital circuit, it can mean any voltage represented by a 1 or any voltage above the logic supply. If you're talking about mains frequency power a high frequency is anything over 120Hz or so, if it's audio it can mean above 20kHz or just 4kHz depending on whether you're talking about treble or ultrasonics, if it's RF it's anything about 3MHz.

author: Unknown
author_rank: Unknown
timestamp: November 21, 2010, 02:50:08 pm
content: Quote from: x18 on November 21, 2010, 01:01:12 pm45GHz is for real-time scopes. Sampling scopes can go higher, although not 640GHz as far as I know.

author: Zero999
author_rank: Super Contributor
timestamp: November 21, 2010, 03:17:24 pm
content: Good luck even finding a cable that will be able to carry a 640GHz signal without significant attenuation.

author: Unknown
author_rank: Unknown
timestamp: November 21, 2010, 03:36:53 pm
content: Quote from: Hero999 on November 21, 2010, 03:17:24 pmAssuming we're talking about fiber, I don't see the problem, since they can transmit light with wavelengths in the order of 1000nm without significant attenuation.

author: Zero999
author_rank: Super Contributor
timestamp: November 21, 2010, 04:23:37 pm
content: Fine, good luck finding a fibre optic cable capable of passing frequencies as low as 640Ghz.

author: TheWelly888
author_rank: Frequent Contributor
timestamp: November 21, 2010, 06:02:45 pm
content: ^^^^Actually optic fibre can already pass 640GHz - check out this electromagnetic spectrum table on the right hand side of this wiki page!http://en.wikipedia.org/wiki/Electromagnetic_spectrum

author: johnmx
author_rank: Frequent Contributor
timestamp: November 22, 2010, 12:17:54 am
content: Quote from: alm on November 21, 2010, 02:50:08 pmYes, it’s an optical sampling oscilloscope:http://www.picosolve.com/main.htmThe wavelength range is from 1525 to 1565 nm.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 22, 2010, 04:44:53 pm
content: Quote from: x18 on November 19, 2010, 08:41:42 amHow much did that cost and are you willing to share your design? A cheap high power 2.4GHz amplifier would be great for the mesh networking community. 802.11 hardware with an output power above 250mW or so gets crazy expensive.

author: Murphy
author_rank: Regular Contributor
timestamp: November 22, 2010, 05:25:30 pm
content: Prices have come down a lot on the 2.4ghz gear, at least on ebay.

author: EEVblog
author_rank: Unknown
timestamp: March 11, 2011, 02:49:10 am
content: Quote from: Time on November 19, 2010, 04:34:50 pmCorrect, I'm not an RF guy.I could do a blog on it, but I don't really have any enthusiasm to do such topics, nor the gear to show results etcDave.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 11, 2011, 06:35:10 am
content: Quote from: blackdog on November 19, 2010, 01:36:59 pmthough old post, but i went to the link. what a mess, dont know where to start.

author: Zero999
author_rank: Super Contributor
timestamp: March 11, 2011, 07:44:05 pm
content: Quote from: TheWelly888 on November 21, 2010, 06:02:45 pmThat doesn't say anything about a fibre optic cable capable of passing 640GHz.The fibre optic article says the lowest frequency used is 184.5THz or 1625nm.Quote from: johnmx on November 22, 2010, 12:17:54 amThat's 191.6 to 196.6THz which is much higher than 45GHz to 640GHz - you won't find a 'scope which can do that frequency range.