how to learn low level RF design

Assuming your talking about the more modern and harder to understand RF in the microwave range.....

Try ham radio. There are allot of v/uhf books around and getting a tech lic (in the USA) which will allow you on that band is only 25 SIMPLE questions. Look for people who are hams that do microwave contesting and "buddy" around with them. Honestly, they will be honored to help.

If your talking HF radio below 100Mhz, your not looking/working hard enough :-)

RF is difficult. You really should have an MSEE to be proficient at it. THe big problem is that RF extends well into the GHz range. Even if you stay in the upper 100's of MHz, it is fairly easy to get tripped up That would be police radios for example.

Post a question and I will try to answer it!

Dave

Designing an HF receiver that can listen to a teeny signal 20kHz from a station that makes a fluorescent lamp glow _is_ hard work :-)

--
Regards, Joerg

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"EE123" wrote in message news: snipped-for-privacy@p2g2000prn.googlegroups.com... On Dec 9, 4:10 pm, snipped-for-privacy@gmail.com wrote: "RF is difficult. You really should have an MSEE to be proficient at it."

I'd not convinced it takes an MSEE -- the choice of school and the courses you take have a lot more to do with it. For instance, Oregon State University -- which likes to think of itself as an "engineering" school -- only has two professors in their microwaves department, and both are heavy on simulation and modeling but not so much more "practical" (or at least common) things like mixers or amplifiers. (Although there are a couple professors in the microelectronics department who really like PLLs, if you're into that.) As such, none of the RF courses offered have you sit down and design and actually build anything more complex than a filter or simple antenna -- no modulators, no amplifiers, no phasing networks, nada. On the other hand, Portland State University -- which isn't well-known as an engineering school -- has individuals such as Richard Campbell

who's into amateur radio and very much does believe in sitting down and building real devices in his classes. But even his offerings pale in comparison to what universities such as Stanford (and MIT and Berkeley and...) offer here:

"THe big problem is that RF extends well into the GHz range. Even if you stay in the upper 100's of MHz, it is fairly easy to get tripped up"

My experience is that upper VHF and low UHF tend to be the hardest, since you're in this no man's land above HF (where you can largely ignore parasitics) but still not into "traditional" microwave terrirtory where you just bite the bullet and specify everything to be so-many-lambda long. (Granted, that also means -- at least for me -- I throw up my hands and say, "no, I can't design your a 10GHz active mixer using discrete transistors" -- whereas an IC designer would say, "sure, no problem!")

---Joel

Yeah, pretty much. ;-)

Cheers! Rich

Google has plenty of hits on "stealth antennas." :-) The ARRL even has books on the topic!

For less then 100 mhz, I'd go with

Experimental Methods in RF Design

-- by Wes Hayward, W7ZOI, Rick Campbell, KK7B, and Bob Larkin, W7PUA

Serious EE in that book as well as a lot of fun. My boss with 45 years in EE but no interest in ham radio stole my copy and wont give it back. For those sceptics out there, its not your normal ARRL/TAB cookiecutter cookbook. But its not Artech House either.

Older over 100 mhz stuff,

The RSGB microwave handbook. The 60s-70-80s one, not the new international one.

Not published any more, but still out there new.

Then get on the microwave mailing reflector and listen for a while.

Steve

** You will not likely get a job doing something you have no ability to do.

Suggest you start off building a "crystal set", these are more interesting than you might think.

Built my first when I was 7 or 8 years old.

Then a one transistor radio, a one valve set tc.

Get yourself a nice RF generator too - essential really.

A frequency counter and spectrum analyser are also needed for working with transmitters.

Also, and importantly - do not attempt to re-invent what others did long ago, instead study what has been made and sold successfully and learn from it.

..... Phil

Yes, but if you have repaired the umpteenth piece of electronics they all know who dunnit ;-)

--
Regards, Joerg

http://www.analogconsultants.com/

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starting, persisting, and finishing.

some suggestions,

1: pick a frequency 2: If both ends are fixed locations, find a good design for directional antennas.

On a sunny day (Tue, 09 Dec 2008 15:57:07 -0800) it happened Joerg wrote in :

hehe. Yes, maybe that is true. In my days as a kid, 'RF' was anything above audio... and audio was 20kHz? Think I started with connecting a headphone to the radio in the living room. Then a crystal receiver with one of those point contact detectors that you had to move around a pin on the crystal to find a spot where it worked. Then a small tube amplifier. Made it oscillating, my first transmitter. Then transistors... low power transistor audio amps, super heterodyne, mixers, IF amps. Then tube audio amps with more power... then TV circuits. Then high power tube linear, ssb, dsb, deflection circuits, video amps, anything, build my own scopes, first with tubes then transistors.

Anyways: to learn RF first build a crystal receiver. Easier these days with good diodes.

At > 1GHz I dunno.... Where I lived at that time, you could detect the TV station with a simple diode and a LC tuned to about 62 MHz. If you listened to it you heard the 50 Hz frame frequency. Such a strong signal, only needed 1 or 2 transistors to drive a CRT..

So, these days, with all digital here, forget about simple receivers like that.

Just buy some PCs, add a wireless access point, good directional antenna, and you can send anything you want over 1 mile, including video, audio, data, what not, without needing a license, and without f*cking up the spectrum. But, the road from crystal receiver to what we have now was fun and interesting for me.

A good RF Engineer needs to understand the following topics (Each requiring a fair amount of study and work to understand):

1. Matching concepts. (Why is matching concepts so critical to RF - must understand - it is a constant theme in RF)

1a. Matching with lumped elemenets 1b. Matching with distibutive elements 1b1. Understanding how distributive (Transmission lines) elements work (First step - a quarter wave short is an open :-)

1. Noise, Noise bandwidths, (as an example, why can you send a signal around the world in morse code with 1 watt, and you need a KW for voice?)

2. Amplifier system concepts , Noise figure, IM products, cascading noise figures

1. Feedback control theory. Concepts of stability, Loop bandwidth and loop response as a function of loop bandwidth. You need to understand this to do Phase Lock Loops, and ALC circuits.

2. Filtering concepts and filter designs. Need to understand Zverev book of filter tables and how to use it. Need to undersatand concepts of group delay and filter trade offs

1. Need to understand , inside and out, how to use a network analyzer and a spectrum analyzer. Absolutelty must get access to these two instruments and really , understnd them. (Must play around with distributive elements on network analyzer)

2. Perhaps most importand is grounding concepts. I would say that in my experience, 50% of all problems I have ever had ultimately boil down to a grounding problem. Even to this day, and I know this, I invariably chase down other issues before I chase grounding, and sure enough, its a grounding problem.

These are your first steps, the circuit design concepts are not so hard, but you must be willing to really really bang your head against the wall to get your circuits to work. You must have tenacity.

And always keep a good analog scope. Always. If the OP doesn't yet have one I'd recommend the Tektronix 2465. Several of my clients followed that recommendation and got them for around $500 off Ebay. "Wow, it's like someone turned on the light!" was a common comment. Start every measurement job with the analog scope first and use a DSO only when the analog one really, really can't do the job. Like on data lines or very low frequency erratic noise.

Sssssht! Don't take away my business base ... ;-)

You forgot one for the guys building analog power circuitry:

1. Always know where the next fire extinguisher is.

--
Regards, Joerg

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Horsefeathers. Microwave is fairly easy. HF & VHF are fairly easy. From about 300 MHz. to a gig things get interesting; distributed and transmission lines are too long, and leaded components have too many unintended parasitics.

Where the hell did you get that number? HF goes from 3 to 30 MHz, VHF from

30 to 300, UHF from 300 to 3 Gig, and so on.

Hey, learn the difference between "your" and "you're" if you want a challenge.

Jim

RF is easy. COMEDY is difficult.

Some of the best I've ever known don't even have a BSEE.

Do tell? I've always thought that RF stopped where light began.

tripped up

Please don't listen to this clown. He isn't even aware that "police radio" (or as we who actually work in the field call it, "public service radio") goes all the way from just barely HF up into the low Gig region. I'd suggest a good read of 47CFR90 would give you some idea of what you are talking about.

Go away if you don't know what you are talking about.

Jim

Good gear for RF is not expensive these days, but perhaps the OP would like to start cheap: Some useful toys: : The Poor Man's Spectrum Analysis kit:

Ok, so its a slightly modified TV tuner, but for up to say 850 Mhz, its a decent vision of whats going on, and you learn about birdies and mixing and splatter and good RF construction practices. You build it once and then rebuild it in die cast boxes to clean up the birdies.

You need a decent oscilloscope , say 10 mhz, solid state deflection , CRT , minimum with it.

Then you read this paper and clean up the IF response and extend the range

I know there are better Spec An kits out there, but t 0-110 mhz doesn't get you much these days.

I will also agree that a decent scope is the best starting point.

A older varacter TV tuner (external pll) with the lid off is a wonderful place to start, even if your only other gear is a 99$ optoelectronics frequency counter.

I once asked Dr Wenzel to calibrate a diode for me, this paper was the result:

Then one of these:

Then one of these:

if you have no budget left after the 1N914 diode, the scope, and the spec an from the dead VCR, you go here:

Then some mini-circuits mmics and vcos.

The pro EEs here might laugh at me for this, but starting at this level with the above stuff in college got me to 10 Ghz SSB phase locked to a GPS reference.

If you have budget, a PTS160 from ebay is also a great bench tool

Steve Roberts

Steve ...

The one thing "pros" will *NOT* do is laugh at somebody who has learned the art and science of making cheap test equipment do the job of high-end equipment, and who knows the limitations of that method.

I was invited to give a session at RF Expo a few years ago and gave a paper on how to make a "tracking generator" from LF to a Gig for $20. (A good zener diode and a few MMIC amplifiers in chain make a dandy broadband noise source.) The moderator (the chief engineer for a "high end" test equipment company) had a hissyfit and claimed that I doctored the data. Fortunately I had the little rascal with me and we simply walked over to a test equipment vendor and hooked the thing up to their spectrum analyzer. Bingo. Red faced moderator.

Jim

to the OP

try the ARRL Handbook

and

These are good practical guides to RF

Mark

he

Thanks, I needed that.

One more good ham radio resource, but written with Attitude:

Green Bay Packet Radio:

Steve