how to learn low level RF design

[[email protected]]

On Dec 10, 7:03 am, [email protected] wrote:

Additionally,

figure out what each of the following components does by going to
websites of manufacturers of these components and reading their
application notes on them:

Isolator/circulator , PIN diode, Coupler, 3dB hybrid coupler, Power
splitter,
PIN diode/ PIN diode switch, Mixer (read all app notes you can find on
mixers), "off the shelf" filter (Read how to spec them and tradeoffs ,
and figure out different types of filters), SAW device, Voltage
Controlled Oscillator, varactor diode. PI/T attenuators. [ ok, just
thought of simple path: just go to "minicircuits" web site and read
every ap note they have and look at all their components and figure
out what they do]


Also, spend a lot of time thinking about sine waves and cosine waves.
Phase shifts, multiplication of sines/cosines. Figure out what
happens when you add two same exactly same frequency sigs together
(Hint you get same freq, with a phase shift and amplitude
adjustment). Spend time understanding concept of group delay and
phase shift.

 

[Simon S Aysdie]

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

He could be Prezident.

 

[Simon S Aysdie]

Green Bay Packet Radio:

http://www.qsl.net/n9zia/

by r.meck and g.white:

http://www.qsl.net/n9zia/metricom/metricom-900.jpg

 

[rex]

Im getting that Experimental methods in RF design book for sure,and I
will look at the other ones too. I found a library with it and I will
try to get the others too. Hope they dont mind if I keep it all for a
while

The library is good, but if you find it valuable enough to keep around,

Google: "experimental methods in rf design"

There are many places you can buy it to keep in your library. Your own
library is a good thing too.

 

[rex]

I'm excited!! Thanks for all the hints and tips folks! I am sure there
are many people like me who want to learn this and now all these
guidelines will be immortalized.

I probably shouldn't mention this since you have lots of good book
references already, but for RF, one book I have is a near-miss great
introduction. The book is "High Frequency Circuit Design" by James Hardy
1979.

I say near miss because it covers a lot of ground and prsents the
subjects in a very clear way -- all good so far -- but the book badly
needed a better editor.

Been a while since I looked at the problems, but I think I remember
examples where the math didn't quite work, a schematic or diagram that
wasn't quite right, stuff that made you scratch your head until you
figured out the book was just a little bit wrong.

So I only mention this book because 90+% of it was very good, but the
mistakes made it frustrating, especially if you were just learning. I
just did a google to see if there was a newer version that might be
better, but no. Seems just the one flawed version.

I still go to it for generally good straightforward coverage of many RF
topics, but I now hold a grain of scepticism if something doesn't seem
quite right and double check with other sources.

 

[T]

The library is good, but if you find it valuable enough to keep around,

Google: "experimental methods in rf design"

There are many places you can buy it to keep in your library. Your own
library is a good thing too.

Another good way is to get your Amateur Extra license. Get the study
guides from the ARRL, they actually present the theory as opposed to
drilling you on the question pool.

 

[JosephKK]

"I am talking about making a transmitter and receiver capable of
sending and receiving voice with 3khz bandwidth 1 mile line of sight,
so I suppose that puts me sub 100MHz, and also sub-par as far as my
effort to teach my self it according to one of you. "

Ignore those who are discouraging you. While it's true that it's unlikely
you'll understand every last little bit of a transceiver design if a handful
of months, that doesn't mean you shouldn't still build one and gain
appreciable knowledge.

"I figure if I could do that, from scratch, using discrete components,
that I would be able to accomplish all of my RF circuit goals for
life, which are basically farting around for fun."

You might find this book useful:
http://www.amazon.com/Build-Intelligent-Amateur-Radio-Transceiver/dp/0070282641

And I would suggest getting your technician class amateur radio license, since
then you can (legally) transmit over many more frequencies than you can
without one.

"The tricky part here is that I must be able to design the circuit from
scratch to have certain specific parameters, and not just monkey copy
something out of the ARRL book. Although that is an excellent
reference."

The ARRL does have a couple of decent design-oriented books besides just the
big monkey-copy book... "Introduction to Radio Frequency Design" by Wes
Hayward is good, as is "Experimental Methods in RF Design."

---Joel

Just the same the FCC has been making major changes to armature radio
licensing, no code any more, just novice, general and extra classes.
Go for it. I will soon.

 

[JosephKK]

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.

That is a little bit different viewpoint.

 

[JosephKK]

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

It is not that anything you contributed is actually incorrect. But do
you have to be nasty about it?

 

[JosephKK]

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

Arrogant overeducated nutter. "Clap, Clap, Clap, back in the box"

 

[JosephKK]

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:

http://www.science-workshop.com/

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

http://www.arrl.org/qex/Henkel.pdf

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:

http://www.techlib.com/files/detect.pdf

Then one of these:
http://www.aade.com/lcmeter.htm

Then one of these:

http://www.aade.com/dfd4.htm

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


http://web.telia.com/~u85920178/

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

This freaky love of GPS derived references astounds me. There is NO
technical justification for it. MARKETING.

 

[Nico Coesel]

I figure if I could do that, from scratch, using discrete components,
that I would be able to accomplish all of my RF circuit goals for
life, which are basically farting around for fun.

Yeah you are right, I "tried" to do this on my own about 8 years ago
before I even started working as an EE. I've learned quite a bit since
then and I bet I could learn it on my own now. But I am never going to
underestimate the difficulty of successful, non-accidental success of
RF circuitry design. If you can do it, you are pretty much in the
highest rung of the EE ladder, IMHO.

The tricky part here is that I must be able to design the circuit from
scratch to have certain specific parameters, and not just monkey copy
something out of the ARRL book. Although that is an excellent
reference.

Learning is copying. So what you basically need to do is get some test
equipment and start building circuits others have made (copying). The
next step is modifying the circuits according to your own
requirements. This will get you the understanding required to design
circuits yourself. But this won't happen overnight.

 

[Joerg]

Just the same the FCC has been making major changes to armature radio
licensing, no code any more, just novice, general and extra classes.
Go for it. I will soon.

But it ain't armature radio

Only when supplied by a nucular power station ...

 

[Joerg]

<snip>

But I still say RF is black magic. ;-)

Nah. After one or two decades things become quite normal

Tim

It's the biasing of JFETs that appears to be a dark art to me. Can get them
to do most of what I want, but not that last little bit... And can't seem
to find any info on this subject other than "It's best to use something like
Electronics Workbench."

They aren't much different than tubes, except that the bias voltages are
almost an order of magnitude lower and production spread in the
pinch-off region is very high. Easily +/-50%. On the bonus side they are
more than two orders of magnitude cheaper than tubes were. And you don't
get zinged so often.

 

[JosephKK]

But it ain't armature radio

Only when supplied by a nucular power station ...

Naw, it just takes a rotating antenna.

 

[JosephKK]

I don't think he's wrapped to tight.

Naw, my spelling brushes are just a little loose.

 

[JosephKK]

Who do you think you are? Radar O'Riley?

If i ever find "A Radar Man with Dipole Feet" again i will send you
copy. Circa 1975 by Jacob van Compernole.

 

[JosephKK]

What's wrong with Merrill I. Skolnik's 'Radar Handbook'?

I would not know. But the target audience, the style and intended
result are different.