Personally, I'd sooner resort to voluntary euthanasia than Maxwell's equations.
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I was taught that when the circuit size exceeds about 1/10 wavelength, Kirchoff's voltage and current laws as they are near DC representations of Maxwell's equations no longer hold, and you need to resort to Maxwell's equations.
Hugh Gilbert
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As I teach my college students: there is NO difference between Audio Frequency AC math and so called "Microwave" math. It all about the circuit models. Wavelength is the issue for what is important. In low frequency electronics, component size is extremely small compared to a wavelength - we ignore parasitic elements because their magnitude is much smaller than the lumped element value of the component so we use simple lumped models and ignore parasitics. At 10 kHz, who cares if the resistor leads have 10 nH of inductance.
However, at 10 GHz that same inductance represents a reactance of 62.8 ohms, significant if you are in a 50 ohm system. Its the argument of "Lumped" vs Distributed" that defines what is important at the frequency of operation. Not arbitrary designations. After I spent time in the MMW world working on systems for Uncle Sam, I would say "Everything below 1GHz is like DC, everything below 20 GHz is IF, and we get serious at 100 GHz". A lot of this thinking reflects availability of parts, the "make vs. buy" decision.
We have the Decimeter spectrum, the Centimeter Spectrum and the Millimeter - nice clear cut decades that define frequency ranges. Where do you think the terms UHF, SHF and EHF came from (look at the military designations). What can we ignore and whats important?
We when pass thru the arbitrary boundary of "Lumped vs Distributed" we leave the realm of simple lumped element circuit models that use voltages and currents to define the behaviors of our circuit elements and we enter the world of transmission line field concepts where we no longer look at I & V as carrying the "power", instead we consider field concepts like the Poynting vector and Maxwell-Heavyside mathematics. The fusion of math at this boundary is that of the EE and physicist - they have to provide the same (similar) answers. When lumped element thinking no longer adequately describes the behavior of your circuit elements, you have to go to alternative distributed field theory concepts (harder math) which, by the way, always works independent of frequency, albeit more cumbersome to solve.
So the frequency that was considered "FBM" over the years changed as our measurement technology changed. In my engineering days 1 GHz "sort of" was where microwaves started (3 GHz was technically the boundary for centimeter waves), and 30 GHz was clearly MMW. Waveguide would work fine at 100 MHz but would be too costly. However, I saw waveguide at 430 MHz for the planetary radar at Arecibo, when I visited in 1986, so, no, waveguide sizes vs frequency are not the defining issue for use, cost & simplicity are.
What was the argument about anyway? Sort of detoured from VNA's. Was it who defines what frequency range as magic vs. plebian ("microwave vs RF")? Depends on what the work is and who is doing the speaking. I have heard UHF TV broadcast engineers "pooh-poohing" AM Radio station engineers "You dont know how tough it is...".
Jeff Kruth
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I was considering the way it was handled as time went on.? I have a copy of a 1952 (or so) Radio Amateur's Handbook.? Their definition of UHF and the like has changed over the years.? They had experimental setups with a 2K21 (?) klystron.
Harvey
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On 11/6/2023 7:01 PM, Dr. David Kirkby, Kirkby Microwave Ltd wrote: On Mon, 6 Nov 2023 at 23:51, Harvey White <madyn@...> wrote:
I think that in some cases it had to do with whether or not you
had (or
could) use waveguide.? Presumably if you could/had to do
waveguide, that
was a "microwave".? I think at one time it included 400 Mhz, as
technology advanced, it crept up to 1 Ghz, and I rather suspect it's
around 2 at this time.
Just lots of guesses here.
Harvey
100 GHz is possible with coaxial cable. I doubt 1 THz is, but I don¡¯t know. (Yes, I could use Google ???)
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On Mon, 6 Nov 2023 at 23:51, Harvey White < madyn@...> wrote: I think that in some cases it had to do with whether or not you had (or
could) use waveguide.? Presumably if you could/had to do waveguide, that
was a "microwave".? I think at one time it included 400 Mhz, as
technology advanced, it crept up to 1 Ghz, and I rather suspect it's
around 2 at this time.
Just lots of guesses here.
Harvey
100 GHz is possible with coaxial cable. I doubt 1 THz is, but I don¡¯t know. (Yes, I could use Google ???)?
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I think that microwaves is 10^-2 ¡ 10^-3 meters free space wavelength range.? Ing. Patricio A. GrecoTaller Aeron¨¢utico de Reparaci¨®n 1B-349Organizaci¨®n de Mantenimiento Aeron¨¢utico de la Defensa OMAD-001Gral. Mart¨ªn Rodr¨ªguez 2159San Miguel (1663)Buenos AiresT:?+5411-4455-2557F:?+5411-4032-0072
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On 6 Nov 2023, at 20:26, Dr. David Kirkby, Kirkby Microwave Ltd <drkirkby@...> wrote:
? On Mon, 6 Nov 2023 at 17:14, G8HUL < g8hul@...> wrote:
They are not the same thing, but in the context of "radio frequency" the term radio is an adjective that just defines a certain range of frequencies, just as "audio frequency" defines a different range of frequencies.? No confusion, they are terms that have been in use for a century or so.
Microwave frequencies defines a sub-set of radio frequencies.
Regards
Jeff
Many people consider microwaves to be above 1 GHz. That¡¯s a sort of reasonable ¡°definition¡±. I have never seen any authoritative document that defines where microwaves start and finish.?
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I think that in some cases it had to do with whether or not you had (or could) use waveguide.? Presumably if you could/had to do waveguide, that was a "microwave".? I think at one time it included 400 Mhz, as technology advanced, it crept up to 1 Ghz, and I rather suspect it's around 2 at this time.
Just lots of guesses here.
Harvey
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On 11/6/2023 6:26 PM, Dr. David Kirkby, Kirkby Microwave Ltd wrote: On Mon, 6 Nov 2023 at 17:14, G8HUL <g8hul@...> wrote:
They are not the same thing, but in the context of "radio
frequency" the term radio is an adjective that just defines a
certain range of frequencies, just as "audio frequency" defines a
different range of frequencies.? No confusion, they are terms that
have been in use for a century or so.
Microwave frequencies defines a sub-set of radio frequencies.
Regards
Jeff
Many people consider microwaves to be above 1 GHz. That¡¯s a sort of reasonable ¡°definition¡±. I have never seen any authoritative document that defines where microwaves start and finish.
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On Mon, 6 Nov 2023 at 17:14, G8HUL < g8hul@...> wrote:
They are not the same thing, but in the context of "radio frequency" the term radio is an adjective that just defines a certain range of frequencies, just as "audio frequency" defines a different range of frequencies.? No confusion, they are terms that have been in use for a century or so.
Microwave frequencies defines a sub-set of radio frequencies.
Regards
Jeff
Many people consider microwaves to be above 1 GHz. That¡¯s a sort of reasonable ¡°definition¡±. I have never seen any authoritative document that defines where microwaves start and finish.?
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The ITU definition/use of the term "RF," for Radio Frequency, may cause conflation between the term "radio" and the term "radio frequency'"
They are not the same terms.
They are not the same thing, but in the context of "radio frequency" the term radio is an adjective that just defines a certain range of frequencies, just as "audio frequency" defines a different range of frequencies. No confusion, they are terms that have been in use for a century or so. Microwave frequencies defines a sub-set of radio frequencies. Regards Jeff
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On Sun, Nov 5, 2023 at 02:35 PM, Jinxie wrote:
Bowick's 'RF Circuit Design'
IMO, Pozar's book is more fundamental. Bowick like Pozar does seem to distinguish between RF design and microwave design... and between those and radio. IMO, they are not the same engineering regimes... and there are important differences. Pozar's book, like Lee's book, is more about microwave design.? I don't know if Boswick's book still has mistakes. But 2007, IMO, makes it a little dated for what 'practical' content it adds to Pozar's 2012 book. Anyway, Pozar's book has more on s parameters... which was the OP, on this thread.
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Roy,
Have you read this?
https://assets.cambridge.org/052183/5267/sample/0521835267ws.pdf
You seem to be making comments about a book you've never read based on the title alone. Name someone making advanced radios that don't have RF ICs. There are none.
I'd expect a good book on quantum mechanics to cover the boundary between classical physics and quantum mechanics in great detail explaining the relationship and the various factors that required the development of quantum mechanics. When is classical physics "good enough" and when it's necessary to shift to quantum mechanics.
Have Fun!
Reg On Monday, November 6, 2023 at 08:03:51 AM CST, Roy Thistle <roy.thistle@...> wrote:
On Thu, Nov 2, 2023 at 03:12 PM, Reginald Beardsley wrote: How you can consider microwaves as not RF is a bit odd. Well that seems to be something that others are saying; Just the same, it is right to point out that while microwaves are not mutually exclusive to the term "radio" neither are they identical with it, Lee mentions that. The ITU definition/use of the term "RF," for Radio Frequency, may cause conflation between the term "radio" and the term "radio frequency'" They are not the same terms. "Radio" is a cultural artifact that is much broader in its cultural significance... even when just confined to engineering. And that's only one difference. IMO... one wouldn't expect a book appropriately entitled "Quantum Mechanics" to be about classical physics... even if it mentioned classical physics frequently.
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On Thu, Nov 2, 2023 at 03:12 PM, Reginald Beardsley wrote:
How you can consider microwaves as not RF is a bit odd.
Well that seems to be something that others are saying; Just the same, it is right to point out that while microwaves are not mutually exclusive to the term "radio" neither are they identical with it, Lee mentions that. The ITU definition/use of the term "RF," for Radio Frequency, may cause conflation between the term "radio" and the term "radio frequency'" They are not the same terms. "Radio" is a cultural artifact that is much broader in its cultural significance... even when just confined to engineering. And that's only one difference. IMO... one wouldn't expect a book appropriately entitled "Quantum Mechanics" to be about classical physics... even if it mentioned classical physics frequently.
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Given the rave reviews here of Tom Lee's book I've ordered a copy (and thanks for the clarifications).
I'm now wondering if it's worthhwhile ordering the latest edition of Chris Bowick's 'RF Circuit Design'? I recall the first edition was a great read with much vital info that was missing from other such publications; only marred by some shocking errors in the worked examples given. I'd imagine they've corrected those in the new edition and expanded on some new topics as well. Does anyone here know?
?
Jinx.
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Re: N connector specification and HP 905A sliding load
Thanks Wally, that protocol sounds good.? I see the mismatch curve is at much greater separations than I was thinking, with the smallest entry on the chart being 5 mils, which is close to the max specfied anyway.? I was worrying about if I warmed up the outer but not the inner, then fixed the lock, then let it cool, that might do some damage to an expensive socket, but I like your plan about only nipping the loick up lightly.
Thanks v much
Neil
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On 02/11/2023 23:36, I_am Wally via groups.io wrote: Neil, there are several versions of the Microwave Connector Care document but this HP 1986 version has the most N connector data on pages 45-52, see in particular figure 19 on page 48 for the effect of a gap.
With my 905A I prefer to follow the manual instructions to butt out all gap but then engage the bidirectional lock knurled sleeve only as firmly as needed to keep the sliding load operating friction from disturbing the butted central line connection.
Play with the lock tightness and line end knob when not connected to any connector so you get a feel for the choice you have in lock firmness.? In my use the connection is brief, but if you should go off and leave the sliding load connected and then temperature cycle the lab, the habit of engaging the lock only as firmly as necessary for measurement will allow the lock clutch to slip if and when needed so the sliding load central line gives rather than pushing over the center conductor of the VNA instrument.
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Re: N connector specification and HP 905A sliding load
Neil, there are several versions of the Microwave Connector Care document but this HP 1986 version has the most N connector data on pages 45-52, see in particular figure 19 on page 48 for the effect of a gap.?
With my 905A I prefer to follow the manual instructions to butt out all gap but then engage the bidirectional lock knurled sleeve only as firmly as needed to keep the sliding load operating friction from disturbing the butted central line connection.?
Play with the lock tightness and line end knob when not connected to any connector so you get a feel for the choice you have in lock firmness.? In my use the connection is brief, but if you should go off and leave the sliding load connected and then temperature cycle the lab, the habit of engaging the lock only as firmly as necessary for measurement will allow the lock clutch to slip if and when needed so the sliding load central line gives rather than pushing over the center conductor of the VNA instrument.
Wally
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And make your own slotted line to measure frequency and other ancient gems.
I worked as a research scientist/programmer. You can bluff people, but you can't bluff the computer. I knew many senior advisors who would not read a book unless the company bought it and paid them to read it. Then they were shocked when they got laid off as they so justly deserved. If you won't invest in yourself, why should someone else invest in you by buying a book you won't bother to read?
Reg
On Thursday, November 2, 2023 at 05:13:22 PM CDT, Neil Smith G4DBN <neil@...> wrote:
Tom's book (ISBN 0521835267) is worth it just for the gems like how to
cook your own point-contact copper-oxide detector diodes using a South
Korean 10-won coin.
I have a WW2 US Army high-impedance headset, a WW2 grenade canister and
some period field-telephone wire, plus some 1944 blued razor blades and
US Army No2 yellow pencils to make a foxhole radio for a BBC TV
programme, but that segment was not filmed so I'm making a Youtube video
about it.? I just HAVE to do the "let's cook some coins" practical
demonstration.? Obviously I'll also have to do some vacuum sputtering of
copper on to various substrates, then some controlled oxidation.? It
would be rude not to.
The book also covers inverse Class F amplifiers, filter design and
pieces about the history of radio. What's not to like???? A brilliant
read.? My copy was once the property of the National University of
Ireland Library.? It was only loaned out once, on the 9th of June 2006.
It does have the WITHDRAWN stamp, so it's not the ill-gotten gains of
some pilfering student or impecunious lecturer.
The thug who borrowed it had the temerity to FOLD DOWN A CORNER of one
page.? Probably never read any of the rest of the book.? The gem that
the bookmark pointed to was Friis's cascaded system noise figure formula.
Right, enough fanboi fawning from me. Find the book at a good price.?
Buy a copy.? Enjoy.
Neil
On 02/11/2023 20:57, Roy Thistle wrote:
>
> According to a quick survey (of course not statistically valid)... of
> the locals..Prof. Lee's book is the best book they never read... or
> couldn't afford to read... topping our at 900 pages... and emptying
> the wallet at 200.00.
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Tom's book (ISBN 0521835267) is worth it just for the gems like how to cook your own point-contact copper-oxide detector diodes using a South Korean 10-won coin.
I have a WW2 US Army high-impedance headset, a WW2 grenade canister and some period field-telephone wire, plus some 1944 blued razor blades and US Army No2 yellow pencils to make a foxhole radio for a BBC TV programme, but that segment was not filmed so I'm making a Youtube video about it.? I just HAVE to do the "let's cook some coins" practical demonstration.? Obviously I'll also have to do some vacuum sputtering of copper on to various substrates, then some controlled oxidation.? It would be rude not to.
The book also covers inverse Class F amplifiers, filter design and pieces about the history of radio. What's not to like???? A brilliant read.? My copy was once the property of the National University of Ireland Library.? It was only loaned out once, on the 9th of June 2006. It does have the WITHDRAWN stamp, so it's not the ill-gotten gains of some pilfering student or impecunious lecturer.
The thug who borrowed it had the temerity to FOLD DOWN A CORNER of one page.? Probably never read any of the rest of the book.? The gem that the bookmark pointed to was Friis's cascaded system noise figure formula.
Right, enough fanboi fawning from me. Find the book at a good price.? Buy a copy.? Enjoy.
Neil
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On 02/11/2023 20:57, Roy Thistle wrote:
According to a quick survey (of course not statistically valid)... of the locals..Prof. Lee's book is the best book they never read... or couldn't afford to read... topping our at 900 pages... and emptying the wallet at 200.00.
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A very basic aspect of books is reading them. If you don't or can't read them they are of no use.
I have a 5000+ volume technical reference library. Many books were very expensive. Some I've read cover to cover and others I've spent 3-4 hours familiarizing myself so I can find the information when I need it. I made a lot of money by being the "expert" on Monday if no one knew anything in a Friday meeting. I had the books and could read at 600-800 wpm. So that determined what I was doing on the weekend. Books I'd only spent a few hours perusing were dragged off the shelves and I plowed through them.
I learned a lot about RF from Tom's book. But I'd spent hundreds of hours with "Solid State Design for the Radio Amateur" and Experimental Methods in RF Design" among many others over the course of the preceding 50 years.
"Planar Microwave Engineering" treats the effects of increasing frequency. How you can consider microwaves as not RF is a bit odd.
Reg On Thursday, November 2, 2023 at 03:57:58 PM CDT, Roy Thistle <roy.thistle@...> wrote:
On Thu, Nov 2, 2023 at 07:44 AM, Reginald Beardsley wrote: Yes, it is the best RF book I've ever read Finally de-crypted, it is Dr. Lee's book. And now we know that's the best book Reg has ever read on RF. According to a quick survey (of course not statistically valid)... of the locals..Prof. Lee's book is the best book they never read... or couldn't afford to read... topping our at 900 pages... and emptying the wallet at 200.00. Some were made to read it... but, that's de rigueur... if you evenly want to bump heads, in the faculty club. Not to say that it's over-page-age... or over priced... for today's text books. (If you want? to pay to save trees... the Kindle version is even more expensive.) I'd say ... if you can get it... 'read' it... or read it, if you've got that much time. The best book on microwave engineering... I never read... because I'd have to outlive Kirk Douglas... is really a bunch of books... The MIT Radiation Laboratory Series. They are tough to understand... and tough to read. And they are free. Some of the things they did... which were microwave 'rocket science' at the time...with cutting edge gear... are things hobbyist can now do... with gear that's available, without mortgaging the homestead. Lastly... before I go back to testing test equipment...IMO, Prof. Lee's book isn't about radio... oddly enough... I think its about planar microwave engineering... but, what do I know.
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N connector specification and HP 905A sliding load
I have an HP 905A sliding load which is complete with all of the
interchangeable pins and bodies for male/female N and APC7, but
there's a warning about never mating the connector pins with a
Precision-N male.? Is there a spec like MIL-C-39012C for Precision
N? That spec has the standard dimensions for checking pin offset,
and runout, but the most recent 1994 version doesn't mention
Precision-N.?? Is that MIL-C spec the canonical spec for N
connectors, or is there a higher authority that defines the
tolerance and dimensions and includes the Precision-N specs?
The manual says I can use IPA to clean the connector bodies
(which have the usual greenish decomposed foam guck on them) but
nothing like Acetone or other solvents. I'm wondering if a gentle
thrash in a warm ultrasonic bath of distilled water and surfactant
then an IPA rinse might be acceptable?? I can't get the guck off
with IPA alone.? Can anyone see why using volatile organic
solvents on the purely metal parts would be a problem? The
airline, load and main body are free of contaminants.? the lock
and slider works fine.
I'm laser-cutting a replacement EVA insert for the box.? I hope
it won't turn to goo and powder in my remaining lifetime.
Last question, the spec says the gap between the shoulder of the
N mail pin and the face of the female socket should be 0.001" to
0.007" but the 905A manual suggests pressing the plunger until the
pin stops moving, then locking it.? That doesn't feel at all
sensible to me.? I'd prefer to push it gently in, then back it off
by a tiny amount in case there's any differential thermal
expansion/contraction that might cause excess pressure on the
socket/pin.
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Jinxie
Dr. David Kirkby, Kirkby Microwave Ltd
Patricio A. Greco