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Smith Chart
I've added a Smith Chart graphic to my All-HF-Band-No-Tuner-Antenna
information on my web page. -- 73, Cecil http://www.qsl.net/w5dxp/smith.htm ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
"Cecil Moore" wrote in message ... I've added a Smith Chart graphic to my All-HF-Band-No-Tuner-Antenna information on my web page. -- 73, Cecil http://www.qsl.net/w5dxp/smith.htm =---- Its a purty chart, too. I've got nothing but respect for folks that have the patience to sit down and figure out how to use one of those. |
"Hal Rosser" wrote in message . .. "Cecil Moore" wrote in message ... I've added a Smith Chart graphic to my All-HF-Band-No-Tuner-Antenna information on my web page. -- 73, Cecil http://www.qsl.net/w5dxp/smith.htm =---- Its a purty chart, too. I've got nothing but respect for folks that have the patience to sit down and figure out how to use one of those. Hal It surprises me to read that you consider the Smith Chart difficult to use. I'd bet that you could figure out how to use one to your benefit within 20 minutes of asking questions of someone who uses them. Jerry |
Jerry:
He may mean it in the sense of using a sliderule--why if you have a program, programmable calculator to give results? Warmest regards, John "Jerry Martes" wrote in message news:Omrne.10735$m%3.9929@trnddc02... "Hal Rosser" wrote in message . .. "Cecil Moore" wrote in message ... I've added a Smith Chart graphic to my All-HF-Band-No-Tuner-Antenna information on my web page. -- 73, Cecil http://www.qsl.net/w5dxp/smith.htm =---- Its a purty chart, too. I've got nothing but respect for folks that have the patience to sit down and figure out how to use one of those. Hal It surprises me to read that you consider the Smith Chart difficult to use. I'd bet that you could figure out how to use one to your benefit within 20 minutes of asking questions of someone who uses them. Jerry |
Hal
It surprises me to read that you consider the Smith Chart difficult to use. I'd bet that you could figure out how to use one to your benefit within 20 minutes of asking questions of someone who uses them. Jerry Jerry, You're probably right. I could probably lean how in an afternoon. I sat down with one I printed out once, and thought I had it figured out. Then when I needed to use it again, I would need to be retrained. I remember how to use an MFJ259 from use to use, though. :-) I just don't have the patience - it just doesn't grab my attention like a gizmo does. |
So now you're pickin' on my slide rule? Is nothing sacred??
I like my slide rule. Its more useful than my solar-powered flashlight. The slide rule works without any power or batteries. :-) And its accurate to 3 (sometimes 4) significant digits. "John Smith" wrote in message ... Jerry: He may mean it in the sense of using a sliderule--why if you have a program, programmable calculator to give results? Warmest regards, John |
Hal:
I too am lazy... I think we found one thing we agree on... a beer in a hammock with a programmable calculator is to be preferred to a table, straightedge and smith chart... besides, I scribble on 'em.... frown Warmest regards, John "Hal Rosser" wrote in message . .. Hal It surprises me to read that you consider the Smith Chart difficult to use. I'd bet that you could figure out how to use one to your benefit within 20 minutes of asking questions of someone who uses them. Jerry Jerry, You're probably right. I could probably lean how in an afternoon. I sat down with one I printed out once, and thought I had it figured out. Then when I needed to use it again, I would need to be retrained. I remember how to use an MFJ259 from use to use, though. :-) I just don't have the patience - it just doesn't grab my attention like a gizmo does. |
I have an old pickett slide around here somewhere--ahhh, like you, never
throw anything away lol.... Warmest regards, John "Hal Rosser" wrote in message . .. So now you're pickin' on my slide rule? Is nothing sacred?? I like my slide rule. Its more useful than my solar-powered flashlight. The slide rule works without any power or batteries. :-) And its accurate to 3 (sometimes 4) significant digits. "John Smith" wrote in message ... Jerry: He may mean it in the sense of using a sliderule--why if you have a program, programmable calculator to give results? Warmest regards, John |
"John Smith" wrote in message ... Hal: I too am lazy... I think we found one thing we agree on... a beer in a hammock with a programmable calculator is to be preferred to a table, straightedge and smith chart... besides, I scribble on 'em.... frown Warmest regards, John Scribbble on 'em?? That implies you have occasionally used the old-fashioned "pencil". Lets narrow it down to the beer and hammock for now. ;-) not partial to calculators, phones, or loud music. |
I should point out, everyone should at least know about a smith and have
used it... kinda gives you a "feel" for the way all the variables work together... it is a good thing... Warmest regards, John "John Smith" wrote in message ... Hal: I too am lazy... I think we found one thing we agree on... a beer in a hammock with a programmable calculator is to be preferred to a table, straightedge and smith chart... besides, I scribble on 'em.... frown Warmest regards, John "Hal Rosser" wrote in message . .. Hal It surprises me to read that you consider the Smith Chart difficult to use. I'd bet that you could figure out how to use one to your benefit within 20 minutes of asking questions of someone who uses them. Jerry Jerry, You're probably right. I could probably lean how in an afternoon. I sat down with one I printed out once, and thought I had it figured out. Then when I needed to use it again, I would need to be retrained. I remember how to use an MFJ259 from use to use, though. :-) I just don't have the patience - it just doesn't grab my attention like a gizmo does. |
"John Smith" wrote in message ... I have an old pickett slide around here somewhere--ahhh, like you, never throw anything away lol.... Warmest regards, John The term "old slide rule" is a bit redundant, some would say. My new slide rule is only about 30 yrs old. Plenty of life left in it. |
I agree - like I said - I have nothing but respect for those who figure them
out. |
Hal Rosser wrote:
So now you're pickin' on my slide rule? Is nothing sacred?? I like my slide rule. Its more useful than my solar-powered flashlight. The slide rule works without any power or batteries. :-) And its accurate to 3 (sometimes 4) significant digits. Solar powered flashlight? Heck, we have a made up loony lefty here in Minneapolis who wants people to use electric powered generators to reduce noise and pollution during emergencies. Morgan Q. E. Wolfe-Slattery, a true Euphorian. I have 2 slide rules that I picked up recently, but I miss my easy on the eyes yellow aluminum Pickett LogLogDeciTrig (I think that's what it was) that got misplaced during a move a couple decades ago. I also wish I still had my HP35, 45 and 11C. I do have a working HP25, 15C and 48SX though. tom K0TAR |
Hal:
Ok, but that was not pointed towards you... just a general, "Aye!" for the smith chart... I can't imagine every ham without one on the wall they just look kewl too, with the world map--and I am quite serious about that... ... many visitors to a station appreciate it if you generate a bit of atmosphere for 'em.... nod-and-a-wink Regards, John "Hal Rosser" wrote in message .. . I agree - like I said - I have nothing but respect for those who figure them out. |
"Hal Rosser" wrote in message . .. Hal It surprises me to read that you consider the Smith Chart difficult to use. I'd bet that you could figure out how to use one to your benefit within 20 minutes of asking questions of someone who uses them. Jerry Jerry, You're probably right. I could probably lean how in an afternoon. I sat down with one I printed out once, and thought I had it figured out. Then when I needed to use it again, I would need to be retrained. I remember how to use an MFJ259 from use to use, though. :-) I just don't have the patience - it just doesn't grab my attention like a gizmo does. Hal First off -- I realize that you are eperienced enough with antenna analysis to know what is needed for matching them. And, if you did want to use a Smith Chart, you'd have done it by now. I wont embarrass myself by telling you anything I know about them. But, they sure can help identify what kind of impedance is needed for a matching network. Any impedance with a real resistive value can be plotted on the chart. Then, its location immediately identifies what reactance will move the unmatched impedance toward a matched location. I think you already knew that. I also think you could teach me how to look at matching devices from a more practical perspective. Jerry |
"Cecil Moore" wrote in message
... I've added a Smith Chart graphic to my All-HF-Band-No-Tuner-Antenna information on my web page. -- 73, Cecil http://www.qsl.net/w5dxp/smith.htm ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- There is an excellent limited, and free, Smith Chart program at this site: http://www.janson-soft.de/seminare/dh7uaf/ Scroll down and look for the for the following, download (308 kB), and unzip. The link below may also work from this posting. Smith V1.91 (Smith.exe), Smith-Diagramm-Programm (Download hier): Demo-Version der FH Bern für Win (bis zu 5 Bauteile, L, R, C, Trafo, Stubs und Trafo-Leitungen mit verschiedenen Wellenwiderständen, kein. A few moments playing with the program should reveal the simplicity and power of the Smith Chart. The program was developed at the University of Applied Science, Berne. 73, Frank |
Jerry Martes wrote:
It surprises me to read that you consider the Smith Chart difficult to use. I'd bet that you could figure out how to use one to your benefit within 20 minutes of asking questions of someone who uses them. The Smith Chart is relatively easy to learn in steps. First step is to learn how to normalize impedances and plot them on the Smith Chart. The 1.0 in the center of the chart is the normalized Z0 of the feedline. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
John Smith wrote:
I should point out, everyone should at least know about a smith and have used it... kinda gives you a "feel" for the way all the variables work together... it is a good thing... For me, the biggest advantage of the Smith Chart is that I can carry it around in my head. It is a graphical math model of a transmission line. A picture is worth a thousand calculators. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Cecil:
I wasn't being cynical, and although I cannot "carry it in my head", it is good for the example chart, I agree, a picture is worth a thousand words--I was not poking fun... but hey, it does look kewl.... I am not above cheap tricks to impress my company... perhaps I admit my failing here to be poked fun at--but the first time I seen one--was pretty damn impressed!!! (still am actually) Warmest regards, John "Cecil Moore" wrote in message ... John Smith wrote: I should point out, everyone should at least know about a smith and have used it... kinda gives you a "feel" for the way all the variables work together... it is a good thing... For me, the biggest advantage of the Smith Chart is that I can carry it around in my head. It is a graphical math model of a transmission line. A picture is worth a thousand calculators. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
"Cecil Moore" wrote in message ... The Smith Chart is relatively easy to learn in steps. First step is to learn how to normalize impedances and plot them on the Smith Chart. The 1.0 in the center of the chart is the normalized Z0 of the feedline. -- 73, Cecil http://www.qsl.net/w5dxp The mention of the Smith Chart and slide rules in the same breath brings back a lot of memories. They put meat and potatoes on the table for me and my family for many years. I was fortunate to be in the right place at the right time at the beginning of space exploration, during which time I had the rare priviledge of developing antenna systems for several different spacecraft while working at the antenna lab of the RCA Laboratories, and at RCA's Space Center, the RCA Astro-Electronic Division until I retired in 1980. The most challenging assignment was developing the antennas that flew on the World's first weather satellite, TIROS 1, and several of its successors. The challenge involved developing a transmitting antenna array that would radiate right-hand circular polarization from two transmitters and left hand circular from two other transmitters. The four VHF transmitters operated simultaneously on four separate frequencies in two non-harmonically related bands. The real challenge was in developing a matching circuit to couple the four transmitters to the single antenna comprised of two crossed dipoles. The circuit was constructed entirely of printed circuit stripline transmission line. The reason for telling you this is that all the calculations during the development of both the radiators and the matching circuit were performed with only a slide rule and the Smith Chart. There were no calculators or computers available at that time. Without the Smith Chart the impedance calculations would have been so tedious that the project would have failed due to the lack of time to complete them. My Dad gave me a simple wooden slide rule when I was thirteen and taking advanced algebra. Then in my senior class, beginning at fifteen, he gave me an ivory Kueffel and Esser trig rule. While teaching electronic students in the Navy during WW2, I acquired another K and E rule, this time a log log decitrig. Then while developing antennas at RCA in the 50s and 60s I acquired another log log decitrig, this time an aluminum Picket and Eckel. I still have all of these rules in my 'antique calculator' museum. My first calculator was an HP-35, which replaced the slide rules--couldn't believe I was going from three significant figure precision to nine and greater! I later acquired an HP-45, then a 55, followed by a 34-C, 15-C, and a 42-S. I still have batteries fully charged in the last four calculators ready for use. And even though I have several Smith Chart programs, some of which appear in Chapter 15 of Reflections, I still use the slide-rule version of the Smith Chart in solving certain impedance matching problems. That's the story of my love affair with slide rules and the Smith Chart. Walt, W2DU PS--Chapters 10 and 11 in Reflections present a primer in learning how to understand and use the Smith Chart. |
On Wed, 01 Jun 2005 09:15:05 -0500, Cecil Moore
wrote: I've added a Smith Chart graphic to my All-HF-Band-No-Tuner-Antenna information on my web page. I finally got to see the picture. Earlier, it loaded so slowly I only got to see the top 10% after ten minutes or so. If i read it correctly, you are saying that by adjusting the feedline length, you have a 50 match at any band. It sounds like this antenna and feed match.... http://www.qsl.net/w5dxp/notuner.htm -- 73 for now Buck N4PGW |
I can honestly say I've never used a Smith Chart in anger in the whole of my life. Never had one in my possession for more than a minute just to inspect it. Or by chance came across a condensed version in a book. And I've worked on and with transmission lines from 0.1 Hz to 3000 MHz. At frequencies at which the Smith Chart is misleading and useless. I just didn't attend the same school as you lot. It's habit forming like alcohol, tobacco and women. You can't think straight without one in front of you. ;o) But I do appreciate the love and respect you all have for it. ---- Reg. |
Buck wrote:
Cecil Moore wrote: I've added a Smith Chart graphic to my All-HF-Band-No-Tuner-Antenna information on my web page. I finally got to see the picture. Earlier, it loaded so slowly I only got to see the top 10% after ten minutes or so. QSL.NET is notoriously slow. I'm going to get a new web page supplier one of these days. If i read it correctly, you are saying that by adjusting the feedline length, you have a 50 match at any band. Close - by adjusting the feedline length, I have between a 25+j0 ohm and a 100+j0 ohm "match" on any HF ham band. Any purely resistive impedance between 25 ohms and 100 ohms will yield a 50 ohm SWR less than 2:1. Most transmitters are satisfied with an SWR of less than 2:1. Any 450 ohm SWR between 4.5:1 and 18:1 (in the green zone) will yield a 50 ohm SWR less than 2:1 if the proper length of feedline is chosen. It sounds like this antenna and feed match.... It is a tuned feeder that tunes the antenna system to resonance. To get a 50 ohm SWR less than 2:1, the dipole needs to be 1/2 wavelength on the lowest frequency of operation. That makes virtually all antenna feedpoint impedances fall within the green target zone. For instance, this feedline length adjustment will not work on a 102 ft. dipole (G5RV) used on 80m. The low R and high X causes the 450 ohm SWR to be higher than 18:1 so a 50 ohm SWR of 2:1 is impossible without a tuner or network. Here's the math: 450/18 = 25 ohms 50/25 = 2:1 SWR at current maximum point 450/4.5 = 100 ohms 100/50 = 2:1 SWR at current maximum point -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
"Reg Edwards" wrote in message ... I can honestly say I've never used a Smith Chart in anger in the whole of my life. Never had one in my possession for more than a minute just to inspect it. Or by chance came across a condensed version in a book. And I've worked on and with transmission lines from 0.1 Hz to 3000 MHz. At frequencies at which the Smith Chart is misleading and useless. I just didn't attend the same school as you lot. It's habit forming like alcohol, tobacco and women. You can't think straight without one in front of you. ;o) But I do appreciate the love and respect you all have for it. ---- Reg. Reg, you've aroused my curiosity on three points: Why would you use 'Smith Chart' and 'anger' in the same sentence? Why are there any frequencies where the Smith Chart is misleading and useless? Which frequencies are they? How can you say the Smith Chart is misleading and useless if you've never used one, and never inspected one for more than a minute? Walt, W2DU |
On Thu, 2 Jun 2005 08:58:25 -0400, "Walter Maxwell"
wrote: Why would you use 'Smith Chart' and 'anger' in the same sentence? Hi Walt, You've made the mistake of taking Reggie seriously for the wrong points - but as it was by his design that you do so, you can be forgiven. Walt, please note that all occurrences of "You" are meant to apply to the general reader. Those general readers may now turn their attention aside as I diverge into meaning, a dark arena few enter fully prepared to emerge from. As much as he rails about my "Shakespearian" language - style, nothing else; his own - style that is - is as a Primitive. For many who have little appreciation or training in the arts (writing being one of them), being labeled a Primitive is not demeaning, it is merely descriptive. As I offhandedly pointed out in another post, mine is a Norman style to his Anglo-Saxon. The difference is not intelligence, but persuasion. In other contexts, like religion, one might use the word fundamentalist; hence the allusion drawn in the sentence you responded to that ties together two disparate worlds as though the association were an ethical choice. Reg could have as easily compared varieties of wine to a Smith Chart - a gustatorial choice, but still a primitive or fundamental balance. (Myself, to extend the metaphor of religion, I would offer catholic choices.) For either of us, if you simply divorce the style, content will emerge, and I promise you find nothing to argue with. Unless arguing is your only interest in posting, that is. We (Reg and I), each in our own way, go rather the long way around the barn to say something simple. I for one (and Reg by example, so I won't speak directly to his motivation) are not here to simply litter facts across the board. No you all have to suffer understanding too (as too many of you already had the facts available before you asked any question). So as an exercise, when you strip away style, what is left is: But I do appreciate the love and respect you all have for it. 73's Richard Clark, KB7QHC |
Walter:
I think I might be able to guess why---when I first attempted to use one--I tore it up and said some angry words (darn right nasty I suspect)... I was a bit slow catching on with the smith chart, I am sure you all were much more gifted and speedier... grin Warmest regards, John "Walter Maxwell" wrote in message ... "Reg Edwards" wrote in message ... I can honestly say I've never used a Smith Chart in anger in the whole of my life. Never had one in my possession for more than a minute just to inspect it. Or by chance came across a condensed version in a book. And I've worked on and with transmission lines from 0.1 Hz to 3000 MHz. At frequencies at which the Smith Chart is misleading and useless. I just didn't attend the same school as you lot. It's habit forming like alcohol, tobacco and women. You can't think straight without one in front of you. ;o) But I do appreciate the love and respect you all have for it. ---- Reg. Reg, you've aroused my curiosity on three points: Why would you use 'Smith Chart' and 'anger' in the same sentence? Why are there any frequencies where the Smith Chart is misleading and useless? Which frequencies are they? How can you say the Smith Chart is misleading and useless if you've never used one, and never inspected one for more than a minute? Walt, W2DU |
In article ,
Tom Ring wrote: I have 2 slide rules that I picked up recently, but I miss my easy on the eyes yellow aluminum Pickett LogLogDeciTrig (I think that's what it was) that got misplaced during a move a couple decades ago. Keep your eye on eBay. Chances are good that you can pick up the exact model you had before, either used-in-good-condition or new-old-stock, for a reasonable price. I'll admit that there's a danger to this, though. I started collecting slide rules a few years ago, out of nostalgia, and got bitten by the bug. I'm up to about 40 of them now... everything from little 5" slipsticks, to an 8" circular, to an Otis King L cylindrical in really fabulous condition. There are even a few (a Concise circular, and a Pickett aluminum rule) with specialized X/L/C/F scales for doing resonant-circuit calculations. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Dave Platt wrote:
In article , Tom Ring wrote: I have 2 slide rules that I picked up recently, but I miss my easy on the eyes yellow aluminum Pickett LogLogDeciTrig (I think that's what it was) that got misplaced during a move a couple decades ago. Keep your eye on eBay. Chances are good that you can pick up the exact model you had before, either used-in-good-condition or new-old-stock, for a reasonable price. I'll admit that there's a danger to this, though. I started collecting slide rules a few years ago, out of nostalgia, and got bitten by the bug. I'm up to about 40 of them now... everything from little 5" slipsticks, to an 8" circular, to an Otis King L cylindrical in really fabulous condition. There are even a few (a Concise circular, and a Pickett aluminum rule) with specialized X/L/C/F scales for doing resonant-circuit calculations. Oh, I know. I got bit by writing the response. I bought a K&E 1948 rule last night from ebay. 8.25 plus shipping. What a deal. tom K0TAR |
On Wed, 01 Jun 2005 09:15:05 -0500, Cecil Moore
wrote: I've added a Smith Chart graphic to my All-HF-Band-No-Tuner-Antenna information on my web page. This might very well be the best opportunity that I will ever have to get in a plug for SmartSmith, which is not a demo but rather a full featured SmithChart program with extensive Help file and is available completely free at the following: Download Site: http://zaffora.f2o.org/W9DMK/W9dmk.html High Speed Download Site: http://64.217.230.66 Bob, W9DMK, Dahlgren, VA Replace "nobody" with my callsign for e-mail http://www.qsl.net/w9dmk http://zaffora/f2o.org/W9DMK/W9dmk.html |
Reg, you've aroused my curiosity on three points:
Why would you use 'Smith Chart' and 'anger' in the same sentence? ======================================== Just a figure of speech. "Anger" suggests setting about a job with energy, determination and a sense of purpose. As distinct from mere amusement. ======================================== Why are there any frequencies where the Smith Chart is misleading and useless? Which frequencies are they? ======================================== Depending on the size of the errors one is prepared to tolerate and on the calculated parameter of interest - Frequencies at which line attenuation per wavelength is not small. Frequencies at which Zo is not purely real. Frequencies at which CR is not equal to LG. Frequencies at which the reflection coefficient is greater than 1.0 Comment : Zo is never purely real. CR is never equal to LG. And the chart is good only to 2-digit accuracy anyway. But Walt, you already know all this. Have you ever tried the Jones Chart? ;o) ======================================== How can you say the Smith Chart is misleading and useless if you've never used one, and never inspected one for more than a minute? Walt, W2DU ======================================== No problem! Worked it out for myself many years ago. Some years ago I introduced to this newsgroup the excellent book "Transmission Lines" by Robert A. Chipman, 1968. It aroused some interest. Some of you obtained a copy. It has a whole chapter devoted to the Smith Chart and fully describes its limitations, imperfections, short-comings and approximations. But the reason Chipman included the chapter was because of the great savings in labour and time (in HIS day and age) when doing approximate calculations on short, low loss, HF transmission lines such as antenna feedlines for which it was designed. Which is all radio amateurs ever use it for. Hardly any amateurs ever use it in anger. It has other applications. I first programmed a computer for work on transmission lines around 1960. At frequencies between 0.1 Hz and 1 MHz, frequencies at which nobody would dream of using a Smith Chart. So I never became addicted to it. ---- Reg. |
Reg:
Dr. Jones was in heavy competition with my father (Mr. Smith), before my dad developed the "Smith Chart." Darn "Jones Chart" never was any good! grin Warmest regards, John "Reg Edwards" wrote in message ... Reg, you've aroused my curiosity on three points: Why would you use 'Smith Chart' and 'anger' in the same sentence? ======================================== Just a figure of speech. "Anger" suggests setting about a job with energy, determination and a sense of purpose. As distinct from mere amusement. ======================================== Why are there any frequencies where the Smith Chart is misleading and useless? Which frequencies are they? ======================================== Depending on the size of the errors one is prepared to tolerate and on the calculated parameter of interest - Frequencies at which line attenuation per wavelength is not small. Frequencies at which Zo is not purely real. Frequencies at which CR is not equal to LG. Frequencies at which the reflection coefficient is greater than 1.0 Comment : Zo is never purely real. CR is never equal to LG. And the chart is good only to 2-digit accuracy anyway. But Walt, you already know all this. Have you ever tried the Jones Chart? ;o) ======================================== How can you say the Smith Chart is misleading and useless if you've never used one, and never inspected one for more than a minute? Walt, W2DU ======================================== No problem! Worked it out for myself many years ago. Some years ago I introduced to this newsgroup the excellent book "Transmission Lines" by Robert A. Chipman, 1968. It aroused some interest. Some of you obtained a copy. It has a whole chapter devoted to the Smith Chart and fully describes its limitations, imperfections, short-comings and approximations. But the reason Chipman included the chapter was because of the great savings in labour and time (in HIS day and age) when doing approximate calculations on short, low loss, HF transmission lines such as antenna feedlines for which it was designed. Which is all radio amateurs ever use it for. Hardly any amateurs ever use it in anger. It has other applications. I first programmed a computer for work on transmission lines around 1960. At frequencies between 0.1 Hz and 1 MHz, frequencies at which nobody would dream of using a Smith Chart. So I never became addicted to it. ---- Reg. |
Reg Edwards wrote:
Depending on the size of the errors one is prepared to tolerate and on the calculated parameter of interest - Frequencies at which line attenuation per wavelength is not small. There's an attenuation scale on the bottom. Doesn't it just result in an SWR spiral instead of an SWR circle? -- 73, Cecil, http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
"John Smith" wrote in message
... Dr. Jones was in heavy competition with my father (Mr. Smith), before my dad developed the "Smith Chart." Darn "Jones Chart" never was any good! grin Warmest regards, John John, are you telling us that Phillip H. Smith was your Father? I have a letter from him dated in 1972, giving me permission to publish his Chart in one of my articles in QST. Walt, W2DU |
"Reg Edwards" wrote in message ... Reg, you've aroused my curiosity on three points: Why would you use 'Smith Chart' and 'anger' in the same sentence? ======================================== Just a figure of speech. "Anger" suggests setting about a job with energy, determination and a sense of purpose. As distinct from mere amusement. And I thought I understood the English language. Obviously I miss some of the ways you Brits use it. Thanks for the clarification--makes sense now. ======================================== Why are there any frequencies where the Smith Chart is misleading and useless? Which frequencies are they? ======================================== Depending on the size of the errors one is prepared to tolerate and on the calculated parameter of interest - Frequencies at which line attenuation per wavelength is not small. Frequencies at which Zo is not purely real. Frequencies at which CR is not equal to LG. Frequencies at which the reflection coefficient is greater than 1.0 Comment : Zo is never purely real. CR is never equal to LG. And the chart is good only to 2-digit accuracy anyway. But Walt, you already know all this. Have you ever tried the Jones Chart? ;o) You're right, Reg, I do know this, but as Cecil has just now beat me to the punch, the attenuation scale that goes with the Smith Chart allows the complex impedance loci to spiral inward with line length for any given value of line attenuation. The loci is a circle only for lossless lines, but you already know this. ======================================== How can you say the Smith Chart is misleading and useless if you've never used one, and never inspected one for more than a minute? Walt, W2DU ======================================== No problem! Worked it out for myself many years ago. Some years ago I introduced to this newsgroup the excellent book "Transmission Lines" by Robert A. Chipman, 1968. It aroused some interest. Some of you obtained a copy. I used the Chipman tome since around 1969, shortly after it was released. Interesting that you introduced it to this NG in 1968, but I didn't learn of this NG until the 1990s. I have two copies, one at each of my homes in Michigan and Florida. It has a whole chapter devoted to the Smith Chart and fully describes its limitations, imperfections, short-comings and approximations. But the reason Chipman included the chapter was because of the great savings in labour and time (in HIS day and age) when doing approximate calculations on short, low loss, HF transmission lines such as antenna feedlines for which it was designed. Which is all radio amateurs ever use it for. Hardly any amateurs ever use it in anger. It has other applications. I first programmed a computer for work on transmission lines around 1960. At frequencies between 0.1 Hz and 1 MHz, frequencies at which nobody would dream of using a Smith Chart. So I never became addicted to it. ---- Reg. Very interesting, Reg, but of course I knew of your many years of work with undersea lines, so use of computers around 1960 doesn't surprise me. A little bird told me one day that those lines aren't lossless. But, shucks, I coulda found that out if I'd only dug deeper into Chipman, couldn't I? Thanks for the informative response, Reg, Walt |
Walter:
Next you will be wanting the secret of my fathers long life--and how he was able to do it all before the discovery of Viagra!!! innocent-look-and-a-chuckle Warmest regards, John "Walter Maxwell" wrote in message ... "John Smith" wrote in message ... Dr. Jones was in heavy competition with my father (Mr. Smith), before my dad developed the "Smith Chart." Darn "Jones Chart" never was any good! grin Warmest regards, John John, are you telling us that Phillip H. Smith was your Father? I have a letter from him dated in 1972, giving me permission to publish his Chart in one of my articles in QST. Walt, W2DU |
On Fri, 3 Jun 2005 10:49:58 -0400, "Walter Maxwell"
wrote: John, are you telling us that Phillip H. Smith was your Father? Hi Walt, I'm sorry to have the distinction of telling you that you have now twice tried to bite at air in two postings to the same thread. [Outlook Express is a jinx for you to use!] There is no "John Smith" corresponding to this group. Brett uses this "handle" for whatever reason, but certainly not because he thinks that his veil is impenetrable. 73's Richard Clark, KB7QHC |
"John Smith" wrote in message ... Walter: Next you will be wanting the secret of my fathers long life--and how he was able to do it all before the discovery of Viagra!!! innocent-look-and-a-chuckle Warmest regards, John "Walter Maxwell" wrote in message ... "John Smith" wrote in message ... John, your father was a genious. His pioneering in the field of wave guides at Bell Labs is legend. I also have his book, "Electronic Applications of the Smith Chart," from which I drew many concepts for use in Reflections to disprove prevalent myths concerning SWR and other mechanics of reflections. Consequently, there are many references to his book in mine, including two entire chapters to aid in learning how to use his Chart. Walt, W2DU |
"Richard Clark" wrote in message ... On Fri, 3 Jun 2005 10:49:58 -0400, "Walter Maxwell" wrote: John, are you telling us that Phillip H. Smith was your Father? Hi Walt, I'm sorry to have the distinction of telling you that you have now twice tried to bite at air in two postings to the same thread. [Outlook Express is a jinx for you to use!] There is no "John Smith" corresponding to this group. Brett uses this "handle" for whatever reason, but certainly not because he thinks that his veil is impenetrable. 73's Richard Clark, KB7QHC Holy Cow, Richard, you've just diagnosed the pain in my jaw. Silly me. I guess that means that the 'John Smith' we're corresponding with came over on the Mayflower. Walt, W2DU |
On Fri, 3 Jun 2005 11:14:51 -0400, "Walter Maxwell"
wrote: Why would you use 'Smith Chart' and 'anger' in the same sentence? ======================================== Just a figure of speech. "Anger" suggests setting about a job with energy, determination and a sense of purpose. As distinct from mere amusement. And I thought I understood the English language. Obviously I miss some of the ways you Brits use it. Thanks for the clarification--makes sense now. Hi Walt, I won't accuse you biting air on this one, again, Reg is in his usual yarn spinning and this time both of you evidence the myth of those who "use" a language believing they "know" that language. Brits are terrible exemplars of best English usage. So are Americans, but they rarely behave like they own the language they dominate (that is changing as we write - the rest of the world is going to soon claim that crown). Reg has in fact fallen off the Anglo-Saxon wagon (or should I say cart?) by trying to fit a new definition to an Old French import to our common language. In a way, he has succumbed to the worst traits of Americanizing English through cavalier redefinition. Anger has always (to English speakers at least) meant just what you thought it to mean - relating directly to the sense of pain or affliction. Somehow Reg wants to convert those rather daily experienced negative associations into something bright and cheerful. Perhaps he has been reading too many missives from our White House's pronouncements on the conduct of the war.... Anger comes by way of the Old French anquisse, or the Modern French angoisse, derived from the Latin augustia meaning compression. Most folks do not smile in anticipation of anguish becoming their "sense of purpose." Not unless you are a fundamentalist perhaps. Who would'a' thunk that this thread could be such a trove of language instruction? ;-) 73's Richard Clark, KB7QHC |
On Fri, 03 Jun 2005 08:52:00 -0700, Richard Clark
wrote: Most folks do not smile in anticipation of anguish becoming their "sense of purpose." Not unless you are a fundamentalist perhaps. From my copy of the "Concise Dictionary of the English Language" (available at project Gutenberg): Angre ... affliction, sorrow, wrath, pain, inflammation ... by way of the Icelandic angr. Angren ... to annoy, injure, make angry ... by way of the Icelandic angra. Angwisch ... anguish anguyssh ... angoise anguise ... anguisse ... angustia, tightness from angere, to squeeze. Amusingly enough, every one of these terms encountered in line are directly following: Angles ... the English, the people of 'Angul' a district of Holstein .... Englis. What a larf (or for the rest of the English speaking world, Hoot). 73's Richard Clark, KB7Q aich C |
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