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Computer alternative to Smith Chart?
I haven't used a Smith Chart in over 30 years, and to say the least, I'm a
bit rusty. I'm thinking there must be computer programs that can do the calculations with values you just plugs in. Any recommendations? I'm specifically interested in finding the impedances of antenna whips much shorter than 1/4 wave. -- Bob D. ND9B |
Computer alternative to Smith Chart?
I'm curious. How do you use a Smith chart to find an antenna impedance?
There certainly are programs specifically designed to find such things as antenna impedances. The free EZNEC demo program from http://eznec.com would be adequate and ideal for your purpose. Roy Lewallen, W7EL Bob D. wrote: I haven't used a Smith Chart in over 30 years, and to say the least, I'm a bit rusty. I'm thinking there must be computer programs that can do the calculations with values you just plugs in. Any recommendations? I'm specifically interested in finding the impedances of antenna whips much shorter than 1/4 wave. |
Computer alternative to Smith Chart?
On Sun, 9 Jul 2006 17:30:57 -0500, "Bob D." wrote:
I haven't used a Smith Chart in over 30 years, and to say the least, I'm a bit rusty. I'm thinking there must be computer programs that can do the calculations with values you just plugs in. Any recommendations? I'm specifically interested in finding the impedances of antenna whips much shorter than 1/4 wave. There's a nice impedance spiral in Kraus: "Antennas". |
Computer alternative to Smith Chart?
I haven't used a Smith Chart in over 30 years, and to say the least, I'm a
bit rusty. I'm thinking there must be computer programs that can do the calculations with values you just plugs in. Any recommendations? For Linux (and probably other Unix-type systems running X) there's a nice free program called Linsmith. -- 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! |
Computer alternative to Smith Chart?
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Computer alternative to Smith Chart?
On 2006-07-09, Bob D. wrote:
I haven't used a Smith Chart in over 30 years, and to say the least, I'm a bit rusty. I'm thinking there must be computer programs that can do the calculations with values you just plugs in. Any recommendations? I'm specifically interested in finding the impedances of antenna whips much shorter than 1/4 wave. For real operating systems (anything Unix based -- Linux OSX or a real Unix) try Linsmith http://jcoppens.com/soft/linsmith/index.en.php |
Computer alternative to Smith Chart?
You will find half dozen programs which deal with performance of short
verticals at the website below. From the Index, go to "Download programs from here" and read the one-line description under each program name. ---- .................................................. .......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. .......... |
Computer alternative to Smith Chart?
Bob D. wrote:
I haven't used a Smith Chart in over 30 years, and to say the least, I'm a bit rusty. I'm thinking there must be computer programs that can do the calculations with values you just plugs in. Any recommendations? I'm specifically interested in finding the impedances of antenna whips much shorter than 1/4 wave. Hi, Bob - http://zaffora.f2o.org/W9DMK/W9dmk.html has one. About 3/4 of the way down the page. It won't help you find antenna impedance unless you plan to measure the Z at the input end of the line and use the tool to get antenna Z. As has been said, you can use EZNEC to model your antenna and get its impedance. However, a Smith chart can be very useful for matching a thing to another thing. The one I use (a demo) I got from the University of Applied Sciences in Berne, Switzerland. I like it. However, it appears that it has been removed from the host. If you want it, I can send it to you. It is zipped to 306 kb in size. Cheers, John |
Computer alternative to Smith Chart?
Andy adds:
I have often used a modified Smith Chart , called an Impedance/Admittance chart , to do matching..... If the impedances are not greatly mismatched, it is very easy and accurate.... and very very intuitive... The ones I used have the impedance cordinates in black and the admittance coordinates in red..... I found them extremly useful in the design of an automated antenna tuner which I designed for a Texas Instruments Marine SSB unit, back in the late 70s..... You could literally track the impedance transormation mentally with series and shunt elements..... Andy W4OAH |
Computer alternative to Smith Chart?
"AndyS" wrote in message ups.com... Andy adds: I have often used a modified Smith Chart , called an Impedance/Admittance chart , to do matching..... If the impedances are not greatly mismatched, it is very easy and accurate.... and very very intuitive... The ones I used have the impedance cordinates in black and the admittance coordinates in red..... I found them extremly useful in the design of an automated antenna tuner which I designed for a Texas Instruments Marine SSB unit, back in the late 70s..... You could literally track the impedance transormation mentally with series and shunt elements..... Andy W4OAH ========================================== As an Engineer in my eighties with a long association with transmission lines of all sorts I have never used a Smith Chart, in anger, in the whole of my life. I have always used log tables, sliderules, pocket calculators or, more recently, dedicated computer programs. Use of mathematics gives one a more 'intuitive' insight into how transmission lines work than any chart. But it's a just a matter of opinion and depends on one's basic education. As useful as they were only at HF, Smith Charts became redundent when the personal computer came in. Old habits die hard! ---- Reg. |
Computer alternative to Smith Chart?
Reg Edwards wrote:
"AndyS" wrote in message ups.com... Andy adds: I have often used a modified Smith Chart , called an Impedance/Admittance chart , to do matching..... If the impedances are not greatly mismatched, it is very easy and accurate.... and very very intuitive... The ones I used have the impedance cordinates in black and the admittance coordinates in red..... I found them extremly useful in the design of an automated antenna tuner which I designed for a Texas Instruments Marine SSB unit, back in the late 70s..... You could literally track the impedance transormation mentally with series and shunt elements..... Andy W4OAH ========================================== As an Engineer in my eighties with a long association with transmission lines of all sorts I have never used a Smith Chart, in anger, in the whole of my life. I have always used log tables, sliderules, pocket calculators or, more recently, dedicated computer programs. Use of mathematics gives one a more 'intuitive' insight into how transmission lines work than any chart. But it's a just a matter of opinion and depends on one's basic education. As useful as they were only at HF, Smith Charts became redundent when the personal computer came in. Old habits die hard! ---- Reg. Reg, have you ever taken the time to learn _how_ to use one? Actually, they're just as mathematical as the formulas you've always used, and, for some people, just as useful. 73, Tom Donaly, KA6RUH |
Computer alternative to Smith Chart?
"Tom Donaly" wrote Reg, have you ever taken the time to learn _how_ to use one? Actually, they're just as mathematical as the formulas you've always used, and, for some people, just as useful. ======================================= Yes. Many years ago I attended a lecture. The lecturer handed round Smith Charts as a tutorial. We spent 10 minutes on it. But these days I'm well out of practice. The Smith Chart was only of any use at HF and above. That's what it was invented for. Fine for radio amateurs who only use the HF bands and above. It followed on from previous, more complicated Victorian Age charts to ease calculations involving complex Hyperbolic functions. Very good while it lasted. Small, dedicated computer programs these days are more accurate and time saving than charts and their 'what-if' operating procedures are much more educational. But I appreciate the sentimental attachment, indeed affection, many old timers have for the good old Smith Chart. By all means carry on using them. ---- Reg. |
Computer alternative to Smith Chart?
I think that is the engineer in you speaking!
I find the Smith Chart interesting as a tool. I am more interested in how it works while you are interested in what it is good for! My desk drawers still contain a couple of slide rules, a polar planimeter, a drafting set and a Kurta Calculator. In spite of being surrounded by an assortment of computers, I keep a good battery in my HP Calculator and I remain fond of nomograms. The Smith Chart is a tool. I cannot possibly have too many tools... Of course I have archived the programs at g4fgq as well... We could quit teaching Calculus as well, Computers make quick work of graphic solutions! On Tue, 11 Jul 2006 17:28:24 +0100, "Reg Edwards" wrote: The Smith Chart was only of any use at HF and above. That's what it was invented for. Fine for radio amateurs who only use the HF bands and above. It followed on from previous, more complicated Victorian Age charts to ease calculations involving complex Hyperbolic functions. Very good while it lasted. Small, dedicated computer programs these days are more accurate and time saving than charts and their 'what-if' operating procedures are much more educational. But I appreciate the sentimental attachment, indeed affection, many old timers have for the good old Smith Chart. By all means carry on using them. ---- Reg. John Ferrell W8CCW |
Computer alternative to Smith Chart?
John Ferrell, W8CCW wrote I think that is the engineer in you speaking! I find the Smith Chart interesting as a tool. I am more interested in how it works while you are interested in what it is good for! ============================================ John, you've weighed me up fairly well. On the other hand I see much beauty in Mathematics. And program source coding is the labour of love and a Work of Art. But Maths is a much neglected subject in our Western schools and universities these days. Even teachers don't know what five sevens are - and that's only arithmetic. I once asked a prospective Member of Parliament just before a General Election what seven nines are. He didn't know. He lost his £500 deposit. Didn't get enough votes. Otherwise he might have ended up as Chancellor of the Exchequer. ============================================ My desk drawers still contain a couple of slide rules, a polar planimeter, a drafting set and a Kurta Calculator. In spite of being surrounded by an assortment of computers, I keep a good battery in my HP Calculator and I remain fond of nomograms. ============================================ My Casio scientific calculator must be about 10 years old. I've never changed the battery. ============================================ The Smith Chart is a tool. I cannot possibly have too many tools... ============================================ I bet you are an amateur carpenter as well. ============================================ Of course I have archived the programs at g4fgq as well... ============================================ Don't throw away your old computer. Being DOS programs there are ominous signs they won't work too well on new versions of Windows. ============================================ We could quit teaching Calculus as well, Computers make quick work of graphic solutions! ============================================ I deliberately avoided graphics. Graphics depend on screen driving software thus losing portability between machines. My favourite Victorian is Oliver Heaviside. He invented the beautiful Operational Calculus which magically transforms ordinary calculus into simple algebra and converts functions of frequency on transmission lines into functions of time. Now everything is going digital at Megabits per second he was about 130 years in advance of his time. All the best to you and yours. ---- Reg, G4FGQ. |
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