I just found this very nice Java application written by Ward, AE6TY. He
calls it SimSmith. You'll need Java loaded on your computer to run it. http://www.ae6ty.com/Smith_Charts.html I've had some email conversations with the author, and he's been quite responsive to questions. There are two pieces of documentation on this page. I strongly suggest printing and studying them to understand the user interface. SimSmith models loss in lines. Ward says that he is continuing to work on SimSmith, and that an updated version with a new user interface is close to release. I was able to import an antenna measurement I'd made at the shack end of a known length of feedline using my Ten Tec VNA as an S2P file, and transpose it with SimSmith to obtain the impedance at the antenna. I can now use that transposed data to design a matching network. I was also able to import SWR data from EZNEC (lastz.txt) and design a matching network for it. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Guys,
Smith charts are great once one has made it up the steep learning curve. A alternative simple approach for common needs is the TLW program. The TLW program which came with the ARRL Antenna Handbook on CD computes: 1) Load complex impedance given the shack end coax type and cable type and length. Also the reverse. 2) Matching network values 3) Coax loss vs coax length at a specified frequency for a dozen or so coax lengths. Mismatch loss is also edited. 4) Plots current and voltage vs distance from the xmitter toward the load. One may be pretty surprised how high voltages can climb with various mismatches. Very handy. The downside of these "end of coax" tools is that many of us have runs made up of mixed coax types. This can be confounding. You have to know the length(s)! Also the coax parameters in the models are nominal and may not reflect your 10 year old coax. VNA's generally handle the "as is" coax parameters. I don't have a $500+ VNA floating around. 73 de Brian/K3KO On 5/13/2012 15:18, Jim Brown wrote: > I just found this very nice Java application written by Ward, AE6TY. He > calls it SimSmith. You'll need Java loaded on your computer to run it. > > http://www.ae6ty.com/Smith_Charts.html > > I've had some email conversations with the author, and he's been quite > responsive to questions. There are two pieces of documentation on this > page. I strongly suggest printing and studying them to understand the > user interface. SimSmith models loss in lines. > > Ward says that he is continuing to work on SimSmith, and that an updated > version with a new user interface is close to release. > > I was able to import an antenna measurement I'd made at the shack end of > a known length of feedline using my Ten Tec VNA as an S2P file, and > transpose it with SimSmith to obtain the impedance at the antenna. I > can now use that transposed data to design a matching network. I was > also able to import SWR data from EZNEC (lastz.txt) and design a > matching network for it. > > 73, Jim K9YC > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.2171 / Virus Database: 2425/4996 - Release Date: 05/13/12 > > ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2171 / Virus Database: 2425/4996 - Release Date: 05/13/12 ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2171 / Virus Database: 2425/4996 - Release Date: 05/13/12 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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