I have discovered that attempting to write an in depth FAQ on both 600Ω True Ladder Line and doublet’s, has proven to take a lot more time than I planned.
In the meantime, I’ll share these helpful links so you can read up on the subject.
Thanks and 73!
- Here’s a great little online calculator where you can choose all types of feedline to compare losses. Of course, the 600Ω open wire feed line comes out on top!
- This link to an old page on the Wayback Machine, shows a modeling effort by VK1OD on the Cobra Ultralight, linear-loaded antenna and spells out the significant drawbacks of this antenna. Here’s a quote from him. “System losses are relatively high, and in some frequency bands are so high as to be unacceptable for most applications.” Yes, I understand that many people use this antenna and do just fine. However, you can do much better. People frequently ask me if the W7FG True Ladder Line antenna is similar. NOT AT ALL! I’ll leave you to form your own opinion. There have been a few discussions on QRZ forums on this very topic. It's interesting reading. Note that the links on the page, as well as any images, are not working, as is frequently the case with any of the archived pages found on the Wayback Machine Archive.
- This link takes you to the ARRL website and an article about Random Length Multiband Dipoles. The example they use is fed with the 450Ω window line rather than True Ladder Line 600Ω feed. The tuning and efficiency will be better with 600Ω and the SWR change during a rain storm will be much less, if any at all. This is one key reason for choosing 600Ω over 450Ω.
- Let’s not forget the great Wikipedia. Here’s a simplified explanation of a dipole with several animations to drive home some of the theory of the dipole. Keep in mind they reference a “resonant” dipole; not a doublet.
- This next link is to a LOOOOOONG, six page article about ladder line fed antennas, by Harold Melton, KV5R. I frequently hear from hams that after finding his website and reading over the six pages, and finally getting an objective viewpoint on MYTHS –vs- TRUTH, they decide to take the plunge and purchase one from me.
- This link is to an excellent article by Dick Cebik W4RNL (SK) called “Introducing the All-Band Doublet”. There’s a fair amount of technical information however, I think he’ll convince you of the benefits of an open wire fed, True Ladder Line Doublet.
These links were all tested and working as of August 18, 2018. If you discover that one is broken, please send a message through my contact page and I will correct it right away.
I'll continue to add more as time permits.
I welcome suggestions for links as well as comments.
Thank you & 73,