Building and Testing an HF Slot Antenna - Mark Smith KR6ZY 

Nice presentation, Smitty. You expanded a LOT on areas that W6NBC did not elaborate upon, particularly the phasing and resultant patterns. My two cents for you: 1) Your 1:1 balun is raising havoc where it is located, as it cannot properly handle the complex, high-impedance load on the antenna side. It's anyone's guess what type of saturation loss and/or impedance transformations are occurring in your balun. IIRC, Portune mentions placing a CURRENT BALUN (common mode choke) on the TX side of the tuner, and not a voltage balun. Big difference there. He also states that the ground terminal of the RT600 tuner should be tied to a ground rod, strongly implying that his double delta is NOT intended to be fed as a truly balanced, isolated load. His article stresses numerous times to NOT place a balun in-between tuner and antenna. Your less than satisfactory matching results are suspect. 2) Portune has no issues whatsoever having his RT600 tune the double loops on 80m, nor anywhere else 80 - 6m for that matter. Two loops in series is approx. 100 feet of wire...pretty darn close to a 1/2 wave on 80m. The antenna is only slightly short electrically...and should not appear as reactive as it does on your installation. Again...I suspect that the 1:1 balun location is causing problems. 3) I use an RT600 to successfully tune a VERY short (20') vertical on 80m. A properly-constructed 4:1 UNUN, designed to accommodate a highly-reactive antenna load, makes the high-impedance load a lot easier for the RT600 to tune, but it is not an absolute necessity. Search for the articles by G8JNJ where he discusses the use of baluns and ununs in-between a remote tuner and a highly reactive load. His research and supporting test data are real eye-openers and likely will apply here as well. Thanks again and 73, W1LJ

Hi Mark, I just watched your video on your slot antenna experience. Thank you for making this video, the content is really useful to me. However I want to make a completely different observation and I want to comment specifically on your presentation, and even more specifically on the energy and enthusiasm that you brought to the camera. While your content was simple to understand and presented in a logical, easy to follow manner, what I enjoyed the most is that you made me feel you were sincere and personal and honest and all those good things. You presented a great topic in a cheerful manner that was easy on the eyes and ears. Thank you. Leon Uys ZR6N (AG5RH when I visit the kids in Texas)

Can you built a double delta for a specific band without a tuner?

This is a great presentation, Smitty! Thanks for another project I can add to my list... 😂 73

I've built the neutron star antenna size doesn't matter It's about complex conductive 144 point box. The flowers of life in 3D starburst pattern

On the subject of the Double DELTA Slot or HF Slot antenna; If size were not so restricted and for a permanent application would there be any benefit in super sizing it? ie. Having something on the idea of a 16 to 24 foot cross section and whatever complimentary hight increase might coincide? Any guidance would be greatly appreciated! Thank you kindly Gary

Does the length of top spreaders have a specific size or can it be say 4m across the top?

Is this thing for nvis?

How can you possibly expect to tune this antenna through a 50 Ohm choke(UNUN/BALUN). Put the choke on the coax side of the auto tuner, where it can do it's job. Are the .s1p files with or without the choke? If it is without the choke, the parallel has impedances from 2.2 Ohm to over 300 Ohm. A LC tuner should tune this to a very low SWR. And Mark, put the links in the description, so they are clickable. LB8X