While not a Delta-loop per-se, I built a 40 metre portable full wavelength sky-loop (which works on 40, 20, 15, 10m) of very thin and light wire and used tripod supported fibreglass poles on Mount Elliot (VK2/HU-098) 6.5 years ago. It would never have been possible without help from other CCARC club members.
Did it perform? yes.
Was it directional? not that I could tell.
Was the effort worth it and did I ever try it again? no (the thin wire managed to tangle itself up so badly when I packed it away that it was junked).
Whenever considering a portable antenna, one major factor for me is - can I carry it to the summit and put it up and take it down with little effort, repeatedly. For a long time my “go to” antenna has been a SOTABeams “band-hopper” linked dipole antenna (which could be modified for 10/12/15m in answer to your original request) but on my most recent activations, I have switched to the Komunica HF-PRO-2-PLUS-T loaded vertical (there are similar antennas from non-European distributors and manufacturers but they are more expensive). It gives me a compact size (especially with the change to a telescopic radiating element from the fixed one in the previous (non -PLUS-T) model) and using it with my own modified photo-tripod, it performs reasonably well, needs little space and no on-site support for a fibreglass mast to be able to set-up and best of all it’s quick to set-up and take down.
I hope to compare this antenna against the linked-dipole tomorrow morning on 40 & 20m. Both of my summits tomorrow are within forests so this will make it hard for the vertical but we’ll see how it performs against the dipole.
Here’s my report on my three easy activations last Wednesday, where I only used the loaded vertical.
DD5LP/P – November 18th 2020 – DM/BM-374 Wülzburg, DM/BM-226 Dürrenberg & DM/BM-135 Hesselberg. | DD5LP / G8GLM / VK2JI blog
Oh yes the loaded vertical covers from 80 metres through 2 metres, so another advantage of not needing multiple antennas but on VHF, I suspect it wont perform as well as a “proper” VHF antenna.
I’ll be interested to hear how the Delta-Loop performs if you decide to build one Andy, especially if it is directional.