I recently came across a design for a multi band end fed half wave antenna for 80m-10m by G0KYA link here. Essentially its an EFHW cut for 40m with a trap(110uH) and an additional 2 – 2.5m of wire at the end for 80m. I already had a 49:1 autotransformer / matching unit from RF Comms ebay shop. I mounted the wire in an inverted L configuration, a little fine tuning was needed but I ended up with an antenna that is usable on 80, 40, 20, 15 & 10 without an ATU and other band inbetween with an ATU.
SWR measurements:- 80m 1.7, 40m 1.2, 20m 1.6, 15m 1.8, 10m 1.9
I’ve had contacts in every continent with this antenna albeit on digi modes such as FT8.