Geoff VK2TGO recently gave a lecture on an end fed antenna for 40-20-10m. This antenna is fed using a 9:1 unun, just under 13 metres of wire and a loading coil near one end. The antenna wire itself can be deployed in many ways: vertically, as an inverted V (with the feedpoint at one of the low ends) or as a sloper.
This is a light, versatile antenna for portable use!!
Lecture slides and construction details: