I am about to install a Multi-Band loop which will be resonant on 40m, 20m, 15m and 10m. It needs a 4:1 balun - but other than this balun, this is cheap to build and is well within the possibilities of many small ham radio stations. It will give me some TX and RX gain on the higher bands and it will also be a lovely TX / RX antenna during the day for NVIS 40m.