I didn't see my suggestion so here it is. Buy an Isotron for 20 meters. It is 21 1/2" long and 5 " across the reflector. Will work if you don't have a metal roof. Mine is in the attic. It is a 1/2 wave dipole has omni directional configuration. Easy to take for outdoors if that is your wish. Cost is about $80. See K1CRA Store. I have worked both coasts, Alaska, all over Canada and into Mexico with 100W.
You can add 2 more bands with only one feed line. The Isotrons are a little touchy to get to resonance but once done they work just fine. Enjoy.
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