Imagine a situation: You have lightweight, 40ft aluminum mast, which itself can serve as radiator, or can be used to support wire antenna, or small sized vertical (maximum top loading is 10 lbs). Antenna will be placed on the roof of 9 stage building. Roof is made from reinforced concrete and sized 180x30 feet. What will be your choice for good DXing, 1/2 or 1/4 vertical, or dipole, slopper, inverted V or ? I've modeled all possible types of antenna, which I can fit in above mentioned restrictions (Verticals, deltas, sloppers, hb9cv, squares, zigzag, etc.). But, I'd like to hear any practical recomendations from experienced users.