How directional a dipole gets is determined by how high it is above the effective electrical ground. That doesn't mean just how far from dirt. It also can vary because a structure can/does act as a 'partial' 'ground' depending on what it's constructed of. So, the attic of a two story house isn't as far from the effective ground as you might think. Until a dipole gets above something like one full wave length above the effective ground, it isn't going to be 'too' directive. And even when quite high, the 'nulls' off the ends still pick up and radiate a signal, just not as strongly as from off the 'sides' of the dipole. That 'null' is never as 'empty' as some people think.
How well will that dipole work in your attic? I wouldn't even make a guess at it. It will perform less well than if it were outside, didn't have anything between it and the signal it's trying to receive. Just too many variables with attics and what's in them for me to make a prediction about performance.
then you get to ply the polarity game, horizontal and vertical polarization. There can be quite a difference with that. Try it both ways if you can. String it horizontal, then if the attic is tall enough, run one leg of that dipole straight up/down and the other leg horizontal. That makes for a one-legged groundplane antenna. Attic not tall enough to do that? Then make the up/down leg as long as possible, then bend the rest of it sideways (opposite the direction of the horizontal leg). A dipole's shape isn't very strict, you can bend one quite a bit before it really makes a huge difference. That's also where that tuner can come in handy too.
- 'Doc
