A "shorty 40" is a coil-loaded dipole, something like half of normal length.
As K8GU mentioned, an "active" antenna is for receiving only.
The last time I lived in a second-story apartment that was the top floor, so I climbed up on
the roof in the middle of the night and tucked a long wire under the shingles with one end
dropping down into my window. You might not have that option, however.
There are lots of types of indoor antennas you can try - performance depends heavily on
the type of materials used in constructing the building. Stucco walls, for example, contain
a layer of metal screen (as does some reinforced concrete) that does a pretty good job of
blocking RF. Every apartment is different, so you really have to experiment to see what
works best in your situation.
A loaded dipole of some sort strung across the ceiling is one possibility. The resonant frequency
will shift due to the proximity to the walls, electrical wiring, etc. The longer you can get it the
better - one possibility is to drill a small hole through the wall near the ceiling to pass it between
rooms. If you can manage a circumference of about 120' (30' on a side of a square) then feeding
it as a loop might work. Otherwise, a simple approach is to bend the ends around a bit and put
a big loading coil at the feedpoint: by adjusting the taps on the coil for both the coax and the
antenna (or, my favorite, using some extra turns of wire wrapped around the coil to connect to
the coax) you should be able to get a good match. Performance depends on the effective length
of the antenna and, of course, the environment it is in.
Something you can stick out the window, or assemble temporarily on a balcony (if you have one)
is likely to be a better solution because it gets the radiator outside the building. One approach is
to use an antenna that looks like an acceptable device such as a flag pole. In one apartment I
used a mobile whip stuck horizontally out of a second story window and fed against the aluminum
window frame as a ground. (All the window frames in the whole building were bonded together.)
If you don't have such a good ground plane available, then you may need to use one or two quarter
wave radial wires strung around the baseboards of your condo as best you can for a ground.
Whether you use a telescoping fiberglass fishing rod, golf ball retriever pole, mobile whip, or some
sort of commercial antenna for this is a matter of personal preference and local circumstances.
Of course, a thin "invisible" wire out the window to a tree is even better, but isn't always practical.
At one townhouse we tossed a wire over the roof and brought it inside the windows on both sides
of the building to form a loop.
Another option that may work well, especially for the higher bands, is a "magnetic loop" antenna.
These are more commonly available for 20m - 10m and have a very narrow operating bandwidth,
usually requiring a remote control tuning mechanism, but you might manage a 40m loop like this:
http://www.alexloop.com/index.html
