What are some good ways to participate if you don't have an HF radio? (Alternatively, what's a good way to get into HF if you live in a small apartment)?
(I already have my license)
(I already have my license)
Even if you don't have access to an attic, there are antenna constructions that can work for apartments. Have a look at "ARRL's Small Antennas for Small Spaces" and RSGB's "Stealth Antennas" as starting points.
Alternatively, you could consider a portable solution where you carry a small HF rig and some wire in a backpack. The Yaesu FT-857D is very popular for this as it's small, all bands, all modes and does 100W. If you search for "Yaesu FT-857D backpack" you will find many suggestions. It's not in production anymore but you might find it second hand. For Yaesu, other options include the FT-891 (no VHF/UHF) and the more bulky FT-991A. Icom has the IC-7100, which is also a little more bulky than the FT-857D.
HF in small apartment is very difficult.