Some questions that might help narrow down to a solution: what kind of area do you live in? Relatively rural, suburban, urban? What do you want to hear? Loop antennas are often great solutions for radios and situations such as yours. There are all sorts of limited space antennas on the market and, aside from building one yourself to known good plans, you often get what you pay for. There are very small loops that cost a lot of money that perform really amazingly and then there's a lot of junk.