As a very former amateur radio operator I can tell you it is largely about size. If you have a yard and can string wires between trees that is what will do it. A 1/2 wave dipole is something like this
<- 1/2 wave ->
-----------------------
| |
---------| |-----------
| |
| | <- To your receiver
A 1/2 wave at am radio frequencies is something like 500 feet so if you live in an apartment this is out but if you have loads of land all it takes is cheap wire.
Disclaimer: This is from memory when I was a teen 30 years ago and might not be accurate.