Total posts : 45366
Cage Monopole is right now my favorite type of both AM and FM antenna, and I have ongoing experiments in both departments.
A three element cage presents a solid signal but a four element adds a very slight but measurable increase in the signal power.
I have not tried more than four elements.
What astounds me (FM, probably also AM) is that the 4-element cage monopole totally stops multi-pathing caused by persons walking near the antenna or within the signal field.