You Do Need power plug adapter while traveling from Serbia to Antigua and Barbuda.

Here is Why You Need An Adapter

The outlet and plug type used in Antigua and Barbuda are A and B and in Serbia are C and F. This is how they look like.

Serbia

In Serbia, outlets of type C and F are in use.

Type C

Type F

Antigua and Barbuda

In Antigua and Barbuda, outlets of type A and B are in use.

Type A

Type B