Compatibility summary
You will need a travel adapter in Antigua and Barbuda; plug types used there differ from Singapore.
Plug comparison
Singapore plug types: G
Antigua and Barbuda plug types: A B
There is no common plug type between Singapore (G) and Antigua and Barbuda (A B). You need a travel adapter.
Voltage comparison
Singapore: 230V, 50Hz
Antigua and Barbuda: 230V, 60Hz
Voltage difference is within a range many devices tolerate; check your appliance label.