See the Porto Metro Website: http://www.metrodoporto.pt/en/.
You will need line E which runs straight from the Aeroport to Campanha.
Trains appear to run every 20 minutes around 10.00 on a Sunday.
Timetable for whole system in pdf format can be found here:
http://bit.ly/amyX7z
(You need page 25)
System Map in pdf format here:
http://bit.ly/d5Osz4
