As a result of the secession of Brazil in 1822 as well as a domestic dynastic conflict between 1828 and 1834, the standard of the victorious side was hoisted in Lisbon as the new national flag. It would survive for 80 years, until the abolition of monarchy in 1910. This new flag design displayed two equal fields (blue and white) divided along its length, with the royal coat of arms cedtered over the division boundary. The naval ensign differed from the land flag in the way the colours occupied the background (blue 1/3, white 2/3) with a consequent positional shift of the arms.
Sources: Wikipedia(en):Flag of Portugal | Flags of The World (FOTW) website:Portugal - 1830 historical flags
Sizes: large ensign W12 x L18 mm, small ensigns W8 x L12 mm, jack W6 x L9 mm, pennant W4 x L48 mm.