It's not sector artillery its circle artillery.
But anyway it's dumb that the PE get a similiar one for T3 and this is T4.
It's good versus blobs of any elite infantry that come running in and it can kill snipers and stopped tanks.
When I use it I wait till a lot of men are in my land then call it.
It is different from the axis sector arty (which is the original) and allys are getting way too many axis like options already with all those new shiny units to play with.
Also axis sector arty is not that great, you need to use it correctly.