I think I understand what a radar contact is, but what does a sweep result mean? My apologies if this addressed in the rule book - I didn't see it.
Seems like a sweep result is often more useful than a contact result.
To be honest, this game mechanic is not very historical. I have designed for flavour rather than history. My aim was to create a single game mechanism that would encompass everything from Freya-AN (interpreting range and azimuth information) to those PPI top-down plots of a recognisably modern kind.
So terms like 'Contact' and 'Sweep' can be deceptive and we should be careful of assigning real-world mappings to them.
Looking at historical radar use, these early radars were imprecise and there was an art to reading scopes. In the case of Freya-AN it involved judging the size of a cathode ray spike to one or either side of a range scope. Getting plots was something of a black art.
So while Contact and Sweep could be vaguely interpreted as the totality of range and azimuth information available to the fighter controller, they really do not map to real-world practice. What the mechanic does in the game is:
(a) Capture some of the delay time involved in getting a good fix, and
(b) Give a sense of some of the impreciseness and human fallibility in figuring out a fix.