I am certain their antenna doesn't do any "azimuth encoding". It seems to be a standard blade antenna, made by somebody like
Antcom.
What they probably do is make use of the variation of the antenna gain versus azimuth (i.e. the antenna won't be perfectly omnidirectional) in conjunction with the Mode C pulse shape distortion which is going to be distance related.
They do call it "directional antenna" after all.
But I still can't see how they can resolve between say 3 o'clock and 9 o'clock targets because that antenna appears to be symmetrical left-to-right.
It is possible their antenna distorts the incoming pulse according to the direction it comes in from.
There are plenty of reviews online but those I have read are too banal and devoid of detail to make much sense of.