No. Side lobes and interferometry fringes are different things, although both arise from interference/diffraction effects.
- Side lobes are part of an antenna’s directional beam pattern. A dish has a strong central main lobe, with weaker lobes at angles away from the main beam. They exist even with one dish.
- Interferometry fringes arise when you combine the signals from two or more antennas. As the source moves across the sky, the path-length difference between the antennas changes, causing the signals to alternate between constructive and destructive interference. This produces the repeating maxima and minima—the fringes.
There is an important connection: the observed response of a two-dish interferometer is essentially the interference fringe pattern multiplied by the individual dishes’ beam pattern.
Very approximately:
Individual dish beam:
MAIN LOBE
/\
/ \
/\ / \ /\
/ \____/ \____/ \
side side
lobe lobe
Two-dish interferometer fringes:
/\ /\ /\ /\ /\ /\
/ \/ \/ \/ \/ \/ \
-----/--------------------------\-----
So in your ezCon interferometry plots, the repeated oscillations you’re seeing as the source passes through the combined beam are fringes, not simply the side lobes of the dishes.
And this explains your question yesterday about moving the dishes closer together: reducing the baseline makes the interferometry fringes wider/farther apart, whereas the individual dish’s main beam and side-lobe structure remain essentially unchanged.