Often seen in visibilities on the shortest baselines

Sidelobes and ripples from bright sources such as the Sun (and Cyg A at low frequencies) can be seen in images even though the source may be offset by many primary beams!

Radio Frequency Interference (RFI) is often variable, showing bursts of activity - predominantly shows up on baselines with low fringe rate (N-S baselines) and when pointed at low elevation

RFI is almost always narrow band, and thus may be controlled and possibly excised by observations in high-spectral resolution mode where it can be isolated to a few channels

Having a system with a high degree of linearity is critical to dealing with RFI effects, as the signals tend to be strong

Cross Talk between closely separated antennas can sometimes be a serious problem on physically short baselines, and especially on shadowed antennas