Radar side lobes

​Side lobes are naturally occurring areas of transmitted energy that are part of virtually any transmitter used in marine electronics.  Radar, echo sounders (fishfinders) and sonars all generate a "main beam",  which is also known as the "main lobe".  "Side lobes" are transmitted energy that is outside of the "main beam" or "main lobe".   
 
Reflections from side lobes can sometimes cause false targets and/or "noise" on your display.   All Furuno products have gain and clutter controls to help minimize the affects of side lobe returns.  Many installation menus and settings exist for fine-tuning Furuno products.