A near object detection system includes a plurality of sensors, each of the sensors for providing detection coverage in a predetermined coverage zone and each of the sensors including a transmit antenna for transmitting a first RF signal, a receive antenna for receiving a second RF signal and means for sharing information between each of the plurality of sensors in the NOD system. One or more of the fins are dimpled, mechanically or molded, to provide concavities and projections on opposite sides of the fins or alternating concavities and projections on opposite side of the fins. The system may provide some indication that the thermal grill should not be contacted. A tap associated with a peak can be identified in a Fourier analysis of the Hlog spectrum.