US Patent 7532151 Proximity sensor

A microwave oscillating portion 30 has an output oscillator function that is capable of adjusting automatically a frequency of microwaves radiated from an electrically conductive member made of an outer panel 11-14 as an antenna at a specific frequency of a sufficiently short wavelength in relation to a size of the electrically conductive member made of the outer panel 11-14. The microwave oscillating portion 30 can detect a human and an object of a detection object 27 in a detection area 11A-14A set at an outside of the outer panel 11-14 that is integrally or separably mounted on a vehicle 1.