A transmitting unit of a short-range radar includes a first pulse generating unit, a second pulse generating unit, an oscillator and a switch, and while complying with the spectrum mask specified for a UWB short-range radar, emits a predetermined short pulse wave not interfering with the RR prohibited band or the SRD band into the space. The ADC has a reference voltage supply. The difference in composition permits fine control over the refractive index of the coated particles, allowing good matching tooth enamel and to the binder materials used in the composite. The housing defines a curvilinearly-shaped recess longitudinally aligned with the channel when the housing is in engagement therewith. The two measured values are compared with one another in an evaluation unit.