A multi-element antenna with sufficiently small return loss and mutual coupling signals to allow the simultaneous transmission of powerful radar signals and the reception of faint target return signals. A fluid dispensing means which is attachable to the otoscope for ejecting fluid through said ear speculum into the ear canal, the fluid dispensing means being mounted on the gripping body of the otoscope. The power unit has an output shaft and a mounting structure. A substrate ID code consisting of a plurality of laser marks is inscribed in the solder mask or in a portion of an encapsulant on the bottom surface away from the circuit to show the substrate lot number on the bottom surface.