Device for transferring signals from an at least partially metal housing designed for use in an explosion-prone region

A device for transferring signals using electromagnetic waves of a certain wavelength, the device comprising:

• a housing made at least partially of metal and configured for use in an explosion endangered area, wherein the housing has a defined thickness and an essentially rotationally symmetric outer contour;
• a transmitting/receiving unit disposed in the housing and configured to produce and/or receive the electromagnetic waves;
• an antenna disposed in the housing and adapted for out-coupling and/or in-coupling of the electromagnetic waves and for transferring the electromagnetic waves to and from the transmitting/receiving unit;
• a slot-shaped housing opening adapted to enable the signals to be transferred by the electromagnetic waves into and out of the housing via interaction with the antenna;
• and
• a formed part, which is made of a material having a relative dielectric number significantly greater than one, including a projected slot-shaped region complementary to the housing opening with which the formed part extends to a predetermined maximum depth into the housing opening, wherein the predetermined maximum depth is configured such that a sphere or hemi-sphere having a gauge diameter does not contact the formed part when seated on the housing opening,
• wherein the formed part includes a region of a minimum breadth adjoining the slot-shaped region and surrounding the slot-shaped region, wherein the formed part with the surrounding region is pressed in the region surrounding the housing opening against an interior of the housing and the minimum breadth of the surrounding region is configured such that, for a gas conforming to the standard IEC 60079-1, a shortest path through the housing opening from the interior to an outside of the housing is:
• at least 3 mm when a volume defining a free space enclosed by the housing is less than or equal to 10 cm3;
• at least 6 mm when the volume is greater than 10 cm3 and less than or equal to 100 cm3;
• or
• at least 10 mm when the volume is greater than 100 cm3.