At the present time, physicians often treat patients with atrial fibrillation using radiofrequency catheter systems to ablate conducting tissue in the wall of the Left Atrium of the heart around the ostium of the pulmonary veins. The protrusions can be either cast formed or machined in place. The first hinge portions are provided on both ends of a lower end portion of the cover body so as to rotatably support the cover body. The discharge lamp further comprises a connecting element made of an insulating material which transversely connects the lead-in wires within the discharge tube. The dielectric layer is etched using the first mask layer and the second mask layer in combination as an etching mask, wherein a contact opening is formed in the dielectric layer. The resulting signal field is acquired by a number of reception antennas of a second antenna array, which are arranged at different spatial positions and thus allow a spatial resolution of the frequency-converted signals.