Electrosurgical apparatus for delivering RF and/or microwave energy into biological tissue

An electrosurgical instrument for delivering electromagnetic energy to biological tissue, the instrument comprising:

• a distal end assembly comprising:
• an active tip comprising a planar body made of a first dielectric material separating a first conductive element on a first surface thereof from a second conductive element on a second surface thereof, the second surface facing in an opposite direction to the first surface;
• an electrically conductive protective hull mounted on an underside of the active tip, the protective hull having a smoothly contoured convex undersurface facing away from the planar body;
• and
• a coaxial feed cable comprising an inner conductor, an outer conductor coaxial with the inner conductor and a second dielectric material separating the inner and outer conductors, the coaxial feed cable being for conveying radiofrequency (RF) electromagnetic (EM) energy or microwave EM energy,
• wherein the inner conductor is electrically connected to the first conductive element,
• wherein the first conductive element and the second conductive element are arranged to emit the RF EM energy or the microwave EM energy from the coaxial feed cable at a distal side portion of the planar body,
• wherein the protective hull is soldered to the second conductive element,
• wherein the protective hull comprises an upper surface for abutting the second surface of the planar body, and wherein the upper surface comprises a recess for retaining a solder preform, and
• wherein the protective hull has a U-shaped recess for receiving a portion of the coaxial feed cable comprising the inner conductor, the second dielectric material and the outer conductor, wherein the portion of the coaxial feed cable is crimped within the U-shaped recess of the electrically conductive protective hull to deform the cable and retain the cable in the U-shaped recess by an interference fit, such that the deformed outer conductor abuts the sides of the U-shaped recess to form a direct electrical connection between the outer conductor and the protective hull, and thereby to the second conductive element.