Patent ID: 7602330

Claim:
An antenna structure for use in a level measurement device for measuring a level of a material held in a container, comprising: a horn antenna; an emitter assembly comprising: a plug including a port for coupling to a waveguide from the level measurement device, and an emitter having a surface for interfacing with a corresponding surface on the plug; and a coupler for coupling the horn antenna to the level measurement device, wherein the coupler further comprises: a first mechanism for coupling the horn antenna to the level measurement device, and a second mechanism for coupling the emitter assembly to the level measurement device, wherein the first mechanism is independently operable of the second mechanism, and the first mechanism couples the horn antenna to the level measurement device indirectly via the second mechanism, wherein at least a portion of the emitter assembly is arranged in the horn antenna, wherein the second mechanism comprises a retaining ring having: a recess for supporting one end of the emitter, and a plurality of fasteners for securing the retaining ring to the level measurement device, wherein the emitter includes a tip section and a constant diameter section, the constant diameter section having a diameter corresponding substantially to the diameter of the recess, and wherein the plug comprises: a tip section providing a waveguide coupling port, and a conical section having a surface for interfacing with the emitter.