Microwave ablation antenna assemblies

1. A microwave ablation antenna assembly comprising:

an elongate body which extends from a first end to a second end thereof, and which defines therein a hollow inner volume and a longitudinal axis of the microwave ablation antenna;

an applicator tip portion mounted on the second end of the elongate body;

an elongate coaxial conductor assembly for connection to a source of microwave energy, the elongate coaxial conductor assembly having a circular cross-section and extending from the first end of the elongate body towards the second end of the elongate body through the hollow inner volume, the elongate coaxial conductor assembly having an inner conductor, a dielectric layer arranged radially outwardly of the inner conductor and extending along the inner conductor, and an outer conductor arrange radially outwardly of the dielectric layer and extending along the dielectric layer, the inner conductor defining a signal feed-point of the elongate coaxial conductor assembly at a distal end thereof towards the second end of the elongate body;

a dipole tip portion which extends from the signal feed-point of the elongate coaxial conductor assembly towards the applicator tip portion, and which is electrically connected with the inner conductor of the elongate coaxial conductor assembly; and

a choke assembly comprising:

a choke dielectric element comprising a cylinder of solid dielectric material arranged radially outwardly of the outer conductor of the elongate coaxial conductor assembly, and extending along a part of the outer conductor;

a first choke conductor extending along, around and adjacent to a first portion of the choke dielectric element, radially outwardly thereof, the first choke conductor being electrically connected with the outer conductor of the elongate coaxial conductor assembly; and

a second choke conductor extending along, around and adjacent to a second portion of the choke dielectric element, radially outwardly thereof, the second choke conductor being electrically connected with the outer conductor of the elongate coaxial conductor assembly, and being spaced apart longitudinally from the first choke conductor along the elongate coaxial conductor assembly; and

a second dielectric element arranged radially outwardly of the first and second choke conductors and the choke dielectric element and extending over and along the first and second choke conductors and is in direct contact with a portion of the choke dielectric element located between the first and second choke conductors, but not in direct contact with any other part of the choke dielectric element, and wherein the second dielectric element extends along and around the dipole tip portion.

2. The microwave ablation antenna assembly as claimed in claim 1 , wherein the first choke conductor is provided by an electrically conductive layer on the choke dielectric element.

3. The microwave ablation antenna assembly as claimed in claim 1 , wherein the second choke conductor is provided by an electrically conductive layer on the choke dielectric element.

4. The microwave ablation antenna assembly as claimed in claim 2 , wherein the electrically conductive layer on the choke dielectric element comprises a metallic material.

5. The microwave ablation antenna assembly as claimed in claim 1 , wherein the first choke conductor is electrically connected with the outer conductor of the elongate coaxial conductor assembly via a soldered connection conductive paint, or conductive epoxy.

6. The microwave ablation antenna assembly as claimed in claim 1 , wherein the second choke conductor is electrically connected with the outer conductor of the elongate coaxial conductor assembly via a soldered connection, conductive paint, or conductive epoxy.

7. The microwave ablation antenna assembly as claimed in claim 1 , wherein the choke dielectric element is provided by a single continuous member surrounding the part of the outer conductor of the elongate coaxial conductor assembly.

8. The microwave ablation antenna assembly as claimed in claim 1 , wherein the outer conductor of the elongate coaxial conductor assembly terminates at an end point spaced longitudinally from the signal feed-point of the inner conductor.

9. The microwave ablation antenna assembly as claimed in claim 1 , wherein the elongate body is cylindrical, and the elongate coaxial conductor assembly, the dipole tip portion and the choke assembly extend substantially centrally through the hollow inner volume of the elongate body.

10. The microwave ablation antenna assembly as claimed in claim 1 , further comprising a dielectric fluid in the hollow inner volume of the elongate body.

11. The microwave ablation antenna assembly as claimed in claim 1 , wherein the second dielectric element comprises a fluid dielectric material.