Choked dielectric loaded tip dipole microwave antenna

1. A microwave antenna assembly comprising:

a feedline including an inner conductor, an outer conductor and an inner insulator disposed therebetween;

a radiating portion including an unbalanced dipole antenna having a proximal portion and a distal portion of different lengths and a gap therebetween, wherein the proximal portion includes a portion of the inner conductor and the inner insulator and the distal portion includes a conductive member;

a sleeve disposed around a portion of the outer conductor and the conductive member, the sleeve defining a vacuum chamber therein disposed between a distal end of the outer conductor, a proximal end of the conductive member, and the inner insulator; and

a choke disposed around a portion of the feedline, the choke including an inner dielectric layer and an outer conductive layer, wherein a distal end of the inner dielectric layer is disposed between a distal end of the outer conductive layer and the gap.

2. The microwave antenna assembly according to claim 1 , further comprising:

a connection hub including a cable connector coupled to the feedline, an inlet fluid port and an outlet fluid port.

3. The microwave antenna assembly according to claim 2 , further comprising:

a seal disposed around a distal end of the outer conductive layer of the choke; and

a coolant jacket coupled to the connection hub and the seal thereby defining a proximal chamber around the feedline.

4. The microwave antenna assembly according to claim 3 , further comprising:

a solid dielectric loading having central cavity defined therein adapted to fit about the radiating portion, the solid dielectric loading being coupled to the seal.

5. The microwave antenna assembly according to claim 4 , wherein the solid dielectric loading is formed from a dielectric material having a dielectric constant from about 2.5 to about 150.

6. The microwave antenna assembly according to claim 3 , further comprising:

an inflow tube coupled to the inlet fluid port and disposed within the proximal chamber for supplying a dielectric coolant fluid thereto; and

an outflow tube coupled to the outlet fluid port and in fluid communication with the proximal chamber for withdrawing the dielectric coolant fluid therefrom.

7. The microwave antenna assembly according to claim 2 , further comprising:

a tip having an insertion base, a tapered end and a pointed end, wherein the tip is coupled to the distal portion of the unbalanced dipole antenna; and

a sheath coupled to the connection hub and the tip, thereby defining a chamber around the feedline and the radiating portion.

8. The microwave antenna assembly according to claim 2 , further comprising:

an inflow tube coupled to the inlet fluid port and disposed within the chamber for supplying a dielectric coolant fluid thereto; and

an outflow tube coupled to the outlet fluid port and in fluid communication with the chamber for withdrawing the dielectric coolant fluid therefrom.

9. The microwave antenna assembly according to claim 1 , wherein the outer conductive layer is shorted to the outer conductor of the feedline.

10. The microwave antenna assembly according to claim 1 , wherein the inner dielectric layer is selected from the group consisting of a tetrafluorethylene and a perfluorpropylene.

11. A microwave antenna assembly comprising:

a feedline including an inner conductor, an outer conductor and an inner insulator disposed therebetween;

a radiating portion including an unbalanced dipole antenna having a proximal portion and a distal portion of different lengths and a gap therebetween, wherein the proximal portion includes a portion of the inner conductor and the inner insulator and the distal portion includes a conductive member;

a sleeve disposed around a portion of the outer conductor and the conductive member, the sleeve defining a vacuum chamber therein disposed between a distal end of the outer conductor, a proximal end of the conductive member, and the inner insulator; and

a choke disposed around a portion of the feedline, the choke includes an inner dielectric layer and an outer conductive layer, wherein the outer conductive layer is shorted to the outer conductor of the feedline and a distal end of the inner dielectric layer is disposed between a distal end of the outer conductive layer and the gap.

12. The microwave antenna assembly according to claim 11 , a sheath disposed over the feedline and the radiating portion defining a chamber around the feedline and the radiating portion, the chamber being adapted to circulate dielectric coolant fluid therethrough.

13. The microwave antenna assembly according to claim 12 , further comprising:

a tip having an insertion base, a tapered end and a pointed end, wherein the tip is coupled to the distal portion of the unbalanced dipole antenna.

14. The microwave antenna assembly according to claim 13 , wherein the sheath is coupled to the connection hub and the tip.

15. The microwave antenna assembly according to claim 12 , wherein the sheath is a polyimide catheter.

16. The microwave antenna assembly according to claim 11 , further comprising:

a connection hub including a cable connector coupled to the feedline, an inlet fluid port and an outlet fluid port.

17. The microwave antenna assembly according to claim 11 , further comprising:

an inflow tube coupled to the inlet fluid port and disposed within the chamber for supplying the dielectric coolant fluid thereto; and

an outflow tube coupled to the outlet fluid port and in fluid communication with the chamber for withdrawing the dielectric coolant fluid therefrom.

18. A microwave antenna assembly comprising:

a feedline including an inner conductor, an outer conductor and an inner insulator disposed therebetween;

a radiating portion including an unbalanced dipole antenna having a proximal portion and a distal portion that are of different lengths and a gap therebetween, wherein the proximal portion includes a portion of the inner conductor and the inner insulator and the distal portion includes a conductive member;

a sleeve disposed around a portion of the outer conductor and the conductive member, the sleeve defining a vacuum chamber therein disposed between a distal end of the outer conductor, a proximal end of the conductive member, and the inner insulator;

a choke disposed around a portion of the feedline, the choke includes an inner dielectric layer and an outer conductive layer, wherein the outer conductive layer is shorted to the outer conductor of the feedline and the inner dielectric layer extends past the outer conductive layer, wherein a distal end of the inner dielectric layer is disposed between a distal end of the outer conductive layer and the gap;

a coolant jacket disposed over the feedline defining a proximal chamber around the feedline, the chamber being adapted to circulate dielectric coolant fluid therethrough; and

a solid dielectric loading having central cavity defined therein adapted to fit about the radiating portion, the solid dielectric loading extending from the coolant jacket.

19. The microwave antenna assembly according to claim 18 , further comprising:

a connection hub including cable connector coupled to the feedline, an inlet fluid port and an outlet fluid port; and

a seal disposed around a distal end of the outer conductive layer of the choke, wherein the coolant jacket is coupled to the connection hub and the seal thereby defining a proximal chamber around the feedline.

20. The microwave antenna assembly according to claim 18 , wherein the solid dielectric loading is formed from a dielectric material selected from the group consisting of an alumina ceramic or a polyamide plastic and having a dielectric constant from about 2.5 to about 150.

21. The microwave antenna assembly according to claim 18 , further comprising:

an inflow tube coupled to the inlet fluid port and disposed within the proximal chamber for supplying a dielectric coolant fluid thereto; and

an outflow tube coupled to the outlet fluid port and in fluid communication with the proximal chamber for withdrawing the dielectric coolant fluid therefrom.

22. The microwave antenna assembly according to claim 18 , wherein the coolant jacket is formed from a medical grade metal.