Antenna for an implantable device

1. An implantable device for deployment inside a human or animal body, the device comprising:

at least one sensing component arranged to respond to an electrical signal having a known frequency band;

a housing arranged to house the at least one sensing component;

at least one antenna, the at least one antenna comprising at least one antenna pole connected to the at least one sensing component, the antenna pole comprising at least one helical coil and a connecting stem;

wherein the at least one sensing component comprises a first sensing component and a second sensing component and the at least one antenna is arranged to be in electrical communication with the first sensing component and the second sensing component; and

the known frequency band comprises a first known frequency band and a second known frequency band different to the first known frequency band;

wherein the first sensing component is arranged to respond to the electrical signal having the first known frequency band and the second sensing component is arranged to respond to the electrical signal having the second known frequency band; and

wherein the helical coil and the stem are arranged so that the bandwidth of the at least one antenna encompasses the known frequency band;

the at least one antenna being external to the housing and having a stem for securing to the housing the at least one antenna comprising an antenna insulating layer insulating it from a fluid of the body; and

an anchor for securing the device within a vascular lumen of a human or animal body, the anchor including at least one strut for securing in a channel within the housing, the anchor comprising an anchor insulating layer insulating it from the fluid of the body;

wherein the at least one antenna and the at least one strut of the anchor are arranged to reduce signal losses in the at least one antenna due to the at least one strut of the anchor;

wherein the anchor is a ground structure for the at least one antenna; and

wherein the at least one strut of the anchor is arranged to diverge or deflect at an angle of at least about 15 degrees relative to the at least one antenna.

2. The device of claim 1 , wherein the at least one antenna comprises a first antenna pole and a second antenna pole;

the first antenna pole and the second antenna pole are arranged to extend in different directions; and

the first antenna pole and second antenna pole are arranged to be substantially coaxial.

3. The device of claim 1 , wherein the at least one antenna comprises a first antenna pole and a second antenna pole;

wherein the first antenna pole and the second antenna pole are arranged to be substantially non-coaxial;

the second antenna pole is provided along an axis that is offset from the axis of the first antenna pole;

the first and second antenna poles are arranged to be generally asymmetrical;

the at least one antenna pole is completely enclosed within a sleeve;

the sleeve is arranged to at least partially insulate the at least one antenna pole; and

the sleeve comprises a dielectric material.