Radiation applicator

An elongate microwave radiator for insertion into a living body to treat biological tissue at a predetermined operating frequency, the radiator comprising a monopole antenna at its tip, the monopole antenna comprising:

• a monopole;
• and
• dielectric material surrounding the monopole, the dielectric material being configured to act as a resonator at said predetermined operating frequency, and encompassing generally the whole of the near-field radiation emitted by the monopole,
• in which the elongate device comprises a coaxial conductor with a central conductor that projects beyond outer screening of the coaxial conductor at the distal end to form the monopole of the monopole antenna, and
• further including a transformer between the coaxial conductor and the dielectric material to reduce reflection of radiation back into the coaxial conductor at the boundary with the dielectric material.

A method of coupling radiation into biological material, the radiation being generated by an applicator comprising a monopole antenna including a monopole surrounded by a dielectric body, the method comprising:

• configuring the dielectric body of the monopole antenna to act as a resonator;
• and
• selecting the dielectric constant of the body in accordance with the wavelength of the radiation in the dielectric so that generally the whole of the near-field of the radiation is encompassed by the dielectric body,
• in which the dielectric constant of the dielectric body varies, and is higher at its core than its outer periphery, and the dielectric constant at its outer periphery is lower than that of the surrounding biological matter.

A method of coupling radiation into biological material, the radiation being generated by an applicator comprising a monopole antenna including a monopole surrounded by a dielectric body, the method comprising:

• configuring the dielectric body of the monopole antenna to act as a resonator;
• and
• selecting the dielectric constant of the body in accordance with the wavelength of the radiation in the dielectric so that generally the whole of the near-field of the radiation is encompassed by the dielectric body, in which
• the dielectric constant of the body is high, but is lower than that of the biological material, and
• the dielectric constant at the core is greater than the dielectric constant of the biological matter.