A biopsy needle (80) having a longitudinal channel (84) formed within an inner conductor (86) of a coaxial antenna is disclosed. The coaxial antenna terminates in a rigid insertion tip (82) e.g. a ceramic cone that is insertable into biological tissue. Microwave energy (e.g. having a frequency of 1 to 100 GHz) delivered to the coaxial antenna is emitted at the insertion tip. The insertion tip may be arranged to match the impedance of the coaxial antenna to a predetermined tissue impedance. The emitted radiation can be used to measure properties of or treat (e.g. ablate) tissue at the insertion tip. Needle biopsy apparatus is also disclosed, in which a microwave energy is controllably delivered to a needle from a microwave generator. The apparatus may include an impedance tuner to dynamically match the impedance of the needle with tissue at the insertion tip.
