ELECTROSURGICAL INSTRUMENT

An electrosurgical instrument for applying radiofrequency (RF) electromagnetic (EM) energy and/or microwave frequency EM energy to biological tissue. The instrument comprises an instrument tip having a planar body separating a first conductive element on a first surface thereof from a second conductive element on a second surface thereof. The instrument comprises a coaxial feed cable comprising an inner conductor, an outer conductor coaxial with the inner conductor and a dielectric material separating the inner and outer conductors. The first conductive element comprises a pattern configured to set an electrical length of the instrument tip to be greater than an electrical length of a reference instrument tip.