Surgical cutting apparatus having a treatment channel and a measurement channel for conveying microwave energy from a source to an antenna at a cutting edge. The measurement channel operates at lower power than the treatment channel for determining when higher energy can be safely applied. The apparatus may deliver microwave radiation at differing frequencies to one or more antennas at the cutting edge, e.g. to provide different treatment effects. The source may generate an output for an antenna whose frequency can be selected e.g. for most efficient operation. Selection may be automatic based on detected magnitude and phase of reflected signals during a frequency sweep of a forward signal. Power delivered to tissue via the cutting element may be manually boosted to deal with large blood vessels. The apparatus may include a reflected power monitor for recognizing behavior in reflected signals received from the antenna to trigger automatic pre-emptive action.