Electrosurgical generator for delivering microwave energy at multiple frequencies

An electrosurgical generator comprising:

• an electromagnetic signal supply unit for generating microwave energy to be conveyed on each of three or more microwave channels, wherein each of the three or more microwave channels is arranged to convey microwave energy at a different frequency;
• an output port configured to be connectable to a probe for delivering microwave energy from the three or more microwave channels;
• and
• a signal combiner configured to connect the three or more microwave channels to the output port,
• wherein the signal combiner comprises:
• a band stop filter module disposed at a distal end of each of the three or more microwave channels, wherein the band stop filter module for each microwave channel is configured to block microwave energy at the frequency conveyed on each of the other microwave channels;
• and
• a common signal pathway extending between the output port and a junction at which the three or more microwave channels are connected,
• wherein each microwave channel comprises a trunk transmission line along which microwave energy having the frequency corresponding to the microwave channel is conveyed from the electromagnetic signal supply unit to the junction;
• wherein each band stop filter module comprises a three stub filter for each frequency of microwave energy to be blocked, wherein the three stub filter comprises three stubs connected to the trunk transmission line to present an open circuit in shunt to the junction at a wavelength of the microwave energy to be blocked.