An oven comprising: a cooking chamber configured to receive a load; and a radio frequency heating system configured to provide radio frequency energy into the cooking chamber using solid state electronic components, wherein the solid state electronic components include power amplifier electronics configured to provide a signal into the cooking chamber via an antenna assembly , wherein the power amplifier electronics include at least a first power amplifier and a second power amplifier operably coupled to the cooking chamber by respective ones of a first antenna and second antenna of the antenna assembly, the first and second antennas being operably coupled to respective ones of the first and second power amplifiers via a first coupling structure and a second coupling structure , respectively, wherein a directional coupler is provided at a port section defined at at least one of the first and second coupling structures, wherein the oven comprises a measurement assembly configured to calculate modified S parameters at the port section, wherein the directional coupler is configured to provide a forward parameter and a reflected parameter to the measurement assembly, characterized in that the oven comprises a calibration manager, wherein the measurement assembly is operably coupled to the calibration manager , the calibration manager being configured to receive the modified S parameters to perform calibration of the power amplifier electronics, and wherein the calibration of the power amplifier electronics comprises performing one port calibration followed by performing a transmission calibration. a cooking chamber configured to receive a load; and a radio frequency heating system configured to provide radio frequency energy into the cooking chamber using solid state electronic components, wherein the solid state electronic components include power amplifier electronics configured to provide a signal into the cooking chamber via an antenna assembly , wherein the power amplifier electronics include at least a first power amplifier and a second power amplifier operably coupled to the cooking chamber by respective ones of a first antenna and second antenna of the antenna assembly, the first and second antennas being operably coupled to respective ones of the first and second power amplifiers via a first coupling structure and a second coupling structure , respectively, wherein a directional coupler is provided at a port section defined at at least one of the first and second coupling structures, wherein the oven comprises a measurement assembly configured to calculate modified S parameters at the port section, wherein the directional coupler is configured to provide a forward parameter and a reflected parameter to the measurement assembly, characterized in that the oven comprises a calibration manager, wherein the measurement assembly is operably coupled to the calibration manager , the calibration manager being configured to receive the modified S parameters to perform calibration of the power amplifier electronics, and wherein the calibration of the power amplifier electronics comprises performing one port calibration followed by performing a transmission calibration. <EOS>