A microwave heating system configured for heating a plurality of articles is provided. One or more of the microwave launchers can be offset slightly, such that the microwave energy introduced into the heating chamber is discharged at a launch tilt angle of at least 2°. Additionally, each launcher can include a microwave-transparent window disposed between the microwave chamber and the one or more launch openings and at least 50 percent of the chamber-side surface of the window can be oriented at an angle of at least 2° from the horizontal.