An electromagnetic energy delivery system (10, 100) comprising: a set of radio frequency channels (122A-122D, 222, 322, 422), each channel comprising: a radio frequency feed (26A-26D, 116A-116D, 216, 316, 416) configured to radiate electromagnetic energy; at least one high-power radio frequency amplifier (18A-18D, 114A-114D, 214, 314, 414) coupled to the radio frequency feed (26A-26D, 116A-116D, 216, 316, 416), each high-power radio frequency amplifier (18A-18D, 114A-114D, 214, 314, 414) comprising at least one amplifying component configured to output a periodic signal (113A-113D, 213, 313, 413) that is amplified in power with respect to an input radio frequency common reference signal (110, 210); and a phase-shifting component (112A-112D, 212, 312, 412) configured to modulate the phase of the output periodic signal (113A-113D, 213, 313, 413) with respect to the input radio frequency signal (110, 210); and a controller (14, 108) coupled to the set of radio frequency channels (122A-122D, 222, 322, 422), the controller (14, 108) configured to cause the output periodic signals (113A-113D, 213, 313, 413) from each of the radio frequency channels (122A-122D, 222, 322, 422) to have a time-varying phase difference relative to the common reference signal (110, 210) and a phase difference relative to the other output periodic signals (113A-113D, 213, 313, 413) that is constant when averaged over time. a set of radio frequency channels (122A-122D, 222, 322, 422), each channel comprising: a radio frequency feed (26A-26D, 116A-116D, 216, 316, 416) configured to radiate electromagnetic energy; at least one high-power radio frequency amplifier (18A-18D, 114A-114D, 214, 314, 414) coupled to the radio frequency feed (26A-26D, 116A-116D, 216, 316, 416), each high-power radio frequency amplifier (18A-18D, 114A-114D, 214, 314, 414) comprising at least one amplifying component configured to output a periodic signal (113A-113D, 213, 313, 413) that is amplified in power with respect to an input radio frequency common reference signal (110, 210); and a phase-shifting component (112A-112D, 212, 312, 412) configured to modulate the phase of the output periodic signal (113A-113D, 213, 313, 413) with respect to the input radio frequency signal (110, 210); and a radio frequency feed (26A-26D, 116A-116D, 216, 316, 416) configured to radiate electromagnetic energy; at least one high-power radio frequency amplifier (18A-18D, 114A-114D, 214, 314, 414) coupled to the radio frequency feed (26A-26D, 116A-116D, 216, 316, 416), each high-power radio frequency amplifier (18A-18D, 114A-114D, 214, 314, 414) comprising at least one amplifying component configured to output a periodic signal (113A-113D, 213, 313, 413) that is amplified in power with respect to an input radio frequency common reference signal (110, 210); and a phase-shifting component (112A-112D, 212, 312, 412) configured to modulate the phase of the output periodic signal (113A-113D, 213, 313, 413) with respect to the input radio frequency signal (110, 210); and a controller (14, 108) coupled to the set of radio frequency channels (122A-122D, 222, 322, 422), the controller (14, 108) configured to cause the output periodic signals (113A-113D, 213, 313, 413) from each of the radio frequency channels (122A-122D, 222, 322, 422) to have a time-varying phase difference relative to the common reference signal (110, 210) and a phase difference relative to the other output periodic signals (113A-113D, 213, 313, 413) that is constant when averaged over time.