Use of polyphase continuous excitation based on the Frank sequence in EPR

► The use of a cross-loop resonator (CLR) allows continuous detection of the EPR signal during polyphase excitation. ► Polyphase continuous excitation based on the Frank sequence minimizes power used. ► Increasing excitation power results in a stronger EPR signal at the expense of line distortion. ► For the relaxation times of LiPc the maximum signal is reached at turning angle α = 5°, and the line is broadened by 5%.