Abstract: objectives In order to meet the requirements of measuring the rectangular pulse radiation field with varying repetition frequency in fields outside, the measurement method was researched using peak detection in the frequency domain.MethodsThe measurement process by means of peak detection for the rectangular pulses with varying repetition frequency was analyzed while the operation mechanism of the measurement instrument and the characteristics of the pulses were researched. The reason why the measurement readings were unable to stabilize was discovered, hence the measurement design idea was proposed. The expression for the measurement result was derived, and the quantitative relationship between the measurement result and the peak power of the measured signal was obtained. The mathematical models for the field strength correction coefficient had been established and solved. On the basis of the above, a method for optimizing instrument parameters was proposed to stabilize measurements and simplify the correction the process. ResultsThe experimental results showed that the deviations between the measurement results and the nominal values were less than 0.5 dB, indicating that the measurement method was effective and feasible. ConclusionsThis measurement method allows the measurement resolution bandwidth to be smaller than the signal occupied bandwidth and can obtain the peak field strength and average field strength of the rectangular pulse radiation field with varying repetition frequency, which provides a certain support for controlling electromagnetic environment and is helpful for studying the measurement methods for pulse radiation fields with varying repetition frequency in other signal forms.