Spectral Modification of UWB Radiation Pulses Through the Frequency-Selective Rasorber for In-Lab IEMI Experiments

This letter proposes an absorptive frequency-selective loading method for modifying the spectrum of high-power (HP) ultrawideband (UWB) radiation pulses for in-lab intentional electromagnetic interference (IEMI) experiments. By integrating an absorptive-transparent-absorptive frequency-selective rasorber (FSR) with an established impulse radiating antenna (IRA), the broadband radiation pulse can be reshaped into a mesoband waveform, while the out-of-band components are attenuated through the absorptive response of the FSR. As a representative implementation, a square-loop hybrid-resonator FSR is integrated with a 40-cm-diameter IRA. Full-wave simulations are performed to determine the IRA-FSR separation, analyze the spectral-modification behavior, and compare the source-side backward fields with those of an FSS-loaded reference case. Finally, the prototype is fabricated and experimentally tested. Measured results show that the HP-UWB pulse is converted into a damped sinusoidal waveform with a mesoband spectrum centered at 1.4 GHz and a −3 dB bandwidth from 1.25 to 1.52 GHz.