Frequency-Selective Rasorber with Stable Transmission Amplitude and Insertion Phase Delay

This paper presents a frequency-selective rasorber (FSR) with stable transmission amplitude and insertion phase delay. Two lossy layers with different dimensions can be used to absorb low-frequency and high-frequency incident waves, respectively, achieving an absorption bandwidth from 3 GHz to 18.7 GHz. For the bandpass response of the FSR, the interconnected loop and grid patterns stabilize the transmission amplitude and insertion phase delay, respectively. Simulation results show that the proposed FSR achieves an improved insertion phase delay compared to a dielectric radome of 8.4 mm thickness under the oblique incident angle from 0° to 60° at 12 GHz. Owing to its perfect symmetry, the FSR maintains identical insertion phase delay stability for transverse magnetically polarized waves in the x o z - and y o z-planes. Measurements of the fabricated FSR show good agreement with the simulation ones.