Segment-Matched Modulation Design for Multistate Broadband Microwave Absorber

This paper presents a novel approach to broaden the bandwidth of a microwave absorber via segment-matched modulation. This design is characterized by constructing absorption peaks simultaneously at the low-frequency and high-frequency ends of the original absorption state, thus significantly expanding the absorption envelope. The resistance and reactance conditions required for ideal absorption serve as a guide for the PIN diode to modulate the FSS impedance, thereby clarifying the principle of absorption peak generation. The reflectivity measurements are in good agreement with the simulation results, demonstrating a tunable broadband absorption of 0.61-4.00 GHz. The fractional absorption bandwidth of the proposed absorber is 147% with a thickness of 0.067λL, where λL is the wavelength of the lowest frequency.