Low-Profile Broadband Absorber Based on Multimode Resistor-Embedded Metallic Strips

This article proposes a new method to realize a low-profile broadband absorber. The unit cell of the proposed absorber consists of two layers: a lossy layer with four rotationally symmetric bent metallic strips embedded with two chip-resistors, which is modified from a doubly fed dipole antenna, and a metallic ground separated from the lossy layer by an air spacer. Three resonant modes of the metallic strip embedded with two chip-resistors are generated, and the current in the strip passes through the chip-resistors under different modes and it is finally consumed, resulting in energy dissipation. As a result, an ultrawideband absorber is realized. The designed absorber is fabricated and measured, and the measured absorption band with a fractional bandwidth of 127.9% is achieved for at least 10-dB reflectivity reduction under the normal incidence. In addition, the thickness of the designed absorber is only 0.08λ_L, where λ_L is the wavelength at the lowest operating frequency.