Three-Dimensional Ultra-Wideband Microwave Absorber with Impedance Transforming Slotlines

This paper proposes an ultra-wideband microwave absorber based on three-dimensional (3D) slotline impedance transforming structures, which is capable of achieving a fifth-order absorption response. The 3D microwave absorber employs the impedance transformation design principle along with a synthesis design methodology for Chebyshev response. The proposal is able to achieve arbitrary in-band return loss (RL) level and flexible ripple fractional bandwidth (FBW) with resorting to the synthesis method. For validation, a fifth-order absorber is designed, fabricated, and measured. The measured results demonstrate that the absorber can achieve a wide absorption band with an FBW up to 157% with a minimum of 10dB reflectivity reduction under the normal incidence.