In this Letter, a new frequency-selective absorber (FSA) is presented that has wide-band transmission/absorption/reflection reduction responses. The presented absorber is completed by lossy cross-dog bone and lossless second-order frequency-selective surfaces (FSSs). The modal interaction pole generated by the lossy array is employed to achieve a wide-band transmission. Three absorption bands are combined to realize a continuous stop-band with high absorptivity. Furthermore, the improved absorber structure is investigated to reduce the strong reflection between the absorption and transmission bands. The 10 dB reflection reduction is obtained with a fractional bandwidth of 126.4%. Meanwhile, the - 3 dB fractional pass-band width is 41.3% with minimum insertion loss (IL) of 0.37 dB. The absorption bandwidth of 91.5% is provided with at least 90% absorptivity. The distance between the lossy and lossless layers is only 0.08 $\lambda_L$ L at the lowest operating frequency. Finally, the proposed design is validated by a good agreement between the numerical simulations and experimental measurements.

A low-profile metamaterial loaded antenna array with anti-interference and polarization reconfigurable features is proposed for base-station communication. Owing to the dual notches etched on the radiating electric dipoles, an impedance bandwidth of 75.6%ranging from 1.68 to 3.72 GHz with a notch band from 2.38 to 2.55 GHz can be achieved. By employing the metamaterial loadings that are arranged in the center of the magnetic dipole, the thickness of the proposed antenna can be decreased from 28 to 20 mm. Furthermore, a serial feeding network that consists of several wilkinson power dividers and phase shifters is introduced to attain the conversion between dual linear polarization and triple circular polarization. Hence, the antenna could meet the demand of the future 5G intelligent application.

In this article, a novel multifunctional reconfigurable wideband frequency-selective surface is proposed. Compared with the conventional structures that can only realize two switchable states of transmission and reflection, this design could independently manipulate the TE and TM waves through four modes. Second-order equivalent circuits based on two polarizations are studied to solve the impedance mismatch caused by the asymmetric structure and biasing system, by using compensation capacitors. With different biasing voltages, the passband and stopband can be achieved by second-order filter and multireflection responses, respectively. Each mode does not affect the others, while their transmission or reflection performances in the corresponding modes are almost the same. From 0° to 45° incidences, in the transmission state, high-transmittance windows (the minimum insertion loss is 0.1 dB) with a −3 dB fractional bandwidth of 43.2% are realized. When this design operates in the shielding state, it can prevent the incident energy from penetrating the structure with extremely stable oblique incident performances from lower frequencies to 11 GHz. Finally, a prototype is fabricated for measurements, and the proposed design is validated by the calculated, simulated, and measured results.