Significance The sun (∼6,000 K) and outer space (∼3 K) are two natural energy resources for humans. However, most of the approaches of energy harvesting from the sun and rejecting energy to outer space are achieved independently using absorbers and emitters with static spectral properties. Herein, a spectrally self-adaptive structure with strong solar absorption and switchable emissivity within the atmospheric window (i.e., 8 to 13 μm) is experimentally demonstrated to achieve diurnal solar thermal and nocturnal radiative cooling efficiently. The experiment shows that the proposed structure not only can be heated to 185°C in diurnal mode but also be cooled to −12°C in nocturnal mode. This work opens new possibilities for continuously efficient energy harvesting utilizing the sun and the universe.

No abstract

No abstract

Abstract-A novel low-pass filter (LPF) is designed and fabricated based on stepped-impedance resonator (SIR). Semi-circles are used to reduce the size of the filter. The open-circuited stubs are used in the filter, and its simplified equivalent circuit is also proposed. The measured 3 dB cutoff frequency is 5.2 GHz with no more than 0.3 dB ripple level in the pass-band. From 5.5 to 14 GHz, the investigated LPF has a rejection level better than 20 dB. Measured results show good agreement with simulated ones.

No abstract