In this paper we showed a new approach for the fabrication of a photonic crystal with a three-dimensional structure. By replicating biomaterials such as the wing of Mopho butterfly with TiO2 nanoparticles using the nanoparticles infiltration method, we can derive photonic crystals with unique structures, which is difficult to fabricate by other approaches. New optical properties are anticipated.
In this paper, an ultra-wideband (UWB) filter with a notch band using T-shaped step impedance resonator loaded with cross-shaped open stubs has been presented. The notch band is formed by utilizing intrinsic zero. The characteristics of the new quad-mode resonator have been analyzed using odd-even mode analysis method. It can be shown that it is the intrinsic zero that generates the notch band. In addition, wide tunable notch band form 5–9.3 GHz can be achieved. A UWB filter with a notch band centered at 6.25 GHz using the proposed quad-mode resonator has been designed, fabricated, and tested. Experiment results show that the attenuation in notch frequency is >22 dB while the return loss of the simulation and measurement results are 22 dB/20 dB and 14.5 dB/11.2 dB in the lower and upper passband, respectively, which illustrate that the simulation and measurement results are in agreement.
A C-band high-temperature superconducting six-channel multiplexer (sextaplexer) is proposed in this paper. A distributed coupling scheme is introduced, with which the bandpass filter (BPF) in each channel can be designed individually. The computational complexity of the proposed method is linearly increased as the number of the channels is getting larger, which is much lower than the traditional method. The proposed coupling scheme requires no extra matching network, which helps to reduce the size of the multiplexer circuit. The sextaplexer consists of six high-order BPFs with cascaded quadruplet structure. A pair of transmission zeros can be introduced to make the BPF have high selectivity. The example sextaplexer works at the C-band and each fractional bandwidth is about 0.8%. The center frequency ratios and the isolations of each adjacent channel can reach 1.01 and 42 dB, respectively. The measurement results match well with the simulation results, which verifies the effectiveness of the proposed method.
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