This paper presents the design of a broadband bandpass filter for the Ku-band based on a Half-Mode Substrate Integrated Waveguide (HSIW) structure. The filter utilizes HSIW as the main resonant cavity and employs stepped impedance microstrip lines as input and output ports. Two H-shaped slot resonators are used to introduce two transmission zeros for the upper stopband, and stepped impedance resonators are added on the open boundary of HSIW and the feeding lines to introduce five transmission zeros for the lower stopband. This design enhances the filter's selectivity and out-of-band suppression capability. Simulation and test results show that the filter operates in the frequency range of 12.91 GHz to 18.12 GHz with an insertion loss of -2.38 dB and a typical return loss of -10dB. Additionally, out-of-band suppression reaches -30 dB or lower at 20.62 GHz to 28.87 GHz and 4.33 GHz to 10.52 GHz. The verified performance demonstrates that the filter exhibits favorable transmission characteristics and out-of-band suppression capabilities.

This paper presents a C-band (4–8 GHz) transconductance-controlled variable gain low noise amplifier (Gm-VGLNA) with excellent gain-flatness. The impedance and gain of the improved amplifier-cell (IA) are analyzed, and a current-controlled E-mode pHEMT load (CEL) structure is proposed to improve the gain-flatness performance in a wideband frequency range. The Gm-VGLNA is designed and fabricated using a 0.25 μm GaAs pHEMT process. The measured results demonstrate a gain range of 11.5 dB, a return loss better than −8.3 dB over the operating frequency range, and a minimum noise figure of 2 dB. The best gain-flatness achieved is ±0.22 dB while the small signal gain is 15.2 dB, with gain-flatness better than ±0.78 dB over the entire operating gain range.

Two-dimensional van der Waals heterostructures can combine properties of individual materials to enable high-performance photodetection. Here, a novel ReS2/graphene/WSe2 heterostructure, prepared by dry transfer, demonstrates air-stable, high-performance, polarization-sensitive, and broadband photodetection. Dark current can be strongly suppressed by the built-in electric field of the heterostructure. The specific detectivities are up to 10(10) Jones and 10(9) Jones under zero and reverse bias, respectively. Response time is on the order of a millisecond. The polarization-sensitive photodetection has been observed in the heterostructure due to the low lattice symmetry of ReS2. Broadband photoresponse from visible to infrared range has been demonstrated. A high photoresponsivity of 1.02 A W-1 is achieved for illumination at the wavelength of 785 nm. This work provides a viable approach toward future high-performance, air-stable, and polarization-sensitive broadband photodetectors.