Wideband Gap-Waveguide Phase Shifter Based on a Glide-Symmetric Ridge

This paper presents a gap-waveguide phase shifter based on ridged unit cell with glide-symmetric configuration. The proposed unit cell design provides higher phase shift compared with a conventional ridged unit cell whose ridge height and waveguide width are tuned to achieve a stable phase shift. Through the insertion of glide-symmetric holes with semi-circle base in the ridged waveguide, a stable phase shift in a wide frequency range is achieved. Depending on the radii of the holes, the stable phase shift can be covered the desired frequency range. A 90^o phase shifter in millimeter-wave range is designed in order to validate the analysis. The impedance bandwidth of the phase shifter is from 32 GHz to 42.5 GHz (28.18%) providing a phase shift of 90^o+- 2^o in the entire frequency range.

Wideband Gap-Waveguide Phase Shifter Based on a Glide-Symmetric Ridge

This paper presents a gap-waveguide phase shifter based on ridged unit cell with glide-symmetric configuration. The proposed unit cell design provides higher phase shift compared with a conventional ridged unit cell whose ridge height and waveguide width are tuned to achieve a stable phase shift. Through the insertion of glide-symmetric holes with semi-circle base in the ridged waveguide, a stable phase shift in a wide frequency range is achieved. Depending on the radii of the holes, the stable phase shift can be covered the desired frequency range. A 90^o phase shifter in millimeter-wave range is designed in order to validate the analysis. The impedance bandwidth of the phase shifter is from 32 GHz to 42.5 GHz (28.18%) providing a phase shift of 90^o+- 2^o in the entire frequency range.

Comparative Modelling and Thermal Analysis of AlGaN/GaN Power Devices

The use of Aluminum Gallium Nitride (AlGaN) as a power switching device material has been a promising topic of research in recent years. Along with Silicon Carbide (SiC) and Gallium Nitride (GaN), AlGaN is categorized as a Wideband Gap (WBG) material with intrinsic properties best suited for high power switching applications. This paper simulates and compares the thermal and electrical performance of AlGaN and Silicon (Si) MOSFETs, modeled in COMSOL Multiphysics. Comparisons between similar AlGaN/GaN and Si power modules are made in terms of heatsink requirements. The temperatures for the same operating voltage are found to be significantly lower for the AlGaN MOSFETs structures, compared to Si. The heatsink size for the AlGaN/GaN is found to be smaller compared to Si for the power modules.

Measurement of Resistivity of Silicon Carbide by Discharge Time of Equivalent Capacitance of the Sample

According to the Classical Electrical Theory of Capacitor-to-Resistance Discharge, the Sample of Sic can Be Equivalent to a Parallel Circuit of Resistance and Capacitance. due to the High Resistance of the Wideband-Gap Semiconductors and the Long Discharge Time of the Capacitance, the Samples Resistivity can Be Calculated Manually or by Computer by Applying a Pulse Voltage to the Sample and then Accurately Measuring its Discharge Time. the Measuring Equipment Consists of Sample Stage, Pulse Generator, Charge Converter and Digital Oscilloscope. if High-Speed Data Acquisition Card and Industrial Computer are Used Instead of the Digital Oscilloscope, the Measurement Repeatability can Be Better than 1%, and the Measurement Range is within 104-1012 Ω•cm.