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This paper presents a filtering power divider (PD)/power combiner (PC) using substrate integrated waveguide (SIW)-based 180^o hybrid. The utilized 180^o hybrid includes a standard H-plane 3-dB coupler and a broadband 90^o phase shifter. The phase shifter is composed of non-radiating longitudinal slots patterned on the top conducting surface of the SIW. We have added the filtering property to the structure by an array of dissimilar transverse slots. The slots dimensions are obtained by the extracted external quality factor, coupling coefficient and the relationship between them and the slots dimensions. The proposed structure is designed for 8.2 GHz and investigated by ADS simulator. The results show the fractional bandwidth of the sum and difference ports are 13.7% and 14.93%, respectively. For sum operation, the minimum insertion loss is 3.78 dB and the return loss is above 25 dB in the passband. For difference operation, the minimum insertion loss is 3.81 dB and the return loss is above 26 dB in the passband  

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In this manuscript a compact high speed optical Mach-Zehnder modulator with very low energy consumption based on hybrid plasmonic waveguide is presented. Compared to dielectric waveguide-based structures, large propagation constant of optical modes in hybrid plasmonic waveguides reduces the propagation length required for attaining necessary phase shift for proper operation of Mach-Zehnder interferometer. On the other hand, strong light confinement in hybrid plasmonic waveguide facilitates realization of relatively short bends (with small bend radius) and compact Y-junctions which in turn reduces the overall footprint of modulator. Our simulations show theoretical modulation speed of more than 1 THz and very low energy consumption about 17 fJ/bit. In addition, the modulation depths as high as 25 dB are achievable by applying voltages between + 3 V and -3 V, in a push-pull configuration. Apart from electrodes, the overall footprint is about ~120 mm² which is, based on our knowledge, very smaller than that of common Mach-Zehnder modulators.

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Ultrasonic nondestructive testing is a powerful tool for detection of defects as well as characterization of various properties of materials. In ultrasonic testing, it is very important to know the exact wave velocity in the material because most measurements somehow depend on wave velocity. Many other characteristics of materials such as elastic constants also depend on wave velocity. While variations of wave velocity in ambient temperatures is very small, these variations could be noticeable at high temperatures. In this paper, a simple and innovative experimental method is proposed for measurement of ultrasonic wave velocities at high temperatures. To keep the ultrasonic probe far from the hot sample, a special waveguide is designed. The wave velocity measurements are performed by pulse-echo ultrasonic testing technique and variations of ultrasonic wave velocities at temperatures ranging from 40oC to 160oC are investigated. It is observed that the velocity of ultrasonic waves decrease with increase in temperature. Experimental results are compared with theory and measurement uncertainties are calculated. These uncertainties are ±0.01 m/s and ±0.003 m/s for longitudinal and transverse wave velocities, respectively. The theoretical and experimental results agree very well.