Design of 90 degree-switched-line Phase Shifter with Constant Phase Shift Using CRLH TL

The design of a 90 degree-switched-line phase shifter using composite right/left handed transmission line (CRLH TL) is presented in this paper. To achieve a relatively constant phase shift over a large bandwidth, a CRLH TL implemented using lumped elements and a right-handed transmission line (RH TL) are used as the reference and delay arms, respectively, of the phase shifter. Computer simulation is used to study and design the phase shifter. The phase shifter is also fabricated and measured to verify the simulation results. For comparison, a conventional 90±-switched-line phase shifter is also designed and simulated. Simulation and measurement results show that, the proposed phase shifter has a constant phase shift, a high return loss and a low insertion loss across the operating frequency band.published_or_final_versionThe 2014 Progress In Electromagnetics Research Symposium (PIERS 2014), Guangzhou, China, 25-28 August 2014. In PIERS Proceedings, 2014, p. 1655-165

A compact 6-bit phase shifter with high-power capacity based on composite right/left-handed transmission line

The EuMC 2010 Conference was one of the 4 conferences held during the 13th European Microwave Week (EuMW2010): "Connecting the World", Paris, France, 26 September-1 October 2010A compact 6-bit phase shifter with high power-handling capacity is designed based on the use of metamaterial, composite right/left-handed transmission line (CRLH-TL). Eight PIN diodes mounted on the fingers of the CRLH-TL are used as switches to control the phase incursion of the input signal. Different phase shifts are achieved by using different states of the switches (PIN diodes) determined by 6 controlling bits. Since the surface current flowing through each of the switches is only a fraction of the total current through the device, the power handled by each of the PIN diodes is much smaller than the total power through the device; thus the power-handling capacity of the phase shifter can be greatly improved. The phase shifter is designed to provide a phase-shift range from 0° to 360° at a step of 5.625° and operate in the frequency band from 9.2 to 9.8 GHz. Simulation results and measurement results of the prototype agree closely and show that the phase shifter has a much higher power-handling capacity than that of the PIN diode and low insertion losses across the operating frequency band. © 2010 EuMA.published_or_final_versionThe 40th European Microwave Conference (EuMC 2010), Pairs, France, 28-30 September 2010. In Proceedings of EuMC 2010, 2010, p. 437-44

A rectangular-shaped time-delay line inspired by CRLH TL unit cell for UWB operation

This paper presents the design of a rectangular-shaped ultra-wideband (UWB) time-delay line inspired by the use of composite right/left-handed transmission line (CRLH TL) unit cells. A rotated version of a conventional CRLH TL unit cell is used as the basic elements to achieve UWB operation. For comparison, time-delay lines using the right-handed transmission line (RH TL) and CRLH TL unit cells are also studied, fabricated and tested. Simulation and measurement results show that our proposed time-delay lines have high return loss, low insertion loss, UWB operation and much longer time delays than that of the time-delay line based on RH TL. © 2010 IEEE.published_or_final_versionThe 12th IEEE International Conference on Communication Systems (ICCS 2010), Singapore, 17-19 November 2010. In Proceedings of 12th ICCS, 2010, p. 27-3

A compact and UWB time-delay line inspired by CRLH TL unit cell

This paper presents the design of compact and ultra-wideband (UWB) time-delay lines inspired by the use of composite right/left-handed transmission line (CRLH TL) unit cell. A conventional CRLH TL unit cell is used as the basic elements for the design of time-delay lines and a rotated version of the unit cell is used to achieve ultrawide bandwidth operation. Time-delay lines for large time delays are designed by cascading the proposed unit cells, optimized using computer simulation and then fabricated on PCBs. A compact UWB time-delay line is designed by bending the time-delay line in a meander. For comparison, the time-delay line using the right-handed transmission line (RH TL) is also fabricated. Simulation and measurement results show that our proposed time-delay lines have ultrawide bandwidth operation and much longer time delays than that of the time-delay line based on RH TL. They also have the advantages of high return losses and low insertion losses. © 2010 IEEE.published_or_final_versionThe 2010 IEEE Region 10 International Conference (TENCON 2010), Fukuoka, Japan, 21-24 November 2010. In TENCON (IEEE Region 10 Conference) Proceedings, 2010, p. 868-87

Splicing-dependent NMD does not require the EJC in Schizosaccharomyces pombe

Nonsense-mediated mRNA decay (NMD) is a translation-linked process that destroys mRNAs with premature translation termination codons (PTCs). In mammalian cells, NMD is also linked to pre-mRNA splicing, usually PTCs trigger strong NMD only when positioned upstream of at least one intron. The exon junction complex (EJC) is believed to mediate the link between splicing and NMD in these systems. Here, we report that in Schizosaccharomyces pombe splicing also enhances NMD, but against the EJC model prediction, an intron stimulated NMD regardless of whether it is positioned upstream or downstream of the PTC and EJC components are not required. Still the effect of splicing seems to be direct—we have found that the important NMD determinant is the proximity of an intron to the PTC, not just the occurrence of splicing. On the basis of these results, we propose a new model to explain how splicing could affect NMD

Ultra-wideband time-delay line inspired by composite right/left-handed transmission line unit cell

Proceedings of the IEEE International Conference on Ultra-Wideband, 2010, v. 2, p. 607-610This paper presents a design of ultra-wideband time-delay line inspired by the composite right/left-handed transmission line (CRLH TL) unit cell. A rotated version of the conventional CRLH TL unit cell is used to increase the operating bandwidth. The time-delay line is optimized using computer simulation and then fabricated on a PCB for measurement. For comparison, the time-delay lines using the right-handed transmission line (RH TL) and periodic microstrip line (PML) are also designed, optimized and fabricated. Simulation and measurement results show that, for the same length of 60 mm, our proposed time-delay line has a much longer time delay of 2000 ps with high return loss and low insertion loss. © 2010 IEEE.published_or_final_versio

CPW-coupled-fed elliptical monopole UWB antenna with dual-band notched characteristic

This paper presents the results of a coplanar-waveguide (CPW)-coupled-fed elliptical monopole UWB antenna (CCFEMUA) with a dual band-notched characteristic. The antenna has a large bandwidth covering the frequency band from 2.4 GHz to 152 GHz with the return loss larger than 10 dB. Two band notches at 3.7GHZ and 4.8 GHz are realized by cutting two half-elliptical-arc slots on the radiation patch The return loss, radiation pattern, peak gain and efficiency of the antenna are studied using computer simulation.published_or_final_versio

Evaluation of union bounds for space-time codes based on a common function

Error-rate evaluation of Space-Time codes using Union bounds sometimes requires very heavy computational loads and so is impractical to use. In this paper, a Common function shared by different Union bounds is derived and used to develop a modified Union bound (MUB) for error-rate evaluation. Results of numerical evaluations and Monte-Carlo simulation on two 2x2 rotation-based S-T codes show that the MUB provides a good compromise between the required computational load and the accuracy for error-rate evaluation. ©2009 IEEE.published_or_final_versionThe 22nd IEEE Canadian Conference on Electrical and Computer Engineering (CCECE 2009), St. John's, NL., 3-6 May 2009. In Proceedings of the 22nd CCECE, 2009, p. 89-9

Simple dual-band notched design for CPW-coupled-fed elliptical UWB monopole antenna

This paper presents the results of a CPW-coupled-fed elliptical UWB monopole antenna (CCFEUMA) with a simple dual-band notched design for the WLAN Band. The antenna has a large bandwidth covering the frequency band from 2.5 to 14.6 GHz with the return loss larger than 10 dB. Two band notches at the lower (5.15-5.35 GHz) and higher (5.725-5.825 GHz) WLAN band are realized by cutting two half-elliptical arc-slots on the radiator. The return loss, radiation pattern, peak gain and efficiency of the antenna are studied using computer simulation and measurement. © 2012 IEEE.published_or_final_versio

Weakening of the stratospheric polar vortex by Arctic sea-ice loss

Successive cold winters of severely low temperatures in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although these cold winters are thought to be partly driven by dramatic losses of Arctic sea-ice, the mechanism that links sea-ice loss to cold winters remains a subject of debate. Here, by conducting observational analyses and model experiments, we show how Arctic sea-ice loss and cold winters in extra-polar regions are dynamically connected through the polar stratosphere. We find that decreased sea-ice cover during early winter months (November-December), especially over the Barents-Kara seas, enhances the upward propagation of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January-February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes.open11167174Ysciescopu