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The bandwidth of a broadband dual-polarized antenna is enhanced by adding two parasitic elements: a larger parasitic element below the dual-polarized element and a smaller parasitic element above the dual-polarized element. The bandwidth enhanced dual-polarized antenna covers the frequency range from 1.5 to 2.7 GHz with good performance.
THz coplanar waveguides were fabricated on quartz wafers with integrated epitaxially transferred low temperature grown gallium arsenide photoconductive switches. THz radiation was excited on-chip and transmitted through a tapering of the coplanar waveguide structure where it was focused down to ∼ 1.66μm. Theoretical modelling of the device confirms high E-field confinement and concentration.
We present the first room temperature photodection of hundreds on nanowatts using a quantum well mid-infrared detector at 9μm, with a background-limited temperature of 82K and a corresponding background-limited specific detectivity of 1.4×1010 cmHz1/2/W. The photonic architecture consists of an array of double metal nano-antennae and allows to reduce the dark current and increase the absorbed electromagnetic...
Tapered THz coplanar waveguides (CPWs) formed from Co/Cu multilayers with embedded low-temperature-grown gallium arsenide photoconductive switches were designed in order to observe giant magnetoresistance (GMR). Pulsed THz radiation was excited using the switches, and was transmitted through both straight and tapered CPWs. GMR-induced changes in the transmitted THz pulse amplitude were demonstrated.
Arrays of coupled split ring resonators (SRRs) capable of carrying slow short-wavelength magneto-inductive waves have been shown to support the rapidly varying current distributions required for superdirectivity. However, the superposition of both electric and magnetic dipole resonance modes contributing to radiation of SRRs challenge pure physical intuition in the selection of the optimal dimer configuration...
A compact monopole antenna with a volume of only 8×32×5 mm3 for smartphones applications is presented. The antenna consists of two meander monopoles, having an S-shape and L-shape, on one side of the substrate and a tuning stub on the other side. Simulated and measured results show that the antenna has a dual-band of 824–960 MHz and 1700–3800 MHz which can cover the frequency bands for the GSM850,...
A broadband dual-circular polarization (CP) antenna is presented in this paper. The antenna consists of square radiator fed by a feeding network with four outputs. The feeding network is designed using a 3-dB hybrid-coupler chip to obtain a sequential-phase difference of 90° at the four output ports. Simulation shows that the antenna has an impedance bandwidth (IMBW) of 37% (1.1–1.6 GHz) for |S11|<−10...
A planar 8-port MIMO antenna consisting of only 4 slot elements is proposed in this paper. The antenna has a symmetrical structure and is designed to operate from 2.40–2.48 GHz. Each of the 4 slot elements is serving as a common radiator for 2 input ports. A T-shaped defected ground structure (DGS) is cut in the middle of the slot element to increase isolation between the two input ports to more than...
We report on an Erbium-doped fiber laser operated at harmonic mode locking (HML) state with broadband spectrum. Stable pulse train emitted from the light source can continuously vary from 2nd to 17th order with spectrum bandwidth beyond 50 nm. The bandwidth can be up to 57 nm at 10th order HML. The pulse duration is measured to be 966 fs by an autocorrelator, and the corresponding time band product...
Terahertz (THz) and sub-THz frequency emitter-detector technology is receiving increasing attention because of key apphcations in several fields. In particular, ultrafast THz receivers are desired for compact, ultrafast spectroscopy and communication systems. While most of the available THz detectors (thermal, FET …) are currently limited in response time by slow thermal processes and/or by the read-out...
By using a hybrid energy-harvesting mode, a novel self-powered wireless-sensing-node is developed for vibration-type distinguishable environment/event monitoring. The dual-stage piezoelectric vibration energy harvester has threshold-triggered electricity generating function. Such harvesters generate considerable power when the ambient vibration reaches the two preset conditions of acceleration and...
This paper firstly presents an integrated three-axis electrochemical micro seismic sensor, which consists of four sensing units. The direction of the flow is opposite in different channel so that differential current can be calculated. Vertical vibration can also be detected by the addition of the output from four sensing units. Instead of huge volume in conventional three-axis sensor, the integrated...
High temperature vulcanized (HTV) silicone rubber (SiR) is widely used as HVDC cable accessory insulation considering its outstanding electrical properties along with elasticity and thermal resistance. However surface charge caused by corona would accumulate on SiR surface and distort the local field which in consequence led to accessory premature discharge and insulation failure. This paper tried...
Accurately estimating the core power losses under the trapezoidal induction waveform, and analyzing its variation with the duty cycle, are essential for the elaborate design of high-frequency transformers used in dual-active-bridge (DAB) dc-dc converters. In this paper, core power losses under trapezoidal induction waveform are theoretically predicted by considering the specific role of hysteresis,...
In the application of household refrigerator, the linear compressor is popularly adopted due to its no crank mechanism and directly oscillated by the inside drive machine and the helical coil springs.
Using a PPLN waveguide, we selectively up-convert either TM00 or TM01 mode, or any of their superpositions from 1540 nm into TM01 mode at 775 nm, with >70% internal efficiency and better than –16-dB crosstalk.
We demonstrate the generation of 11ps terahertz pulses from spectrally broad metal-metal quantum cascade lasers at 77K via active modelocking, and show the critical role of phase-matching between the terahertz pulse and the microwave modulation.
We demonstrate single-pixel and 2D arrays of THz quantum-well photodetectors featuring extremely sub-wavelength, antenna-coupled resonators. Few-micron sized devices show photodetection in the 100–200 μm range, with a consequent dramatic reduction in the device dark current.
The far-field emission profile of terahertz quantum cascade lasers (QCLs) in metal-metal waveguides is controlled in directionality and form through planar horn-type shape structures, whilst conserving a broad spectral response.
Enhanced electroluminescence in arrays of double metal patch microcavities is demonstrated. The enhancement originates from high Purcell factors and efficient photon out-coupling as the period of the array is increased.
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