The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
There has be significant growth in recent year in the requirement for high quality long-term underwater acoustic data acquisition. One of the primary drivers has been the assessment of long-term trends in noise in our oceans and potential impacts from anthropogenic noise on marine wildlife. These recorders usually fulfill a number of key roles in this sector. These include providing acoustic data...
By introducing side-absorbers to metal-metal waveguides of broadband terahertz quantum cascade lasers, we are able to control and completely suppress higher-order lateral waveguide modes. This change leads to an octave spanning laser spectrum with a 600 GHz wide flat top. In addition, the absence of higher order lateral modes has a strong effect on the pulse generation of injection seeded QCLs. We...
Small Cells (SCs) are considered as a key enabling technique for future 5G cellular networks; whether they are deployed for Macro Cells networks densification or ensuring a standalone broadband access service. However, one of the critical challenges facing SCs deployments is a stable and an economical backhaul network. Particularly, if we consider SC for green-field deployments where operator transport...
We report on a monolithic extracting structure for terahertz quantum cascade laser based frequency combs. For a spectral bandwidth of more than 600 GHz at a center frequency of 2.5 THz a frequency comb with well-defined farfield pattern could be achieved. In addition the dynamic range of the frequency comb has been significantly improved.
In this paper, an input coupler for W band gyrotron TWT (Traveling Wave Tube) has been designed. This input coupler has the ability of efficiently converts a TE10 rectangular waveguide mode into a TE01 cylindrical waveguide mode. The measured results agree well with the simulated results. With the measured −2dB bandwidth of more than 4GHz, the input coupler can be well used in the experiment of W...
Efficient and optimized data transfer in broadband is the anchor point of digital economy in modern era. One the most challenging issues for providing different services in broadband is the bandwidth allocation. That is a real-time multi dimensional problem solving requiring to satisfy QOS and SLA constraints at the same time. In this paper, we present a real-time adaptive framework for the problem...
An ultra-broad bandwidth input/output structure is designed for 0.26 THz sheet beam traveling wave tube (SB-TWT). Adopting the multi-aperture coupler, this structure owns a larger electron tunnel and superior transmission characteristics. In order to maintain vacuum status and meet the operating bandwidth requirement, a new style pill-box window is presented. Employing the hybrid transmission modes,...
Rapidly increasing user data base and escalating bandwidth demand has compelled Telecom Regulatory Authority of India (TRAI) to open up new spectrum bands for Long Term Evolution (LTE) access lying in TeleVision White Spaces (TVWS) for auction. But rural areas are not likely to respond to the such large bandwidths open to them. The paper proposes implementing Wireless Regional Area Network based on...
Silicon RF power amplifiers (PAs) are in various RF front end modules (FEMs) today for handset and WLAN applications. Even though III-V semiconductor-based RF PAs can still offer superior frequency and breakdown performance with higher Pout and power-added-efficiency (PAE) and faster time-to-market, silicon-based RF PAs do have the advantages in offering higher monolithic integration with added functionalities...
With advances of CMOS technologies, the high-speed characteristic of transistors gives additional design margin for millimeter-wave (mm-Wave) PAs. The design of prior-art mm-Wave PAs is now focusing on the optimizations of back-off efficiency while maintaining linearity. This facilitates the transmission of broadband high-order digital modulated signals with decent system efficiency. This paper reviews...
In this article, a super compact enhanced-bandwidth (EB) rat-race coupler (RRC) is initially proposed based on the combined technology of fractal geometry and lumped-element composite right/left handed transmission line (CRLH TL). The close-form broadband derivation and a set of design guideline for fractal implementation are provided which should be a reference value for future design. Fractal perturbation...
The generation of continuous THz-waves by photomixing has several promising features, such as extremely-wide frequency tunability, very narrow linewidth, good frequency stability, and the ability to transmit high-frequency signals through low-loss optical fibers. To make such a scheme work effectively, we developed an InP/InGaAs uni-traveling-carrier photodiode (UTC-PD) [1, 2]. The UTC-PD has a unique...
A broadband aperture-coupled stacked patch array with a 45° polarization is presented. With the stacked patches and air layer structure being used, the elements' bandwidth and radiation efficiency are improved. The array achieves the 45°-polarization radiation through rotating the patches of each element. Experimental results show that a sound impedance match and stable radiation patterns are achieved...
Plane reflector is a two dimensional array which consists of apertures or patchesthis kind of reflectarray is always illuminated by a primary feed hornand then compensate the spatial phase delay by the elements printed on the surface. The main advantage of this structure is the main beam can be designed to tilt or scan a number of beamwidths away from its broadside direction. But the most significant...
In this paper, a novel X-band broadband single-layer unit cell with attached phase-delay lines for reflectarray antennas is proposed to surmount the limitation of the reflectarray bandwidth. The unit cell is composed of three circular rings, each with a pair of gaps which are mutually placed orthogonally, and two identical circular phase-delay lines are attached to the outer ring to provide the required...
A broadband center-fed reflectarray antenna is presented in this paper. Patch with slot ring on ground plane elements are used for bandwidth improvement. It is shown that quasi-linear phase responses with broad frequency band can be achieved by such a phasing element. An 11×11 elements reflectarray is designed and simulated. The results show that the simulated gain is 23.92 dB at the center frequency...
This paper presents a novel transmission line which has a constant phase shifter over a wide band, referenced to a uniform transmission line. The novel transmission line is loaded with lumped element. Compared with the conventional coupled line phase shifter, the configuration shows good performance with simplicity in both design and fabrication. And the use of lumped elements make the size more compact,...
In recently years, fast growing wireless communication systems have encouraged the need for dual-band, multiband and UWB antennas. These systems include Bluetooth which operates at the band 2.4 GHz and WiLAN which operates at 3.5 GHz. Using several radiating patches and reactive load to obtain dual-band or multiband usually increase the difficulty and cost of production. The resulting broadband microstrip...
An optical beam forming network (OBFN) chip for the broadband phased array radar based on silicon photonics integration technology is proposed and demonstrated. Based on the intensive study of the resistances control system and the temperature control system, a novel and effective delay detuning mechanism that provides time delay with large bandwidth and extremely small ripples is realized. The OBFN...
Polarization beamsplitters (PBSs) and polarization rotators (PRs) are essential components for polarization control in silicon photonic integrated circuits. Here, we review our recent work on both component and circuit designs for polarization control.
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.