Design Features

 383 results found for Design Features, displaying items 1 - 20

August 2010   [Test & Measurement]
Measuring MIMO In LTE Tx And Rx Tests
Fourth-generation (4G) wireless communications systems promise to support the demands of customers for increasing network capacity for voice, data, and streaming video. Systems such as Long Term Evolution (LTE) networks incorporate novel communications techniques, such as multiple-input, multiple-output (MIMO) antenna configurations using two or more transmit/receive chains, and takes advantage of the differences in radio transmission paths between...  — Janine Whitacre

August 2010   [Components]
High-Speed DACs Ease Transmitter Designs
Radio transmitters can now be designed with direct digital modulation, due to the availability of high-speed digital-to-analog converters (DACs). This approach is already commonly used to generate multicarrier quadrature-amplitude- modulation (QAM) signals for data transmission over Hybrid Fiber Coax (HFC) links in cable-television (CATV) access networks, and is also used to synthesize microwave intermediate- frequency (IF) signals for instrumentation, ...  — Ajay Kuckreja , et al.

August 2010   [Communications]
Mach-Zehnder Modulators Serve Radio Over Fiber
Millimeter-wave wireless communications networks can take advantage of frequency multiplication schemes that generate high-frequency signals from lower-frequency sources. In one case, frequency multiplication for radio-over-fiber links can be achieved by means of Mach- Zehnder-modulator (MZM) based schemes. With three MZMs biased at their minimum transmission points, and a tunable optical delay line placed between two of the modulators and...  — Muhammad Taher Abuelma’atti

August 2010   [Communications]
What is radio over fiber?
Radio over fiber technology is a growing part of many cellular communications network plans. As broadband services, such as high-speed data and streaming video, become more prevalent in cellular networks, the available bandwidth of those networks will be quickly consumed. In order to conserve or increase capacity, many network planners are looking to millimeter-wave links or optical cables between a base station (BS) and a central control station (CS) in order to route...  — Muhammad Taher Abuelma’atti

August 2010   [Components]
Strategies For Planar Directional Couplers, Part 1
Directional couplers are an important part of analog signal processing in microwave systems, including as portions of power dividers and combiners, in directional filters, attenuators, phase shifters, mixers, amplifiers, modulators, and beam-forming networks for antenna arrays.1-19 They are also essential in test applications allowing, for example, measurements of high-power signals with sensitive test equipment by coupling a small sample...  — Leo G. Maloratsky

August 2010   [Components]
Hilbert Fractal Curves Form Compact Diplexer
Metamaterials have shown great promise as substrates for compact RF and microwave filters. By forming composite right/left-handed (CRLH) transmission lines (TLs) on such materials, it is possible to take advantage of the dual-band properties of these structures by merit of their unique hyperbolic- linear relationship. By applying CRLH TLs in a Hilbert fractal-shaped geometry, it was possible to design a diplexer operating at 0.96 and 1.69 GHz and...  —

August 2010   [Components]
UWB Antenna Stops Two Bands
Ultrawideband (UWB) wireless communications systems operating from 3.1 to 10.6 GHz offer low-power, high-speed links for a variety of applications. However, they must often compete with interfering signals from a number of existing transmitters that may fall within the wide UWB operating range. Of course, stop-band filters can be added to a system where needed to remove interference, but adding filters increases system complexity and cost. A better...  — Tan Chiy How , et al.

July 2010   [Components]
X-Parameters Aid MMIC Design
The most common method to accurately characterize RF/microwave components under linear conditions has been through the use of S-parameters. However, modeling nonlinear behavior of certain components, such as amplifiers and mixers, is challenging because S-parameters cannot be applied effectively and accurately under large-signal conditions. Approximation techniques have been used for modeling nonlinear behavior—with partial success— by...  — Jack Sifri

July 2010   [Components]
Reviewing Avionics Antenna Modules, Part 2
A ntenna modules provide system integrators with a means of saving weight and volume in an airborne avionics platform. As mentioned in Part 1 of this article in June 2010 Microwaves & RF (see. p. 72), combination Traffic Collision and Avoidance System (TCAS) and Transponder suites used on many aircraft rely on four different antennas, ten cables, and separate ...  — Leo G. Maloratsky

July 2010   [Components]
Modeling PA Behavior And Memory Effects, Part 2
Developing a behavioral model for power amplifiers with memory effects requires including nonlinear phenomena. As shown in Part 1 (Microwaves & RF, June 2010, p. 84), nonlinear amplifier behavior is usually characterized by AM-AM and AM-PM conversion. As will be shown in Part 2, models incorporating these effects can be validated by the appropriate measurements. ...  —

July 2010   [Components]
Wideband Limiter Fits SOT-323 Pack
Limiters protect wireless receiver front-ends from irreversible damage due to signal overload. By combining Schottky and PIN diodes in a hybrid limiter design that can be mounted in a compact SOT- 323 surface-mount package, it has been possible to develop a low-cost limiter with 1 dB or less insertion loss from 10 MHz to 1.7 GHz with an input-power turn-on threshold (PTH) of only +2 dBm at 450 MHz. To the authorâ??s knowledge, this is the first ...  — Chin-Leong Lim

July 2010   [Computer-Aided Engineering]
Form Microstrip Couplers With Shielded Membranes
Membrane-supported transmission lines and circuits are excellent candidates for millimeter-wave applications where conventional substrate-supported architectures begin to suffer from parasitic effects at the dielectric/ air interface.1-3 Transmission lines based on the technology, known as shielded-membrane-microstrip (SMM) transmission lines, have been used to realize an asymmetric tapered coupled-line coupler operating from 10 to 60...  — Nasreddine Ben Ahmed , et al.

July 2010   [Communications]
Front End Fits SDR Picocells
Software-defined-radio (SDR) approaches are being used in compact cellular base stations, including in picocellular systems serving small areas such as onboard commercial aircraft. Wireless communications systems onboard an airplane must provide high-quality audio, video, and data services conveniently but without interference with the aircraft’s navigation systems. As a result, a picocell solution must perform with sufficient suppression of...  — Wei Hong , et al.

June 2010   [Test & Measurement]
Check Chirp Effects On FMCW GPRs
Ground-penetrating radar (GPR) systems are powerful tools for nondestructive, noninvasive subsurface detection.1,2 These systems are suitable for measuring the geometric parameters of buried objects,3 locating bars of armor, detecting cavities or breaks inside structures,4 and groundwater detection.5 GPR has widespread application in civil engineering for such tasks as investigating reinforced concrete ...  — Roslee Mardeni , et al.

June 2010   [Components]
Reviewing Avionics Antenna Modules, Part 1
Avionics systems designers constantly seek savings in size and weight through integration. The approach also lowers the number of cables needed and the power requirements. The use of integrated antenna modules is one approach that helps to achieve reductions in size, weight, and power usage in modern integrated avionics systems.1 Part 1 of this two-part article will review active antenna modules for avionics systems; next month, Part 2...  — Leo G. Maloratsky

June 2010   [Test & Measurement]
Modeling PA Behavior And Memory Effects, Part 1
Digital wireless communications systems offer numerous advantages over their analog predecessors, including improved services and security.1-4 But these digital systems also place greater demands on analog components in the system, including the power amplifiers (PAs) because of the complexity of the digitally modulated waveforms.5 To achieve the required levels of PA performance in terms of power, linearity, and...  —

June 2010   [Components]
Microstrip Approach Benefits Quad Splitter
Quadrature power split- Qtpehras,s e wdiitfhfe rtehnecier b9e0tw-deeegn. output ports, are useful components in communi- cations systems applica- tions. They can be used, for example, to realize amplifiers, phase shifters, and balanced mixers for receivers and transmitters.1,2 Because of the wavelength dependence of microstrip and stripline circuits, however, maintaining the small size of a printed quadrature power splitter can be challenging. The current...  —

June 2010   [Components]
Design An X-Band Frequency Synthesizer
Digital microwave radio (DMR) applications require frequency sources with stable outputs and low phase noise. One possible solution is an Xband frequency synthesizer designed for use from 7.7 to 8.2 GHz. It is based on multiplying by three a reliable source operating from 2.56 to 2.74 GHz with outstanding phase-noise performance to achieve final output signals with -84 dBc/Hz phase noise offset 10 kHz from the carrier. The prototype...  — H. Ameri , et al.

May 2010   [Components]
Taming Temperature In High-Power PIN Switches
Thermal management is one of the critical disciplines in high-power, high-reliability PIN diode design. Although power levels can vary dramatically for components operated under continuous-wave (CW) and pulsed conditions, the goal of any thermalmanagement effort is the effective dissipation of power to prevent thermal buildup in the component and system in which it is used. Fortunately, the task is made simpler by moderately priced infrared ...  — Michael Hebert

May 2010   [Components]
Antenna Assists MW Power Transmission
Power from space, by means of microwave power transmission using the sun as the energy source, has been a vision of many for decades. The power system would employ large solar- power satellites in geostationary earth orbit, and the system would consist of a solar energy collector to convert solar energy in direct current electricity, a DC-to-microwave converter, a large antenna array to beam the microwave power to the ground, and a receiving antenna on the...  — Dr. A. Kumar





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