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ISSUE DATE: AUGUST 2006 | |
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August 2006 - In This Issue [Cover Story] Signal Cancellation Improves DDS SFDR Direct digital synthesizers (DDS) are commonly used for sinusoidal signal generation in RF communication systems and test equipment. An integral component of DDS is the digital-to-analog converter (DAC). Although a DAC is intended to perfectly reproduce an analog signal from its digital equivalent, the conversion process is rarely perfect. The DAC's digital resolution (number of bits) is a limiting factor that introduces quantization errors resulting in a noise floor. ... — Ken Gentile , et al. [News] Charting The Course For 45 Years Of Microwaves Magazines come and go, but few survive for 45 years. In that passage of years, many fine people, places, and things have come and gone as well, while some have also survived the 45 years. Many should be remembered, and perhaps there is a book in it somewhere. For now, this celebration of 45 years of editorial service to the microwave industry will offer a sampling of what has come before. This magazine began as a section in sister publication, Electronic... — Jack Browne [News] Special Section: Microwave Legends BILL HEWLETT and DAVE PACKARD — In 1938, these friends and Stanford University alumnae set up their first workspace in a garage in Palo Alto, CA. Their initial capital was reportedly $538. They created the first Hewlett-Packard product—a resistance-capacitance audio oscillator. The HP Model 200A was used to test sound equipment. Sixty years later, they had a $25-billion company that was central to propelling technology forward ... — Nancy Friedrich [News] Crosstalk: An Interview with Microphase Corp.’s Necdet "Ned" Ergul MRF: Why did you start the company? Ergul: In 1952, I joined Belco Research Laboratories in Newark, NJ in their filter group because I had always been interested in microwave electronics. I was a project leader charged with development of high-temperature, UHF, and microwave transmission-line filters. At that time, they had research contracts in-house for filter networks for the US Army and Navy operating in the frequency range of 400 MHz.... — Jack Browne [Design Features] Understanding Mismatch Effects In Power Combining Circuits Power combining theoretically increases an amplifier's effective output power by coherently summing N identical output stages. For example, if one output stage produces 1 W power, coherently combining four stages will effectively increase the output power to 4 W. Practically, the output power will be degraded by the combiner loss and the practical amplitude and phase errors introduced. As the number, N, of channels increases, the difficulty in maintaining minimally ... — Howard Hausman [Design Features] Building A Receiver For WiMAX Testing Wireless applications using WiMAX high-date-rate technology are poised for growth in the next several years. Based on orthogonal-frequencydivision-multiplexing (OFDM) techniques, WiMAX holds the promise of broadband wireless access (BWA) as part of the "last mile" of multimedia services networks. Last month, this three-part article series on WiMAX testing opened with a review of the WiMAX physicallayer (PHY) and media-access-control (MAC) protocols as outlined in the... — Huseyin Arslan , et al. [Design Features] Upconverter Mixer Makes Most Of LTCC For ISM Applications Wireless applications for many conjure up images of cellular networks in bands around 800 to 900 MHz and 1800 to 2000 MHz. But a growing number of wireless applications are making use of unlicensed spectrum in the Industrial-Scientific-Medical (ISM) bands around 2400 to 2500 MHz and 5725 to 5875 MHz. To facilitate designs at these higher ISM frequencies, Mini-Circuits (www.minicircuits.com) has developed a... — Mini-Circuits' Engineering Dept. [Design Features] Optical Switches Link Multiple Receivers To Remote Antennas Optical fiber provides many undisputed benefits for data-transmission systems. It also offers significant performance advantages in RF transmission systems, in spite of the fact that RF engineers have mistakenly considered fiber-optic cables to have lower dynamic range and higher costs than metal coaxial cables. Because of these beliefs, optical fiber has been limited to RF applications where long-distance transmissions have been beyond the capabilities of coaxial ... — Bruce Mead [Product Technology] Economy Spectrum Analyzer Spans 100 kHz To 7.1 GHz Spectrum analyzers can cost $50,000 and more for coverage into the microwave range. Because not every test lab or production facility can afford such luxury,-Anritsu's (Morgan Hill, CA) engineers designed the MS2717A as an Economy Spectrum Analyzer—an instrument for the masses. Although costing less than $12,000 (USD), it delivers performance that will have many users rechecking that price tag. The MS2717A features a frequency range covering most wireless applications, from 100... — Jack Browne [Product Technology] Spectrum Analyzer Doubles As Phase-Noise Test Set Spectrum analyzers are versatile test tools capable of displaying wide-dynamic-range signals over broad frequency ranges. The new FSUP Signal Source Analyzers from Rohde & Schwarz (Columbia, MD) goes beyond traditional spectrum analyzers, however, by including the equivalent of a phase-noise test set. Available in models operating from 10 MHz to 8.0 GHz, 10 MHz to 26.5 GHz, or 10 MHz to 50 GHz, the FSUP Signal Source Analyzers combine superb performance with fast and... — Jack Browne [Product Technology] "Invisible" Wireless Antenna Offers In-Building Coverage In-building wireless systems extend the coverage of unfettered communications networks within confined spaces. Because propagation of radio waves through concrete and metal is extremely lossy if at all possible, service providers rely on omnidirectional antennas such as the Ultrasphere in-building wireless antenna from Laird Technologies (St. Louis, MO) to stretch their coverage areas within shopping malls and office buildings. The beauty of the Ultrasphere is its... — Jack Browne [Editorial] Marking 45 Years Of Microwaves An anniversary is meant to be a celebration of a significant achievement. For example, when a couple celebrates their first anniversary of marriage, it is a celebration of having survived all the ups and downs that come during that first year. But when they celebrate their 40th year together, they are recognizing something special, an almost indestructible bond that they have built together. In the microwave industry, companies come and go almost as quickly as... — Jack Browne |
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