Measuring Advances In RF/Microwave Test Equipment

Oct. 11, 2007
Test-equipment manufacturers are responding to the requirements of their customers with more flexible and powerful instruments that can quickly change functions by means of software.

Test-equipment manufacturers try to stay one or two steps ahead of the needs of their customers. To do this, they often listen to many customers and hope to anticipate their next set of requirements. Test-equipment suppliers often strike up strategic alliances with leading component and integrated- circuit (IC) developers in order to keep abreast of different technologies that can provide an edge in the next measurement solution.

Recent advances in RF and microwave test equipment and software are generally meant to simplify testing, increase measurement speed, or improve accuracy, or a combination of the three. At the recent AutoTestCon show (September 18-20, Baltimore, MD), for example, Agilent Technologies ( offered the latest news on the Agilent Virtual Rack platform. The combination of hardware and software provides a straightforward way for aerospace and defense companies to create flexible test system frameworks. The Virtual Rack platform decouples all system elements within a matrix-based architecture, replacing programming for system integration with configuring components and services. As a result, integration is independent of specific interfaces or programming languages.

Agilent has also been working on improving accuracy of microwave measurements, such as noise figure. The company recently announced source-corrected noise-figure measurement capability through 26.5 GHz for the Agilent PNA-X series of vector network analyzers. The technique is detailed in the White Paper, "Making Source-Corrected Noise-Figure Measurements," available for free on the Microwaves & RF website (

Rohde & Schwarz ( enhanced its VNA offerings by creating the ZVL series of VNAs that also include a full-featured spectrum analyzer. The ZVL family includes models covering 9 kHz to 3 GHz and 9 kHz to 6 GHz, both available with a spectrum analyzer option for the same frequency ranges. In addition to a VNA with 50 dB typical directivity and bidirectional test sets for all four S-parameters, these instruments offer the option of a spectrum analyzer with 1-Hz resolution, 5-ms sweep speed, and better than -95 dBc/Hz phase noise offset 1 kHz from the carrier.

The general trend to fit more functions in smaller packages can be seen by the modular, fast-tuning frequency synthesizers offered by Wide Band Systems ( Measuring just 6.5 x 6.5 x 1.05 in. and consuming maximum power of 18 W from ±15- and +5.2-VDC supplies, the compact frequency synthesizers provide 5-microsecond switching speed from 2 to 18 GHz with +10 dBm output power. The low-phase-noise synthesizer is ideal for automatic-test-equipment (ATE) applications that require multiple signal sources or fast throughput testing, such as in radar-cross-section (RCS) and antenna measurements.

Programmed Test Sources ( recently announced enhancements to its 10-to-1600-MHz fast-switching model PTS 1600 frequency synthesizer. The new model PTS 1600 X-142 shares the low phase noise (better than -120 dBc/Hz offset 10 kHz from the carrier) and fast switching speed (3 to 20 microseconds) of the original PTS 1600, but adds extensive wideband modulation, including AM, FM, and phase modulation.

In order to achieve more cost-effective use and reuse of test equipment, military users have adopted a "Synthetic Instrument" (SI) approach to ATE systems, using flexible function blocks that can be modified by control software. The VMESG series of frequency synthesizers from Elcom Technologies (, for example, was developed for SI applications from 2 to 18 GHz. It features 200 microsecond switching speed with phase noise of -100 dBc/Hz offset 100 kHz from the carrier and fits into a compact, plug-in VME module. The SI test system approach of building systems with software-definable function blocks, is often referred to as virtually instrumentation (VI). Additional suppliers of SI equipment Agilent Technologies, Aeroflex (, and National Instruments (

As a companion technology to SI equipment, the local-area-network (LAN)-based standard LAN Extensions for Instrumentation (LXI) is gaining momentum in a wide range of commercial and military automatic-testequipment (ATE) applications. The industry consortium that promotes LXI, the LXI Consortium (www.lxistandard. org), recently released information from a survey of member manufacturers that showed annual sales of LXI-based test equipment now exceeding $200 million (USD). The LXI Consortium also announced a membership or more than 400 companies, including Agilent Technologies, Keithley Instruments, Pickering Interfaces, Rohde & Schwarz, and VXI Technology.

Developers of test equipment are often motivated by expected growth in emerging markets, such as WiMAX. Anritsu Co. (, for example, recently introduced a portable handheld test solution for deploying, installing, and maintaining Mobile WiMAX networks. The capability is built into the company's BTS Master and Spectrum Master handheld instruments allowing RF, demodulation, and over-the-air measurements on WiMAX signals. The capability is available as three options for performing a wide range of mobile WiMAX measurements, including channel spectrum, power versus time, adjacent-channel power ratio (ACPR),and various error-vector-magnitude (EVM) measurements.

Another market for potential test growth is in ultrawideband (UWB) communications, an area opened for commercial applications several years ago by the Federal Communications Commission (FCC). Although the number of low-power USB transceiver integrated circuits (ICs) on the market is still small, some test-equipment manufacturers are preparing for future interest, including Tektronix ( with their recent announcement of Tektronix Ultra-Wideband Software (Tektronix UWB) for the company's DPO/DSA70000 oscilloscopes. The software extends the debugging and analysis capabilities of the real-time oscilloscopes, which operate through 20 GHz, to include realtime analysis of UWB signals. The software/hardware combination supports measurements of signal power spectral density (PSD) with a single 50-GSamples/s acquisition and 5-MHz resolution bandwidth to create a spectrum-analyzer-like display. The company also recently announced the availability of its RFXpress? software for RF/IF/IQ waveform creation and editing of digitally modulated signals for the company's AWG5000 and AWG7000 arbitrary waveform generators. The software supports standard modulation formats, such as QPSK, QAM, and GMSK, and custom modulation formats.

Software was also in the news at Keithley Instruments ( as the company recently released its SignalMeister? Waveform Creation Software for the firm's line of RF vector signal generators, such as the model 2910 RF vector signal generator. The PC-based software helps create arbitrary waveform files that can be downloaded to the 2910. The software is also supported by an extensive waveform library with a wide range of formats, including the TD-SCDMA being deployed in China's wireless networks. The 2910 vector signal generator features a software-definedradio (SDR) architecture for functional flexibility.

In a related move, Keithley recently acquired Lyocom, Inc., a privately held company located in Richfield, OH that develops software algorithms for generating and analyzing complex waveforms. The acquisition extends Keithley's wireless test capabilities to include WiMAX, MIMO (Multiple Input Multiple Output), and WLAN test applications.

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