Portable VNA Tests Two Ports To 6 GHz

This handheld, battery-powered instrument brings error-corrected one- and two-port measurements from 2 MHz to 6 GHz to both commercial and military field operators.

Vector network analyzers (VNAs) represent one of the "standard" test tools for RF and microwave engineers. Their capability to provide error corrected amplitude and phase characteristics of active and passive components make them invaluable in the research lab and on the production floor. But unless one was willing to bring a rack of equipment outdoors, VNAs have not been known as "on-site" test tools. That is, until the introduction of the 2-MHz to 4-GHz model MS2024A and 2-MHz to 6-GHz model MS2026A VNA Master battery-powered, handheld VNAs from Anritsu Co. (Morgan Hill, CA). The palm-sized powerhouses make vector-corrected one-port and (one-path) two-port magnitude and phase measurements in a package that weighs less than 6.4 lbs. with rechargeable battery.

The VNA Masters (Fig. 1) build on the company's popular line of Site Master and Spectrum Master on-site portable test tools, packing the equivalent of a rack-sized mainframe instrument into a portable case that can easily be carried to the top of an antenna tower. Both instruments provide about three hours of operation on a single battery charge. In addition, they can operate from a +12-VDC transformer or power source, such as a car battery. Each VNA Master measures 12 × 8 × 3 in. (305 × 203 × 76 mm).

The VNA Masters incorporate the test sets and measurement receivers of a full scale VNA, with the addition of microprocessors and digital-signal-processing (DSP) integrated circuits (ICs) optimized for battery use (see table). The analyzers run with a straightforward user interface that is controlled by both hard and soft keys on each instrument's front panel. In fact, most of the RF measurements can be accessed with the push of one of these hard keys.

The compact analyzers offer a choice of measurements from two menus: a "VNA" menu and a "field" menu. The former provides measurements of S11 and S21 log magnitude, S11 and S21 phase, S11 Smith Chart, S11 VSWR, and fault location. The latter offers a choice of return loss, VSWR, cable loss (Fig. 2), distance-to-fault return-loss/VSWR (Fig. 3), two-port gain (Fig. 4), one-port phase, two-port phase, and a Smith Chart display. Using the company's precision measurement components, better than 42 dB corrected directivity can be achieved over the full frequency range of each instrument. Measurement results are shown on an 8.4-in. SVGA TFT LCD screen that is clearly visible even in bright daylight. The analyzer scan display as many as six marker son the screen, each with delta marker capability. VNA Masters can even display impedance matching results on an impedance Smith Chart display.

Each VNA Master is shipped with enough internal memory to store more than 1000 measurement traces and test setups. And if that is not enough, information can be transferred to an external computer by means of the VNA Master's Ethernet connection or Universal Serial Bus (USB) interface. Each VNA Master also includes a Compact Flash memory card slot for storing test results and setup information on a low cost solid-state memory card.

For those who might be misled by the small size and appearance of these instruments, they are truly error-corrected VNAs capable of achieving system dynamic range to 80 dB from 2 MHz to 3 GHz, 70 dB from 3 to 5.5 GHz, and 65 dB at frequencies above 5.5 GHz. Vector correction for one-port measurements removes systematic errors associated with the reflection measurement including directivity, source match, and reflection tracking. Vector correction for one-path, two-port measurements removes reflection errors, transmission response errors, and transmission source-match errors. Two-port measurements can be performed at two output-power settings: high (0 dBm) for characterizing passive devices such as antennas and cables and low (?35 dBm) for evaluating the gain of an active device, such as an amplifier.

As with many of the company's other "Master" series instruments, the VNA Masters are available with a number of useful options. For example, Option 5 is a power monitor option that enables a VNA Master to make power measurements as high as 50 GHz with the company's 560 and 5400 series detectors. The broadband detectors provide flatness of better than 0.5 dB to 18 GHz, with a power measurement range of ?50 to +16 dBm. Examples include the model 560-7S50-2 with WSMA connectors for measurements from 0.01 to 26.5 GHz and the model 560-7VA50 with V connectors for measurements from 0.01 to 50 GHz. Display formats include absolute power (in W or dBm) and relative power (in dB or percent). Built-in auto averaging automatically reduces the effects of noise while zeroing allows optimum measurement accuracy at low power levels.

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Option 31 adds a built-in Global Positioning System (GPS) receiver to the VNA Master for determining precise location (latitude, longitude, and altitude) and Universal Time (UT) information. The information can verify that measurements, such as those being made on a cellular tower, are being made at the correction location. The location and UT information can also be used to stamp traces taken indoors when compiling a report. Option 10 equips each VNA Master with an integral bias tee for active component testing. The bias tee delivers bias voltages from +12 to +24 VDC in 3-V steps to the center pin of the RF input connector. It eliminates the need for an external bias supply in both field and production/ laboratory measurements.

Master Software Tools
A nice bonus included with each VNA Master is the Master Software Tools package. This easy-to-use Windows-based data management and analysis software complements the functionality of the VNA Master with a host of data management, archiving, analysis, printing, and reporting tools. For example, the software helps make the connection between a USB or Ethernet personal computer (PC) and the VNA Master; obtain VSWR, cable loss, distance-to fault,-phase, or Smith Chart plots from one return-loss measurement; add or modify limit lines, upload new cable and signal standards; upload traces to the VNA Master for field comparison against historical or reference data; and display power level, calibration status, GPS information, and bias tee information along with a trace in one report.

The VNA Masters are unlike conventional VNAs in that they are built for the field. They can withstand electrostatic discharge (ESD) damage levels as high as 10 kV and meet the environmental requirements of MIL-PRF-2800F Class 2. They are designed for operating temperatures of ?10 to +55C and conform to the EN 61010-1 safety standard for Class 1 portable equipment. They also meet the European Community (EC) requirements for CE marking.

The instruments are truly global test tools, equipped with menu-selectable English, Spanish, Italian, French, German, Japanese, Korean, and Chinese languages. In addition, they can be customized for two additional languages using the Master Software tools. P&A: $13,125 and up (MS2024A) and $15,645 and up (MS2026A); 10 wks. Anritsu Co., Microwave Measurements Div., 490 Jarvis Dr., Morgan Hill, CA 95037-2809; (800) ANRITSU, (408) 778-2000, Internet: www.us.anritsu.com.

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