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Battery powered vector network analyzers go afield

Posted: 19 Dec 2005 ?? ?Print Version ?Bookmark and Share

Keywords:Anritsu? VNA Master MS2024A? VNA Master MS2026A? VNA? vector network analyzer?

vector network analyzers

With a frequency accuracy of 25ppm, Anritsu Co.'s VNA Master MS2024A and VNA Master MS2026A battery-powered instruments are arguably the first handheld VNAs (vector network analyzers) offering the ability to make 1-port and 2-port magnitude and phase measurements that are as good as what you'd get in the lab.

These 6-lb. VNAs, measuring 12-by-8-by-3-inches in size, can replace racks of benchtop gear, and their USB and Ethernet ports give you the requisite connectivity needed to transfer data to other lab equipment.

Not mentioned in Anritsu's press statement is the fact that these nomadic RF sniffers, with their TFT (thin-film transistor) SVGA liquid crystal displays, can also be optionally fitted with power detectors and GPS (Global Positioning System) satellite receivers. The connectors for these options are mounted on the top edge of the enclosures, along with the customary RF connectors.

Measure RF power
The power monitor (Option 5) lets you measure broadband power up to 50GHz. It minimizes mismatch uncertainty with detector flatness better than 0.5dB (up to 18GHz). The power monitor also features a measurement range from -50dBm to 16dBm (with a display range from -80dBm to 80dBm).

In use, power monitoring will display absolute power in dBm or watts, or relative power in dB or as a percentage. Built-in auto averaging also automatically reduces noise effects. Similarly, zeroing circuitry ensures measurement accuracy at lower levels.

For its part, the GPS receiver (dubbed Option 31) provides location in latitude, longitude, and altitude, as well as Universal Time information. The MS2024A and MS2026A can then stamp traces and store GPS location information. The GPS option includes a mag-mount antenna with a 15-foot cable that lets the antenna be popped onto the hood of a vehicle.

Master tools
The press release refers to the systems' PC-based Master Software Tools Suite, mentioning that it permits you to create menus in standard and custom languages. The Master Software Tools do more than that though. It acts as a data management and analysis system for managing, archiving, analyzing, printing, and reporting findings.

Running under Windows 2000 or Windows XP, the toolset communicates with a MS2024A or MS2026A using USB or Ethernet. Once a connection is established, the tools let you readily ascertain parameters such as VSWR (voltage standing-wave ratio), cable loss, and phase, and you can even plot Smith charts based on one return loss measurement.

Unique frequency-domain reflectometry
You can also make DTF (distance-to-fault) measurements on antenna cables and transmission lines using a MS2024A or MS2026A. To do that, these boxes use a unique FDR (frequency domain reflectometry) technique to identify signal-path degradation in coax and waveguides.

Note that FDR is different from TDR (time-domain reflectometry). The FDR technique uses a swept RF signal instead of TDR's DC pulses; Anritsu claims FDR is more sensitive than TDR measurements.

What's more, FDR can locate faults and degradation at the system level, not just locate DC opens or short circuits in cables. DTF displays RF return loss, or VSWR data-vs.-distance. Since DTF automatically accounts for attenuation versus distance, the display accurately indicates the return loss or VSWR of an antenna. You can use it to find subtle cable discontinuities, things like damaged lightning arrestors, damaged or dented coax shields, and moisture-related and corrosion-related impedance bumps.

Utilities and storage
Back to the Master Software Tool. It also lets you add or modify limit lines and markers, and help compare traces using an intelligent drag-and-drop user interface. You can also display power levels, show calibration status, GPS information, and bias tee information along with a trace. The software also lets you upload cable and signal standards, and known traces for field comparison purposes. In fact, you can use the utility to store an unlimited number of traces to your PC.

Speaking of software and PCs, Anritsu's press comments refer to internal memory. The memory can store more than 1000 traces and setups, and you can copy stored information to (or from) a removable CF (Compact Flash), to get as much as 64-Mbytes of non-volatile storage. Stored measurements can also be downloaded to your PC using Ethernet or USB for processing by the Master Software Tools.

When you consider that these handhelds cost only about $13,000 to $15,000, they shape up as useful instruments that should go a long way to troubleshoot problems in the lab and in the field. Moreover, their internal memories and CF storage can make then easier for untrained or semi-skilled personnel to use.

- Alex Mendelsohn

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