Performing component verification in the field using a rugged vector network analyzer: Page 2 of 5

May 07, 2014 // By Rolland Zhang, Agilent Technologies
The installation and maintenance of specialized systems—radio networks, satellite ground stations, radars—often requires in-field verification and adjustment of filters, diplexers, duplexers and antennas. Although the preferred tool is a vector network analyzer (VNA), typical benchtop units are neither portable nor rugged enough for field use.
Accounting for the range of potential problems

Any scenario that involves accurate device characterization usually conjures up images of a network analyzer and one or more calibration kits on a lab bench. Today, more and more engineers and technicians need to make accurate measurements in remote locations and harsh environments—and they want to do so with less equipment and in less time.

Extreme conditions make it difficult to perform essential measurements and get accurate results. Indoor tests may be in limited space, perhaps near other operating equipment. Examples include vehicles, aircraft, ships and submarines. Hazards to the equipment-under-test include heat, stress, vibration and mishandling. Also, oils and other contaminants may leak into the components.

Outdoor measurements may be performed in extreme temperatures, heavy precipitation and strong winds, and perhaps with hostile combatants nearby. These conditions have the potential to damage cables, antennas, filters and other system elements.

Severe conditions make it difficult to produce accurate, repeatable measurements of characteristics such as voltage standing wave ratio (VSWR), return loss, insertion loss, isolation, distance-to-fault (DTF), S-parameters and cable loss. What’s more, the possible physical configurations and distances will dictate the practicalities of making one- or two-port measurements.

The need to carry a minimum amount of equipment into the field has implications for calibration. More external accessories mean more a larger, heavier field kit. Complex calibration setups mean spending more time in nasty conditions, and can lead to user errors in the cal process.

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