Performing component verification in the field using a rugged vector network analyzer: Page 4 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.
Utilizing built-in calibration capabilities

FieldFox offers several types of calibration, ranging from simple to advanced. The simplest types are CalReady and QuickCal. Neither requires an external cal kit, and this reduces the amount of equipment to be carried into the field. It also means fewer steps and therefore shorter total measurement times.

With CalReady, the instrument is already calibrated at power-on (or after a preset) and is ready to go without any additional steps. It applies full two-port error correction at the test ports.

QuickCal enables the user to perform calibration without additional accessories. Because the cal plane is extended out to the actual connection to the DUT, this method can compensate for test cables and adapters placed between the instrument and the DUT.

In field applications, QuickCal coupled with a full two-port configuration provides the best balance between precision and practically. It also offers the optimum blend of speed, accuracy and cal simplicity.

Figure 2 compares two measurements of forward transmission, S21, made on a short coaxial cable using QuickCal and a traditional full two-port mechanical calibration. As shown, there is very little difference between the two traces, and this suggests the value of QuickCal as an alternative to mechanical calibration when making measurements in the field.

Figure 2. By extending the measurement plane to the DUT, QuickCal can produce results that are comparable to those from a full two-port calibration.

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