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Convenient Calibration Techniques for FieldFox Handheld Analyzers

2019-04-22  |  4 min read 

Handheld analyzers, the instrument of choice for engineers conducting RF and microwave tests in the field, offer a lot of conveniences. At the top of the list - access to all of the measurements you need from one portable instrument without compromising measurement accuracy, especially at higher frequencies. Selecting a portable instrument that offers the measurements at the frequencies you need is only half the battle. Keeping the instrument calibrated will give you the most accurate measurements possible.

To make handheld instrument calibration very convenient, Keysight developed a built-in calibration, CalReady, which is immediately available when the FieldFox instrument is turned on. Other methods can be deployed in the field to provide higher quality calibrations needed for certain measurements.

One option is the use of QuickCal, a simple field calibration technique that can be performed on any 26.5 GHz or below FieldFox instrument  Figure 1 shows a comparison of the measured insertion loss (S21) of a short coaxial cable using QuickCal (yellow trace) with a traditional full 2-port mechanical calibration (blue trace). The full 2-port calibration process requires seven connections to multiple high-quality calibration standards. QuickCal can be performed without any calibration standards. QuickCal offers the user a significant time savings and it enables the instrument to make a very accurate measurement.


Figure 1: Coaxial cable measurement using a full 2-port calibration (blue trace) compared with the same measurement using QuickCal (yellow trace) on a FieldFox vector network analyzer.

Selection of the calibration type trades off measurement accuracy against speed and the complexity of the calibration process. Because each test configuration may require the use of adapters and test cables between FieldFox and the DUT, it is important to understand the applications and limitations of each calibration type available in FieldFox.

Configured as a VNA, FieldFox measures complex device parameters such as magnitude and phase of reflection and transmission characteristics of one-port and two-port Devices. The measured com­plex parameters are also known as scattering parameters or S-parameters. Configured as a CAT analyzer, FieldFox also measures the reflection and trans­mission characteristics of a DUT but only reports the magnitude characteristics. Both the VNA and CAT modes use QuickCal to remove the effects of any test cables and adapt­ers attached to the instrument

Bi-directional measurements using transmission/reflection (T/R) hardware can require a full 2-port configuration and calibration for highest level of measurement accuracy. This approach eliminates most systematic errors from the test system.

Download the application note, Techniques for Precise Measurement Calibrations in the Field to learn more about recent advances in VNA calibration. You will also learn different calibration types for a variety of RF and microwave devices including cables, filters and amplifiers.