Near Field Signature Analysis (NFSA) Overview and Concept

Precision placement and accurate measurement of Virtual Test Points™ in RF and Microwave Diagnostics

Combining the Huntron Access® Robotic Probing Station, Huntron Workstation Software and the new Test Evolution (TEV) Non-Contact RF Near Field Probe sets the standard for Near Field Signature Analysis (NFSA - listed under patent 7,496,466: System for Fault Determination for High Frequency Electronic Circuits). Local synthetic measurement technology including the sensor, receiver and signal processing in one compact RF Probe assembly allows the sensing of EM fields emanating from RF circuitry.
A specific XYZ position in a Near Field is defined as a Virtual Test Point™ (VTP) where a NFSA measurement is made. A Near Field measurement is a dB level reading of a RF signal at a specified frequency. The NFSA signature is derived from these measurements and their FFT waveforms. Identical circuits emanate nearly identical fields at the VTP. The combination of Huntron Prober and TEV RF Probe allows accurate positioning and measurement of VTP's. This provides the repeatability to measure VTP's from 30MHZ to 3GHZ.

Near Field Signature Analysis (NFSA) is close proximity sensing of EM fields emanating from RF circuitry. Near Fields are close to active circuits with the strength dependent on power and circuit design. AC circuits radiate a unique frequency and magnitude “signature” being a function of frequency of operation, magnitude, distance to the test probe and geometric location of the probe.

Near Field Signature Concept

The NFSA Non-contact Probe takes the functionality and sensitivity of a spectrum analyzer and puts it mechanically into the reactive near field of an operating circuit. Utilizing Huntron Workstation software, field measurements are made in an automated manner relative to stored values and use software to collate anomalies indicating substandard behavior to an operator. The need to distinguish between good and suspect assemblies does not require knowledge of the

absolute vector magnitude within the reactive near field of a given circuit. It merely requires the consistent placement of a probe within that space and comparative measurements.
To measure near fields, precise and repeatable probe placement is essential. Robotic positioning places the RF Probe over the circuit under test to obtain the Near Field Signature. This position or Virtual Test Point™ can be stored for recall later when another circuit is tested. Huntron Workstation software is used to map Virtual Test Point™ positions and process the Near Field Signature information.

See the Huntron Access NFSA in action - view the Access NFSA video (requires Windows Media Player)

Download a Case Study of Near Field Signature Analysis as presented at AutoTestCon 2008

Near Field Signature Analysis Benefits

• Non-contact Diagnostic Fault Location in RF Circuits
• Examine PCA Status (Good or Bad) without the need to remove Conformal Coating
• Significantly Reduced operator intervention
• Automated data-logging and storage of measurements
• Quick location of failures
• Repeatable high frequency in-vitro measurements
• New Product Characterization and Production Testing

For more information on Near Field Signature Analysis from Huntron and Test Evolution Corp., download the Near Field Signature Analysis data sheet