High Frequency Cable Defect Dcreening Tool/method
Original Publication Date: 2004-Jul-07
Included in the Prior Art Database: 2004-Jul-07
This disclosure presents a hardware concept that tests shielding effectiveness on cable assemblies by providing a relative measurement of the leakage currents produced when injecting a signal onto the cable shield.
High Frequency Cable Defect Dcreening Tool /method
EMC testing for cable assemblies in large enterprise system environments requires multiple system configurations be set up and tested using large numbers of cable assemblies. This testing is time consuming and requires several design iterations when margins are not adequate. Often there is no way to individually distinguish minor shielding defects in high performance cables that would contribute to EMI leakage especially in the multiple GHz range. Consequently there is an urgent need to a screening to that identifies those cables with shielding defects which contribute to EMI excessive leakage. Disclosed is a screening tool that allows high frequency shielding performance on individual cables to be measured in a production environment. A cable assembly is plugged to an enclosed, shielded test fixture, a signal of a predetermined magnitude is injected into the enclosure and a current probe measures the amount of 'noise' on the cable shield as shown in the figure.
C able B raid to C o n n e c to r In te rfa c e
The objective of the above measurement system is to determine the magnitude of the leakage current riding on the cable braid. The magnitude of the leakage current is inversely proportional to the shielding effectiveness of the cable and connector termination integrity. In other words the more effective the shielding then lower level of leakage current can be expected. The cable defect detection tool comprised of the following components:
Dual role spectrum analyzer
Functions as a signal source feeding sweeping signal to a tracking generator.
Functions as a receiver monitoring leakage current picked up by a current probe
on the STI cable under test. Tracking generator
Relays sweeping signal to the stub antenna inside a shielding...