The EMxpert ERX+ consists of a patented scanner, a built-in adapter, a built-in spectrum analyzer and a customer-supplied PC running EMxpert software (EMxpert setup diagram). The EMxpert ERX+ measures the magnetic field (H-Field) in two orthogonal directions using H-field probes.
The patented scanner is a passive device that couples the very-near-field emissions from the device under test. The measurements of these coupled fields are done with the spectrum analyzer and the adaptor synchronizes the spectrum analyzer and the patented scanner.
The EMxpert software knows the insertion loss of each individual probe across the frequency range so it can apply compensation for the internal losses of the scanner.
The software will also apply the antenna factor compensation that will result in accurate H-field data being displayed. Interpolation between probes is done by the software so that features smaller than the probe spacing can be resolved.
The patented scanner consists of 1,218 H-field (magnetic) probes that operate between 150 kHz and 8 GHz. Probes are wide band but not very sensitive across this band thus they are very good at rejecting background noise.
Each row and column on the patented scanner corresponds to a unique probe that is spaced every 7.5 mm into an electronically switched array, which provides an effective 3.75 mm resolution. Electronic switches enable the probes to sweep the entire board under one second when Level 1 is selected.
The scanner is placed right under the Gorilla Glass. X/Y step motors move the scanner (1218 probes) for higher resolution scans under the Gorilla Glass. After placing the DUT on the Gorilla Glass, user can select from seven different levels of resolution (0.12 mm – 7.5 mm).
The image on right is a representation of a 2 x 2 scan area on the scanner. At level 1, spatial scan is executed in real-time i.e. scanner doesn’t move. The data is collected by each probe that is placed in the center of each grid.
At level 2, each grid is divided into four subgrids. Scanner first moves the orange dots and collects data from four subgrids. Scanner then moves to black dots and collects data from four subgrids. Scanner then moves to green dots and collects data from four subgrids and finally, scanner moves to purple dots and completes the scan.
At each level, one grid is divided into four subgrids which means four measurement points. Level 7 is the highest resolution (120 microns) and the maximum number of measurement points in one grid can be 4,096.