Field strength monitors and electric field probes are used in conjunction to detect the qualities of the electric field a device or system is emitting. Field strength monitors serve as essential receiving and signal analysis tools during frequency interference and electromagnetic compatibility testing. Electric field probes, known as e field probes, are generally comprised of a dipole antenna, a non-perturbing line of transmission and an RF detector. Engineers hold the antenna apparatus and move around the area of the device under test, determining the strength of the signal and the course of EMI.