The Electromagnetic Environments Simulator (EMES) is a large transverse electromagnetic (TEM) cell that propagates a uniform, planar electromagnetic wave through the cell volume where test items are placed. EMES can be used for continuous wave (CW) Electromagnetic Radiation (EMR) and transient Electromagnetic Pulse (EMP) testing. The electric field is vertically polarized between the center conductor and the floor. If it is desired to illuminate test objects at different polarizations, the test object can be rotated.
EMES can be used to conduct susceptibility testing, to characterize the shielding performance of test objects, or for basic and applied research. Recently, an experiment was conducted in which a direct-drive waveform was induced by electromagnetic fields in the working volume and injected into test components to monitor susceptibility.
The EMR and EMP sources are housed in the control room. Only one source can be connected at a time through a transition feed to the test cell, or working volume. The EMP source simulates a fast-risetime, high-altitude EMP burst. The CW EMR source provides up to 5 kW of power in a frequency range of 100 kHz to 250 MHz. The working volume is essentially a truncated, tri-plate, rectangular coaxial transmission line with a 50-Ohm intrinsic impedance that terminates into a 50-Ohm load. Radio frequency (RF) absorbers are used at the load to suppress high frequency modes to preserve the uniform, planar nature of the EM propagation in the working volume.
Electric and magnetic fields in the working volume can be measured with either ground-plane or free-field D-dot or H-dot sensors, respectively. Other test object diagnostics such as current and voltage probes can be used as well. Diagnostic signals are fed to the screen room in the control room via 1 GHz fiber optic links, if necessary. High bandwidth oscilloscopes and spectrum analyzers are used to acquire transient and CW measurements.
Performance Characteristics for EMES
|TEM Cell||24 m (L)|
|Working Volume Dimensions||
4x11x5 m (HxWxL)
|Electric Field intensity (max)|
|CW 100 KHz-250 MHz||≤ 125 V/m @ 4 m|
|Pulsed||250 kV/m @ 4 m|