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A new electric-field cage is described, capable of generating uniform DC or quasi-static AC electric fields for sensor calibration and testing. This unique facility is a large parallel-plate capacitor with guard rings to control fringing fields. The cage dimensions and endplate voltages can be adjusted to meet the needs of a variety of experiments. The current size is 2.4 m high by 3.0 m wide (endplates) by 4.2 m long (in the field direction). Arbitrary AC waveforms (up to ±750 V p-p between 10 Hz and 1 kHz) or DC voltages (up to ±60 kV) can be generated in the lab with plate separations between 0.6 m and 4.2 m to generate fields up to 2.5 kV/m (AC) or 200 kV/m (DC). Techniques to minimize corona discharge at the highest voltage levels were used in the construction of the cage. Currently, the accuracy of the E-field in the cage is on the order of 1%, and the directionality of the field is better than 0.5° over volumes greater than 1 m 3 for all anticipated test scenarios. This meets or exceeds the specifications of world-class standards for E-field calibration facilities, and does so in a volume that is 15-500x larger than the facilities described in these standards. I. CAGE DESIGNThe ARL electric-field cage is essentially a large, parallelplate capacitor. A smaller, but similarly-constructed facility is described in [1]. A horizontal electric field is generated by applying a voltage between the two vertical endplates. Twenty conducting "guard tubes" minimize fringing and provide about 20 dB of shielding at ELF frequencies. The cage is illustrated in figure 1. E = V/d E = V/d 8' x 10' endplate (1/8" Al plate) 6" Al tube (corona shield) Styrofoam supports (8) Access door and mounting point (for grounded sensors) 6" PVC tube (insulating frame) 3" PVC tube (8 struts) Stiffeners (4x on back side) 2" Al tube (20 "guard tubes") E = V/d E = V/d 8' x 10' endplate (1/8" Al plate) 6" Al tube (corona shield) Styrofoam supports (8) Access door and mounting point (for grounded sensors) 6" PVC tube (insulating frame) 3" PVC tube (8 struts) Stiffeners (4x on back side) 2" Al tube (20 "guard tubes") Fig. 1. ARL Electric-field cageThe plates can be driven to opposite DC voltages or 180° out-of-phase for AC waveforms. Bipolar operation provides a virtual ground in the center of the cage that is useful for testing electrically-floating sensors. Alternately, one endplate can be grounded for testing ground-based sensors. II. MODELINGDetailed Method of Moments (MoM) models [2] of the cage and the surrounding laboratory were developed to help design the cage, and predict the accuracy and uniformity of the E-field throughout the cage. Using these models, we discovered that the proximity of other conductors in the lab, including the floor, ceiling, walls, lab benches and other furniture significantly reduced the accuracy of the desired field, but that unwanted fringing could be controlled using "guard tubes". 18,530 line-charge elements were used to model the endplates, guard tubes, lab bay and furniture in the final configuration as sho...

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