This poster presents a new base station antenna design and preliminary results on electric field mapping for localizing a UWB-MICS robot in an arena. A batch of new base station antenna prototypes, was built and measured at EPFL - LEMA. A microstrip-fed compact monopole design, built in the inexpensive FR4 substrate, was chosen. Reflexion coefficient measurements and radiation pattern simulations meet the project specifications. The presented prototype is electrically small and therefore affected by the feeding and surroundings – the final revision will take the actual deployment points into account. An existing LEMA ray-tracing code was adapted for use in the project. A simple scenario was tested as proof-of-concept, estimating the electric field in the arena taking into account three reflections. The model will be improved by using the real radiation pattern from the base station antenna and improving the boundary conditions.