Multipath simulators are a technique for characterizing wireless terminals, such as for instance mobile phones. A multipath simulator distributes the measurement signal over an array of antennas encircling the test object. When building a multipath simulator, the antenna array should be given an optimal design with respect to the characteristics of the test objects, the parameters to be measured, and the desired measurement accuracy. This report presents mathematical relations which can be used for optimizing the antenna array. The relations are mostly derived theoretically using simple assumptions, and in some instances found from numerical simulations. The report assumes an array with the antennas evenly distributed on a circle with the test object at the center, and a measurement signal power which is uniformly distributed over the array. Considered measured quantities include power, correlation coefficient, and the statistical distribution of amplitudes.