An experimental study of light modulation at 16 Gc/sec, using the linear electro‐optic (Pockels) effect, has been performed. The principal result has been the demonstration of a new type of traveling‐wave‐like light modulator, which takes advantage of the fact that in crystals which have a 4¯ axis (such as KDP— potassium dihydrogen phosphate) an electric field parallel to this axis is equivalent to a field in the opposite direction if the crystal is rotated 90° about the axis. The modulator is made of a stack of crystals alternately rotated 90° with respect to one another and of a height such that the electric field changes phase by 180° in the time light takes to pass through one crystal. In this way, the electrically induced birefringence increases with optical path even though the microwave modulating field is a standing wave with no spatial variation in the direction of light propagation. For the experiments to be described, the microwave field is obtained with a multimode solid dielectric cavity efficiently driven in its TE101mode. Results on simple devices containing two and three crystals are reported, and a discussion of the general properties of this type of device is presented. In addition, the magnitude of the electro‐optic effect in KDP and ADP (ammonium dihydrogen phosphate) has been found to be the same at 16 Gc/sec, within experimental errors of 25% in ADP and 12% in KDP, as the low‐frequency clamped effect in these materials, in agreement with previous observations at 9 Gc/sec. Results concerning the variation with optical wavelength of the electro‐optic effect in these materials at 16 Gc/sec are also reported.