Dual sample cavities are described in which the standard sample sees both the primary modulation field and also an opposing secondary modulation field from a very small adjacent compensation coil. Both primary and secondary fields are at the same modulation frequency. The geometry permits solution of dual sample cavity design problems at Q‐band, where the microwave cavity is small relative to the volume of space occupied by the primary modulation field and at X‐band when magnets with a small volume of homogeneous field are employed.