The objective of this project is to design, build and calibrate a variable frequency microwave exposure system for biological material. Specifications were written for the desired system. A field uniformity at the specimen of 90 percent over a 4 inch diameter circle, a continuous frequency variation in the range of 1 to 10 GHz, and a power level range at the specimen of 0.010 to 10 mW/cm2 are specified. The electromagnetic radiation produced by the system can be either continuous wave fields or modulated fields.