The objective is to develop hardware for rf environment presentation in hardware-in-the-loop missile system evaluation laboratories. T present, rf guided missiles are tested in hardware-in-the-loop (HIL) laboratories using one of two techniques for the presentation of target signatures, jamming sources and environmental effects. The less expensive of the two techniques generates appropriate angles and angular rates using microwave horns servo-positioned in one or two axes. Advantages of the servo-positioned approach include moderate cost and the capability to handle power levels required for simulation of threat representative jamming sources. Disadvantages of the servo-positioned horn technique include in ability to represent target glint and restriction to scenarios including one or two sources. The second technique employs an array of horns driven by a complete network of microwave devices. Advantages of the horn array include the ability to represent many targets and to simulate complex target signature phenomena. Disadvantages include cost and the inability to handle the relative and absolute power levels required for tests in the jamming environments. A microwave vector voltmeter has been developed that is capable of performing these functions over a portion of the microwave spectrum while overcoming all of the above mentioned disadvantages. The processing of a modulation signal input to the vector modulator will employ direct digital synthesis (DDS) techniques.