Millimeter wave sensor and communication technology may prove to be one of the key technologies of the 21st century covering a broad range of applications including high-speed telecommunication, medical diagnostics and security. The ultimate (commercial) success of these systems depends on their monolithic integration which brings about significant size and cost reduction. A crucial element in such systems is the antenna element which has to be able to send and receive signals in a desired direction in space with sufficient angle resolution. The traditional way to realize such a component is by placing a conventional antenna with a broad predefined radiation pattern in front of a parabolic reflector to achieve a high angle resolution (directivity). However, this approach demands the mechanical adjustment of the reflector to change the direction of transmission/reception: a solution not viable for integrated applications. In this project we aim for the design and realization of an electrically tunable reflector as an alternative. The reflector consists of a large number of small antenna elements each terminated by an electrically tunable capacitor (varactor). By tuning the bias voltage of the varactors, the reflection properties of the elements and thus of the whole reflector can be adjusted. Of particular importance here is the resulting antenna radiation pattern (directivity) and beam steering capabilities.