This work aims at studying the Gallium Arsenide dual gate (MÊS) FET and some of its properties as a microwave device. Initially, a model for the single gate FET is developed based upon the Gradual Approximation. It includes the gate to drain capacitance and transit time bias dependences. From this model, a model for the dual gate FET is obtained. Then, properties of the dual gate FET related to its use as gain controlled amplifier and mixer are studied. The properties that make it suitable for gain controlled amplifiers are pointed out. Also, the bias region that optmizes OL-RF rejection when it is used as a mixer, is obtained. Using a relatively simple empirical expression and a fast and efficient data acquisition strategy, a DC model is obtained from experimental data. As an example, this model is used to determine the optimum bias point with respect to gain for a measured device. Two amplifiers were built a new design technique. This technique makes use of an open line on the second gate to keep the gain flat without the need of mismatching at the lower frequencies. In each one of the amplifiers, a different technique is used to match the drain. This work is a step towards the use of the full capabilities of this versatile microwave device, the dual gate FET.