Frequency Tunable MESFET Active Patch Antenna/Oscillators

An integrated transistor-excited patch antenna/oscillator configuration that provides control of oscillation frequency and E-plane radiation pattern by way of an integral stub transmission line is presented. The configuration has been analyzed experimentally through six different models¿three involving changing patch widths and three involving changing stub length. The latter three are characterized for the case when the stub end is shorted directly to the adjacent patch surface with a capacitor. This modification changes both the oscillating frequency and the radiation pattern of the structure. It is observed that the stub supports both microstrip and coplanar waveguide modes¿a feature that potentially can be exploited because of the additional degree of freedom available.