BEAM-STEERING OF A MICROSTRIP ANTENNA BY USE OF A HYBRID FEED

A new hybrid structure of microstrip antenna is presented which allows a radiating microstrip element to be fed by two perpendicular lines: one is a coplanar microstrip line and the other is under the ground pl ane and feeds the patch by electromagnetic coupling through an apertur e in the ground plane. With this hybrid feed structure we obtain two i ndependent feeding networks. Two antenna beams are formed using these feed networks. One beam is at the vertical of the antenna array, and t he second beam is tilted 15-degrees from the vertical. The coupling be tween the feeds of this microstrip antenna is measured to be less than -38 dB.