A double-/spl Pi/ stub proximity feed U-slot patch antenna

The design and measured results of a rectangular U-slot patch antenna proximity fed by a double-/spl Pi/ stub feed are described. Using approximately 0.09/spl lambda/ of air gap separating the upper and lower dielectric, an impedance bandwidth of 26% centered at 4.4 GHz and a gain of 6 dBi have been achieved. The proposed antenna is noted to be tolerable to lateral displacement of the feed and produces a better impedance matching than the single /spl Pi/-stub antenna. The radiation patterns obtained are stable across the passband.