Experimental study of the rectangular patch with a U-shaped slot

Huynh and Lee (see Electronics Letters, vol.31, no.16, p.1313, 1995) presented measurements which showed that a coaxially fed rectangular patch with a U-shaped slot can attain 10-40% impedance bandwidth, with good pattern characteristics. In contrast to the method of bandwidth enhancement using parasitic patches which either increase the thickness or the lateral size of the antenna. The U-slot patch is a single-layer single-patch wideband structure which preserves the thin profile and small size advantages of the microstrip antenna. We present extensive experimental results on the U-slot patch, including cross polarization measurements and the effects of patch size, slot size and feed position on the performance. The results of a two-element array of U-slot patches are also presented.