Single-Layer Single-Patch Four-Band Asymmetrical U-Slot Patch Antenna

A single-layer single-patch four-band U-slot patch antenna, with linear polarization, is proposed for WiMax and WLAN systems. Using this antenna, impedance bandwidths (|S₁₁|<;-10 dB) of 2.1%, 3.3%, 7.1% and 5.0% were achieved at central frequencies 3.35 GHz, 3.70 GHz, 5.20 GHz and 5.80 GHz, with gains of 7.6 dBi, 8.6 dBi, 8.5 dBi and 9.0 dBi, respectively. This antenna was made by cutting four asymmetrical U-slots in the patch. This structure has the following advantages: (1) the feed is simple, (2) the antenna has single-layer, (3) the structure of the antenna is simple, (4) the asymmetry of the U-slot arm provides one more degree of freedom in the design, (5) the antenna is inexpensive. The design guideline for the proposed antenna is given and the acceptability of the design is verified by other scenarios. The simulated and measured results are in good agreement.