A compact dual frequency double U-slot rectangular microstrip patch antenna for WiFi/WiMAX

摘要

This letter presents design of a compact (0.32(g) x 0.15(g)) dual frequency rectangular microstrip patch antenna for wireless applications. Dual frequency operation is achieved by inserting a pair of symmetric face-to-face U-slots, which results in excitation of TM10Z and TM01Z modes, on a narrow radiating patch upon appropriate offset coaxial feeding. In addition to compactness, the embedded slots provide two degrees of freedom for tuning the resonant frequencies independently. A physics based approach is adopted in deriving empirical expressions for lower and upper resonant frequencies by analysing the surface current distribution on the patch. Parametric studies of the slots' dimensions show that it can cover the frequency ranges from 1.72 to 4.1 GHz without giving rise to any grating lobes. This antenna geometry can be used for various standards like GSM (1800-1900 MHz), DCS (1710-1880 MHz), PCS (1880-1990 MHz), UMTS (1920-2170 MHz), LTE2300 (2300-2400 MHz), WiFi (2400-2480 MHz), WiMAX (3467-3521 MHz), etc. by appropriately choosing slot parameters. Many typical designs of the proposed antenna geometry are possible with different slot dimensions according to the requirement of these bands. One such design which supports WiFi and WiMAX has been fabricated on FR4 substrate. The measured results for this antenna are also included here.