Compact Wideband Patch Filtenna With Enhanced Out-of-Band Suppression

A compact broadband patch filtenna with enhanced stopband suppression is presented in this letter. The designed antenna is configurated with a simple structure having two substrates of 0.04 lambda(0) spacing (lambda(0) is the free space wavelength at the center frequency). A rectangular patch with Pi-, Gamma-, and inverted Gamma-shaped slots is printed on the top substrate and fed by a coaxial probe. The abovementioned three slots create additional resonance modes to broaden the impedance bandwidth and generate two out-of-band radiation nulls to enhance the stopband suppressed level. An antenna prototype with a dimension of 0.56 lambda(0) x 0.56 lambda(0) x 0.06 lambda(0) is fabricated to demonstrate its characteristic. A stable gain of 7.2 +/- 0.4 dB over the wide impedance bandwidth of 17% (1.88-2.23 GHz) is achieved, and the out-of-band suppression level is beyond 20.6 dB. These features make the filtenna a promising candidate for the PCS 1900/UMTS 2000 bands in mobile communication systems.