Compact Wideband Patch Filtenna With Enhanced Out-of-Band Suppression
Quan Da Liu, Qingfeng Dong, Jun Wen, Liang Hua Ye, Duo‐Long Wu, Xiu Yin Zhang
Abstract
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 0.04λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> spacing (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free space wavelength at the center frequency). A rectangular patch with Π-, Γ-, and inverted Γ-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 0.56λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.56λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.06λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> 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.