Synthesis and Design of Filtering Antenna With Flexible Passband and Radiation Null Based on Parallel Scheme
Meng Yang, Bian Wu, Chi Fan, Han-Yu Xie, Jianzhong Chen, Liang Wu
Abstract
The synthesis and design methods of a novel filtering antenna with flexible passband and radiation null based on parallel scheme are presented in this letter. The filtering antenna is constructed by parallelly connecting two inverted-fed resonant antenna elements to a common feed point. The two resonant antenna elements can be separately designed and adjusted. A specific filtering performance with a radiation null can be synthesized using the proposed sum-of-transfer-functions method based on resonant frequencies and quality factors of the two elements. Finally, a practical filtering antenna centered at 5.78 GHz with the bandwidth of 190 MHz and a radiation null at 5.6 GHz is fabricated. The gain of 5.0 dBi is reached within the total size of 0.864 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.576 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.020 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , where <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <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 of the center frequency.