Design of a Compact Wideband Filtering Antenna with High Frequency Selectivity
Hao Gui,
Zhonggen Wang,
Wenyan Nie,
Ming Yang and
Mingqing Wang
A low-profile monolayer filtering antenna with compact size is presented in this paper. The antenna features a simple structure, comprising a substrate, a stepped defective ground structure, an asymmetric Y-shaped branch, and a microstrip feedline with an L-shaped branch. The asymmetric Y-shaped branch and L-shaped branch feedline collaborate to introduce two additional resonant frequency points, thereby broadening the impedance bandwidth. Furthermore, two radiation nulls are introduced on either side of the passband, which enhances the frequency selectivity of the band edges and optimizes the antenna's radiating and filtering performances. To verify the proposed design, a prototype of the compact filtering antenna was fabricated and measured. The measured and simulated results show good agreement. The design achieves a wide impedance bandwidth of 44.6% (4.88~7.68 GHz) at a center frequency of 6.22 GHz, a peak realized gain of 5.7 dBi, and a compact size of 35 mm × 29 mm × 0.8 mm. Two radiation nulls on either side of the passband result in an excellent bandpass response, with out-of-band rejection reaching 18.2 dB. Finally, the antenna's excellent radiation performance and filtering characteristics make it suitable for wireless communication applications in the 5G Sub-6 GHz and WiFi-6E bands.
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