A low-profile wideband bowtie antenna backed by artificial magnetic conductor (AMC) ground is presented for gain enhancement. The proposed bowtie antenna, loaded with an open stub in the upper layer, has broadband property. By using an AMC reflector, consisting of 6×9 metallic patches, the bidirectional radiation of the bowtie antenna is changed to unidirectional radiation. The distance between the bowtie antenna and the AMC surface is only λ/10 at 3.75 GHz. Both the bowtie antenna and the AMC surface are fabricated and measured. The measured results demonstrate good and stable performances, including maximum gain of 8.27 dBi, and flat gain response with variation of 0.6 dB in the wide impedance matching (S 11 < −10 dB) band from 3.05 GHz to 4.35 GHz (35.1%). Furthermore, the maximum cross-polarization level is −17 dB for both E and H planes, and the measured front-to-back ratios are more than 18 dB. Good agreement between the simulated and measured results validates the proposed design approach.
Abstract-A low-profile broadband dual-polarized antenna with high isolation and low cross polarization is presented in this letter. The proposed antenna employs two different feeding mechanisms. On one hand, two out-of-phase probes loaded with two small circular patches make the proposed antenna operate in horizontal mode. On the other hand, two pins connecting two eyebrow-shaped patches and the ground form a magnetic loop which enables the proposed antenna to achieve vertical polarization. By elaborately adjusting the feeding structures, measurements demonstrate that the proposed antenna not only achieves 10-dB return loss bandwidths of 49% (1.7-2.8 GHz) and 28% (2-2.65 GHz) for port 1 and port 2, respectively, but also maintains a high isolation better than 32 dB over the entire common frequency band. Meanwhile, within the main lobes, the cross polarization levels, both in E-plane and in H-plane, stay lower than −25 dB for port 1 and −20 dB for port 2. In addition, the proposed antenna with a profile of 0.13λ 0 achieves the maximum gains of 8.4 dBi for horizontal polarization and 8.2 dBi for vertical polarization.
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