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Abstract: A planar Rotman lens antenna that generates multiple beams is presented over a wide angular range. The proposed multi‐beam antenna consists of a Rotman lens and a ten‐element printed Yagi antenna array. By properly comparing optical aberrations, expressing as the normalized path length errors Δl, the suitable ratio of on‐axis to off‐axis focal length (g = G/F) is acquired so as to minimize phase errors for the array elements. Ten dummy ports are employed to reduce the performance deterioration caused by energy reflection. A prototype with seven input ports was fabricated and measured, covering a wide scanning angle of 60° (–30°, 30°). The measured beam patterns show that the seven beam gains are distributed from 11.9 to 13.6 dBi under operating of 8.15 GHz. Both the simulated and measured results are used to verify the design approach. [ABSTRACT FROM AUTHOR]

A novel wideband circularly polarized (CP) antenna is presented in this article. The proposed antenna consists of a four-leaf clover patch, four L-probes, and wideband networks. Based on the tightly coupled mechanism, the four L-probes are formed as a ring with the adjacent ones kept close for strong mutual coupling. Consequently, the proposed antenna realizes a wideband impedance matching. Meanwhile, the four-leaf clover patch is put closely inside of the ring for further improving the impedance bandwidth, which is proximity-coupled fed by the four sequential-rotation L-probes with phase of 0°, 90°, 180°, and 270°. The four L-probes are connected to the respective ports of a wideband feeding network by a two-stage impedance transforming network. The measured results indicate that the proposed design has an impedance bandwidth of 66.7% from 1.0 to 2.0 GHz for VSWR ≤ 2 and a 3-dB axial ratio bandwidth of 56.5% from 1.08 to 1.93 GHz. Furthermore, in the operating bandwidth, stable and symmetry radiation patterns and high gain are obtained. The design has a 3-dB gain bandwidth of 38% from 1.3 to 1.9 GHz with a peak gain of 8.5 dBic. [ABSTRACT FROM AUTHOR]