An injection molded circularly polarized endfire multibeam antenna with wide axial ratio beamwidth coverage using rhombic waveguide element

摘要

This article presents a circularly polarized (CP) endfire multibeam antenna with wide axial ratio (AR) beamwidth coverage. It is based on a dielectric loaded waveguide structure and consists of a 4 x 4 Butler matrix and four rhombic waveguide elements. Regarding to each element, it decomposes the incoming linearly polarized waves into two orthogonal modes with equal amplitude and obtains 90 degrees phase difference between the two modes via their different dispersion characteristics to realize CP radiation. Study found that the proposed element has low cross-polarization performance within a wide beamwidth, which contributes to realize wide 3-dB AR beamwidth coverage in the multibeam array. In fabrication process, injection modeling and electroplating techniques are employed to construct the proposed antenna. By using this way, the structure splitting and misalignment problems, which usually existed in conventional designs, can be avoided, and the antenna weight can be maintained to a moderate level. Through the experiment, it is found that the proposed antenna can achieve an overlapped 3-dB AR bandwidth of 10.7% from 9.7 to 10.8 GHz and a wide 3-dB AR beamwidth coverage of 91 degrees.

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