Using Additive Manufacturing to advance fresnel zone plate lens antenna design and prototyping
Fresnel zone plate (FZP) lens antennas, consisting of a set of alternative transparent and opaque concentric rings arranged on curvilinear or flat surfaces, have been widely used in various fields for sensing and communications. Nevertheless, the state-of-art FZP lens antennas are limited to a single band due to the frequency-dependent feature, which hinders their use in multi-band applications.
In this work, a shared-aperture dual-band FZP metalens antenna is proposed by merging two single-band FZP metalens antennas, operating at distinct frequency bands, seamlessly into one. Instead of using conventional metallic conductors, double-screen meta-grids are devised in this work to form the concentric rings. Because the meta-grids show distinct transmission/reflection properties at different frequencies, the performance of one set of concentric rings operating at the one band will not be affected by the other operating at the different band.
In addition, to compensate for the phase shift introduced by the meta-grids, an additional dielectric ring layer is added atop the FZP taking advantage of additive manufacturing. Thus, the radiation performance of the dual-band FZP lens antenna is comparable to that of each single FZP metalens antenna. For proof-of-concept, an antenna prototype operating at the dual-band, 75 GHz and 120 GHz with a frequency ratio of 1.6, is fabricated using an integrated additively manufactured electronics (AME) technique. The measured peak gains of 20.3 dBi and 21.9 dBi are achieved at 75 GHz and 120 GHz, respectively.
