A 3-D-Printed Transparent Planar Lens Antenna for Millimeter-Wave Applications

This letter presents a transparent Fresnel-zone-plate lens antenna with multiple beams at 31.5 GHz. The lens is fabricated using 3-D-printing technology with an optically transparent material. It employs two phase states, 0<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> and 180<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula>, to achieve phase compensation and incorporates air rings as a medium for 0<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> phase compensation, resulting in ease of manufacture and high transparency. Five magnetoelectric dipole antennas are designed to excite the lens, generating five radiation beams that cover a range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula>20<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> with a maximum scan loss of 3 dB across a wide bandwidth of 22.2% from 28 GHz to 35 GHz. The antenna achieves a peak gain of 21.9 dBi while maintaining a reflection coefficient lower than −10 dB. The fabricated prototype demonstrates that leveraging 3-D-printing technologies provides a simple and cost-effective solution for creating transparent, high-gain antennas for millimeter-wave applications.