Abstract
The gain of an antenna can be enhanced through the integration of a lens, although this technique has traditionally been restricted to planar antennas due to fabrication limitations of standard manufacturing processes. Here, through a unique combination of three-dimensional and two-dimensional inkjet printing of dielectric and metallic inks, respectively, we demonstrate a lens that has been monolithically integrated to a nonplanar antenna (helix) for the first time. Antenna measurements show that the integration of a Fresnel lens enhances the gain of a two-turn helix by around 4.6 dB, which provides a peak gain of about 12.9 dBi at 8.8 GHz. The 3-dB axial-ratio bandwidth of the antenna with the lens is 5.5%. This work also reports the complete characterization of this new process in terms of minimum feature sizes and achievable conductivities. Due to the monolithic integration of the lens through a fully printed process, this antenna configuration offers a high-gain performance by using a low-cost and rapid fabrication technique.