24-GHz LTCC Fractal Antenna Array SoP With Integrated Fresnel Lens

Abstract

Abstract-A novel 24 GHz mixed LTCC tape based System-onPackage (SoP) is presented which incorporates a fractal antenna array with an integrated grooved Fresnel lens. The four element fractal array employs a relatively low dielectric constant substrate (CT707, ε r = 6.4) where as the lens has been realized on a high dielectric constant superstrate (CT765, ε r = 68.7). The two (substrate and superstrate) are integrated through four corner posts to realize the required air gap (focal distance). The fractal array alone provides a measured gain of 8.9 dBi. Simulations predict that integration of this array with the lens increases the gain by 6 dB. Measurements reveal that the design is susceptible to LTCC fabrication tolerances. In addition to high gain, the SoP provides a bandwidth of 8%. The high performance and compact size (24 mm x 24 mm x 4.8 mm) of the design makes it highly suitable for emerging wireless applications such as automotive radar front end.

Antenna‐in‐package Designs in Multilayered Low‐temperature Co‐fired Ceramic Platforms

“…This design eventually achieves a gain of 15 dBi at 24 GHz, while maintaining a high level of compactness as compared to similar designs [57,58]. fabricated sample [56] In addition to the gain enhancement techniques, there has been work focusing on surface wave suppression in LTCC. As mentioned above, this issue is relevant to LTCC AiP designs because LTCC substrates have relatively high dielectric constants and can be quite thick for some designs.…”

“…The additional process can increase the complexity and cost of fabrication. Another approach for gain enhancement is to focus the antenna radiation beam by using 3D structures in a multilayered LTCC, such as a superstrate layer or a lens structure [55,56]. For example, an LTCC-based Fresnel lens structure has been demonstrated to enhance the antenna gain in [56].…”

“…Another approach for gain enhancement is to focus the antenna radiation beam by using 3D structures in a multilayered LTCC, such as a superstrate layer or a lens structure [55,56]. For example, an LTCC-based Fresnel lens structure has been demonstrated to enhance the antenna gain in [56]. As shown in Figure 7.16, the antenna array has been realized in a standard LTCC tape system (CT 707, εr = 6.4), whereas to make a compact Fresnel lens, a very high permittivity LTCC substrate (CT765, εr = 68.7) has been used.…”

Design of silicon‐based fractal antennas

“…This structure is realized through multiple iterations on a basic geometrical shape such as triangle, rectangle, circle, or square [7]. Among these, carpet fractal has its resemblance with the square patch [12]. The first step of the design is to construct a solid square patch which can be termed as the zero order iteration.…”

“…Fractal antennas have been demonstrated in PCB and LTCC mediums [11, 12]. According to authors best knowledge, there has only been one demonstration of a silicon‐based fractal antenna, where Sierpisnki carpet topology has been investigated [13].…”