• 3-D printed heterogenous substrate bandpass filters

      Nesheiwat, Issa (2021-09)
      With the demand for increasing frequencies in today’s communications systems, compact integrated circuits are challenging to achieve. Compact filters have typically been realized by modifying the circuit design including using LC resonators, defective ground structures, and adjusting the length ratios of resonators. Heterogenous substrates with controlled regions of dielectric loading offer a new design approach when it comes to manufacturing an RF component. In this thesis, additive manufacturing is used to selectively place low-K and high-K dielectric materials to achieve a compact form factor, improved bandwidth, and higher suppression in re-entry modes. First, microstrip coupled strip lines are simulated to model the basic coupling effects of loading a substrate. Next, three 2.45GHz parallel coupled bandpass microstrip filters are designed with differing substrates: low-K, high-K and high-K loaded to analyze the impact of loading within the substrate. The filter substrates are manufactured using a dual-extrusion FDM 3-D printer to combine both dielectrics, low-K ABS, and high-K PrePerm ABS1000, into a single heterogeneous substrate. Compared to the low-K dielectric alternative, the high-K loaded filter demonstrated a 30.8% decrease in length, while maintaining similar bandwidth and suppression of re-entry modes. Compared to the high-K filter, the high-K loaded filter showed a 9.4dB reduction in re-entry mode suppression, while maintaining similar footprint size.
    • Analysis of ground plane size, topography and location on a monopole antenna's performance utilizing 3-D printing

      Ciraco, Vito (2021-09)
      The monopole antenna is widely used in communication applications and is typically mounted on various surfaces that act as ground planes; a prime example being the roof of a car. The shape of the ground plane can drastically change the patterns of the electromagnetic radiation of a monopole antenna as well as its RF performance. Extensive work [1,12-13] has been done on the numerical modeling of arbitrarily shaped ground planes. However, due to their geometric complexity, there is very little work reported on the practical testing component of physical antennas with these obscure ground plane structures. This thesis illustrates how the additive manufacturing process presented can be used to physically realize arbitrarily shaped ground planes and provides a low-cost process to verify the numerical model. Ground Planes were modified while maintaining the same antenna length to evaluate the impact on antenna performance. The antenna was not optimized or changed to a standard antenna design. Varying radius spherical ground planes are modelled, as well as modified ground plane structures to evaluate the impact of the ground plane on a 1.3GHz monopole antenna's performance and in some cases to modify the antenna's performance in terms of gain, bandwidth, and radiation pattern. Designs such as the planar ground with horn was found to enhance monopole bandwidth by more than 5 times that of a standard planar ground but significantly deteriorate the antenna's radiation pattern. Moreover, complex geometry such as the fin sphere ground plane offered a 25% increase in gain relative to the standard sphere ground. Designs like the edge-mounted sphere can offer directive gain and radiation characteristics simply by altering the antennas' location mount location with respect to its ground plane. The techniques presented in this thesis offer new ways of producing 3-D printed ground planes for RF applications that are easier to manufacture, lighter in weight, and can enhance antenna performance over their conventional counterparts.