Date Approved

2-2019

Graduate Degree Type

Thesis

Degree Name

Engineering (M.S.E.)

Degree Program

School of Engineering

First Advisor

Dr. Jeffrey Ward

Second Advisor

Dr. Karl Brakora

Third Advisor

Dr. Bogdan Adamczyk

Academic Year

2018/2019

Abstract

A prototype binary frequency shift keying (BFSK) RF link operating in the 2.4 GHz ISM band was identified as a need for a potential undergraduate engineering laboratory activity. This system would be used to showcase various RF circuit engineering principles and techniques such as controlled trace impedances, frequency mixing, voltage-controlled oscillators, distributed element filters, and power splitters. This investigation focused on designing a prototype system that put a priority on ease of measurement and circuit tuning to help foster a more hands on approach. Each major circuit element was broken into separate PCBs to increase the modularity of the design and allow for each of them to be measured independently of the system. All schematic capture and layout was performed in Altium Designer. The RF system was able to transmit up to 60 cm with an input power of 0 dBm without any dedicated amplification. The use of a distributed element 2.4 GHz bandpass filter was used as an opportunity to investigate the impact on filter performance that different substrates and filter subtypes had on the overall filter design. Four substrates of various thickness, 50 to 62 mils, and dielectric constants, εr = 3.55 to 10.2, were used for stepped impedance, edge-coupled, hairpin, and elliptic filters. All 16 of the filters were designed using Genesys 2015, laid out using Altium 2015, and routed on a LPKF ProtoMat S103 circuit board router. It was found that the stepped impedance and elliptic filters required traces less than 2 mils wide which are not easily manufacturable. Only the edgecoupled and hairpin designs were built. Out of these eight designs, the substrates with the lower dielectric constants performed the closest to their simulated results. However, this could have been due to unanticipated challenges when routing the higher dielectric materials that was not present for the lower dielectrics.

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