Micah Stickel

A millimeter-wave bandpass waveguide filter using a width-stacked silicon bulk micromachining approach

A 30-GHz bandpass filter is realized in a novel waveguide topology, through the use of bulk micromachining of standard (low-resistivity) silicon wafers. In this new design, the width of the rectangular waveguide structure is created through the stacking of etched silicon wafer pieces. This width-stacking approach eliminates the presence of convex corners in the design, resulting in more controllable etching. Also, this design enables the simple implementation of the split-block technique, which alleviates Ohmic contact resistance issues. This latter aspect, combined with a double-sided etching strategy that enables deep cavities to be formed, leads to very high-Q silicon micromachined resonators (Q/sub 0//spl ap/4500). A three-cavity bandpass filter was fabricated and tested leading to a deembedded insertion loss of 1dB at a center frequency of 29.7GHz, with a 3-dB bandwidth of 0.654GHz (2.2%). These results validate this new micromachined waveguide approach, and demonstrates a significant improvement over other millimeter-wave micromachined waveguide filters.

Impact of lecturing with the tablet PC on students of different learning styles

Using the tablet PC as a lecturing device offers the instructor a new set of tools upon which their teaching can be based. Since the general student body consists of many different types of learning styles, these new tools can provide a means to reach a wider range of students than the traditional blackboard-based lectures. However, as a first step towards assessing the effectiveness of the tablet PC as a teaching tool, it is important to determine if it is well received by students of all learning styles. It is the purpose of this paper to report on the impact of the tablet PC on the students in four different courses, which were given over a period of three semesters. This impact was measured through a survey which was completed by the students at the end of each term. Overall, the students in all courses (a total sample size of 280) were quite positive about the use of the tablet, with 56% of the students stating that “The technology of the tablet…greatly improves my learning experience.” It was found that there were no statistically significant differences in how the students of different learning styles responded to the use of the tablet PC. In fact, all learning style groups reacted quite positively to its introduction into the classroom. However, some results indicate that a large group of students have a preference towards a more active classroom. This shows that if the tablet PC is to be an effective means of teaching, its advantages must be leveraged to facilitate an active-learning environment.

Volumetric negative-refractive-index metamaterials based upon the shunt-node transmission-line configuration

A volumetric negative-refractive-index transmission-line (NRI-TL) metamaterial is presented. This structure constitutes a natural extension of the planar NRI-TL metamaterials1 and maintains the desired features of broad bandwidth and low transmission loss. Unlike their planar counterparts, the proposed volumetric NRI-TL metamaterials can effectively couple incident plane waves from free space. The proposed topology can be readily made by stacking layers that are individually fabricated using standard multilayer printed-circuit board techniques at microwave frequencies. However, the creation of the volumetric structure results in the presence of a parasitic parallel-plate mode. This mode can interfere with the desired backward wave mode of the metamaterial, causing a stop band to appear. To facilitate the rapid analysis of this new design, a multiconductor transmission line model was developed. Through the use of this model and full-wave simulations, it will be demonstrated that this unwanted parallel-plat...

Lessons learned from the first-time use of tablet PCs in the classroom

The tablet PC (TPC) is quickly becoming a widely used tool for engineering education. However, as with any new education initiative, care must be taken to introduce this properly. This paper will present the lessons learned from the experiences of two first-time TPC users in the Electrical and Computer Engineering Department at the University of Toronto. The courses were a second-year differential equations & linear algebra course, and a third-year electromagnetic waves course. To evaluate the effectiveness of the TPCs the same survey was given to both classes, with a total of 129 responses. Generally, these students strongly supported the use of the TPC, however, as this paper will show, caution must be exercised when incorporating the TPC into the classroom. This is evident by considering how the popularity of the TPC as a learning tool is correlated with the types of learners present in the class. In most of the literature dealing with TPCs, no such correlation is presented, but as the results of this survey show, it is an important relationship to consider. In this paper we will summarize our approach for using the TPC, present the results of the survey, and discuss some lessons learned.

Effective use of tablet PCs for engineering mathematics education

Recently, there has been a growing interest in the use of tablet PCs (TPCs) as a means for improving engineering education, primarily in technical courses such as basic physics. However, there has been little discussion on how to apply this technology to engineering mathematics courses. The purpose of this paper is to present an approach for teaching mathematics to engineering students with the TPC. The approach was implemented in a second-year differential equations and linear algebra course within the Electrical and Computer Engineering Department at the University of Toronto. The effectiveness of the approach was tested qualitatively through a survey of 89 students, and quantitatively through a comparison between the three lecture cohorts of the course, since two of the cohorts were taught with a traditional blackboard technique. The survey results were quite positive, yet the more interesting results are found from the grade comparisons. These results indicate that the TPC-based instruction had the greatest impact on the students in the bottom half of the class. In this paper, the approach will be discussed and survey and grade comparison results will be presented.

Growing evanescent waves in a cutoff rectangular waveguide loaded with an inductive iris and a capacitive post

There has been much interest recently in the area of engineered materials with unusual electromagnetic properties known as metamaterials. Of particular interest are those metamaterials that are characterized by a negative refractive index (NRI). The existence of growing evanescent waves is one of the very interesting phenomena that has been observed within such NRI materials. It is the purpose of this paper to investigate the presence of growing evanescent waves within a cutoff rectangular waveguide. It will be shown through theoretical analysis, full-wave simulations, and experimental results that the development of such a wave is not unique to NRI materials. Indeed, it is possible to generate such growing evanescent waves through the simple loading of a cutoff rectangular waveguide with a shunt capacitive post. The further loading of the waveguide with a shunt inductive iris can impedance match the growing evanescent wave to a standard decaying evanescent field, thus producing an evanescent field patter...

High-Q microstrip-fed bulk micromachined silicon cavities

Bulk micromachining of silicon wafers to fabricate rectangular waveguide components has been the focus of much research over the past decade. Over that time, a number of different fabrication techniques have been presented. However, for resonator applications, these fabricated topologies restrict the cavity height to less than two wafer thicknesses. To allow for much deeper cavities, an enabling fabrication procedure for micromachined waveguide components has been proposed. In this paper, a regular height bulk silicon micromachined cavity of constant cross section, fed using a microstrip line, has been presented. The relatively low measured Q/sub 0/ factor for this cavity was due to the poor soldered connections between the top and bottom plates. A new enabling micromachined cavity design has also been introduced, which achieves a very high unloaded (Q/sub 0//spl cong/4500, measured) quality factor.