Microwave Engineering Education
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High Frequency Design Engineering Education Microwave Engineering Education By Tom Perkins Senior Technical Editor Abstract at age 96 in 2010, so he got to see and experi- Exploring some of the According to recently ence incredible advances. The addition of history, current trends, released statistics by circuits with distributed constants in Fred and what the classroom The Alliance for Science Terman’s Radio Handbook is certainly note- of the future may look and Technology Research worthy. As time went by a number of contem- like. in America, slightly over porary textbooks became available such as 25 percent of high school Foundations of Microwave Engineering by students in the United Robert E. Collin, 1966; Microwave Engineering States are interested in Science, Technology, Passive Circuits by Peter A. Rizzi, 1988; and Engineering, Mathematics and Statistics Microwave Engineering by David M. Pozar, (STEM). According to the US Department of 3rd Edition, 2004. The latter book, originally Education the percentage of bachelor’s published in the 1990s, is widely used today. degrees conferred in STEM fields in the Numerous books devoted to specialized tech- United States was lower in 2008-2009 (24.2 nology within our field have been published percent) than it was in 1998-1999 (25.6 per- over the years. I would guess that active cent). Engineering education and particular- microwave amplifier and oscillator devices ly majors in microwave electronics have gone would top the list, including lots of material through significant change in the past 60 devoted to monolithic microwave integrated years. Our High Frequency Electronics circuits (MMICs). Editorial Calendar for April 2013 includes the topic of Engineering Education. Having Prerequisites an increasing interest in this general topic The problem with many current EE cur- and having both taken and taught courses in riculums is that only one Emag course is microwaves, I decided to tackle this topic. required. One reason that students hesitate This article explores some of the history, cur- to take other electives in this area is because rent trends, and what the classroom of the they are intimidated by the mathematics. future may look like. Defense-centric companies do little to pro- mote their work and therefore students are At the Campus Bookstore generally unaware of the excitement and The first textbooks available for the bud- fulfillment derived from designing and build- ding microwave technology field, which was ing a radar system, satellite hardware, often considered more of an art than a sci- MMICs, antennas, etc. They generally pursue ence in the middle of the 20th century, were digital and computer courses, thinking per- 1) the incredibly comprehensive and still use- haps if they go down another path they will ful 28 volume MIT Radiation Laboratory miss out on the lucrative future opportuni- Series, 2) a book titled Waveguide Handbook ties. Now that A/D’s are sampling at 5 GHz edited by Nathan Marcuvitz which famously and higher, digital technology will play a became Volume 10 of the Rad Lab Series, and large role, but there has to be an understand- a few others such as 3) Theory and Application ing that signals travelling on the digital sig- of Microwaves by Arthur Bronwell and Robert nal lines are at GHz frequencies and hence a Beam, 1947. Interestingly, Dr. Marcuvitz died good knowledge of microwave transmission 28 High Frequency Electronics High Frequency Design Engineering Education lines, radiation, noise, and signal isolation will be required. Most credible microwave courses require pre- requisites, in addition lots of basic math and physics courses, such as Electro-Magnetic Fields and Solid State Device Physics. Because of heavy emphasis on materials technology and semiconductor foundry activity since the 1980s, there may be a necessity for materials science and chemistry courses, also. A downside is that a num- ber of schools have dropped microwave engineering courses or relegated them to post-graduate status. The reasons are not clear, but likely the lack of interested students coupled with relatively high costs, particularly in maintaining laboratories, are factors. There are approximately two dozen schools in the United States that offer microwave courses in the undergraduate curriculum. Examples are Ohio State University, University of Illinois at Urbana-Champaign, Penn State University, Georgia Tech, Arizona State, University of Colorado, University of Massachusetts, University of Mississippi, and the University of Figure 1 • Reflex klystron including cutaway view. Michigan. There are very good schools worldwide with some emerging opportunities now in places like Brazil, India, and China. Schools offering both undergraduate and graduate level courses worldwide (not complete) can be found at: http://www.microwaves101.com/encyclopedia/colleg- es.cfm Example of a Comprehensive Study Program The University of Michigan at Ann Arbor, has tradi- tionally offered many in-depth courses in our field. The University of Michigan offers fundamental courses such as Microwave Circuits I focusing on CAD tools, passive and active circuits and use of modern laboratory equip- ment. CAD software providers often provide universities with free programs recognizing that the student user will grow into and request the products in the work environment later. The same goes for test equipment which is sometimes offered to institutions at a reduced rate or even donated. Years ago this was often not the case. Labs were usu- ally equipped with left-overs and discarded equipment Figure 2 • Alford Model 3300 slotted line. even going back to WWII surplus gear. Not necessarily a bad thing—I once took advantage of the fact that I had ates of microwave curriculums seem to have no idea of worked with klystrons (Figure 1) in college. In the early what Lecher wires or slotted line (Figure 2) is. This is a 1970’s, I was asked to make some time-consuming phase bit unfortunate because basic laboratory devices give shifter measurements for a new project. All the then- one a “visual” feel for standing waves and related phe- modern microwave signal sources (like Alford sweepers) nomenon. The Smith Chart may be going the same way. were in high demand. So I spotted a klystron with its Now back to the University of Michigan example. somewhat draconian power supply on the shelf, hooked They have a Radiation Laboratory (RAD). Quoting from it up, and made my measurements. No one bothered my the University’s webpage: set-up for weeks, because most didn’t know what it “Areas of focus include antennas, from HF to tera- was—or maybe were afraid of high voltages. Speaking hertz frequencies; computational electromagnetics and of old equipment, I have found that many recent gradu- modeling techniques; electromagnetic wave interactions 30 High Frequency Electronics High Frequency Design Engineering Education with the environment; microwave and millimeter remote tools, the development cycle of new circuits and devices sensing; plasma electrodynamics and space electric pro- would be much slower and therefore more expensive. pulsion; polarimetric radars and radiometric imaging; radar scattering computations and measurements; radio Modern Classroom Amenities wave propagation predictions for mobile communica- Classrooms of old were typically equipped with black tions; RF and microwave front-end design for wireless or green chalkboards, chalk, and erasers. Now they are applications; RF integrated circuit design; and RF/ equipped with white boards, computer projection sys- microwave and millimeterwave micromachined active tems, internet connections, and Wi-Fi services. Even and passive components and subsystems; Terahertz more recent are electronic white boards with lecture electronics and applications; optically-assisted millime- capture cameras. According to Dr. Robert Henry of the ter-wave integrated circuits; low-temperature plasmas; University of New Hampshire, these amenities intro- laser physics and spectroscopy; plasma chemistry; plas- duce higher costs, including 3 to 4 year replacement ma and photochemical materials processing; amorphous cycles for hardware, cost for new software, more square thin films; pulse power plasmas; environmental applica- footage per student, more initial course development tions of plasmas; fundamental electromagnetic theory; time, training faculty in use of the equipment and soft- engineered electromagnetic structures (metamaterials, ware, and additional IT support personnel. Students frequency selective surfaces, electromagnetic bandgap often bring devices such as iPods, laptop computer, and structures); antennas; plasmonics and near field optics smart phones into the modern classroom. Resources now and imaging.” available include electronic textbooks, Wikipedia, Obviously the cost for all this is significant and may YouTube, search engines, Skype, and free content lec- explain why some schools have dropped actual hands-on tures on radar, electronic warfare, LTE, etc. laboratory activity completely from their curriculum. Instructional Delivery Coming of Computers Prior to the advent of electronic media, it was gener- Starting over four decades ago, computers have had ally accepted that face-to-face delivery was the best an impact on how and what is taught in engineering method. Increasingly, we now have on-line delivery aug- programs at the college and university level. No longer mented by incredibly well orchestrated graphics and does a student have to walk to some remote campus