74 June 2011

Richard Campbell and Robert H. Caverly

Digital Object Identifier 10.1109/MMM.2011.940593

Richard Campbell (rick.campbell@analog.com) is with Analog Devices Northwest Labs, 1100 NW Compton Drive, Beaverton, Oregon 97006, USA. Robert H. Caverly (robert.caverly@villanova.edu) is with the ECE Department, Villanova University, 800 Lancaster Ave, Villanova,

Pennsylvania 19085, USA.

RF Design in the Classroom

Few electrical engineering students arrive on campus with the basic skills needed to turn a concept into working hardware that solves a problem. Even university seniors typically have had few opportu-

nities to practice design; that is, given a constrained set of tools, skills, and components, create, evalu-ate, and implement a unique solution to a particu-lar problem or to address a particular need. Class assignments generally have limited scope, a short time limit, and one correct answer—in the back of the book. Students have limited opportunities to ask “what if?” and test their own partially-formed ideas in the lab. This is particularly true in the field of radio frequency integrated circuit (RFIC) design, where complimentary metal-oxide-semiconductor (CMOS) design and fabrication cycle times are long enough that many MSEE students do not even have a chance to power up and test the integrated circuitry described in their own thesis, let alone in the even-more time-constrained undergraduate program.

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This has profound negative implications for both microwave engineering education and the profes-sion, with a generation of engineering graduates defining design as something done sitting at a com-puter. The current generation of students easily grav-itate to the computer-aided design (CAD)/simulation environment, but two critical steps of the scientific method are missing: evaluating experimental results and modifying the underlying ideas (that is, closing the design-fabricate-test loop). Without the science and subsequent verification, to the students, engi-neering evolves into little more than an expensive video game. Fortunately for electrical engineering students, interests like peripheral interface con-troller (PIC) processor software, signal processing algorithms, and terahertz measurements offer short design cycles and rapid feedback on the imperfec-tions of one’s ideas. Students with the design gene can then naturally gravitate to projects where they create and test new ideas.

Before we declare engineering education irrelevant and return to recruiting microwave designers from physics, it is useful to note that automotive design engineers, naval architects, and aeronautical engineers seldom build and test full-sized cars, ships, and planes during their academic years. They work with scale models, and in many cases, they enter college with years of experience. For young professional aeronauti-cal engineers, unmanned aircraft are now the hottest technology.

A scale model isn’t necessarily a smaller version of the real thing. A scale model car may be a con-venient size to hold in one hand—but so is a scale model of a molecule. For a microwave/millimeter-wave/submillimeter-wave engineer, a scale model may be much larger than actual size. As an example, the Cascade Microtech 140–220 GHz wafer probes were designed using X30 scale models and initially evaluated in the 6-GHz range [1]. Since the speed of light is constant, when we scale microchip circuitry to a convenient discrete-component size, the fre-quency is reduced by the same factor. This has major benefits when connecting test equipment. Much of the circuitry on a current generation RFIC is simply an integrated implementation of old high-frequency (HF) discrete radio circuitry from the early discrete

semiconductor era. The state of that discrete-com-ponent, HF-ultrahigh frequency (UHF) art is still quietly evolving, (below the radar, one might say) as documented in the activities of IEEE Microwave Theory and Techniques Society (MTT-S) Technical Committee 17 [2]. These scale-model relationships between accessible HF-very-high-frequency (VHF)-UHF technology and cutting-edge millimeter-wave on-chip projects permit students to participate in the design and test process without the need for expen-sive fabrication runs, costly test equipment, or a long wait for a design to move through a integrated circuit fabrication process.

An example of the use of this scaling concept is applied to a receiver front end and shown in Figures 1 and 2, both of which show receiver front ends designed and built by the author (Campbell). Each consists of a low-noise amplifier (LNA), filters, and a frequency mixer. The 2-GHz front end is fabricated using the TriQuint TQTrx process, and the 50-MHz front end using the ExpressPCB miniboard service. The layouts are similar, with the LNA along one side and the down-converter circuitry occupying the rest of the area. Total cost of the 50-MHz hardware was less than the Portland State Microwave Engineering course textbook. The design was studied using Linear Technology’s free SPICE simulator and tested on the author’s home bench.

These and other HF and frequency modula-tion (FM) broadcast receiver projects have been a staple of RF Design classes at many other univer-sities such as Cal Tech, Virginia Tech, Villanova, and others for decades (see, for example, the work by David Rutledge [3]). The following describe approaches to microwave and RF electronics engineering design projects taken recently at two universities on opposite sides of the United States: Portland State University and Villanova University.

For a microwave/millimeter-wave/submillimeter-wave engineer, a scale model may be much larger than actual size.

76 June 2011

The Portland State University ApproachSince 2004, a microwave engineering design sequence at Portland State University has empha-sized the scale modeling aspects of HF-VHF cir-cuitry. HF-VHF projects are analyzed, designed, built, measured, redesigned, and implemented by

students. The scale modeling is not limited to micro-wave applications; several students have used the Smith chart to design speaker crossover networks for audio systems.

Portland State Skills and BlocksThe approach at Portland State University has been to identify and study a few key skill sets and four key functional analog RFIC blocks. The basic skills are basic electromagnetics, including transmission line impedance and reflections

• the Smith chart • scattering parameters • prototype construction and measurement tech-niques

• evolving the designand the four blocks are

• amplifiers • frequency mixers • oscillators • filters.

Antennas and free space are needed to radiate, propagate, and collect signals, but antennas and propagation are the realm of other classes and other IEEE Societies. A modern wireless system will gen-erally include digital signal processing and connec-tion to a computer, but the Portland State approach has been to separate the wireless RF functions from the need for digital hardware—much as a basic photography class might use film and chemical processing.

The hardware projects have changed every year to introduce new problems, encourage new ideas, and discourage recycling a roommate’s project from a previous year. The projects have a set of requirements

• less expensive than the course textbook • 20–40 hours total construction and evaluation time • some blocks must simulate well • some blocks must not simulate well • basic circuits should not work the first time power is applied

• all blocks must interconnect to make a complete wireless system

• everything must self-test using student-owned test equipment.

This is a curious set of constraints, particularly the suggestion that first-time success is undesir-able. Experienced microwave engineers under-stand that a first prototype working on the bench usually reveals limitations and omissions from cir-cuit models and simulations. Engineering students tend to think of the simulation schematic as the finished circuit and the hardware as something a technician assembles. In some cultures, engineers avoid any contact with hardware. Interestingly,

Figure 2. Printed circuit 50-MHz scaled model of the 2-GHz receiver front end on an ExpressPCB process. It performs similar functions as the one in Figure 1, with inductors, capacitors, FETs, transformers, filters, low-noise amplifiers, and frequency mixers but includes the local oscillator in the lower left corner of the board. (Photograph courtesy of R. Campbell.)

Figure 1. Die photograph of a 2-GHz receiver front end on TriQuint’s TQTrx process. It performs similar functions as the one in Figure 2, with inductors, capacitors, FETs, transformers, filters, low-noise amplifiers, and frequency mixers. (Photograph courtesy of TriQuint.)

The Portland State approach has been to separate the wireless RF functions from the need for digital hardware.

June 2011 77

those are often the students who have the most fun when a professor assigns a project in which they actually get to wind a toroid and solder a diode with short leads.

Grading ProjectsAt Portland State, projects are graded pass/fail. This is a harsh introduction to real-world concepts, but perhaps a welcome relief from begging for extra credit with a written report full of excuses.

The individual blocks are interconnected into a complete wireless system that must work by the final week of the quarter. If the transmitter gener-ates enough power to light a small incandescent bulb and is clearly audible in another student’s receiver across the classroom, both the transmit-ter and receiver are known to work. This bootstrap wireless system development, with the receiver serving to test the transmitter and vice versa, was the basis of the old U.S. Federal Communications Commission (FCC) Amateur Radio Novice License in the 1950s and 1960s. Every student does an indi-vidual project with enough professor oversight to ensure somewhat independent work. Comparing results and collaboration on construction techniques are encouraged, and working systems are demon-strated in the classroom during lecture breaks. A typical class at Portland State has 40 students, so there is always a friendly competition for the most sensitive receiver and brightest light bulb. Students who achieve early success with the hardware and understand the function of each block in the trans-mitter and receiver become student mentors for the rest of the class.

Evolving ProjectsStudents have access to well-equipped laborato-ries, but transmitters and receivers are tested in the classroom using batteries, earphones, and clip-lead antennas. For the first five years, all hardware operated at 7 MHz. Short 7-MHz receiver anten-nas are ineffective, and #47 light bulbs don’t radi-ate well. In 2005, Mark Hansen built both the first transmitter and a companion receiver described in [4], connected them to a half-wave dipole at his home, and made several contacts out to 60 mi using his amateur radio call sign KI7N. In subse-quent years, a number of students have expressed interest in obtaining amateur licenses and commu-nicating over longer distances. For the 2009–2010 academic year, enough students committed to obtaining licenses that a new set of projects was designed to be tested outdoors with transmitters operating under Part 97 of the U.S. FCC regula-tions. To ensure spectral purity, a printed circuit board kit VHF source was designed by Camp-bell, to be analyzed and constructed by students

and serve as the core of student transmitters and direct conversion receivers at 50.1 MHz. The VHF source kit uses only discrete components, with each stage studied and analyzed by students. The kit then becomes the oscillator in their transmitter and receiver block diagrams, and students design, build, and test the remaining blocks. This was a very popular evolution in the projects, with several students communicating over a mile from campus to a nearby hilltop.

Lessons LearnedLessons learned by the students include basic pro-totype construction, measurements with the avail-able tools, circuit modifications, the interactions of blocks, system engineering to the individual transis-tor level, applied scientific method, creative design, evaluation, and redesign to new specifications. Some of these topics are lecture subjects and some happen naturally in the lab. There is no organized lab for the course, there are only expectations, dead-lines, and a large group of students all working on the same project.

A Detailed Look at One ProjectFigure 3 is the schematic of a 7-MHz signal gen-erator having a 0.25-W output power, designed by Wes Hayward as a first transmitter [4]. The three stages include an oscillator and two amplifiers. Some initial redesign is required by students, as power is supplied by a 9-V battery instead of the 12 V specified by Hayward. The oscillator works well and can be analyzed on paper, but simula-tions are difficult and not particularly enlighten-ing. Students are encouraged to build the oscillator first and observe the output on an oscilloscope or listen to it on another student’s receiver. The boot-strap approach ensures that the first student with a working receiver is much in demand. The buffer amplifier is a good vehicle for the common elec-trical engineering design approach, as it simulates well and simulations agree with measurements once the student learns the subtle techniques of toroid transformer fabrication. The class C output amplifier works well, the optional simulations may be useful, and the output network is a good Smith chart design exercise.

Students are encouraged (in some years required) to build and test the first transmitter one stage at a time. If the only test equipment is the receiver, the

Portland State projects are graded pass/fail; a harsh introduction to real-world concepts.

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signal gets louder in the earphone when the battery is connected to the second stage. The third stage pro-vides enough 7-MHz RF power to light a #47 incan-descent flashlight bulb. The output stage is a classic power amplifier (PA) design—on paper, output power

is a simple function of supply voltage and imped-ance presented to the device. Students quickly learn that device size and drive level are important as well. Clever designers analyze and modify the circuit to obtain more light—a uniquely appropriate way of sorting the bright students.

One goal of the program is for students to learn to build a working prototype given only a schematic. Everyone quickly discovers that a schematic is not enough for students with no experience. The compan-ion receiver (to the 7-MHz signal generator shown in Figure 3) schematic is shown in Figure 4. Close-up pho-tographs in Figures 5–7 illustrate construction tech-

niques and show details of interconnections for the receiver circuit.

VHF-UHF Prototype Construction, Design Evolution, and Product EngineeringParasitics are critically im -portant in VHF and UHF design when using discrete components. Most student VHF and UHF filter designs simply don’t work when ini-tially fabricated because stu-dents fail to take into account lead and trace lengths and device parasitics. As a means

Figure 3. Schematic of a quarter-watt output power, 7-MHz signal generator used in microwave circuit design courses at Portland State University.

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Clever designers analyze and modify the circuit to obtain more light—a uniquely appropriate way of sorting the bright students.

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to show the impact of these nonideal circuit construc-tion considerations, a number of examples in the class-room are used to introduce UHF prototype techniques, with near-zero lead length over unetched ground plane. This construction method works well through at least 1 GHz. The upper frequency limit for “ugly construc-tion” (a term introduced by Hayward for RF prototype construction over an unetched printed circuit ground plane) is limited only by the skills and depth of under-standing of the practitioner. Examples of the ugly con-struction technique for VHF construction are shown in Figures 8–10. Figure 8 is a low-power, 100 mW PA for use in the 144 MHz frequency range (the U.S. amateur radio 2-m band). Note the short component leads and

close proximity to the ground plane. Figure 9 shows the prototype of a 50.1 MHz signal generator, and Figure 10 shows the full printed-circuit-board ver-sion. Again, small component lead lengths and con-struction close to the ground plane help ensure little difference in performance between the prototype and finished product.

Figure 5. The receiver is simple, small, and draws 8 mA from a 9-V battery, but it detects signals from thousands of kilometers away when connected to a half-wave dipole antenna 10 m above the ground. (Photograph courtesy of R. Campbell.)

Figure 6. Detailed photograph of the RF tuned circuit, local oscillator, and mixer. The mixer in this application is often called a “product detector.” The antenna input is the small coax cable soldered to the board at the left. The simple Pierce oscillator with a 7.030-MHz crystal and trimmer capacitor (green) are on the lower left part of the board. The product detector with its trifilar toroid, two diodes, and bypass capacitor are in the upper right. The audio low-pass inductor is the gray cylinder on the bottom right. (Photograph courtesy of R. Campbell.)

The upper frequency limit for “ugly construction” is limited only by the skills and depth of understanding of the practitioner.

Figure 7. Photograph showing details of the product detector and audio section. The gain is low enough that there is no need for a volume control, even though the band noise is clearly audible in the headphones. One simple way to implement a volume control would be a 100-V variable resistor directly across the head-phone jack. The resistor varies the gain by reducing the Gm 3 Rload product for the output stage. (Photograph courtesy of R. Campbell.)

Figure 8. A prototype 144 MHz 100 mW power amplifier used to illustrate concepts of parasitics in VHF design [5]. (Photograph courtesy of R. Campbell.)

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It is difficult to overestimate the importance of hav-ing a design class taught by a practicing design engi-neer. Students in the 2008–2009 microwave engineering class were lectured on every stage of the development of the VHF signal source from Maxwell’s equations through a production printed wiring board and com-ponent kit. This was then used during the 2009–2010 academic year. This kit is commercially available from Kanga US [6]. The process is more difficult than it appears. Product engineering is as challenging as the initial design.

System Engineering at the Transistor LevelThe new discipline of system engineering involves manipulating block diagrams. Blocks are designed and understood by circuit designers, using devices designed and understood by device engineers, who give modeling engineers enough information that simulators written by computer scientists can be blindly used by designers to achieve first-pass system success. Professional engineers may focus on one of the above disciplines, but students should be familiar with each one.

Primitive wireless systems offer the opportu-nity for students to dig into every aspect of the system, from the underlying theory to complex interactions between nonlinear circuit blocks. The Portland State microwave design students are per-mitted to use any circuit block for their wireless system design project that they can describe to the individual component level. The diode-ring mixer shown in Figure 11 is one example of a component that a few students understand well enough to use as a block.

The Villanova University Approach

Undergraduate Curriculum TrackThe Villanova University approach to microwave and RF education is similar in scope to the Port-land State program and begins with the required engineering electromagnetics course in the junior year (the overall undergraduate curriculum track is shown in Figure 12 on the left branch). The focus at Villanova differs from the Portland State model in that the course projects are more directed to the VHF or UHF range. The VHF-UHF range projects allow the use of both lumped and/or distributed element approaches to the design-fabricate-test loop completion, providing prompts for conversations on lumped-element parasitics at these frequencies. To provide a contemporary look at microwave and RF design, lectures on on-chip components such as on-chip passive structures (on-chip resistors, capacitors, inductors, and transformers) are introduced dur-ing the relevant discussions on the electromagnetic

Figure 11. Microphotograph of a Mini-Circuits ADE-1 ring diode frequency mixer. (Photograph courtesy of R. Campbell.)

Figure 9. “Ugly Constructed” prototype 50.1 MHz signal source—December 2008. Ugly Construction uses components with short leads soldered together over an unetched copper-clad board ground plane. (Photograph courtesy of R. Campbell.)

Figure 10. Assembled production kit VHF signal source from Kanga US—April 2009. (Photograph courtesy of R. Campbell.)

The Villanova microwave engineering course includes weekly laboratories where students perform basic microwave measurements and learn to use a contemporary microwave and RF CAD tool.

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origins of these elements (details of this introduc-tion can be found elsewhere [7]). In the upper UHF range, the use of distributed elements is possible, due to their more reasonable microstrip lengths and overall board sizes.

The microwave engineering course emphasizes passive circuit design with the following high-level list of topics, using a widely used text [9]:

• transmission line theory, which covers lossless lines, the Smith chart, and impedance trans-formation, impedance matching, and lossy lines

• network theory, which covers Z, Y, S, and ABCD multiport parameters, and S and T two-port parameters

• practical transmission lines, which covers wave-guides, coaxial lines, strip-style transmission lines, and transmission line filters (a brief look in this first course with more details in the follow-on course)

• microwave power directivity, which covers power dividers and directional couplers

• microwave and RF system concepts, includ-ing distortion prediction using intercept points, dynamic range (linear and spurious free), system gain and noise figure, and communications link budgets.

The microwave engineering course includes weekly laboratories where students perform basic microwave measurements and learn to use a con-temporary microwave and RF CAD tool (the most recently used CAD software was Ansoft Designer SV). In addition to these weekly reinforcement exer-cises, the students are assigned a project to use the tools studied throughout the semester to design, simulate, layout, and test a prototype microstrip low-pass filter circuit based on an LC ladder proto-type in the nominal 1,000-MHz frequency range.

The students use CAD for the design and simula-tion and implement the final prototype using inex-pensive 1.58 mm (0.0625 in) thick single-sided FR-4 printed-circuit board. Over the years, students have constructed these commensurate line filters using

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Figure 12. RF and microwave engineering undergraduate curriculum flow at Villanova University. (© 2007 ASEE. Used with permission [8].)

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Figure 13. Examples of student-designed, nominal 1.0 GHz, passive microstrip, commensurate line, low-pass filters based on LC ladder prototype circuits: (a) milled and (b) copper tape versions. (c) The measured performance of the top circuit. [(a) Photo courtesy of R. Caverly. (b) and (c) © 2007 ASEE. Used with permission [8]].

Primitive wireless systems offer the opportunity for students to dig into every aspect of the system, from the underlying theory to complex interactions between nonlinear circuit blocks.

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easily obtainable 6.35 mm or 12.7 mm wide copper tape (0.25 and 0.5 in, respectively), cut to width and length using single-sided razor blades (never double-sided razors). More recently, a PC milling machine has been employed to take CAD layouts and fabri-cate them directly on the FR-4. Passband insertion losses of less than 0.2 dB and stop-band rejections of greater than 50 dB are easily obtained using both techniques. The students then use an HP-8510B vec-tor network analyzer to measure the S-parameters of their final prototype and compare with the original set of specifications. Figure 13 shows examples of two third-order commensurate line filters using both construction techniques.

The RF circuit design course is a follow-up course to the microwave engineering course and focuses on more active RF and microwave circuits. It uses a num-ber of hardware and CAD design projects to reinforce student understanding. In this course, the students

design, fabricate, and test a HF receiver front end and correlate the system design specifications and mea-surements with the material presented in the course as well as the systems concepts introduced in the pre-vious course. The RF circuit design course covers the following high-level list of topics:

• advanced filtering, which covers low-pass, high-pass, band-pass, and band-notch filtering using LC prototypes, m-derived/constant-k filters, and transmission line resonators

• antenna and signal control, using primarily p-i-n diodes and field-effect transistor (FET)-based switches

• mixer design, using both passive (diode, FET-based resistive) and active (biased transistor) unbalanced and balanced mixer circuit topologies

• amplifier design, for low power and/or low noise as well as high power (amplifier Classes A–F and includes a discussion on the concept of conduc-tion angle to define the classes)

• oscillator design, using primarily reactance-based feedback

• antenna design, with a focus on low profile pri -nted circuit antennas.

The major course project for the RF circuit design senior elective is the design, simulation, and fab-rication of a 900-MHz receiver front end [this

frequency was chosen since it is the one transmitted by global positioning system (GPS) satellites for radio location] that down converts the 900-MHz signal to an intermediate frequency (IF) of approximately 50 MHz. As the previous list of top-ics is covered in lecture, an attendant CAD exercise and construction project is assigned as part of the classroom experience. Both distributed and lumped ele-ment solutions are utilized to give the undergradu-ates a chance to explore both technologies as part of the course experience. A block diagram for this 900-MHz receiver system is shown in Figure 14. Com-mercial off-the-shelf com-ponents are used for the LNA and the diode mixer, with microstrip passive circuits (of the student’s own design) used for the input band-pass filter (BPF),

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Figure 14. (a) RF front end block diagram and (b) a photograph of the corresponding student-designed circuit. [(a) © 2007 ASEE. Used with permission [8]. (b) Photograph courtesy of R. Caverly.]

It is difficult to overestimate the importance of having a design class taught by a practicing design engineer.

June 2011 83

amplifier biasing circuitry, and branch-line coupler. To provide a real-life component to the project, a set of beacon transmitters in the 900-MHz frequency range (available in our geographic region) are used for testing signals. These local beacon transmit-ters continuously transmit an easily identified sig-nal of 30 s of continuous carrier and 30 s of Morse code identification. (There are a number of beacons throughout the United States and other countries that may be found through the amateur radio com-munity to provide this real-world component of the project at other schools).

Undergraduate Independent Study ProjectsOnce some students get a taste of RF and microwave engineering, they want to explore these concepts even further. Over the last several years, senior stu-dents have carried out a number of high-efficiency PA projects. These PA projects have been based in the VHF band (primarily 144 MHz) and have con-centrated on switching-type amplifiers (Class E and F). All students doing these projects have had the first microwave engineering course and are taking the RF circuit design course concurrently; these PA pro jects do not overlap the material in the second course (which is receiver oriented, as described pre-viously). Using CAD packages such LT-SPICE, the students gain insight into the impact and utility of waveform engineering [10] and the impact in the time domain on the interplay between wave-shaping networks and the overall amplifier efficiency. Figure 15 shows an example of one such student-designed 144 MHz PA. All design work and construction, including board layout (notice the student artist ini-tials in the figure) is done by the students. With a 4.0-V power supply, this circuit exhibited a 70.48%

power-added efficiency (PAE) (85.1% drain effi-ciency) with approximately 1.8 W of output power into a 50-V load.

ConclusionTeaching microwave engineering using projects in the HF-VHF-UHF frequency range has a number of benefits. Students are able to move quickly from simu-lations to working hardware and connect test equip-ment to circuit nodes while discovering the differences between a simulated project schematic (without para-sitics and other real-life issues) and actual working hardware. Using frequency scaling, these designs may be translated to much higher frequencies, where they may be fabricated on chip. Students develop creativity and confidence when design cycles are short enough that multiple iterations of a project may be completed in a single academic year.

AcknowledgmentSome of this material is based on work supported by the National Science Foundation under Grant 0203459.

References[1] R. Campbell, M. Andrews, and L. Bui, “A 220 GHz wafer probe

tip with reduced stray fields,” in IEEE MTT-S Int. Microwave Symp. Dig., Long Beach, CA, June 2005, pp. 651–654.

[2] MTT-17HF-VHF-UHF [Online]. Available: http://www.mtt- archives.org/~mtt17/index.html

[3] D. Rutledge, “The electronics of radio—Teaching college electron-ics with an amateur transceiver,” IEEE Microwave Mag., pp. 94–99, June 2000.

[4] W. Hayward, R. Campbell, and R. Larkin, Experimental Methods in RF Design. Newington, CT: ARRL, 2003, pp. 1.17–1.19.

[5] R. Campbell, “VHF experiments part 4,” CQ-VHF Mag., pp. 26–29, Autumn 2010.

[6] Kanga US, company Web site. [Online]. Available: http://www.kangaus.com/

[7] R. Caverly, “Introducing undergraduate research results in RF mi-croelectronics into the undergraduate ECE curriculum,” in Proc. 2004 ASEE Conf., June 2004, pp. AC2004-1028-1–AC2004-1028-7.

[8] R. Caverly, “Curriculum and concept module development in RF engineering,” in Proc. 2007 ASEE Annu. Conf., June 2007, pp. AC2004-1028-1–AC2004-1028-8.

[9] D. Pozar, Microwave Engineering, 3rd ed. New York: Wiley, 2004.

[10] S. Cripps, RF Power Amplifier Design for Wireless Communications. Norwood, MA: Artech House, 2006.

Figure 15. Student-designed 144 MHz Class E power amplifier. (Photograph courtesy of R. Caverly.)

Students develop creativity and confidence when design cycles are short.