4:00 PM, Tuesday, 24 May
The MIT IAP 2011 Radar Course: Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar (SAR) Imaging1
Dr. Gregory L. Charvat, Mr. Jonathan H. Williams, Dr. Alan J. Fenn, Dr. Stephen M. Kogon, Dr. Jeffrey S. Herd
Recently MIT Lincoln Laboratory sponsored a short radar course at MIT main campus during the January 2011 Independent Activities Period (IAP). The objective of this course was to generate student interest in applied electromagnetics, antennas, RF, analog, signal processing, and other engineering topics by building a capable short-range radar sensor and using it in a series of field tests. The underlying philosophy being that students have a vested interest in making their own radar work properly, causing them to dig deeper into these subjects on their own volition thereby providing a self-motivated learning experience. A series of lectures on the basics of radar, modular RF design, antennas, pulse compression and SAR imaging were presented. Teams of three students received a radar kit. Nine teams participated in the course.
The radar kit was an S-band coherent frequency modulated continuous wave (FMCW) radar centered at 2.4 GHz with less than 20 mW of transmit power developed by the authors. To reduce cost, the antennas (transmit and receive) were made from coffee cans in an open-ended circular waveguide configuration. To clearly show the RF and analog signal chain, all components were mounted on a block of wood similar to an early 1920’s radio set. The microwave signal chain was made from six Mini-Circuits coaxial components. The analog signal chain was implemented on a solderless breadboard for quick fabrication and easy modification. The video output and transmit synchronization pulses were fed into the right and left audio inputs of any laptop computer. To make the kit portable it runs on eight AA batteries. The total cost of each kit was $360.
The radar operates in three modes; doppler vs. time, range vs. time, and Synthetic Aperture Radar (SAR) imaging. To record data a student uses the .wav recorder program in the laptop. MATLAB scripts read the .wav data and form the appropriate plots.
Of the nine student groups all succeeded in building their radar, acquiring doppler vs. time and range vs. time plots. Seven of the nine groups succeeded in acquiring at least one SAR image. Some groups improved their radar sets by improving the signal processing algorithms, developing real-time radar graphics user interfaces (GUI’s), and by making a more robust chassis.
Most students were from MIT but a small contingent were from Northeastern University and one student built this radar as an independent study at Michigan State University. Great enthusiasm was generated after each field test. Students were engaged throughout the course and they continue to ask questions about how to improve the performance of their radar sets and how to make more sophisticated systems. Many students discussed scattering theory at length when trying to interpret their SAR imagery.
In summary, it is difficult to introduce the current generation of students to the field of applied electromagnetics, RF, analog, and signal processing because of the numerous challenging prerequisites needed before the rewards can be realized. By presenting these difficult topics at a high level while at the same time making a radar kit and performing field experiments, students became self motivated to explore these topics. In the long term, courses using this continuous engagement philosophy could help fill the gap as the current generation of radar engineers continues to retire.
Gregory L. Charvat grew up in the metro Detroit area, where the hands-on approach to engineering within the automotive culture was a great influence on his life. He earned his PhD in electrical engineering in 2007, his MSEE in 2003, and BSEE in 2002 from Michigan State University where he worked as a graduate research assistant for theElectromagnetics Research Group. He is currently a technical staff member at MIT Lincoln Laboratory since September of 2007.
Dr. Charvat is an IEEE member. He has authored or co-authored 4 journals, 20 proceedings, 1 magazine article, and 5 public talks on various topics including; applied electromagnetics, synthetic aperture radar (SAR), analog and RF design, and phased array radar systems. He maintains a website (www.mit.edu/~gr20603) and a blog (mrvacuumtube.blogspot.com) on the topics of radar, SAR imaging, amateur radio, audio design, and antique radios. He has developed 4 rail SAR imaging sensors, 2 MIMO phased array radar systems, an impulse radar, and holds a patent on a harmonic radar remote sensing system. Many of his projects have been featured on Make Magazine blog and his DIY rail SAR has been featured on the Popular Science Blog and Slashdot. He is currently writing a book, Small and Short Range Radar Systems, with CRC Press.
Greg served as a chair on the 2010 IEEE Symposium on Phased Array Systems and Technology steering committee and is currently serving as chair of the IEEE Antennas and Propagation Society (AP-S) Boston Chapter.
The joint meeting of the Life Member; Antennas & Propagation; Aerospace & Electronic Systems; and Geoscience and Remote Sensing Societies will be held at the Lincoln Lab auditorium, 244 Wood Street, Lexington, MA at 4:00 PM. Refreshments will be served at 3:30 PM. Registration is in the main lobby. Foreign National visitors to Lincoln Laboratory require visit requests. Please pre-register by e-mail to reception@ll.mit.edu and indicate your citizenship. Please use the Wood Street gate. For directions, go to http/www.ll.mit.edu. For other information, contact Len Long, Chairman, at (781) 894-3943 orl.long@ieee.org
[1] This work is sponsored by the Department of the Air Force under Air Force Contract #FA8721-05-C-0002. Opinions, interpretations, conclusions and recommendations are those of the authors and are not necessarily endorsed by the United States Government.
