Ian Wood graduated from the University of Victoria with a MASc in Electrical Engineering. His research involved developing a compact, planar imaging array for use in radio astronomy. He worked as a student researcher at the Herzberg Institute of Astrophysics, assisting in the production of 84-116 GHz receiver cartridges for the Atacama Large Millimeter Array Telescope. He currently works for CST of America where he provides advanced antenna simulation solutions for customers in a variety of application fields.The development of new multimedia services and intelligent sensor systems is progressing at a rapid pace and requires the use of agile antenna frontends that are compact, highly efficient and cost-effective. These antennas are rarely off-the-shelf solutions. On the contrary, custom-tailored solutions are usually required in order to optimise the performance, and facilitate the integration into the final product.
In many applications, the best compromise for an antenna solution with respect to cost and performance is a planar array. In general, a planar array can be defined as an antenna in which all of the elements are situated in one plane. The antenna elements themselves can be patches or other planar or buried structures. The range of applications of planar arrays include agile RF-frontends for mobile satellite terminals, radar systems for automotive and security applications, and millimetre wave point-to-point or point-to-multipoint radio links for multimedia wireless networks.
Real-life communications systems can include antenna arrays with only a limited number of transmitters and receivers as well as very large arrays with hundreds of receive and transmit channels. A skilful symbiosis of industrial development and innovative research projects is the key to provide cost-effective products. Some typical applications will be described in the next sections.
Considerable experience is required for the design and realisation of planar antenna arrays at microwave frequencies, especially when broadband solutions are demanded. It is not only necessary to develop innovative concepts beyond the standard patch design, but it also becomes unavoidable to cope with material and manufacturing tolerances when realising the antennas on soft and hard substrates. Special care has also to be invested in the RF-feeding network and the transition between antenna and RF-circuitry, as the latter can become a bottleneck at high frequencies, hence limiting the available bandwidth.
In order to provide cutting-edge solutions, it is important not only to develop systems based on state-of-the art antenna concepts. Fast and highly accurate EM solvers are indispensable tools to simulate the whole antenna system. Access to prototyping tools and accurate measurement facilities are also required. The seamless integration of all these services helps reduce the number of iterations to obtain high-performance antennas, thus leading to reduced development time. A complete, industrial solution for complex planar arrays must cover the whole development chain, starting with the conceptual design and the development of new concepts and solutions, going through the prototyping and optimisation process, including antenna characterisation and diagnosis, up to the preparation of line production and qualification phase. Some of the key steps will be discussed in this talk.
Meeting will be held at MIT Lincoln Laboratory A-Café, 244 Wood Street, Lexington, MA. For directions please see:http://www.ll.mit.edu/about/map.html
For more information, contact Antennas & Propagation chair, Gregory Charvat at Gregory.charvat@ll.mit.edu
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.
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.
Are you interested in learning about radar by building and testing your own imaging radar system?
MIT Professional Education is offering a course in the design, fabrication, and test of a laptop-based radar sensor capable of measuring Doppler and range and forming synthetic aperture radar (SAR) imagery. Lectures will be presented on the topics of applied electromagnetics, antennas, RF design, analog circuits, and digital signal processing while at the same time you build your own radar system and perform field experiments. Each student will receive a radar kit, designed by MIT Lincoln Laboratory staff, and a course pack.
This course will appeal to those who want to learn radar systems engineering or SAR imaging, use radar technology in a product or experiment, or make components or sub-systems.
You do not have to be a radar engineer but it helps if you have at least a bachelor’s degree in electrical engineering or physics and are interested in any of the following: electronics, electromagnetics, signal processing, physics, or amateur radio. It is recommended that you have some familiarity with MATLAB. Each student is required to bring a laptop (with a stereo audio input) with MATLAB because this will be used for data acquisition and signal processing.
During the course you will bring your radar kit into the field and perform experiments such as measuring the speed of passing cars or plotting the range of moving targets. A SAR imaging competition will test your ability to form a SAR image of a target scene of your choice from around campus.
