Tuesday, November 30, 2010

MIT IAP Course Offering: Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar Imaging

To interested MIT students, please sign up now:

Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar Imaging

Dr. Gregory L. Charvat, Mr. Jonathan H. Williams & Dr. Alan J. Fenn, Dr. Stephen M. Kogon, Dr. Jeffrey S. Herd
Mon Jan 10, Fri Jan 14, 21, Mon Jan 24, Fri Jan 28, 10am-12:00pm, TBD

Enrollment limited: advance sign up required (see contact below)
Signup by: 07-Jan-2011
Limited to 24 participants.
Participants requested to attend all sessions (non-series)
Prereq: Participants supply their own laptop with MATLAB installed

Are you interested in building and testing your own imaging radar system? MIT Lincoln Laboratory is offering a course in the design, fabrication, and testing of a laptop-based radar sensor capable of measuring Doppler, range, and forming synthetic aperture radar (SAR) images. You do not have to be a radar engineer but it helps if you are interested in any of the following; electronics, amateur radio, physics, or electromagnetics. It is recommended that you have some familiarity with MATLAB. Teams of three will receive a radar kit and will attend a total of 5 sessions spanning topics from the fundamentals of radar to SAR imaging. Experiments will be performed each week as the radar kit is implemented. You will bring your radar kit into the field and perform additional experiments such as measuring the speed of passing cars or plotting the range of moving targets. A final SAR imaging contest will test your ability to form a SAR image of a target scene of your choice from around campus, the most detailed and most creative image wins.

Saturday, November 27, 2010

Real-time through-wall imaging using an ultrawideband multiple-input multiple-output (MIMO) phased array radar system

The paper, 'Real-time through-wall imaging using an ultrawideband multiple-input multiple-output (MIMO) phased array radar system,' from the IEEE 2010 International Symposium on Phased Array Sys. & Tech has been posted to IEEE Explorer.

If you are interested in real-time radar imaging, phased array radar, and SAR imaging then you may find this to be a fascinating project and a good read, enjoy!

ABSTRACT

A real-time acquisition and processing architecture has been developed for an ultrawideband (UWB) S-band (2–4 GHz) multiple-input multiple-output (MIMO) phased array radar system that facilitates greater than 10 Hz imaging rates, providing a video-like radar image of what is behind a concrete wall. Video rate imaging enhances the interpretability of range vs. range through-wall and free-space radar imagery. Images are formed without a-priori information. Video framerate imaging is achieved by designing an electronically switched bi-static array using high-performance microwave components, a multi-threaded data pipeline, and efficient hardware-accelerated processing algorithms. Experiments successfully image low radar cross section (RCS) objects, fast moving objects in free-space, and a human behind a 10 cm-thick solid concrete wall.

Monday, November 22, 2010

ARRL sweeps 2010 on the homebrew 20m SSB transceiver

Worked 68 stations during sweeps this weekend on the homebrew 20m SSB transceiver, 40 watts PEP on one band only. This was the first time i have operated sweeps. My goal was 100 but i had to do some auto repairs on sunday that got in the way while the band was open.

Worked many stations well into Sunday evening. I greatly appreciate the operators who were patient enough to receive my exchange, sometimes letting me try it numerous times through the QRM. It was fairly easy making contacts during the day but the evening was challenging.

For next year: I am considering building a large solid state power amplifier or adding 80m capability because the frequency plan should facilitate both 80 and 20.

Saturday, November 20, 2010

ARRL Homebrew Challenge III, Bring it on!

Last month in QST the ARRL Homebrew Challenge II was announced. I plan on competing this year. The challenge is to build a SSB/CW transceiver in 12 months that is either mono-band (10 or 6m) or dual band (both 10 and 6m).

To prepare for the competition i am re-organizing my 714 drawers full of small parts inventory and cleaning up the lab from the homebrew 20 m SSB transceiver project.

Looking forward to seeing the other competitors radios. Hopefully i will be able to make the time to complete mine by Nov. 1.

Thursday, November 18, 2010

MIT Radiation Laboratory Book Series, all 28 volumes


I recently acquired the entire MIT Radiation Laboratory Series from a friend of mine in the IEEE. This series of 28 volumes thoroughly documents to the point of providing design tables, derivations, design examples, schematics, scalable designs, the radar research conducted at the MIT Radiation Laboratory during the Second World War.

For example, one of the most famous volumes is Marcuvitz, Waveguide Handbook.

Hopefully i will be making some interesting things using this new (to my library) reference.


Thursday, November 11, 2010

Paper posted to IEEE explorer: An Ultrawideband (UWB) Switched-Antenna-Array Radar Imaging System


If you are interested in near-field phased array radar systems one of my papers from the 2010 IEEE Intl. Symposium on Phased Array Sys. & Tech, 'An Ultrawideband (UWB) Switched-Antenna-Array Radar Imaging System,' has been posted here to IEEE Explorer. To view the slides from this conference go here.

(This project is my DIY phased array radar that i built in my garage in grad school.)

Abstract:

Abstract—A low-cost ultrawideband (UWB), 1.926-4.069 GHz, phased array radar system is developed that requires only one exciter and digital receiver that is time-division-multiplexed (TDM) across 8 receive elements and 13 transmit elements, synthesizing a fully populated 2.24 m long (λ/2 element-to- element spacing) linear phased array. A 2.24 m linear phased array with a 3 GHz center frequency would require 44 antenna elements but this system requires only 21 elements and time to acquire bi-static pulses across a subset of element combinations. This radar system beamforms in the near field, where the target scene of interest is located 3-70 m down range. It utilizes digital beamforming, computed using the range migration synthetic aperture radar (SAR) algorithm. The phased array antenna is fed by transmit and receive fan-out switch matrices that are connected to a UWB LFM pulse compressed radar operating in stretch mode. The peak transmit power is 1 mW and the transmitted LFM pulses are long in time duration (2.5-10 ms), requiring the radar to transmit and receive simultaneously. It will be shown through simulation and measurement that the bi-static antenna pairs are nearly equivalent to 44 elements spaced λ/2 across a linear array. This result is due to the fact that the phase center position errors relative to a uniform λ/2 element spacing are negligible. This radar is capable of imaging free-space target scenes made up of objects as small as 15.24 cm tall rods and 3.2 cm tall metal nails at a 0.5 Hz rate. Applications for this radar system include short-range near-real-time imaging of unknown

targets through a lossy dielectric slab and radar cross section (RCS) measurements.


Friday, November 5, 2010

Project completed: Homebrew 20m SSB transceiver is on the air! Here is a demo video, schematics, photos

video

After watching youtube videos of DIY or homebrew amateur radio SSB HF transceivers, and wanting to make one since i was in middle school, i became motivated to design and build this 20m SSB transceiver. I began this project in March of 2010 and have just completed it the first week of Nov 2010.

The radio produces 40 watts PEP transmit power, NF is probably around 1-2 dB, low phase noise VFO and BFO used.

Making a radio is an art form. The looks are old-school using parts recycled from old pieces of test equipment and military surplus. Old equipment labels are on the front (covering up holes from the recycled Autographics computer chassis) warning the user 'Danger High Voltage,' and explaining that this 'modulation tester' was built under FAA contract.


I hope that others use this as a reference for their designs or as motivation to try building a radio, of any kind weather it be a kit or a crystal radio or all-band HF transceiver.

Tuesday, November 2, 2010

Paper has been posted to IEEE explorer: An ultrawideband (UWB) switched-antenna-array radar imaging system




If you are interested in DIY phased array radar, or near-field phased array radar, this paper has been posted to IEEE explorer, enjoy! Among many other things, this paper shows that it is possible to build something technically relevant/advanced on a small budget in your garage in order to prove a concept.

ABSTRACT

A low-cost ultrawideband (UWB), 1.926–4.069 GHz, phased array radar system is developed that requires only one exciter and digital receiver that is time-division-multiplexed (TDM) across 8 receive elements and 13 transmit elements, synthesizing a fully populated 2.24 m long (λ/2 element-to-element spacing) linear phased array. A 2.24 m linear phased array with a 3 GHz center frequency would require 44 antenna elements but this system requires only 21 elements and time to acquire bi-static pulses across a subset of element combinations. This radar system beamforms in the near field, where the target scene of interest is located 3–70 m down range. It utilizes digital beamforming, computed using the range migration synthetic aperture radar (SAR) algorithm. The phased array antenna is fed by transmit and receive fan-out switch matrices that are connected to a UWB LFM pulse compressed radar operating in stretch mode. The peak transmit power is 1 mW and the transmitted LFM pulses are long in time duration (2.5–10 ms), requiring the radar to transmit and receive simultaneously. It will be shown through simulation and measurement that the bi-static antenna pairs are nearly equivalent to 44 elements spaced λ/2 across a linear array. This result is due to the fact that the phase center position errors relative to a uniform λ/2 element spacing are negligible. This radar is capable of imaging free-space target scenes made up of objects as small as 15.24 cm tall rods and 3.2 cm tall metal nails at a 0.5 Hz rate. Applications for this radar system include short-range near-real-time imaging of unknown targets through a lossy dielectric slab and radar cross section (RCS) measurements.