Co-array-based Synthetic Aperture Active Imaging at Millimetre Wave Frequencies

ABSTRACT

Imaging technique based on aperture synthesis scheme using sub-arrays and post data acquisition beam forming at the millimetre wave frequencies is investigated theoretically and experimentally. Technique has been extended for use in three-dimensional imaging and multiple target scenario. Simulation results verifying the proposed technique are presented. This approach can be used to construct three-dimensional images using separate transmitting and receiving arrays. A program based on this imaging technique has been written in MATLAB to simulate the target scene and to investigate reconstruction of the image theoretically and with the data collected experimentally. Experimental verification has been done using horn antennas as transmitting and receiving apertures having 10° beam width and 24 dB gain at 30 GHz. Precise positioning of transmitting and receiving antennas is one of the critical requirements at millimetre frequencies. A practical system designed to work on this technique, would necessarily require precise fabrication and positioning especially at higher millimetre wave bands as the whole process is phase sensitive. But, the preliminary results show that the method has good active imaging performance indicating potential applications of this technique in the future at higher millimetre wave frequencies.

KEYWORDS:

• Active imaging
• aperture synthetic
• co-array-based imaging
• GHz frequencies
• Ka-band
• millimetre wave image

Acknowledgements

The authors are thankful to R. C. Agarwal, Director, Defence Electronics Applications Laboratory, Dehradun (Uttarakhand), India for granting permission to publish this paper and to use lab facilities for experimental verification of the method. The authors would also like to acknowledge the help efforts provided by Rajesh Roy of DEAL, Dehradun, in conducting the experimentation work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

R. P. Dixit

R. P. Dixit received the post graduate degree in physics from Garhwal University in 1978. He joined DRDO in 1981 at DRDL, Hyderabad. He worked on design and development of active and passive microwave and millimetre wave components, slotted array antennas, and printed antennas for missiles. In 1985, he joined Millimetre Wave Group at DEAL, Dehradun. He has been engaged in design and development of various components and systems at millimetre wave frequencies. He has designed and developed various transceivers. Presently, he is engaged in the development of transceivers using MIC/MMIC technology. He has contributed more than 50 technical papers in National/International conferences and journals. His present interests include active and passive MM wave sensors.

E-mail: [email protected]

Kiran Sharma

Kiran Sharma received the post graduate degree in physics from H.N.B. Garhwal University, Srinagar, Uttarakhand in 2004. She received the PhD degree in physics from H.N.B. Garhwal University in 2011. The title of her thesis was “Theoretical Study and Modelling of Electrical Characteristics of Polycrystalline Silicon Novel Devices TFTs, MOSFETs, & Solar Cells”. She has 10 years teaching experience at Graphic Era University, Dehradun. She is the head of department, Department of Physics, Graphic Era University, Dehradun. Her present interests include semiconductor device modelling (polycrystalline silicon solar cells, TFTs, MOSFETs, and nano crystalline silicon TFT) thin-film technology. She has been guiding four research scholars at Graphic Era University.

E-mail: [email protected]

S. C. Jain

S. C. Jain, after completing the MSc degree in physics, joined Defence Electronics Applications Laboratory, DRDO, in 1969. He has worked in various projects, such as troposcatter communication systems, multispectral scanner, image processing using phase conjugation techniques, correlator using joint transform correlation techniques and image processing software development. During 1985–1986, he was awarded Indo US Fellowship. He has been a visiting scholar to the University of Alabama, USA. He received the PhD degree in 1989. He has more than 95 publications in the journals of repute and conferences. He has been a group director, Image Analysis Centre. He has guided a thesis on automatic registration technique and guiding research work in MMW imaging.

E-mail: [email protected]