Low-cost digital beamforming based radar systems

• Main Author: Tang, Yue.
• Other Authors: Lu Yilong
• Format: Theses and Dissertations
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: http://hdl.handle.net/10356/55331
• Institution: Nanyang Technological University

There are fast-growing demands for radar systems based on smart antennas in civilian applications such as automotive radar, homeland security, corporate security, environmental remote sensing, and etc. Smart antenna systems are based on digital beamforming (DBF) technologies which are too expensive with conventional implementation for cost sensitive civilian applications. This thesis presents a comprehensive study of low-cost digital beamforming (DBF) radar technology with four contributions. The first contribution is a switched DBF radar system with single receiver for low-cost DBF radar applications. The proposed DBF radar system concept could reduce the number of microwave digital receivers from N to 1 (where N is the number of array elements), greatly reducing system cost, complexity, weight, and power consumption. The second contribution is based on the combination of the earlier proposed switched DBF radar system concept and an innovative application of multiple-input multiple-output (MIMO) technology. The proposed time division multiplexing (TDM) MIMO DBF radar system is based on linear MIMO arrays (M+N antenna elements) and a single transceiver (one transmitter and one receiver). Compared to a conventional MIMO DBF radar system, the proposed concept can reduce the number of transmitter/receivers from M+N to 2, giving a drastic cost reduction. With this concept, two desirable benefits can be achieved, namely drastic reduction of heavy usage of microwave digital components in a MIMO radar system and the considerable expansion of antenna effective aperture beyond its physical size. The third contribution extends the 1-dimensional MIMO DBF radar concept with fan beamforming to the 2-dimentional cross array with pencil beamforming. The proposed MIMO cross array consists of 4 transmitting elements and M+N receiving elements with pencil beamforming with equivalent beamwidth that could be achieved by much larger aperture (up to 4 times) and much more antenna elements (2M2N) by a traditional rectangular planar array. Another contribution is the multi-resolution composite array (MRCA) based on DBF technology for detection of multiple targets with close angular separation. For these scenarios or applications, the whole space could be divided to high signal density targets sector and low signal density background sectors, narrow and wide beamforms are used respectively in different sectors. Compared to conventional single-resolution DBF arrays and multiplicative arrays, the proposed MRCA could obtain the same angular resolution with much less antenna elements. Over all, four kinds of approaches for low-cost DBF systems are proposed. First two contributions are based on reducing the numbers of transmitters and receivers while last two contributions are mainly based on reducing antenna array elements. For all the four new concepts, extensive realistic computer simulation studies are conducted. Demonstrators of the first two concepts (namely, switched DBF radar and TDM MIMO DBF radar) are realized and theoretical analyses are verified experimentally.