Abstract
Collision avoidance and autonomous control of vehicles have become essential needs for providing a high-quality and safe life. This paper introduces a new generic scheme for a virtual antenna array (VAA) and its application in a train collision-avoidance system (TCAS). The proposed TCAS shall have the capability of identifying the range and angle of an object in front of a moving train and provide the required alerts. Thereby, a new virtual array distribution for both the transmitting and the receiving antenna arrays is introduced to get a long-range object detection and high-resolution multi-input multi-output (MIMO) system. This can be accomplished because the VAA radiation pattern is the multiplication of the radiation patterns for both the transmitting and receiving antenna arrays, which is different than each one of them alone. In this work, the VAA is utilized in radar systems in which the radar range depends on the multiplication of the gain of the transmitting and receiving antennas. So, we introduce a new scheme for the general design of VAA-based radars. A prototype for the antenna system was fixed on a of Texas Instruments platform for the cascading radar. One of the main problems of the VAA is the loss of radiated power in undesired directions, which affects the maximum detection range in beamforming systems and degrades the diversity gain in MIMO applications. These issues have been solved by the introduction of the practical implementation of a proposed high-gain, low side lobe level VAA system for automotive radar that is based on the integration of four AWR1243 RF chips operating in a frequency range of 76 GHz to 81 GHz. It was implemented using low-power 45 nm (TI) RFCMOS technology. The measured gain of the realized VAA was 47.2 dBi, which was 1.815 times higher than that of the Texas instrumentation linear frequency modulated continuous wave (TI’ LFMCW) radar, which was 26 dBi. The proposed VAA saved 45% of the required implementation area compared to the TI’ LFMCW antenna array. The VAA system was fabricated and tested in an anechoic chamber, and it was found that the simulated and measured patterns of the proposed VAA were highly matched in terms of half-power beamwidth and side lobe level.
Highlights
Radars and multi-input multi-output (MIMO) radars have been extensively used as contactless sensors in critical applications such as vital-sign detection and human localization [1], imaging systems [2], and static and dynamic monitoring of bridges [3].In [1], the authors introduced an extensive review of the utilization of MIMO radars in biomedical applications, such as monitoring the health conditions of humans and detecting their presence in different environments
virtual antenna array (VAA) Analysis have the same side lobe levels (SLLs), the SLL of the resulting pattern is the square of the Taking the proposed general scenario shown in Figure 2, where the receiver antenna individual SLL value, which can be calculated as twice the negative value of the individual array is made of P subarrays, each consisting of an M-elements uniform linear array
Configurations that took into consideration the available area, number of transmitters, and configurations that took into consideration the available area, number of transmitters, and number of receivers
Summary
Radars and multi-input multi-output (MIMO) radars have been extensively used as contactless sensors in critical applications such as vital-sign detection and human localization [1], imaging systems [2], and static and dynamic monitoring of bridges [3]. In [7], a virtual array beamforming (VAB) technique for generating simultaneous multiple transmit/receive beams at different directions was introduced In this technique, each antenna element from the utilized L-elements linear antenna array transmits a distinct orthogonal waveform. In [22], a novel VAA synthesis technique based on the method of moments (MoM) and the genetic algorithm (GA) was introduced for the synthesis of planar antenna arrays (PAAs) in radar systems This technique mimicked PAAs by using two orthogonal linear antenna arrays (LAAs) whose excitation coefficients were optimized to achieve a pattern highly matched to that of the desired PAA.
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