Waveform Design for 4D-Imaging mmWave PMCW MIMO Radars with Spectrum Compatibility

peer reviewed4D-imaging mmWave radars offer high angular resolution in both azimuth and elevation, but achieving this requires a large antenna aperture size and a significant number of transmit and/or receive channels. This presents a challenge for designing transmit waveforms that must be separable on the receive side and have low auto-correlation sidelobes. This paper focuses on designing an orthogonal set of sequences for 4D-imaging radar sensors based on PMCW technology. We propose a Coordinate Descent-based iterative optimization framework that optimizes a set of phase-modulated constant modulus waveforms based on weighted integrated sidelobe levels on the required region of interest. The optimization also incorporates the radar’s proximity to other radar sensors and communication systems by spectrum shaping. The efficiency of the suggested strategy, which achieves low sidelobe levels and is compatible with spectrum limits, is shown through simulation results

A Novel Method Describing the Space Charge Limited Region in a Planar Diode

A novel and rather simple method is presented to describe the physics of space-charge region in a planar diode. The method deals with the issue in the time domain and as a consequence transient time behavior can be achieved. Potential distributions and currents obtained using this technique, supposing zero initial velocity for electrons, reveal absolute agreement with Child's results. Moreover, applying the method for non-zero uniform initial velocity for electrons, gives results which are in good agreement with previous work

Precise Calculation of Electrical Capacitance by means of Quadruple Integrals in Method of Moments Technique

In this paper, the capacitance of a parallel plate air-gap rectangular capacitor, and a unit cube capacitor have been calculated. Because of its generality and simplicity, the method of moments (MOM) Technique is utilized. In order to improve the accuracy of the calculations, the use of quadratic integrals instead of binary integrals has been proposed. A neat form is provided for the analytical solution of the integrals required for the method of moment. The results show that there is a very small error in calculating the capacity even with coarse boundary division. The described formulas and codes can easily be used for similar purposes

MIMO Virtual Array Design for mmWave 4D-Imaging Radar Sensors

peer reviewedThe recently developed 4D-Imaging mmWave MIMO radars have significant advantages over conventional radar sensors because they offer a large virtual array in both azimuth and elevation. However, the physical placement of transmit and receive antennas to achieve the desired virtual array, while considering cost and efficiency is not intuitive. In this paper, we propose an optimization framework for optimally placing the transmit and receive array physical elements. The proposed framework obtains a sequence of optimal placements based on the coordinate descent by defining a desired virtual array and number of transmit and receive antenna elements as the objective. The objective function is then monotonically minimized in each iteration of the proposed algorithm, converging to a solution that guarantees the desired number of transmit and receive antenna elements, while the obtained virtual array is as close to the desired virtual array as possible. The simulation results are validated by simulating the virtual array of multiple commercially available 4D-Imaging radar products

Waveform Selection for FMCW and PMCW 4D-Imaging Automotive Radar Sensors

peer reviewedThe emerging 4D-imaging automotive MIMO radar sensors necessitate the selection of appropriate transmit wave-forms, which should be separable on the receive side in addition to having low auto-correlation sidelobes. TDM, FDM, DDM, and inter-chirp CDM approaches have traditionally been proposed for FMCW radar sensors to ensure the orthogonality of the transmit signals. However, as the number of transmit antennas increases, each of the aforementioned approaches suffers from some drawbacks, which are described in this paper. PMCW radars, on the other hand, can be considered to be more costly to implement, have been proposed to provide better performance and allow for the use of waveform optimization techniques. In this context, we use a block gradient descent approach to design a waveform set for MIMO-PMCW that is optimized based on weighted integrated sidelobe level in this paper, and we show that the proposed waveform outperforms conventional MIMO-FMCW approaches by performing comparative simulations