Israel Hinostroza

Around-the-corner radar: Detection and localization of a target in non-line of sight

This paper examines the problem of detecting and locating an NLOS target in an urban environment by exploiting multipath radar returns. We propose a detection-localization algorithm based on a matched subspace filter approach that works in the target state space directly. A real experimentation was carried out to show that a portable radar can provide images of multipath returns in NLOS cases that can be clearly interpreted thanks to a simple ray tracing model. The application of the detection-localization algorithm on experimental radar measurements shows that the target can be detected and located but that the mitigation of strong ambiguities inherent to the multipath detection-localization problem remains a challenging problem for the application at hand.

Concentric ring array of connecting spirals with WAVES

A dual circularly polarized wideband array working over a 2:1 bandwidth was previously developed. This array had the following requirements: 2:1 bandwidth, capable of steering up to 30° in theta, dual circular polarization, Relative Sidelobe Level (RSLL) < −10dB, Axial Ratio (AR) < 3dB and reflection coefficient (S11) < −10dB. In this paper, we extend the array bandwidth to 15:1 through adding connections between the arms of neighboring spirals to improve the S11 at lower frequencies and using the WAVES (Wideband Array with Variable Element Size) technique to reduce the RSLL at higher frequencies.

State estimation of an octorotor with unknown inputs. Application to radar imaging

This paper focuses on the design of a linear Kalman filter and an extended Kalman filter for the estimation of an octorotor unmanned aerial vehicles (UAV) state in the context of Synthetic Aperture Radar image reconstruction. A comparison to a linear interpolation method is also proposed. The Kalman filters are developed based on a complete nonlinear model of the UAV and its linearized form. A particularity of the considered platform is that the control signals are not measured and have to be estimated as well as the UAVs state. The proposed techniques are then tested on a UAV simulator and a radar imaging simulator.

Phase error analysis of a dual polarized concentric ring array

In a previous work a dual-polarized non-uniform concentric ring array of spirals has been developed. This array used the sequential rotation technique as a means to enhance the arrays axial ratio and the non-uniform concentric rings to reduce the relative side lobe level. In the present paper the effects of realizing the phases of the sequential rotation using digital phase shifters are analyzed, considering both the phase-quantization and the phase-error effects in the broadside radiation of the array. We show that by considering a 2-bit phase shifter with a centered Gaussian error (sigma=5°) in each element of the array the axial ratio is kept under 1dB over the whole bandwidth, with a maximal degradation of 0.85dB when compared with the array without phase-errors or phase-quantization. We also show that the side lobe level suffers a maximal degradation of 4dB for the 2-bit phase shifter, however it is not affected by the phase error.

Optimizing communication in TMA for radar

A Time Modulated Array (TMA) based technique is used to simultaneously do a radar function in the main lobe and a communication function in the side lobes. It uses an averaging to do the radar function, while the communication is done with the variation from an intermediary pattern to another. An optimization of the secondary function (communication) is carried out. The QAM communication is optimized for the case of STMA.

Large bandwidth analysis in multifunction antenna for radar and communication applications

Large bandwidth analysis of the communication function for a single antenna system providing simultaneously radar and communication functions is studied. The system is composed of a slotted waveguide (for the communication function) feeding a horn antenna (for the radar function) so as to assign to each function different polarizations. Additionally, by switching between two slot arrays on the waveguide, a BPSK communication is achieved independently of the horn radiation.

Low frequency bandwidth in connected spiral arrays

Connecting the arms of spirals in a dual circularly-polarized array significantly increases the array bandwidth. The connections decreased the low frequency cutoff from 1 GHz (without connections) to 350 MHz of the original array without connections (1 GHz). In this paper, an analysis at even lower frequencies is carried out revealing that the array is still useful at the original low frequency cutoff divided by 10 (100 MHz).