The direction of arrival (DOA) estimation problem is formulated in a compressive sensing (CS) framework, and an extended array aperture is presented to increase the number of degrees of freedom of the array. The ordinary least square adaptable least absolute shrinkage and selection operator (OLS A-LASSO) is applied for the first time for DOA estimation. Furthermore, a new LASSO algorithm, the minimum variance distortionless response (MVDR) A-LASSO, which solves the DOA problem in the CS framework, is presented. The proposed algorithm does not depend on the singular value decomposition nor on the orthogonality of the signal and the noise subspaces. Hence, the DOA estimation can be done without a priori knowledge of the number of sources. The proposed algorithm can estimate up to $((M^2-2)/2+M-1)/2$ sources using M sensors without any constraints or assumptions about the nature of the signal sources. Furthermore, the proposed algorithm exhibits performance that is superior compared to that of the classical DOA estimation methods, especially for low signal to noise ratios (SNR), spatially-closed sources and coherent scenarios.

In this article, three novel slotted substrate integrated waveguide (SIW) antenna elements are demonstrated with different radiator configurations, namely, two arms Archimedean antenna, single‐arm spiral antenna (monofilar), and four concentric circular loops antenna. Additionally, their near, as well as far‐field characteristics, have been investigated. The two arms Archimedean spiral antenna has a superior radiation characteristic of 18% return loss bandwidth (RLBW), 12% boresight axial ratio bandwidth (ARBW), and five dBi directivity. Furthermore, a 1 × 10 slotted SIW travelling wave antenna array has been designed, fabricated, and measured. The performance of the proposed antenna array versus the last reported antenna was evaluated and the proposed antenna array performance is superior to that of the others. Moreover, the measurements of the proposed array have a good agreement with the simulation results in which, 35%, 13% RLBW, and ARBW, respectively, have been achieved. The directivity of the proposed antenna array is 14 dBi.

This paper presents an enhanced approach to projectile path estimation using Frequency-Modulated Continuous Wave (FMCW) radar sensors distributed across multiple vehicles in a tactical formation. Building upon established FMCW radar signal processing techniques, we implement and analyze a multi-sensor approach that significantly improves the accuracy of key path parameters: pass range, pass time, and velocity. Through detailed simulation, we demonstrate that a four-vehicle formation achieves approximately 75% error reduction across all parameters compared to single-vehicle sensing. This improvement directly enhances the performance of active protection systems for military vehicles by enabling more precise threat assessment and countermeasure deployment. Our results validate theoretical predictions that triangulation from multiple sensing positions provides more robust parameter estimation, particularly for projectiles with linear trajectories. The methods described can be implemented with existing FMCW radar technology and standard data fusion algorithms, making this approach practical for near-term deployment.

In this paper, a novel wide axial ratio bandwidth (ARBW), high gain, and low profile lefthand circularly polarized [4 × 4] elliptical microstrip array suitable for Ku-band satellite TV reception applications is introduced. A careful study has been done to get the optimum design to be suited for these application requirements. A circularly polarized microstrip patch with two stubs opposite to each other to produce two orthogonal modes is presented. The proposed element has 1.49 GHz 10-dB return loss bandwidth (RLBW), 0.44 GHz 3-dB Axial-ratio band (ARBW), and 6.9 dBi gain. A novel substrate integrated waveguide (SIW) feeding structure is investigated. Using the advantage of the output ports phase response of the SIW feeding network, two structures have been investigated. First, a [2 × 2] circular array has been designed, and although it has reached a good RLBW, this structure does not achieve the required ARBW for the above-mentioned application. Further, a compact [2 × 2] sequential feeding network is designed to widen the ARBW. The measurement shows a very good result with about 12 dBi gain, 14.8% RLBW, and 12% ARBW. Finally, a [4 × 4] duple sequential feeding array is designed to increase the gain of the antenna to about 19 dBi, with 13% RLBW and 20.7% ARBW. In addition to that, the final antenna profile is 0.0184λ.