International Journal of Microwave and Wireless Technologies最新文献

This paper details the design and development of a planar switched beam network using 4 × 4 Butler matrix (BM) over a thin and flexible type biocompatible substrate. Four mils thick liquid crystal polymer (LCP) is used as a substrate here (ϵr = 2.92, tanδ = 0.002). The proposed design is centered at 28 GHz, targeting commercial millimeter-wave applications. Floral-shaped antenna with defective ground structures has been implemented as basic radiating elements. The whole structure is based on microstrip line configuration. The architecture occupies an area of 23.85 × 19.20 mm2 over the LCP substrate. Individual components of the BM are detailed here, followed by a system analysis of the whole integrated structure. The present work also covers the electrical equivalent circuit modeling of the whole beam-forming network. The fabricated prototype offers better than 18 dB return losses at each input port for the desired frequency band with 6 dBi (max.) peak gain and 500 MHz bandwidth around the center frequency. Port-to-port isolation of better than 15 dB is achieved with this topology. Experimental and simulated results are in good agreement in all aspects. A comparative study is also chalked out to highlight the significance of the current research work with respect to alike earlier reported structures.

This paper presents a methodology designed to leverage multitemporal sequences of synthetic aperture radar (SAR) and multispectral data and automatically extract urban changes. The approach compares results using different radar and optical sensors, describing the advantages and drawbacks of using SAR data from the COnstellation of small Satellites for the Mediterranean basin Observation (COSMO)/SkyMed, SAtélite Argentino de Observación COn Microondas (SAOCOM), and Sentinel-1 constellations, as well as nighttime light data or Sentinel-2 images. Multiple indexes obtained from multispectral data are compared, too, and results obtained by an unsupervised clustering procedure are analyzed. The results show that using different datasets it is possible to obtain consistent results about different types of changes in urban areas (e.g., demolition, development, and densification) with different levels of spatial details.

The electromagnetic scattering problem over a wide incident angle can be rapidly solved by introducing the compressive sensing theory into the method of moments, whose main computational complexity is comprised of two parts: a few calculations of matrix equations and the recovery of original induced currents. To further improve the method, a novel construction scheme of measurement matrix is proposed in this paper. With the help of the measurement matrix, one can obtain a sparse sensing matrix, and consequently the computational cost for recovery can be reduced by at least half. The scheme is described in detail, and the analysis of computational complexity and numerical experiments are provided to demonstrate the effectiveness.

A system-in-package for a wideband digital radar, in D-band, requires broadband, high-gain antennas combined with broadband chip-to-package and package-to-printed circuit board (PCB) interconnects. This paper demonstrates a wideband, low-loss quasi-coaxial signal transition, and a novel electric split ring resonator (eSRR)-based antenna-in-package (AiP) with a modified reflector concept, for improved gain, in embedded wafer level ball grid array (eWLB) technology. A complete chip-to-package-to-PCB interconnect is also demonstrated by combining the quasi-coaxial transition with a chip-to-package interconnect. The quasi-coaxial signal transition has the largest impedance bandwidth among ball grid array-based quasi-coaxial signal transitions. For the modified reflector concept, a horn-shaped cavity is micromachined in the PCB substrate and remetallized with aerosol-jet printing, placing the reflector 0.25λ from the antenna. The antenna gain is improved with up to 5.3 dB. The AiP with the horn-shaped reflector is the single element with the highest gain, in eWLB technology, above 100 GHz.

In this paper, we introduce a compact 6 × 8 channel multiple-input multiple-output frequency-modulated continuous-wave radar system capable of determining the three-dimensional positions of targets despite utilizing a linear virtual array. The compact system, containing two cascaded radar transceiver ICs, has 48 virtual channels. We conduct a direction of arrival estimation with these virtual channels to determine the azimuth angle. To overcome the spatial limitation of the linear array, we use frequency-steered transmit antennas, which vary their main lobe direction during the frequency chirp, allowing the elevation angle to be determined by using a sliding window fast Fourier transform algorithm. In this study, we present the system’s concept along with the associated signal processing. By taking measurements in different scenarios, each with differently placed corner reflectors, we investigate the capability of the system to separate adjacent targets concerning range, azimuth, and elevation. These measurements are additionally employed to point out the design trade-offs inherent to the system.