Millimeter-wave Radar Applications Research Articles

Erratum: Fe-doped buffer layer with graded layered AlGaN/GaN HEMT for millimeter-wave radar applications

Erratum: Fe-doped buffer layer with graded layered AlGaN/GaN HEMT for millimeter-wave radar applications

Fe-doped buffer layer with graded layered AlGaN/GaN HEMT for millimeter-wave radar applications

Fe-doped buffer layer with graded layered AlGaN/GaN HEMT for millimeter-wave radar applications

Structural Health Monitoring of Aerospace Structures using Guided Electromagnetic Waves in a Dielectric Waveguide at Ka-Band

Dielectric waveguide (DW) antenna systems are widely used in millimeter-wave radar applications. A large and innovative field is structural health monitoring (SHM) of aerospace structures. The proposed research aims at detecting structural changes and potential defects at Ka-band on metallic structures that represents the device under test (DUT). To determine the severity of damage compared to the pristine structural state, dimensionless damage indicators (DI) are calculated after the root-mean-square deviation (RMSD) and root-mean-square correlation coefficient (RMSCC) methods. The geometric design of the DW is crucial for a barrier-free propagation of guided electromagnetic waves (GEW) of a specific frequency bandwidth inside the dielectric material. In the presented approach, a rectangular DW is designed through numerical modelling which contains a polypropylene matrix, aluminum walls and two K-connectors, each with an inserted pin. The DW is attached to the surface of a nearly plane DUT connected externally to a vector network analyzer (VNA) that measures the elements of the scattering matrix (S-parameters). The reflection and transmission behavior, reflected in the S-parameters, provide information about the interaction of the GEW with a damage. It was found that damage sizes of 2mm can be detected reliably with the proposed methodology. The full paper will present and discuss numerical simulations with CST Microwave Studio with a comparison to experimental measurements.

Design of Microstrip Array Antenna for Vehicle Millimeter Wave Radar

The design and construction of a microstrip array antenna especially intended for vehicle millimeter-wave radar applications in the 77–81 GHz frequency range is presented in this study. This study relies on earlier research on single-patch antennas to provide a full array design that satisfies the demanding performance requirements necessary for sophisticated car radar systems. The study carefully models and analyzes the antenna array using the High-Frequency Structure Simulator (HFSS) to get an azimuth angle of 90° within a 6 dB beamwidth and a pitch angle of 10° ± 1° within a 3 dB beamwidth. Achieving a gain of more than 13 dBi, keeping sidelobe levels below −15 dB, and guaranteeing isolation of more than 35 dB are all priorities in the design process. Precision and interference avoidance are crucial in high-resolution, short-range radar systems, and these factors are essential to the antenna’s operation. The array’s small form factor, along with factors like easy integration and economical production, make it an excellent choice for contemporary automobile radar applications. The research addresses the wider ramifications of this technology in vehicle safety and navigation in addition to diving into the technical issues of antenna design, such as the optimization of element spacing, array layout, and material selection. By exploring the limits of high-frequency antenna performance, this work advances the fields of autonomous cars and wireless communication technologies. The designed antenna array architecture is very adaptable, as shown by its possible applications ranging from point-to-point transmission and satellite communication to vehicle radar systems. The goal of this effort is to improve the capabilities of vehicle radar systems, which will lead to safer and more effective autonomous navigation solutions.

A Method for Low Sidelobe Substrate-Integrated Waveguide Slot Antenna Design Applied for Millimeter-Wave Radars

With the development of millimeter-wave radar systems, substrate-integrated waveguide (SIW) slot antennas have been widely used. This paper presents a computational approach for calculating the equivalent normalized admittance of slot in low sidelobe SIW longitudinal slot antennas. In contrast to the existing methods, this method takes into account the impact of the N-slots coupling on the admittance. Through this method, fitting functions for resonant length and conductance are obtained, which describe the relationship between the resonant length, resonant conductance, and offset of slots. Moreover, based on the two fitting functions, a low sidelobe SIW longitudinal slot linear antenna is designed for millimeter-wave radar applications at 77 GHz. This antenna consists of a transition from the standard WR-12 waveguide to the SIW and a set of radiating slots. The simulation results indicate an impedance bandwidth of 4.8% and a gain of 13.2 dBi. The sidelobe level in the H-plane is below −28 dB, which meets the desired specifications and confirms the accuracy of the presented method.

Compact Wearable Antenna with Metasurface for Millimeter-Wave Radar Applications.

Three metasurfaces (MTS) are designed to be combined with a series end-fed 1 × 10 array antenna with a modified Dolph-Chebyshev distribution for imaging applications in the millimeter frequency range, 24.05-24.25 GHz. A reduction in secondary lobes and an increase in FTBR can be achieved while preserving gain, radiation efficiency, SLL and size using an MTS-array combination. Moreover, as a result of each single-layer MTS-array combination, operation bandwidth is widened, with gain and radiation efficiency enhancement. The overall devices' size is 86.8 × 12 × 0.762 mm3. The envisioned application is collision avoidance in aid to visually impaired people at a medium-long distance.

A 27–35 GHz wideband PIN-diode limiter low noise amplifier MMIC with sub-2.4 dB noise figure

In this paper, a thorough co-design procedure for the integrated PIN-diode limiter and low noise amplifier (LNA) is presented. A 27 GHz–35 GHz wideband integrated limiter low noise amplifier (limiter-LNA) is fabricated with the combined PIN/0.15-μm-pHEMT technology for millimeter-wave radar applications. The PIN-diode limiter and the LNA are co-designed to improve the small signal performance. To improve the noise performance and the input-matching of the limiter-LNA, a novel limiter design method with the modified lossy TL model is presented. The measurement results illustrate that the small-signal gain is 20 ± 0.7 dB, the noise figure (NF) is 1.9 dB–2.4 dB, the output power at 1 dB compression point (OP1dB) is larger than 12.1 dBm and the dc power consumption is only 96-mW. The limiter-LNA is capable of handling 38 dBm continuous wave (CW) input-power without failure. The chip area including testing pads is 2.3 mm × 1.0 mm.

A Pillbox Based Dual Circularly-Polarized Millimeter-Wave Multi-Beam Antenna for Future Vehicular Radar Applications

In this paper, a dual circularly-polarized (CP) multi-beam antenna is proposed for future vehicular radar applications. The antenna is composed of two pillbox reflector beamforming networks (BFNs) and a series-fed microstrip line based dual CP leaky-wave antenna (LWA) array, which has a symmetrical structure and can obtain both left hand circular polarization (LHCP) and right hand circular polarization (RHCP) by switching the exciting current direction of the microstrip line. Besides, a shorted stub is loaded in the LWA to suppress the open-stop band (OSB), and thus achieve the broadside radiation and good impedance matching of the LWA. To realize the dual-polarized radiation characteristic with low-cost passive beam scanning capability, two pillbox BFNs are connected at both sides of the LWA to share the LWA aperture. The two different BFNs can excite different CP radiation patterns. A prototype of the proposed antenna is fabricated in the frequency band 23.5–24.5 GHz, and the measured results approve that the proposed antenna can realize ±36° beam scanning range with −4.0 dB crossover level, and the gain is higher than 17.7 dBi in the operating band. The advantages of the proposed antenna, including low-profile, low-cost, passive beam scanning ability, and dual circular polarization, make it an attractive choice for low-cost millimeter-wave radar applications.

Circularly Polarized Periodic Leaky-Wave Antenna Based on Dielectric Image Line for Millimeter-Wave Radar Applications

In this letter, a novel design of a circularly polarized dielectric image line (DIL) based periodic leaky-wave antenna (P-LWA) is presented, which is comprised of only dielectric radiation discontinuities, side gratings, and inclined slots. The unit cell of the proposed design is first optimized with a full-wave eigenmode simulator for the center frequency of 79 GHz. Later, a total of 10 unit cells are cascaded to form the DIL P-LWA, which is connected to an in-plane dielectric transition to feed the antenna from a standard WR12 waveguide. Full-wave simulation and experimental results are provided to verify the functionality of the proposed design in the frequency range 75-85 GHz, where the measured main beam is scanned from -10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> to 8 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> with an axial ratio below 4.2 dB. The simulated gain in the same range varies from 11.2 to 12.7 dBi. The proposed design can be a suitable candidate for millimeter-wave radar applications.

Multi‐beam SIW leaky‐wave antenna with 2‐D beam scanning capability for millimeter‐wave radar applications

In this article, a multi-beam substrate integrated waveguide (SIW) leaky-wave antenna (LWA) is proposed for millimeter-wave radar applications, which owns the advantages of 2-D scanning capability, high gain, low profile, and single layer configuration. The proposed antenna consists of a beam-forming network (BFN) based on a 2-D SIW parabolic reflector with eight waveguide feedings, and a 16-element LWA array. The open-stopband of the LWA is suppressed by employing a longitudinal slot into a conventional transverse slot LWA unit. In the E-plane, the BFN can generate eight desired distributions of the amplitude and the phase gradients which steers beam from −17.3° to 30.8° with the crossover level higher than −5.22 dB. In the H-plane, the frequency scanning LWA array can offer a continuous beam scanning range from −23° to 19° with operating frequency from 21 to 29 GHz. Finally, the antenna is prototyped and experimentally verified. The measured results are in accord with the simulated ones. The characteristics of the proposed antenna make it a very promising solution for applications in low-cost millimeter-wave radar systems.