Radar Applications Research Articles

Application of a Ground-Penetrating Radar in the Characterization of the Archaeological Environment of Site GO-JA-02, Serranópolis-GO: A Non-Invasive Approach for Archaeological Excavation Planning

Application of a Ground-Penetrating Radar in the Characterization of the Archaeological Environment of Site GO-JA-02, Serranópolis-GO: A Non-Invasive Approach for Archaeological Excavation Planning

Multi-band reconfigurable microwave photonic transceiver towards high-performance integrated radar.

As an effective approach to overcome the electronic bottlenecks of conventional electrical radars, microwave photonic radars have demonstrated significant superiority in their perception and recognition capabilities. However, trade-offs exist among the reconfigurability, signal time-bandwidth product (TBWP), linearity, and phase coherence of current photonic radars, which ultimately weaken the overall performance. To address these challenges, a photonic transceiver based on electrically assisted synchronized lasers is proposed and demonstrated, which combines high resolution and multi-band reconfigurability. Optical coherent heterodyne linear frequency-modulated (LFM) radar signal generation and photonic dechirping reception are implemented through the synchronized lasers at the transmitter and receiver, respectively. In a proof-of-concept experiment, reconfigurable LFM signals covering the L- to Ka-band with improved linearity and phase coherence are generated. Furthermore, the proposed photonic transceiver operates in the Ka-band with an ultra-large signal TBWP of 4 × 106, enabling high-resolution ranging and inverse synthetic aperture radar (ISAR) imaging. A range resolution of 1.92 cm and an imaging resolution of 1.92 cm × 1.89 cm are obtained, which require a receiver sampling rate of only 5 MSa/s. Featuring a simple structure, flexible reconfiguration, and integration compatibility, the demonstrated photonic transceiver opens new opportunities for next-generation miniaturized radar application scenarios.

520 μJ Microsecond Burst-Mode Pulse Fiber Amplifier with GHz-Tunable Intra-Burst Pulse and Flat-Top Envelope

We present a 520 μJ microsecond burst-mode pulse fiber amplifier with a GHz-tunable intra-burst repetition rate and a nearly flat-top pulse envelope. The amplifier architecture comprises a microsecond pulse seed, a high-bandwidth electro-optic modulator (EOM), two pre-amplifier stages, a waveform-compensated acoustic-optic modulator (AOM), and two main amplifier stages. To address amplified spontaneous emission (ASE) and nonlinear effects, a multistage synchronous pumping scheme that achieved a maximum energy output of 520 μJ and has a peak power of 160 W was used. To produce a flat-topped burst pulse envelope, the AOM generates an editable waveform with a leading edge and a high trailing edge to compensate for waveform distortion, resulting in a 5 μs nearly flat-top pulse envelope at maximum energy. The laser provides an adjustable intra-burst pulse repetition rate range of 1–5 GHz through the high-bandwidth EOM modulation. The intra-burst pulse jitter time of the laser remains below 4.31 ps at different frequencies. Moreover, the beam quality of the amplifier is M2x = 1.04 and M2y = 1.1. This amplifier exhibits promising potential and can be further amplified as an optical drive source for high-power, large-bandwidth microwave photon (MWP) radar applications. Meanwhile, it is also potentially applicable as a pulse source for high-speed optical communications, the high-precision processing of special materials, and LIDAR ranging.

Advanced Scattering Analysis of Targets Under Plane Waves and Electromagnetic Vortex Waves for Stealth Applications

This study investigates the scattering characteristics of typical metallic targets under the influence of electromagnetic vortex waves, with a focus on Radar Cross Section (RCS) and Orbital Angular Momentum Radar Cross Section (ORCS). Using the physical optics approximation, the induced current density on the target surface was calculated, and the backscattered field was derived. The comparative analysis highlights the advantages of electromagnetic vortex waves over plane waves in stealth applications, with an in-depth examination of the impact of different OAM modes on power distribution and flat plate scattering characteristics. The unique properties of electromagnetic vortex waves show promising applications in stealth radar and target detection. Furthermore, the study discusses the potential for using OAM waves in enhancing radar system performance, target identification, and electronic countermeasures. The ability of OAM waves to provide selective detection capabilities and reduce RCS under certain conditions makes them particularly valuable for military stealth applications. The combination of MIMO technology with OAM waves is also explored as a means to further improve detection capabilities and flexibility. The findings suggest that electromagnetic vortex waves have a broad range of applications beyond stealth, including radar sensing, imaging, and rotational Doppler detection, thereby opening new avenues for advanced radar technologies

Identification and High-Accuracy Range Estimation with Doppler Tags in Radar Applications

Identification and High-Accuracy Range Estimation with Doppler Tags in Radar Applications

Beam Shaping by Phase-Only Waveform Encoding for Transmitting Array Antennas in Radar Applications

Beam Shaping by Phase-Only Waveform Encoding for Transmitting Array Antennas in Radar Applications

A combined aperture‐coupled membrane microstrip patch antenna array

AbstractA novel lightweight L‐band combined aperture‐coupled microstrip antenna has been proposed for synthetic aperture radar (SAR) applications. The proposed antenna element is composed of only two membranes. This design innovatively integrates the coupling aperture with the radiating patch, significantly reducing the number of required dielectric layers to achieve a simplified and lightweight structure. The feed line is placed on the front side to facilitate integration with the transmit/receive (T/R) module. Simulation results demonstrate that the antenna element exhibits excellent radiation pattern performance and bandwidth. A passive antenna array utilising polyimide as the dielectric material was fabricated and measured to validate its performance. This array employs a 4‐stage Wilkinson power divider network. Measurements show that S1,1 is below −15 dB in the frequency range from 1.15 to 1.49 GHz, with a maximum efficiency of 72.87%. Additionally, an phased array antenna was fabricated and tested. This array demonstrated stable radiation pattern performance over an azimuthal scan range of and an elevation scan of . This design offers a new option for antenna modules in spaceborne SAR applications.

Stepped-Frequency PMCW Waveforms for Automotive Radar Applications

Stepped-Frequency PMCW Waveforms for Automotive Radar Applications

An 8–18 GHz ultrawideband gap waveguide folded bandpass filter for radar applications

An 8–18 GHz ultrawideband gap waveguide folded bandpass filter for radar applications

Applicability of Ground Penetrating Radar for Soil Profile Studies – An Investigation in Piedmont Plain in Parts of Saharanpur District, Uttar Pradesh

Soil profile studies especially identification of different soil layers is a vital component in soil survey. The present study was undertaken to assess the applicability of ground penetrating radar (GPR), a widely adopted geophysical technique and instrument for soil profile studies under different landforms (piedmont and alluvial plain) located in the Indo-Gangetic Plain region in Saharanpur district of Uttar Pradesh. GPR survey was conducted using dual frequency antennas (200 and 600 Mhz) at specific locations corresponding to landforms of piedmont and alluvial plain along transect. The radargrams generated by standard processing of ground scan data showed widely varying patterns in both the landforms, corresponding to the variations in soil layer distribution. From the radargrams generated, a clear distinction could be made between the soils of piedmont as well as alluvial plain. The radargram of alluvial plain showed very smooth transition between soil layers whereas in case of piedmont plain, the profile appears to be discontinuous as well as irregular. The soils of alluvial plain showed clear/distinct soil layer distribution till nearly 75cm depth in contrast to the piedmont soils which exhibited parabola patterns in radargram indicating the presence of stones/boulders within very short depth from the surface. The results regarding identification of contrasting soil layers using GPR were validated and found to be in agreement with standard soil profile information of the sampling sites in different landforms. GPR being a non-destructive technique could help in acquiring large number of such observations in much lesser time providing vital information for land use planning as well as soil mapping activities.

The RADARSAT Constellation Mission for Soil Moisture Retrieval of Bare Soil by Compact Polarimetry and Random Forest Regression

The RADARSAT Constellation Mission (RCM) performance evaluation is currently in progress for core Synthetic Aperture Radar (SAR) applications. This study aims to investigate the retrieval of Soil Moisture Content (SMC) in bare soil with RCM compact polarimetry and Random Forest Regression (RFR). The focus is on RH (right circular transmit and linear horizontal receive signal) and RV (right circular transmit and linear vertical receive signal) backscattering, which are the primary RCM Compact Polarimetric (CP) products. SMC retrieval is pursued over a wide range of radar incidence angles. Then, an attempt is made to retrieve SMC at higher radar incidence angles only. Furthermore, soil moisture maps are produced and used for analyzing the captured soil moisture variability. CP SAR images acquired with the RCM SC30MCP mode over three Canadian experimental sites are considered in our study. The sites are equipped with calibrated Real-Time In-Situ Soil Monitoring for Agriculture (RISMA) stations. A RFR retrieval algorithm was able to predict SMC with a correlation of 0.75 when compared to in-situ soil moisture measurements. A Root Mean Square Error (RMSE) = 5.9%, a bias = −1.5%, and an unbiased RMSE (ubRMSE) = 5.7% are achieved. A degradation in performance is reported for SMC retrieval under higher radar incidence angles. Results of our study indicate promising performance for capturing near-surface soil moisture variability under bare soil conditions.

On the Experimental Antenna Measurements: Study and Investigations

This study focuses on the experimental measurement and analysis of antenna characteristics, aiming to provide a deeper understanding of antenna performance in real-world conditions. The investigation involves systematic assessment of key parameters such as radiation patterns, gain, impedance, and bandwidth. Using a variety of measurement techniques and equipment, including network analyzers, signal generators, and anechoic chambers, the study evaluates different types of antennas under various test scenarios. The experimental results are compared with theoretical predictions to identify discrepancies and refine antenna design methodologies. The findings of this study offer valuable insights into the practical performance of antennas, highlighting the importance of precise measurements in the design and optimization of antenna systems for communication and radar applications. The results also underscore the necessity of accounting for environmental and operational factors in antenna performance assessments.

Integrative Approaches to Monitoring Cultivated Land Subsidence in Hilly Regions: Applications of Differential Interferometric Synthetic Aperture Radar and Small Baseline Subset Interferometric Synthetic Aperture Radar Technologies

Integrative Approaches to Monitoring Cultivated Land Subsidence in Hilly Regions: Applications of Differential Interferometric Synthetic Aperture Radar and Small Baseline Subset Interferometric Synthetic Aperture Radar Technologies

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

A Fluted E‐Shaped Antipodal Vivaldi Antenna With Rectangular Strips for Surface Scanning Application

ABSTRACTIn this paper, a fluted E‐shaped antipodal Vivaldi antenna (AVA) loaded with rectangular‐shaped strips is proposed for ground‐penetrating radar (GPR) application. The corrugation method is implemented by introducing multiple slots in the uppermost and lowermost arms of the antenna, followed by adding additional 10 strips to broaden and stabilize the impedance bandwidth. The electrical dimension of the antenna is 1.07λ × 1.8λ × 0.004λ. The proposed modified AVA (MAVA) exhibits a high fractional bandwidth of 144.8% over an ultrawideband of 1.6–10 GHz. The peak gain achieved by the antenna is 8.97 dBi. The proposed antenna offers a stable unidirectional radiation pattern along E‐ and H‐plane throughout the spectrum with maximum radiation efficiency of 96%. A prototype of the proposed antenna has been fabricated and tested where the measured results bear close resemblance with the simulated results. The pertinence of proposed antenna for GPR subsurface scanning was examined through a field test where scanned result signifies its aptness for such submissions.

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

A novel approach to simulate moving targets in automotive radar applications

AbstractIn the field of automotive radar testing, radar target simulators (RTS) based on fibre delay technology are limited by production processes, typically achieving distance steps of only 1 cm. Meanwhile, simulators utilising digital DRFM (Digital Radio Frequency Memory) technology face similar constraints, with a minimum distance step size of 3 cm, dictated by the ADC sampling rate (corresponding to a sampling rate of 5 GHz). In both types of simulators, abrupt changes in target distance result in phase discontinuities due to the step size being greater than the wavelength, ultimately distorting the target velocity spectrum. This paper proposes a phase compensation method based on instantaneous frequency measurement for a digital DRFM simulator, which ensures the continuity of the phase in the RTS output signal, achieving an ideal simulation of the target velocity spectrum. Additionally, it enables millimetre‐level distance stepping.

An innovative approach for FMCW radar vital sign monitoring with removal of respiratory harmonics

Frequency Modulated Continuous Wave (FMCW) radar shows broad research potential in monitoring vital signs. However, the harmonic components generated by the human respiratory process overlap with the frequency band of the heartbeat signal, posing challenges to precisely monitoring the heartbeat signal. To address this issue, this paper introduces the singular spectrum analysis method, which accurately identifies and removes respiratory harmonics by adding a sine signal with the same frequency as the respiratory harmonics to the original time series. Furthermore, the paper introduces energy entropy and the Pearson correlation coefficient to comprehensively decompose physiological signals to optimize the traditional variational mode decomposition algorithm, proposing the EE-VMD and PCC-VMD algorithms. Experimental results demonstrate that the SNR increased, and the accuracy of measuring respiratory rate and heartbeat rate has significantly improved. The results presented in this paper not only advance theoretical methodologies for the monitoring of human vital signs but also underscore the practical applicability of FMCW radar in this domain.

Gain and bandwidth enhancement using superstrate loaded 2×2 circular-array antenna for X-Band and RADAR applications

ABSTRACT This article demonstrates the fabrication, and measurements of a corporate offset-fed 2 × 2 array electromagnetically coupled patch (EMCP) circular-antenna based on the Fabry-Perot cavity principle. Single element antenna has a low gain of 6.28 dBi and is enhanced to 13.45dBi by loading the array with a superstrate. The antenna parameters −10 dB fractional bandwidth (FBW) and gain are improved by an air gap with 4-stacked circular patches and 4 stubs in the proposed design. The peak gain of the 2 × 2 array without superstrate was 8.88 dBi at 8.19 GHz, which is enhanced to 13.82 dBi at 9.55 GHz by parasitic loading and superstrate. The FBW of the proposed array antenna was enhanced by arranging four stubs between the 4-circles in the superstrate structure. The −10 dB FBW without stubs was 24.82% (7.62–9.73 GHz) and with stubs it became 38.47% (7.73–11.0 GHz). Adjustment of the height of the superstrate at 2.0 mm not only enhanced the gain and bandwidth but also advancement in the unidirectional radiation patterns. The array is prototyped is measured to validate the reflection coefficients and radiation characteristics and they found an excellent match with simulated results. The suggested array is most suitable for energy launchers in transitions, RADAR, military, satellite, X-band communications, and microwave laboratory applications.

W‐band LNA employing current reuse and non‐linearity cancellation in 28 nm CMOS for automotive radar and 6G applications

AbstractThis work reports a W‐band 2‐stage stacked LNA featuring post‐distortion non‐linearity cancellation (PDC) with programmable gain and enhanced common‐mode (CM) stability, fabricated in TSMC 28‐nm complementary metal oxide semiconductor (CMOS). The PDC technique employs diode‐connected NMOS transistors to enhance linearity. The diodes are connected to drains of the stage one and, therefore, are isolated from the input, leading to minimal impact on input matching. Since the diodes are in strong inversion, they track well with the main transistors, resulting in robust cancellation across PVT. Additionally, the diodes also enhance the CM stability of the LNA by reducing the CM gain. Use of stacked architecture lowers the DC power consumption, through current re‐use in the two stages. Switchable neutralized differential pair cells are used in stage one to achieve variable gain. The LNA consumes 31 mW of power with an IP1dB of ‐5.5 dBm and IIP3 of 6 dBm leading to an figure‐of‐merit (FOM) of 31.3 dB. The peak gain is 13 dB at 84.2 GHz, and it maintains 5 dB gain between 75 and 95 GHz. The LNA has 2.7 dB of programmable gain control. The minimum measured NF is 6.78 dB at 89.4 GHz. The proposed LNA is suitable for high‐linearity receivers for automotive radar and 6G applications.