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A new circular patch antenna with a novel metamaterial structure that achieves high bandwidth and positive gain across the operating band. The proposed antenna was Designed by incorporating three split ring resonators into the patch and fabricating it with 15 ×10 ×1.6 mm3. The use of a metamaterial structure with negative permittivity and permeability reduced mutual coupling in a wideband antenna. The designed antenna shows the isotropic nature at 9.71 GHz in the operating band from 8.80 to 12.89 GHz for X band applications specifically for detecting objects using radars. The optimetrics technique analyzed impedance matching with a good return loss of -30 dB. In comparison to previous works, miniaturization achieved up to 81.94%. The efficiency of 95.6% and isotropic pattern were also achieved at 9.71 GHz using HFSS020R2.

Each of NASA”s three Deep Space Network (DSN) sites has multiple large antennas capable of acquiring VLBI data. The long range plan is to have four 34-meter antennas at each site. At present Goldstone has three; with another under construction. These antennas offer the opportunity to do connected element interferometry (CEI) over the few hundred meter baselines within each complex. Given that all antennas within a site are of nominally the same structural design, are run off the same clock, observe through almost the same atmosphere, and are subject to almost the same geophysics, doing CEI experiments is an excellent way to probe the limits of VLBI accuracy and expose station specific systematic errors. This paper will report on results from the Goldstone California complex over 2016 to 2023 which achieved a per pass baseline precision of about 0.2 mm horizontal and 1 mm in the vertical. There is evidence for 1 mm level systematics. Based on this data we will discuss the implications for whether the IAG’s goal of 1mm station stability in VLBI geodesy is possible for large DSN antennas., Copyright © 2023, All Rights Reserved. This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004)., {"references":["U.S. Geological Survey, map of 2019 Ridgecreast quake"]}

Unlike the original Cloude-van Zyl decomposition of reflection symmetric polSAR data, a recently suggested version of the decomposition for full/quad pol data relies on the Cloude-Pottier mean alpha angle (ᾱ) to characterize the scattering mechanism. ᾱ can be calculated from the eigenvectors of the coherency matrix. By means of the eigenvector-eigenvalue identity (EEI) we can avoid the calculation of the eigenvectors. The EEI finds ᾱ by means of eigenvalues of the 3×3 coherency matrix and its 2×2 minor(s) only and is well suited for fast array based computer implementation. In this paper with focus on computational aspects we demonstrate fast EEI based determination of ᾱ on X-band F-SAR image data over Vejers, Denmark, including a detailed example of calculations and computer code.

In this article, a 4 × 4 miniaturized UWB-MIMO antenna with reduced isolation is designed and analyzed using a unique methodology known as characteristic mode analysis. To minimize the antenna’s physical size and to improve the isolation, an arrangement of four symmetrical radiating elements is positioned orthogonally. The antenna dimension is 40 mm × 40 mm (0.42λ0× 0.42λ0) (λ0 is the wavelength at first lower frequency), which is printed on FR-4 material with a width of 1.6 mm and εr= 4.3. A square-shaped defected ground framework was placed on the ground to improve the isolation. Etching square-shaped slots on the ground plane achieved the return losses S11 < −10 dB and isolation 26 dB in the entire operating band 3.2 GHz–12.44 GHz (UWB (3.1–10.6 GHz) and X-band (8 GHz–12 GHz) spectrum and achieved good isolation bandwidth of 118.15%. The outcomes of estimated and observed values are examined for MIMO inclusion factors such as DG, ECC, CCL, and MEG. The antenna’s performances, including radiation efficiency and gain, are remarkable for this antenna design. The designed antenna is successfully tested in a cutting-edge laboratory. The measured outcomes are quite similar to the modeled outcomes. This antenna is ideal for WLAN and Wi-Max applications.

A low-profile single-ridge waveguide magic-T is proposed as a combination of two T-junctions at an X band. A slot coupling technique is used to reduce the component dimensions in the E-plane, thus leading to a low profile. The device can assume two configurations by arranging the sum and difference ports in the same or opposite direction, an attractive feature in the design of beamforming networks with complex routing. A magic-T prototype is fabricated using laser powder bed fusion additive manufacturing techniques. Good agreement between simulations and measurements is found.

Electromagnetic waves in the X-band (8.2–12.4 GHz frequency) are used for radar, satellite communication, and, in some countries, for wireless computer networks. Shielding allows to protect humans and electronic devices from harmful effects of these waves. Cement-based composites containing conductive material can be used for this purpose, and pyrolysed carbonaceous residues (biochars) are promising in this respect. Two different biochars originated from wood (CB) and sewage sludge (SSB) pyrolysis were used as fillers in cement-based composites. The electromagnetic shielding properties of these composites are analysed vs the type and amount of biochar added. The influence of water content arising from different curing and ageing in ambient conditions is investigated for one set of samples. Results show that CB and SSB contain 74% and 30% of graphitic carbon, respectively. In the composites, SSB particles are bulky and scarcely dispersed, while CB particles are elongated and homogenously distributed. Values of Shielding Effectiveness (SE) > 20 decibel at normal incidence are achieved for the composites containing 18% of CB biochar. The influence of ageing was also investigated for a sample with 18% of wood commercial biochar: increasing wet curing increases the shielding effectiveness, while increasing ageing in air decreases the shielding effectiveness values: after 10 weeks, the measured value is about 5 dB less. The evidence suggests that the amount of physically adsorbed water is responsible for this behaviour, and it should be taken into account when dealing with cement based composites used for electromagnetic shielding.

In this paper, a broad band A-sandwich radome wall structure based on band-pass FSS (frequency selective surface) is proposed for an airborne radar applications. The FSS structure having two square conducting rings, which are embedded on either side of core layer. The conventional and proposed FSS based radome wall is analyzed with different incidence angles (0°, 10°, 20° and 30°) for both TE and TM polarization. The radome wall structure consist of a low density Nomex honeycomb core layer sandwiched between two high density Quartz skin layers. The structure shows the percentage impedance bandwidth of 40.8 % in the frequency range from 7.8GHz to 11.8GHz with sharp roll-off characteristics. The proposed novel approach involves high frequency unit cell simulation, which is carried out using EM Simulation Tool. To understand the practical behavior of the proposed structure for radome application the conformal analysis has been also carried out, with respect to different radius. The superior EM performance of the proposed broadband novel radome wall structure makes it suitable for the design of airborne radome.

An X-band H-plane groove gap waveguide magic-T is presented as a combination of an H-plane and an E-plane T-junction. Two architectures can be derived by orientating the sum and difference ports to the same or opposite directions, respectively. Slot coupling allows the reduction of the device dimensions along the E-plane, and such a low profile can be attractive in all groove gap waveguide applications where compactness is required. A proof-of-concept prototype is fabricated with standard low-cost CNC milling machine manufacturing techniques. Good agreement between simulations and measurements is observed.

Bu çalışmada, X bant uzay uygulamaları için Flame Retardant 4 (FR4) malzemesinin dielektrik ölçüm yaklaşımına dayalı kompakt bir U-Yarıklı yama anten tasarımı sunulmaktadır. Tasarım yöntemine uygun olarak, anten tasarımlarında kullanılacak HFSS tasarım aracına, FR4 malzemesinin dalga kılavuzu yöntemi kullanılarak X-bantta ölçülen frekansa bağlı dielektrik sabiti ve tanjant kaybı değerleri uygulanmıştır. Daha sonra, yaklaşımın anten tasarımları üzerindeki fonksiyonel performansı, literatürdeki standart bir anten tasarımının benzetim ve ölçüm sonuçları ile kıyaslanarak doğrulanmıştır. Doğrulanan sonuçlar ışığında, önerilen tasarım yöntemi kullanılarak X-bant uzay uygulamaları için yanal yan yarıklara sahip yeni bir U-Yarıklı yama anten tasarımı, bir besleme hattı ile sunulmaktadır. Sunulan kompakt anten tasarımı ile merkez frekansta (9,5 GHz) 1,77 dB kazanç ve 8,53 GHz'den 10,63 GHz'e kadar frekans bant genişliği sağlamaktadır., In this study, a compact U-slot patch antenna design based on dielectric measurement approach of Flame Retardant 4 (FR4) material is presented for X band space applications. In accordance with the design method, the measured frequency dependent dielectric constant and tangent loss values of the FR4 material at X-band using the waveguide method is applied to the HFSS design tool to be used in antenna designs. Then, the functional performance of the design method on antennas is verified by comparing the simulation and measurement results of a conventional antenna design in the literature. In the light of the verified results, a new U-slot patch antenna design with lateral side slots for X-band space applications is presented with a feed line by using the proposed design method. The presented compact antenna design provides 1.77 dB gain at the center frequency (9.5 GHz) and the frequency bandwidth from 8.53 GHz to 10.63 GHz.

In this paper, a transparent parasitic slot antenna is proposed for 1U and 2U CubeSats. The proposed antenna is low profile and present physical size suitable for all CubeSat configurations. Moreover, the proposed study introduces a tradeoff between two electromagnetic/ Satellite aims. The first one is about space for the CubeSat solar panels, which is preferred to be wide for producing the maximum energy possible. The second is about the use of CubeSat top face for increasing the antenna peak gain at X-band. The proposed parasitic slot antenna is designed and optimized using ANSYS HFSS and Quasi Newtonian method. The obtained results show that the antenna gain is increased by about 7.0 dBi and 8.0 dBi for both 1U and 2U CubeSats, respectively. In addition to that, the proposed antenna gives large impedance bandwidth of about 600 MHz at X-Band. In general, the constructed transparent slot antenna with parasitic elements mounted on both 1U / 2U CubeSat box presents high antenna performances that make it very candidate for unlimited lifetime CubeSat Communication.

A compact triple-band operation ultra-wideband (UWB) antenna with dual-notch band characteristics is presented in this paper. By inserting three metamaterial (MTM) square split-ring resonators (MTM-SSRRs) and a triangular slot on the radiating patch, the antenna develops measured dual-band rejection at 4.17–5.33 GHz and 6.5–8.9 GHz in the UWB frequency range (3–12 GHz). The proposed antenna offers three frequency bands of operation in the UWB range, which are between 3–4.17 GHz (~1.2 GHz bandwidth), 5.33–6.5 GHz (~1.17 GHz bandwidth), and 8.9–12 GHz (~3.1 GHz bandwidth), respectively. The higher resonating frequency band can be tuned/controlled by varying the width of the triangle slot, while the medium operational band can be controlled by adjusting the width of the SSRR slot. Initially, the simulated S-parameter response, 2D and 3D radiation patterns, gain, and surface current distribution of the proposed UWB inverted triangular antenna has been studied using epoxy glass FR4 substrate having parameters εr = 4.3, h = 1.6 mm, and tan δ = 0.025, respectively. In order to validate the simulation results, the proposed UWB antenna with dual-notch band characteristics is finally fabricated and measured. The fabricated antenna’s return-loss and far-field measurements show good agreement with the simulated results. The proposed antenna achieved the measured gain of 2.3 dBi, 4.9 dBi, and 5.2 dBi at 3.5 GHz, 6.1 GHz, and 9.25 GHz, respectively. Additionally, an in-depth comparative study is performed to analyze the performance of the proposed antenna with existing designs available in the literature. The results show that the proposed antenna is an excellent candidate for fifth-generation (5G) mobile base-stations, next-generation WiFi-6E indoor distributed antenna systems (IDAS), as well as C-band and X-band applications.

Conference Name: 2022 Microwave Mediterranean Symposium (MMS) Date of Conference: 09-13 May 2022 Cascode HEMTs exhibit better stability and broad bandwidths performance as compared with common source HEMTs. This paper presents the design of a single stage broadband low noise amplifier based upon 0.15 um GaN HEMT technology in the frequency range of 8 – 12 GHz. Cascode HEMT with inductive source degeneration is utilized. All the design work is done using PathWave Advanced Design System. The LNA provides 9.5 to 10.6 dB with input return loss better than 10 dB and output return loss better than 8 dB in the whole band. The noise figure of the amplifier is below 1.9 dB. The linearity parameters P1dB and OIP3 are greater than equal to 16 dBm and 28 dBm respectively within operating bandwidth. The noise figure of the amplifier is fairly constant over 30 mA to 60 mA bias currents and 9 V – 18 V operating bias voltage. This is a unique finding which is being reported for the first time to the best of authors' knowledge.

Conference Name: 2022 Microwave Mediterranean Symposium (MMS) Date of Conference: 09-13 May 2022 Source degenerated HEMTs are used to achieve good noise matching and better input return loss without degrading the noise figure and reducing the stability. This work presents an MMIC design for the frequency band of 8–11 GHz by using HEMTs with source degeneration in 0.15 µm GaN on SiC technology. All design work is done in the Advanced Design System. The LNA delivers more than 6.9 dB gain with better than 8.5 dB and 9.5 dB input and output return losses, respectively. In addition, the gain ripple is around 2.7 dB. The noise figure of the amplifier is achieved below 1.1 dB with P1dB of 17.2 dBm and %12.7 drain efficiency within the operating bandwidth at the bias conditions of 9 V /20 mA.

In this paper, a novel digitally reconfigurable unit-cell and $4\times 4$ transmitarray operating at X-band is proposed that allows the implementation of beamforming and polarization conversion operations in a programmable way. The lower layer of transmitarray responsible for beam steering consists of two PIN diodes and a circular type patch which has two states of operations with 0 and $\pi $ phase responses which we name “State1” and “State2”. “State1” and “State2” can be represented by a digital notation as “1” and “0” elements. Similarly, the upper layer of the transmitarray responsible for polarization conversion operation consists of two states of operation which we name as “State3” and “State4”, respectively. “State3” and “State4” also can be represented by digital notations as “1” or “0” elements. By coding “0” and “1” elements for the lower side of the transmitarray in a 1-bit sequence, we can steer the beam in our desired direction. Similarly, by coding “0” and “1” elements in a 1-bit sequence element for the upper layer, we can get X-polarized and Y-polarized beams. Combining the upper layer 1-bit sequence and lower layer 1-bit sequence, we can get both polarization conversion and beam steering simultaneously. A $4\times 4$ array with our proposed unit cell was designed and fabricated. A good agreement between simulated and measured results was observed. The proposed design is a promising concept because it can be fabricated using the conventional fabrication process, it is cost-effective compared to conventional phased array antenna for satellite and radar applications. A $4\times 4$ array was taken just to check the transmission and reflection coefficients of the proposed unit cells. A very small transmitarray was manufactured and experimentally characterized just as a proof of concept, to verify that the unit cells work properly.

We present an X-band two-stage power amplifier (PA) in 65-nm CMOS process using a transformer (TF)-based voltage combining technique (VTC) which achieves the highest figure of merit (FOM) among recently reported CMOS PAs. The PA architecture is constructed with two-stage push-pull amplifiers with a three-way voltage power combiner and splitter which play the main role to achieve outstanding performance. The power combining was applied in the voltage domain to increase the output device size aiming at boosting the output power of the CMOS PA. We constructed a compact two-stage PA with a push-pull structure with conjugate matchings at the input, inter-stage, and output with the capacitive neutralization technique to improve the power gain and drain efficiency. Working under a 1.2-V supply with DC quiescent current of 865-mA, the proposed PA achieved a maximum saturated output power of 25.1 dBm with a 1-dB power bandwidth of 3-GHz from 8.4-GHz to 11.4-GHz, a peak power added efficiency (PAE) of 25.4% at 10.2 GHz, a power gain of 25.9-dB at 9.5-GHz with a 3-dB gain bandwidth of 2-GHz (8.7-10.7 GHz). The total chip size is 0.9 mm2, and the core size excluding pads is only 0.342 mm2.

Data from TanDEM-X in single-pass and bistatic interferometric mode together with the interferometric water cloud model (IWCM) can provide estimates of forest height and stem volume (or the related above-ground biomass) of boreal forests with high accuracy. We summarize results from two boreal test sites using two approaches, i.e., 1) based on model calibration using reference insitu stands, and 2) based on minimization of a cost function. Both approaches are based on inversion of IWCM, which models the complex coherence and backscattering coefficient of a homogeneous forest layer, which includes gaps where free-space wave propagation is assumed. A digital terrain model of the ground is also needed. IWCM is used to estimate forest height or stem volume, since the two variables are assumed to be related through an allometric equation. A relationship between the fractional area of gaps, the area-fill, and stem volume is also required to enable model inversion. The accuracy of the stem volume estimate in the two sites varies between 16% and 21% for height of ambiguity

A circularly polarized (CP) multi-input multioutput (MIMO) dielectric resonator (DR) antenna (DRA) with compact size and four ports is implemented. CP radiation was achieved using the deformed DR geometry excited with aperture coupled feeding. A CPDRA with a single and two ports is investigated. The defected ground structure (DGS) was incorporated into the antenna for improving the isolation between the ports. The DGS was incorporated in such a way that the required phase difference between the generated orthogonal degenerate modes is preserved. This concept could be utilized in implementing a compact four-port CP antenna. The MIMO antenna provides a 10 dB impedance bandwidth of 38% (8.5–12.5 GHz) and a 3 dB AR bandwidth of 9.32% (9.2–10.1 GHz). The gain of the implemented antenna was around 6 dBi in the band where CP radiation was achieved. The MIMO performance parameters were calculated, and their values remained within the acceptable limits. The implemented antenna could suitably be used in X-band applications.

A compact quad-band circularly polarized (CP) G-shaped printed antenna with square slot is proposed in this paper. Two semicircular notches have been etched from lower periphery of the ground to increase the impedance bandwidth (IBW). In order to increase significantly the axial ratio bandwidth (ARBW), a spring-shaped notch is etched from the upper periphery of the ground. For further increase of ARBW and better impedance matching, another notch is etched from G-shaped radiating element. The proposed design exhibits simulated IBW = 22.046 GHz (8.954–31 GHz) with the center frequency fc = 20 GHz, and the measured IBW below –10 dB is from 8.8376 to 20 GHz. The IBW above 20 GHz are not measured due to limitations of the available VNA. The ARBW are 306.3 MHz (fc = 11.6 GHz), 363.1 MHz (fc = 21.3 GHz), 380.7 MHz (fc = 27.6 GHz), and 332.2 MHz (fc = 28.6 GHz), which are within the range of IBW. The maximum simulated peak gain is 5.46 dBi at 25.7 GHz. The proposed antenna is suitable for applications in the X-, K- and Ka-bands in the field of wireless communication.

In this paper, we present a modified UWB antenna with hexagonal slotted ground plane inspired with a double combined symmetric T-shaped slots and dual rotated L-shaped strip for dual band notched characteristics. Initially, the operating frequency range is from 3GHz to 12 GHz. To eliminate the unwanted C-band (3.625-4.2GHz) and the entire uplink and downlink of X-band satellite communication systems (7.25 -8.39 GHz) frequency bands, we are investigating the conventional UWB patch antenna and loaded it with a mentioned strips and slots respectively. The performances of the antenna are optimized both by CST Microwave Studio and Ansoft HFSS. To further analyze the parametric effects of the slots and strips, the surface current distribution is presented and discussed. The antenna gain versus frequency gives an acceptable value except the notched band regions, these values are reduced from its normal to be a negative in the notched bands (3.625-4.2GHz) and (7.25 to 8.39 GHz).

In this paper, a fully-integrated dual-mode X-band radar transceiver that supports Doppler radar and frequency modulated continuous wave (FMCW) radar is proposed. To remove large off-chip DC-blocking capacitors in the Doppler mode, the double-conversion technique and local oscillator (LO) chopping technique are introduced. These techniques remove the DC offset and makes the transceiver more robust to the TX to RX leakage. In addition, they also improve the noise figure (NF) by filtering out 1/f noise of the analog baseband. The FMCW radar is realized using a direct-conversion receiver and a chirp generator. The chirp generator consists of a frequency sweep generator (FSG) and a fractional-N phase-locked loop (PLL). All the analog baseband components including a programable gain amplifiers (PGA) and 1/R4 range compensation filters are integrated on the chip as well as a bandgap and low-dropout regulators. The operating frequency is from 9.7 to 12.3 GHz, which consumes 216 mW in Doppler mode and 201.6 mW in FMCW mode from a 1.2-V supply voltage. The maximum chirp bandwidth is 750 MHz and the maximum receiver gain is 76 dB with 6-dB gain step. The chip size of the transceiver is 7.68 mm2 including all the pads.

Design, development, and measurements of X-band patch antennas for a CubeSat platform are presented in this paper. The challenge was in the design of circularly polarized patch antennas suitable for building an array since the goal is to achieve highest possible radiation efficiency. Therefore, six antenna designs were developed which can be differentiated by the number of PCB layers and by the method of excitation. Also, for achieving circular polarization two shapes were considered, a corner truncated square patch and a nearly square patch. The characteristics of the developed antennas were analyzed and measured showing the advantages and disadvantages of certain designs. Based on the analysis of measured results we reached guidelines that will be used further for designing the full X-band array.

As additively manufactured radio frequency (RF) design expands towards higher frequencies, performance becomes ever more sensitive to print-induced dimensional variations. These slight deviations from design dimensions typically skew RF performance, resulting in low yields or poor device performance. In order to overcome this limitation, RF design paradigms must be developed for non-uniform process and material-specific variations. Therefore, a new generalized approach is developed to explore variation-tolerant designs for printed RF structures. This method evaluates the feature fidelity and S11 performance of micro-dispensed, X-band (8–12 GHz) patch antennas by evaluating the standard deviation in as-printed features, surface roughness, and thickness. It was found that the traditional designs based on optimal impedance matching values did not result in the most robust performance over multiple printing sessions. Rather, performance bounds determined by print deviation could be utilized to improve large-batch S11 results by up to 7 dB. This work demonstrates that establishing the average standard deviation of printed dimensions in any RF printing system and following the formulated design procedure could greatly improve performance over large datasets. As such, the method defined here can be applied to improve large-scale, printed RF yields and enable predictive performance metrics for any given printing method.

Development of satellite and radar applications has been continuously studied to reach the demand in the recent communication technology. In this study, a new oval-square-shaped split-ring resonator with left-handed metamaterial properties was developed for C-band and X-band applications. The proposed metamaterial was fabricated on 9 × 9 × 0.508 mm3 size of Rogers RO4003C substrate. The proposed metamaterial structure was designed and simulated using Computer Simulation Technique (CST) Microwave Studio with the frequency ranging between 0 to 12 GHz. The simulated result of the proposed design indicated dual resonance frequency at 5.52 GHz (C-band) and 8.81 GHz (X-band). Meanwhile, the experimental result of the proposed design demonstrated dual resonance frequency at 5.53 GHz (C-band) and 8.31 GHz (X-band). Therefore, with a slight difference in the dual resonance frequency, the simulated result corresponded to the experimental result. Additionally, the proposed design exhibited the ideal properties of electromagnetic which is left-handed metamaterial (LHM) behavior. Hence, the metamaterial structure is highly recommended for satellite and radar applications.

Bu makalede, X-Bant ’ta hibrit Mikroşerit-YTED (Yalıtkan Taban Entegreli Dalga Kılavuzu) bant geçiren filtrenin optimizasyon çalışması yapılmıştır. Yüksek geçiren bir YTED filtre ile alçak geçiren bir mikroşerit filtrenin seri entegrasyonuyla elde edilen hibrit bant geçiren filtrenin geometrisindeki asimetrik bölümler düzeltilmiştir. Optimizasyon çalışmasında, CST (Computer Simulation Technology) Studio Suite simülasyon programındaki 5 farklı optimizasyon algoritma tekniği hibrit M-YTED bant geçiren filtreye uygulanmıştır. Filtreye uygulanan bu tekniklerin sonuçları karşılaştırılmalı olarak verilmiştir. Metotlar karşılaştırıldığında, geçiş bandındaki S11 değerleri toplamının en düşük değerde olması nedeniyle Parçacık Sürü Optimizasyon Algoritması seçilmiştir. Filtrenin w4 parametresinin değeri 6,165 mm olarak elde edilmiştir. Filtrenin kalite faktörü, optimizasyon çalışmasıyla Guvenli ve diğ., (2021)’nin çalışmasına göre 3,21 kat artırılmıştır. Hibrit Mikroşerit-YTED bant geçiren filtrenin geçiş bandı [ω1-ω2] 7,60 GHz ile 8,40 GHz frekans aralığında, filtrenin merkez frekansı (ω0) 7,90 GHz, filtrenin bant genişliği de 0,80 GHz (%10,01) olacak şekilde tasarlanmıştır. M-YTED bant geçiren filtrenin simülasyon sonuçlarına göre, merkez frekansı 8,15 GHz ve bant genişliği 0,92 GHz'dir (%11,29). Analitik ve simülasyon sonuçları karşılaştırıldığında, analitik sonuçlara göre simülasyon merkez frekansındaki frekans değişimi %1,98 ve bant genişliği değişimi %15’dir. Analitik ve simülasyon sonuçlarının birbiriyle uyumlu olduğu görülmektedir. In this article, the optimization study of hybrid Microstrip-SIW (Substrate Integrated Waveguide) band-pass filter in X-Band has been carried out. Asymmetrical sections in the geometry of the hybrid band-pass filter obtained by serial integration of a high-pass SIW filter and a low-pass microstrip filter are corrected. In the optimization study, 5 different optimization algorithm techniques in the CST (Computer Simulation Technology) Studio Suite simulation program were applied to the hybrid M-SIW bandpass filter. The results of these techniques applied to the filter are given comparatively. Particle Swarm Optimization Algorithm was chosen because the sum of the S11 values in the passband was the lowest when the methods were compared. The value of the w4 parameter of the filter was obtained as 6.165 mm. The quality factor of the filter was increased by 3.21 times with the optimization study according to the study of Guvenli et al. (2021). The passband [ω1-ω2] of the hybrid Microstrip-SIW bandpass filter is designed in the frequency range of 7.60 GHz to 8.40 GHz, the center frequency of the filter (ω0) is 7.90 GHz and the bandwidth of the filter is 0.80 GHz (10.01%). According to the simulation results of M-SIW bandpass filter, the center frequency is 8.15 GHz and the bandwidth is 0.92 GHz (11.29%). When analytical and simulation results are compared, it is seen that frequency change in the simulation center frequency is 1.98% and change in bandwidth is 15%. It is seen that analytical and simulation results are compatible with each other.

The simulation and measurement results of characteristics of the X-band offset reflectarray with the diameter of 460 mm on thin dielectric substrates are presented. The optimization of array main characteristics is performed using electrodynamic simulation by the full-wave method. The experimentally measured antenna characteristics are as follows: the gain is of 27.7 dB, the –3 dB main-lobe beamwidth at the frequency of 9.6 GHz is equal to 4 and 4.5° in the E- and H-planes, respectively. The operating frequency band at the –1 dB gain level is equal to 8.9–10 GHz.

Current satellite remote sensing methods struggle to detect and map forest degradation, which is a critical issue as it is likely a major and growing source of carbon emissions and biodiveristy loss. TanDEM-X InSAR phase height (hϕ) is a promising variable for measuring forest disturbances, as it is closely related to the mean canopy height, and thus should decrease if canopy trees are removed. However, previous research has focused on relatively flat terrains, despite the fact that much of the world’s remaining tropical forests are found in hilly areas, and this inevitably introduces artifacts in sideways imaging systems. In this paper, we find a relationship between hϕ and aboveground biomass change in four selectively logged plots in a hilly region of central Gabon. We show that minimising multilooking prior to the calculation of hϕ strengthens this relationship, and that degradation estimates across steep slopes in the surrounding region are improved by selecting data from the most appropriate pass directions on a pixel-by-pixel basis. This shows that TanDEM-X InSAR can measure the magnitude of degradation, and that topographic effects can be mitigated if data from multiple SAR viewing geometries are available.

Herein, a novel and computationally efficient near field shaping technique for nondestructive hyperthermia applications is presented. The aim of nondestructive hyperthermia studies is to treat cancer cells in the body without damaging the healthy cells using the focused near-field characteristic of the antenna array. However, optimal near field shaping requires an optimization process for having accurately focus the energy into the desired coordinates, which is, a computational expensive and inefficient task due to the nature of full-wave electromagnetic (EM) analysis. To enable computationally efficient, and accurate near field shape optimization, a surrogate model is required. To achieve this, the near field radiation of the designed horn antenna array in free space is obtained by using a fast and reliable technique, analytical regularization method (ARM). After that, by using Artificial Neural Network based regression algorithm, a data driven surrogate model is created using the data samples generated by ARM. By this means, near field shaping optimization for focusing the energy to the region where the tumor is located can be achieved, as a multi-objective optimization problem to be solved via data driven surrogate model assisted optimization techniques. The performance results of K-fold validation and hold-out data sets for proposed data driven surrogate model are calculated using Mean Absolute Error metric which are obtained as 0.9 x 10(-3) and 1.4 x 10(-3) respectively. By observing the presented study case scenario, after 10 min of illumination with antenna array with optimally selected configurations, the targeted area (position of tumor) had reached to the critical temperature of 43 Celsius. Thus, it can be said that the proposed method is an efficient method, both in terms of (1) destroying tumor cells by heating without damaging the healthy cells, and (2) being a computationally efficient method.

The coherent backscatter opposition effect (CBOE) enhances the backscatter intensity of electromagnetic waves by up to a factor of 2 in a very narrow cone around the direct return direction when multiple scattering occurs in a weakly absorbing, disordered medium. So far, this effect has not been investigated in terrestrial snow in the microwave spectrum. It has also received little attention in scattering models. We present the first characterization of the CBOE in dry snow using ground-based and spaceborne bistatic radar systems. For a seasonal snowpack in the Ku-band (17.2 GHz), we found backscatter enhancement of 50 %-60 % (+1.8-2.0 dB) at a zero bistatic angle and a peak half-width at half-maximum (HWHM) of 0.25 degrees. In the Xband (9.65 GHz), we found backscatter enhancement of at least 35 % (+1.3 dB) and an estimated HWHM of 0.12 degrees in the accumulation areas of glaciers in the Jungfrau-Aletsch region, Switzerland. Sampling of the peak shape at different bistatic angles allows estimating the scattering and absorption mean free paths, Lambda(T) and Lambda(A). In the VV polarization, we obtained Lambda(T) = 0.4 +/- 0.1 m and Lambda(A) = 19 +/- 12 m at the Ku-band and Lambda(T) = 2.1 +/- 0.4 m and Lambda(A) = 21.8 +/- 2.7 m at the X-band, assuming an optically thick medium. The HH polarization yielded similar results. The observed backscatter enhancement is thus significant enough to require consideration in backscatter models describing monostatic and bistatic radar experiments. Enhanced backscattering beyond the Earth, on the surface of solar system bodies, has been interpreted as being caused by the presence of water ice. In agreement with this interpretation, our results confirm the presence of the CBOE at X- and Ku-band frequencies in terrestrial snow., The Cryosphere, 16 (7), ISSN:1994-0416, ISSN:1994-0424

A reflect array was created using CST simulations and the MATLAB computer language. In applications needing high gain and efficiency, reflect arrays are gradually replacing parabolic reflectors. Massive reflect arrays take a long time and a lot of effort to build. A feed antenna is required to excite a planar or conformal array of components in order to build a reflect array antenna. They are the most expensive for large antennas that demand a lot of electrical power, while being the most practical and cost-effective option. The "X band" has a variety of frequencies that may be found in the microwave radio region of the electromagnetic spectrum. The X band is a frequency range in communication engineering that ranges from 8 to 12 GHz. Following an intensive study of all pertinent data, the MATLAB code will be thoroughly examined. The data from the CST program will be utilized to build the antenna. The CST construction of a reflect array antenna is simplified by MATLAB code that generates an antenna pattern. A gain of 60 dBi is possible using a reflect array feed antenna and a horn as the feed antenna. This configuration yields a gain of sixty dBi.

Frekans seçici yüzeyler (FSY), belirlenen frekans aralığında yüzeye gelen elektromanyetik dalgaların iletim, yansıma veya soğurma özelliği göstermesini sağlayan periyodik yapılardır. Bu çalışmada birden fazla frekans bandını kapsayacak şekilde (C-bandı (4-8 GHz) ve X bandı (8-12 GHz)), ultra geniş bant aralığına sahip, halka ve kesikli artı şekillerinin birleştirilmesiyle elde edilen yeni UGB FSY ile radar kesit alanının (RKA) azaltımı amaçlanmıştır. Çalışmanın ilk kısımlarında halka ve kesikli artı şekilli yapılar tek tek analiz edilmiştir. Analiz sonucunda en verimli olan iki yapı birleştirilerek elde edilen yeni FSY ile -10 dB kazanç değerinde bant genişliği arttırılmıştır. Önerilen yapı üzerinde temel parametreleri değiştirerek, ultra geniş bantlı (UGB) radar sistemlerinde kullanılabilecek iyi zayıflama düzeyine sahip, dalganın geliş açısından bağımsız ve bant durduran filtre karakteristiğine sahip yapı elde edilmiştir. Frequency selective surfaces (FSS) are periodic structures that allow electromagnetic waves arriving on the surface to show transmission, reflection or absorption properties in the determined frequency range. In this study, radar cross section with the new UGB FSY was obtained by combining ring and dashed cross shapes with ultra-wide band gap, covering more than one frequency band (C-band (4-8 GHz) and X-band (8-12 GHz)). In the first part of the study, the ring and dashed crosshairs were analyzed one by one. As a result of the analysis, the bandwidth has been increased by -10 dB gain with the new FSY obtained by combining the two most efficient structures. FSY designs with a good attenuation level that can be used in ultra-wideband (UGB) radar systems have been carried out. Simulation and analysis of the design were carried out with the CST Studio Suite 3D electromagnetic simulation program.

In dieser Arbeit wird ein low-level-RF (LLRF)-System für die neuartige polarisierbare transversal ablenkende Struktur PolariX TDS entwickelt, installiert und an der FLASHForward-Beamline bei DESY in Betrieb genommen. Die PolariX TDS arbeitet im X-Band bei 12 GHz und erfordert ein LLRF-System, das Signale in diesem Frequenzband messen und verarbeiten kann. Mit einem Ansatz zur Wiederverwendung des bereits existierenden S-Band LLRF-Systems, das Signale bei 3 GHz verarbeiten kann, wird neue Hardware entwickelt, die HF-Signale zwischen 12 GHz und 3 GHz umwandelt. Die zugrundeliegenden Komponenten dieser Konvertierungshardware sind HF-Mischer, Filter, Verstärker und Frequenzvervielfacher. Verschiedene Kandidaten für all diese Komponenten werden charakterisiert und hinsichtlich ihrer elektrischen Eigenschaften verglichen. Da die endgültige Systemleistung stark vom Phasenrauschen abhängt, wird das Hauptaugenmerk der Charakterisierung auf dieses gelegt. Mit den ausgewählten Komponenten werden Leiterplatten entworfen, simuliert, produziert und in hermetisch dichte Gehäuse verpackt, bevor sie in 19"-Module eingebaut werden. Nach der Fertigstellung werden die Module ebenfalls im Labor charakterisiert. Als letzter Schritt wird der Prototyp der PolariX TDS zusammen mit dem entwickelten LLRF-System in der FLASHForward-Beamline installiert. Nach erfolgreicher Inbetriebnahme werden erste Messungen im laufenden Beschleuniger durchgeführt. Zur Analyse des Kurzzeitverhaltens werden mögliche Verfahren zur Eliminierung der Langzeiteffekte durchgeführt. Die Aktorkette, bestehend aus LLRF-System, Klystron und dessen Vorverstärker, wird vermessen und charakterisiert. Die Ergebnisse zeigen eine gewisse Diskrepanz zwischen erwarteten und gemessenen Werten und es wird eine Analyse möglicher Quellen des Problems durchgeführt. Mit Hilfe von strahlbasierten Messungen wird eine Beziehung zwischen der HF und dem Strahl hinsichtlich Phasen- und Amplitudenrauschen untersucht. Dies zeigt eine gute Leistung des Gesamtsystems hinsichtlich der kurzzeitigen Phasenstabilität im Allgemeinen. Es werden jedoch kleine Abweichungen vom erwarteten Verhalten gesehen, analysiert und Verfahren zu deren Behebung vorgeschlagen. Analysen des Langzeitverhaltens zeigen einen groÿen Unterschied zwischen den HF- und den strahlbasierten Messungen, dessen Ursachen noch Gegenstand der Forschung sind. Obwohl nicht so wichtig wie das Phasenrauschen, wird auch das Amplitudenrauschen untersucht und ähnlich wie beim Langzeitverhalten zeigt die gemessene HF eine bessere Leistung als die strahlbasierten Messungen., In this thesis, a low-level RF (LLRF) system for the novel polarizable transverse deflecting structure PolariX TDS is developed, installed, and commissioned at the FLASHForward beamline at DESY. The PolariX TDS operates in the X-band at 12 GHz and requires an LLRF system capable of measuring and processing signals in this frequency band. Using an approach to reuse the existing S-band LLRF system that can process signals at 3 GHz, new hardware is being developed that converts RF signals between 12 GHz and 3 GHz. The underlying components of this conversion hardware are RF mixers, filters, amplifiers, and frequency multipliers. Various candidates for all these components are characterized and compared in terms of their electrical characteristics. Since the final system performance depends heavily on the phase noise, the main focus of the characterization will be on this. With the components selected, printed circuit boards are designed, simulated, produced and packaged in hermetically sealed housings before being mounted in 19" modules. After completion, the modules are also characterized in the laboratory. As a final step, the prototype of the PolariX TDS will be installed in the FLASHForward beamline together with the developed LLRF system. After successful commissioning, first measurements will be performed in the running accelerator. To analyze the short-term behaviour, possible procedures to eliminate the long-term effects will be discussed. The actuator chain, consisting of LLRF system, klystron and its preamplifier, is measured and characterized. The results show some discrepancy between expected and measured values and an analysis of possible sources of the problem is performed. Beam-based measurements are used to analyze the relation between the RF and the beam in terms of phase and amplitude noise. These measurements show good performance of the overall system in terms of short term phase stability in general. However, small deviations from the expected behavior are seen, analyzed, and procedures to correct them are proposed. Analyses of the long-term behavior show a large difference between the RF and beam-based measurements, which causes are still subject of research. Although not as important as the phase noise, the amplitude noise is also investigated and similar to the long term behavior, the measured RF shows better performance than the beam based measurements.

In this dissemination, a glueless compact dual port dielectric resonator antenna (DRA) is proposed for X-band applications. A prototype has been fabricated with RT Duroid substrate and Eccostock (ϵr = 10)-made DRA. The ring shaped DRA is excited by aperture coupled feeds maintaining symmetry between both the ports. Four cylindrical copper rods with four strips have been used to fix the DRA on the substrate and provide additional mechanical stability. Eight copper strips are used to provide impedance matching and impedance bandwidth (IBW) widening. The measured IBW of dual port DRA is 10.5% (8.05–8.95 GHz) and maximum gain of radiator is 6.2 dBi. The proposed antenna becomes compact when the net volume of DRA is approximately 3.5 cm3 and the volume of the substrate is 2.88 cm3, with a surface area of 36 cm2 and operating in X-band, which finds applications in satellite communication, weather radar, synthetic aperture radar, and telemetry tracking and control.

In this study, the quantitative precipitation estimation (QPE) capability of three X-band dual-polarization phased array radars (PAR) in Guangzhou, South China, was demonstrated, with an S-band operational dual-polarization radar as the benchmark. Rainfall rate (R) estimators based on the specific differential phase (KDP) for summer precipitation for both X-band and S-band radars were derived from the raindrop size distributions (DSDs) observed by a 2-dimensional video disdrometer (2DVD) in South China. Rainfall estimates from the radars were evaluated with gauge observations in three events, including pre-summer rainfall, typhoon precipitation, and local severe convective precipitation. Observational results showed that radar echoes from the X-band PARs suffered much more severely from attenuation than those from the S-band radar. Compared to S-band observations, the X-band echoes can disappear when the signal-to-noise ratio drops to a certain level due to severe attenuation, resulting in different estimated rainfall areas for X- and S-band radars. The attenuation corrected by KDP had good consistency with S-band observations, but the accuracy of attenuation correction was affected by DSD uncertainty and may vary in different types of precipitation. The QPE results demonstrated that the R(KDP) estimator produced better rainfall accumulations from the X-band PAR observations compared to the S-band observations. For both the X-band and S-band radars, the estimates of hourly accumulated rainfall became more accurate in heavier rainfall, due to the decreases of both the DSD uncertainty and the impact of measurement errors. In the heavy precipitation area, the estimation accuracy of the X-band radar was high, and the overestimation of the S-band radar was obvious. Through the analysis of the ZH-ZDR distribution in the three weather events, it was found that the X-band PAR with the capability of high spatiotemporal observations can capture minute-level changes in the microphysical characteristics, which help improve the estimation accuracy of ground rainfall.

This article presents results of optimization and development of X-band square waveguide stepped-thickness septum polarizers. Electromagnetic characteristics of the polarizers were simulated and optimized numerically using finite elements method. Optimal dimensions of the 2-, 3-, and 4-section stepped-thickness septum polarizers for various fractional bandwidths have been obtained. It is demonstrated that application of the stepped-thickness septum with 3 sections instead of it constant-thickness counterpart improves return loss and cross-polarization discrimination of the septum polarizer by 2–6 dB and 3–6 dB respectively, depending on fractional bandwidth. A prototype of the optimal waveguide polarizer with 3-section stepped-thickness septum configuration for the operating frequency range 7.70–8.50 GHz was developed, manufactured and tested. Measured values of VSWR and cross-polar discrimination of the prototype together with necessary transitions and bends within the stated above frequency range are less than 1.4 and higher than 30 dB, respectively. The developed compact stepped-thickness septum polarizer is a good candidate to be applied in the quasi-monopulse dual-circular polarization feed system of the ground station reflector antenna for tracking earth observing satellites.

In this study, a method was experimentally verified for further reducing the radar cross-section (RCS) of a two-dimensional planar target by using a dielectric rim in a dielectric barrier discharge (DBD) plasma generator using a frequency selective surface (FSS) as an electrode. By designing the frequency selective surface such that the passbands of the radar signal match, it is possible to minimize the effect of the conductor electrode, in order to maximize the RCS reduction effect due to the plasma. By designing the FSS to be independent of the polarization, the effect of RCS reduction can be insensitive to the polarization of the incoming wave. Furthermore, by introducing a dielectric rim between the FSS electrode and the target, an additional RCS reduction effect is achieved. By fabricating the proposed plasma generator, an RCS reduction effect of up to 6.4 dB in X-band was experimentally verified.

Phased array technology features rapid and directional scanning and has become a promising approach for remote sensing and wireless communication. In addition, element-level digitization has increased the feasibility of complicated signal processing and simultaneous multi-beamforming processes. However, the high cost and bulky characteristics of beam-steering systems have prevented their extensive application. In this paper, an X-band element-level digital phased array radar utilizing fully integrated complementary metal-oxide-semiconductor (CMOS) transceivers is proposed for achieving a low-cost and compact-size digital beamforming system. An 8–10 GHz transceiver system-on-chip (SoC) fabricated in 65 nm CMOS technology offers baseband filtering, frequency translation, and global clock synchronization through the proposed periodic pulse injection technique. A 16-element subarray module with an SoC integration, antenna-in-package, and tile array configuration achieves digital beamforming, back-end computing, and dc–dc conversion with a size of 317 × 149 × 74.6 mm3. A radar demonstrator with scalable subarray modules simultaneously realizes range sensing and azimuth recognition for pulsed radar configurations. Captured by the suggested software-defined pulsed radar, a complete range–azimuth figure with a 1 km maximum observation range can be displayed within 150 ms under the current implementation.

This article belongs to the Collection RF and Microwave Communications A new simple design of an inverted microstrip Gap Waveguide filtering antenna integrated with two stopband filters is proposed in this work. In order to simultaneously provide filtering and radiating functions, we use the direct integration approach to cascade two periodic sets of coplanar coupled EBG resonators with a slot antenna. The analysis shows that the filters can be easily adjusted in the same feeding layer of the antenna, without extra circuitry and without modifying the lines. EBG-filters are compact and offer great flexibility in determining the frequency, width and selectivity of the rejected bands. Experimental results for an X-band filtering antenna prototype are provided showing a 7.3% transmission band centered at 10.2 GHz and a realized gain peak of 2.1 dBi. The measurements demonstrate the filtering capability of the proposed antenna, achieving rejection levels greater than 12 dB and 20 dB for the bands below and above the operation band. The proposed low-complexity design offers good performance as a filter and as an antenna, showing the essential advantages of the Gap Waveguide Technology, including low losses, self-packaging and limited cost. This work demonstrates the possibility of integrating the new coplanar EBG-filters into future Gap Waveguide antenna designs to avoid unwanted radiation, to reduce interfering signals or to provide high isolation in multiband systems. This research was funded by the Spanish Ministerio de Ciencia, Innovación y Universidades grant numbers [Agencia Estatal de Investigación PID2019-107688RB-C21 and TEC2016-79700-C2-R].

An inset fed-microstrip patch antenna (MPA) with a partial ground structure is constructed and evaluated in this paper. This article covers how to evaluate the performance of the designed antenna by using a combination of simulation, measurement, creation of the RLC equivalent circuit model, and the implementation of machine learning approaches. The MPA’s measured frequency range is 7.9–14.6 GHz, while its simulated frequency range is 8.35–14.25 GHz in CST microwave studio (CST MWS) 2018. The measured and simulated bandwidths are 6.7 GHz and 5.9 GHz, respectively. The antenna substrate is composed of FR-4 Epoxy, which has a dielectric constant of 4.4 and a loss tangent of 0.02. The equivalent model of the proposed MPA is developed by using an advanced design system (ADS) to compare the resonance frequencies obtained by using CST. In addition, the measured return loss of the prototype is compared with the simulated return loss observed by using CST and ADS. At the end, 86 data samples are gathered through the simulation by using CST MWS, and seven machine learning (ML) approaches, such as convolutional neural network (CNN), linear regression (LR), random forest regression (RFR), decision tree regression (DTR), lasso regression, ridge regression, and extreme gradient boosting (XGB) regression, are applied to estimate the resonant frequency of the patch antenna. The performance of the seven ML models is evaluated based on mean square error (MSE), mean absolute error (MAE), root mean square error (RMSE), and variance score. Among the seven ML models, the prediction result of DTR (MSE = 0.71%, MAE = 5.63%, RMSE = 8.42%, and var score = 99.68%) is superior to other ML models. In conclusion, the proposed antenna is a strong contender for operating at the entire X-band and lower portion of the Ku-band frequencies, as evidenced by the simulation results through CST and ADS, it measured and predicted results using machine learning approaches.

Silicon carbide (SiC) has good chemical resistance, excellent mechanical properties, thermal conductivity, especially in extreme conditions of application, and has proved to be a very promising electromagnetic absorption material. However, single silicon carbide cannot meet the increasing demand for high performance of absorbing materials. It has become an important research direction to combine it with other absorbing materials to improve its absorbing performance. In this study, a composite absorber material was prepared by 50 wt.% micron-sized beta-silicon carbide (β-sic) powder, mixed with a 0.2 wt.% multiwalled carbon nanotubes (MWCNTs) and 50 wt.% polyurethane (PU) substrate. The mixture was stirred and deaerated to form a slurry, and sprayed onto synthetic fabric. The results showed that the composite material was flexible, with a thickness of less than 2 mm and favorable adhesion. The results obtained by reflection graph of the radar waves, indicated that the return loss within the X-band range (8–12 GHz) was less than −40 dB, indicating favorable radar wave absorption. Therefore, composite materials could thus be used successfully as radar wave absorbers, and was suitable for stealth materials in “asymmetric warfare”.

In this article, we demonstrate a low-cost 7.25-7.75 GHz two-stage low noise amplifier with sub-1-dB noise figure for satellite communication applications. The microstrip technology on Rogers RT5880 substrate with the dielectric constant of 2.2 and thickness of 0.508 mm were utilized to develop a low noise amplifier. The printed-circuit-board technology offers a variety of profits such as being low-cost, lighter-weight and re-configurability after the manufacturing process make this technology charming for satellite communication systems for both commercial and military applications. Since the monolithic microwave integrate circuit technology provide much smaller sized circuits and high electrical performance especially at the millimeter-wave frequencies, the printed microstrip technology can be a significant rival to integrated-circuit technology with its proven reliability, easier, cheaper and faster manufacturing process, compactible electrical performance in X-band applications. Moreover, the proposed amplifier was developed with utilizing California Eastern Laboratories’ CE3512K2 transistor on Rogers-RT5880 and surface mount devices were utilized in the matching networks to reduce the size. In addition, the source-generation and interstage matching topologies were implemented to simplify the matching complexity to enhance the noise and gain. The prototype was manufactured with utilizing LPKF prototyping machine. The developed LNA exhibits a measured gain of 23.5±0.5 dB with the noise figure of less than 0.9 dB and input/output return loss better than 11.5 dB in the operating frequency bandwidth. Furthermore, the developed amplifier has a measured carrier to interference of -59 dBc and P1dB of 13 dBm at the center frequency while consuming a total DC power of 50 mW.

Accurate measurement of water levels and variations in lakes and reservoirs is crucial for water management. The retrieval of the accurate variations in water levels in lakes and reservoirs with small widths from high-resolution synthetic aperture radar (SAR) images such as the TerraSAR add-on for Digital Elevation Measurements (TanDEM-X) and COnstellation of small Satellites for the Mediterranean basin Observation (COSMO-SkyMed) are presented here. A detailed digital surface model (DSM) for the upstream face of the dam was constructed using SAR interferometry with TanDEM-X data to estimate the water level. The elevation of the waterline below that of the interferometric SAR (InSAR) DSM was estimated based on upstream face modeling. The waterline boundary detected using the SAR Edge Detection Hough Transform algorithm was applied to the restored DSM. The SAR-derived water level variations showed a high correlation coefficient of 0.99 and a gradient of 1.08 with the gauged data. The difference between the gauged data and SAR-derived data was within ±1 m, and the standard deviation of the residual was 0.60 m. These results suggest that water level estimation can be used as an operational supplement for traditional gauged data at remote sites.

The research vessel ‘Polarstern’, moored to an ice floe, completed a year long drift with Arctic pack ice in the autumn of 2020. During that expedition, named MOSAiC, a comprehensive data set of airborne laser scanner (ALS) and spaceborne X-band SAR images in the area of the research vessel was acquired. With successful fusion of these two measurements, we can extrapolate sea ice features from the ALS data to the entire SAR scene using a convolutional neural network (CNN). From two preliminary scenes of ALS data we are able to show this for classes of sea ice roughness. This will be the basis for more comprehensive research, once the complete data set is available.

International audience; Multitemporal synthetic aperture radar (SAR) interferometry (InSAR) is a widely used technique to measure the ground subsidence and has already shown its ability to map such phenomena on a large spatial scale with millimetric accuracy from space. In Vietnam, to have independent SAR data for surface risk applications, a new X-band SAR mission (JV-LOTUSat) has been scheduled for launch for the 2019-2020 timeframe. However, Vietnam is located in tropical regions where their conditions are impacted by strong atmosphere. The aim of this article is to provide a better understanding of the capabilities of the X-band for estimating the ground subsidence under tropical atmospheric conditions. Analysis is carried out on two stacks, TerraSAR-X and Cosmos SkyMed X-band, from 2011 to 2014 in Ha Noi. We show that the results on the ground subsidence from InSAR processing can describe consistently the subsidence area based on ground measurements. This article demonstrates that the InSAR technique can be effective at detecting and estimating the subsidence phenomena even with the X-band and under conditions typical of tropical regions. The displacement results from TerraSAR-X and Cosmos SkyMed datasets are consistent, with a correlation coefficient (R2) of 0.91 for the period during which their coverage overlaps. Groundwater overexploitation is one of the main causes of the ground subsidence in Ha Noi. This study provides strong support for the scientific potential of the X-band SAR space-borne mission in Vietnam and other tropical countries because it demonstrates the feasibility of the ground subsidence estimates by the X-band SAR, even in conditions impacted by strong atmosphere.

In the future, the need to identify and sense objects through ultra-low-power or zero-power communication mechanisms will be more crucial than now. Backscattering-based radiofrequency identification (RFID) technology could still play a major role through the possible implementation of low-power identification (ID) and communication directly over other technologies. In this work, RFID capabilities are introduced over the X-band microwave motion sensor (MMS), typically used to detect and locate objects. Specifically, the concept of offset-carrier backscattering modulation is exploited to design a 10.525 GHz RFID system where the reader is purposely and slightly modified commercial and low-cost MMS (a few euros) to make the technology actually reliable. The transponder is instead a new microwave device capable of backscattering an MMS compatible wave modulating ID code and sensor data. The proposed RFID-over-MMS system has been designed, prototyped, and tested to verify the appropriateness of the proposed approach. © 2019 IEEE.