Status of the WEST Travelling Wave Array antenna design and results from the high power mock-up

A mock-up of the WEST TWA antenna was designed in 2019, manufactured during 2020 and installed in the TITAN test facility in the beginning of 2021. The paper presents the current status of the WEST TWA antenna, its mock-up and a possible extrapolation to DEMO. The updated WEST TWA design has a reduced antenna length and features feeding and mechanical support from a single vessel port. The first results of the mock-up at low power, its diagnostic system and the prospects are explained. Extensions versus a TWA antenna for WEST, and a possible DEMO TWA system are briefly discussed.

Sensitivity Analysis of FWI Applied to OVSP Synthetic Data for Fault Detection and Characterization in Crystalline Rocks

We have performed several sensitivity studies to assess the ability of the Full Wave Inversion method to detect, delineate and characterize faults in a crystalline geothermal reservoir from OVSP data. The distant goal is to apply the method to the Soultz-sous-Forêts site (France). Our approach consists of performing synthetic Full Wave 2D Inversion experiments using offset vertical seismic and comparing the estimated fields provided by the inversion, i.e., the estimated underground images, to the initial reference model including the fault target. We first tuned the inversion algorithmic parameters in order to adapt the FWI software, originally dedicated to a sedimentary context, to a crystalline context. In a second step, we studied the sensitivity of the FWI fault imaging results as a function of the acquisition geometry parameters, namely, the number of shots, the intershot distance, the maximum offset and also the antenna length and well deviation. From this study, we suggest rules to design the acquisition geometry in order to improve the fault detection, delineation and characterization. In a third step, we studied the sensitivity of the FWI fault imaging results as a function of the fault or the fault zone characteristics, namely, the fault dip, thickness and the contrast of physical parameters between the fault materials and the surrounding fresh rocks. We have shown that a fault with high dip, between 60 and 90° as thin as 10 m (i.e. lower than a tenth of the seismic wavelength of 120 m for Vp and 70 m for Vs) can be imaged by FWI, even in the presence of additive gaussian noise. In summary, for a crystalline geological context, and dealing with acceptable S/N ratio data, the FWI show a high potential for accurately detecting, delineating and characterizing the fault zones.

A new species of freshwater amphipod (Crustacea, Peracarida, Hyalellidae) from Southern Brazil

The freshwater amphipod of the genus Hyalella is typical from continental American waters and shows high levels of endemicity and Brazil has the second largest diversity. A new species is described here, Hyalella longipropodus n. sp. that occurs in a spring of southern Brazil in the municipality of Palmeira das Missões, in the northwestern region of state of Rio Grande do Sul, southern Brasil. Hyalella longipropodus n. sp. shows the following character states: antenna 2 more than half body length, gnathopod 2 propodus elongated, uropod 1 inner ramus of male without apical curved setae, uropod 3 peduncle with seven strong distal setae with accessory setae, ramus of uropod 3 with ten cuspidate setae with accessory setae. Hyalella longipropodus n. sp. occurs in sympatry with H. gauchensis, but these differ especially in the size and shape of gnathopod 2, the presence of curved setae on uropod 1 in H. gauchensis and the absence in H. longipropodus n. sp., antenna length (longer in H. longipropodus n. sp.) and number of cuspidate setae on uropods 1, 2, and 3. Besides the morphological differences, H. longipropodus n. sp. presented genetic differences always above 19% for the COI gene and 29 % for the 16S rRNA gene, when compared with other species found in the northwestern region of the state of Rio Grande do Sul, showing that it is really a species not yet described by science.

Single-nanoantenna driven nanoscale control of the VO2 insulator to metal transition

The ultrafast concentration of electromagnetic energy in nanoscale volumes is one of the key features of optical nanoantennas illuminated at their surface plasmon resonances. Here, we drive the insulator to metal phase transition in vanadium dioxide (VO2) using a laser-induced pumping effect obtained by positioning a single gold nanoantenna in proximity to a VO2 thermochromic material. We explore how the geometry of the single nanoantenna affects the size and permittivity of the nanometer-scale VO2 regions featuring phase transition under different pumping conditions. The results reveal that a higher VO2 phase transition effect is obtained for pumping of the longitudinal or transversal localized surface plasmon depending on the antenna length. This characterization is of paramount importance since the single nanoantennas are the building blocks of many plasmonic nanosystems. Finally, we demonstrate the picosecond dynamics of the VO2 phase transition characterizing this system, useful for the realization of fast nano-switches. Our work shows that it is possible to miniaturize the hybrid plasmonic-VO2 system down to the single-antenna level, still maintaining a controllable behavior, fast picosecond dynamics, and the features characterizing its optical and thermal response.

Miniaturized Dielectric Disc Loaded Monopole Antenna

This paper deals with miniaturization technique based on frequency reduction using top loaded dielectric discs. In contrast to a simple monopole, the resonant frequency of monopole loaded with two dielectric discs changes from 1.98 to 1.29 GHz, resulting 34.84% reduction in resonant frequency keeping the antenna length (36.00 mm) unaltered. It is well-known fact that dielectric material can trap the energy to be delivered from source to antenna and as a result, it is unable to radiate efficiently. Then any approach to use the dielectric material for miniaturization process must, therefore, antenna coupled in such a way that it can radiate efficiently. The dielectric disc on top of monopole creates an inductive situation in a similar way to oppositely directed wire loop compensate the capacitive effect present at monopole causes the reduction in resonant frequency. This concept is implemented without sacrificing any desired features like bandwidth, radiation characteristics and efficiency (more than 98%) and analyzed with an equivalent circuit model. Experimental results illustrate good agreement with simulation results. This monopole antenna in car can be designed for GPS system, car to car communication, GSM or CDMA operation.

Design and Optimization for 77 GHz Series-Fed Patch Array Antenna Based on Genetic Algorithm

This paper proposes a method for designing a 77 GHz series-fed patch array antenna. Based on the traditional genetic algorithm, the study explores different array topologies consisting of the same microstrip patches to optimize the design. The main optimization goal is to reduce the maximum sidelobe level (SLL). A 77 GHz series-fed patch array antenna for automotive radar was simulated, fabricated, and measured by employing this method. The antenna length was limited to no longer than 3 cm, and the array only had a single compact series with the radiation patch about 1.54 mm wide. In the genetic algorithm used for optimization, the maximum sidelobe level was set equal to or less than −14 dB. The measurement results show that the gain of the proposed antenna was about 15.6 dBi, E-plane half-power beamwidth was about ±3.8°, maximum sidelobe level was about −14.8 dB, and H-plane half-power beamwidth was about ±30° at 77 GHz. The electromagnetic simulation and the measurement results show that the 77 GHz antenna designed with the proposed method has a better sidelobe suppression by over 4 dB than the traditional one of the same length in this paper.

SIMULASI ANTENA DIPOLE ½ λ DENGAN FREKUENSI KERJA 128,4 MHz UNTUK RADIO PEMANCAR ATIS MENGGUNAKAN SOFTWARE SIMULASI DI BANDAR UDARA INTERNASIONAL HUSEIN SASTRANEGARA BANDUNG

VHF telecommunications radio equipment, especially ATIS equipment is equipment used to inform information around the airport, such as weather, taxiways, runaway, etc. ATIS equipment works on frequencies between 118-137 MHz. The problem that arises is in the ATIS equipment that is the lack of antenna beam coverage on the ATIS radio transmitter, which is <100 NM, while the normal ATIS beam range is in the range of 150-200 NM. The author simulates dipole antenna ½ λ using the CST studio SUITE software application and compares the results of the simulation with the antenna specifications on the current ATIS equipment. Antenna simulation is done by making antenna dimensions and calculating the wavelength parameters, antenna length, antenna gap width, then the simulation results with the antenna length of 1040 mm and a gap of 5.545 mm, and a diameter of 3 mm, the results obtained are VSWR of 1.51 and return loss of -13,804, with a bandwidth of 12.13 MHz. These parameters were compared with the ATIS equipment antenna specifications at Bandung Husein Sastranegara International Airport and there was an increase in parameters after simulating.

Trait-environment relationships are predictive, but not general across species

Understanding the relationships between organisms and their environments is increasingly important given human impacts on global conditions. However, predicting how community diversity and composition will change in the future remains challenging (Mouquet et al 2015). One recent approach is to use traits to mechanistically inform how environmental conditions affect performance (i.e., trait-environment relationships), under the assumptions that these measures relate to each other in predictive and general ways. Unfortunately, results have been inconsistent, ignore phenotypic plasticity, and rely heavily on observational data (Shipley et al 2016). We evaluated the predictability and generality of trait-environment relationships in a controlled experimental microcosm system of four daphniid species. We cultured each species along a stressful gradient (conspecific density), measuring performance (fecundity) and traits related to performance (body length, 2nd antenna length, eye diameter, relative growth rate, and age at first reproduction). Using structural equation models, we evaluated the role of traits in mediating changes in individual fecundity in response to conspecific density. We built models for each species separately considering within-species trait variation, and for all species together by considering all trait variation across the four species. Results from this controlled system highlight that the relationship between individual traits and the environment (conspecific density) is strong and predictive of performance (fecundity), both within- and across-species. However, the specific trait-environment relationships which predicted fecundity differed for each species and differed from the relationships observed in the interspecific model, suggesting a lack of generality. These results will inform and improve the use of traits as a tool for predicting how changing environments will impact species abundances and distributions.

Compact Wideband Dual-Frequency Antenna Based on a Simplified Composite Right/Left-Handed Transmission Line with Hilbert Curve Loading

This paper addresses the issues of low bandwidth, gain, and efficiency of miniaturized microwave antennas by proposing a novel wideband dual-frequency coplanar waveguide antenna design based on a simplified composite right/left-handed (SCRLH) transmission line structure with Hilbert curve loading. The multifrequency characteristics of the SCRLH transmission line structure are evaluated theoretically, and the antenna parameters promoting bandwidth broadening under zeroth-order resonance (ZOR) and first-order resonance (FOR) mode operation are evaluated. The bandwidth broadening in the ZOR and FOR modes is accordingly revealed to be independent of the antenna length, and the structure therefore facilitates wideband operation under miniaturization. Finally, the dual-frequency ZOR and FOR mode antenna design with center frequencies of f0 = 1.865 GHz and f1 = 2.835 GHz is validated via simulation, and the performance of a compact prototype antenna is evaluated experimentally. The −10 dB return loss bandwidths at f0 and f1 are 187 MHz (from 1.773 GHz to 1.96 GHz) and 368 MHz (from 3.002 GHz to 3.37 GHz), and the corresponding relative bandwidths are 10.1% and 11.5%, respectively. The experimentally measured peak gains and radiation efficiencies at f0 are 1.54 dB and 81.3%, respectively, and those at f1 are 1.71 dB and 74.2%, respectively.

Synthetic Aperture Radar for Small Satellite

Small satellites are growing because they have shorter development cycles, lower cost, new technologies, and more frequent access to space. Sensors for Small satellites come with trade-offs to allow them fit within the mass, size, power and weight constraints imposed by the platform, these trade-offs between sensor system parameters can affect the mission requirements. Considering traditional SAR mission, each frequency band has different capability of penetration and special image characteristics, so the final SAR application will determine the appropriate bands needed. Small satellites come with constraints on the SAR sensor, so an analysis of SAR sensor system parameters (antenna length, antenna width and average transmitted power) at L, C and X band given a determined performance parameters is presented to analyze the effect of these frequency change on the system parameters and to determine the frequency band that is more suitable to fit within the small satellite SAR sensors constraints.