Compact and Planar End-fire Antenna for PicoSat and CubeSat Platforms to Support Deployable Systems

A miniaturized planar Yagi-Uda antenna for integration with PicoSats or other SmallSat missions is proposed. Miniaturization techniques, such as meandering and 1-D artificial dielectric concepts to reduce the guided wavelength, are employed to overcome space constraints imposed by the SmallSat footprint while still maintaining good performance for the FR-4 antenna. Simulations and measurements have been carried out on the Unicorn-2 PicoSat chassis from Alba Orbital and are in good agreement. Also, antenna dimensions have been reduced between 15% and 66% when compared to a more conventional planar Yagi-Uda antenna working at the same frequency. This compactness allows for simple integration with the deployable solar panel array of the Unicorn-2 PicoSat spacecraft. Full end-fire radiation is achieved and peak gain values are about 5 dBi for the antenna when fully integrated on the satellite chassis, offering an attractive solution for downlink connectivity. This compact antenna design can also be used within an array for beam steering or integrated within the solar cell modules of other PicoSats, CubeSats and SmallSats. Applications include Earth observation, remote sensing, as well as SmallSat to ground station communications. The planar Yagi-Uda antenna may also be useful wherever end-fire radiation is required from a compact antenna structure

Use of Omniflow® II Biosynthetic Graft for the Treatment of Vascular Graft and Endograft Infections

Background: Vascular graft/endograft infection is a rare but life-threatening complication of cardiovascular surgery and remains a surgical challenge. Several different graft materials are available for the treatment of vascular graft/endograft infection, each having its own advantages and disadvantages. Biosynthetic vascular grafts have shown low reinfection rates and could be a potential second best after autologous veins in the treatment of vascular graft/endograft infection. Therefore, the aim of our study was to evaluate the efficacy and morbidity of Omniflow® II for the treatment of vascular graft/endograft infection.Methods: A multicenter retrospective cohort study was performed to evaluate the use of Omniflow® II in the abdominal and peripheral region to treat vascular graft/endograft infection between January 2014 and December 2021. Primary outcome was recurrent vascular graft infection. Secondary outcomes included primary patency, primary assisted patency, secondary patency, all-cause mortality, and major amputation.Results: Fifty-two patients were included with a median follow-up duration of 26.5 (10.8–54.8) months. Nine (17%) grafts were implanted in intracavitary position and 43 (83%) in peripheral position. Most grafts were used as femoral interposition (n = 12, 23%), femoro-femoral crossover (n = 10, 19%), femoro-popliteal (n = 8, 15%), and aorto-bifemoral (n = 8, 15%) graft. Fifteen (29%) grafts were implanted extra-anatomically and 37 (71%) in situ. Eight patients (15%) presented with reinfection during follow-up, most of these patients received an aorto-bifemoral graft (n = 3, 38%). Intracavitary vascular grafting had a 33% (n = 3) reinfection rate and peripheral grafting 12% (n = 5; P = 0.025). The estimated primary patencies at 1, 2, and 3 years were 75%, 72%, and 72% for peripherally located grafts and 58% (at all timepoints) for intracavitary grafts (P = 0.815). Secondary patencies at 1, 2, and 3 years were 77% (at all timepoints) for peripherally located prostheses and 75% (at all timepoints) for intracavitary prostheses (P = 0.731). A significantly higher mortality during follow-up was observed in patients who received an intracavitary graft compared to patients with a peripheral graft (P = 0.003).Conclusions: This study highlights the efficacy and safety of the Omniflow® II biosynthetic prosthesis for the treatment of vascular graft/endograft infection, in absence of suitable venous material, with acceptable reinfection, patency, and freedom of amputation prevalences, especially in replacing peripheral vascular graft/endograft infection. However, a control group with either venous reconstruction or another alternative graft is needed to make firmer conclusions.</p

Antenna Elements Integrated into the Parachutes of Planetary Entry Probes

This presentation was part of the session : Ongoing and Proposed EDL Technology DevelopmentSixth International Planetary Probe WorkshopThe canopy of the parachutes of planetary entry probes may be used to integrate elements of the antennas in charge of the communications with the orbiter spacecraft during the descent. The additional surface provided by the parachute may allow the implementation of higher gain antennas compared to more conventional solutions where the antenna is installed on the lander. For missions where the acquired scientific data needs to be transmitted during the descent through the atmosphere, the higher gain could maximize the scientific return of the mission. In this paper, designs for a steerable S-band patch array antenna located on the canopy of a disk-gap-band parachute are presented. A retrodirective technique is used to point the antenna beam in the direction of the orbiter. The design concept is flexible and can be adapted to different mission requirements and constraints (frequency band, etc.). Different configurations are analysed in terms of the antenna performance, the aerodynamics of the parachute, the link budget, and the impact on the mission at system level. A system prototype is being built and will be dropped from a balloon for testing. Finally, recommendations on the developments required for this technology as well as on its potential applications are provided, including the analysis of the possible use of these antennas for planetary exploration balloons.European Space Agenc

Scan-optimized integrated lens antennas

In this paper the scan properties of integrated lens antennas with a quarter-wavelength matching layer are analyzed. For beam scanning on and within a cone, optimum feed positions are determined. It appears that for beam scanning on a cone the elliptical lens is the best choice if a small scan angle is required while the extended hemispherical lens should be used in case of a large scan angle. For beam scanning within a cone it is recommended to select an elliptical lens if a large average directivity is required while the extended hemispherical lens appears to be the best choice if a small variation in the directivity is important

Phase-Sensitive Near-Field Measurements and Electromagnetic Simulations of a Double-Slot HEB Integrated Lens-Antenna Mixer at 1.1, 1.2 and 1.6 THz

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