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"Rapportage thema 0 Huidige kennis van soortenrijke dijkvegetaties en de relatie met bodem en sterkte, HWBP Future Dikes: soortenrijke grasbekleding fase 1." Voorafgaand aan het nieuwe onderzoek dat wordt beschreven in Thema’s 1 tot en met 4 van Future Dikes is eerst uitgebreid onderzoek gedaan naar wat er al bekend is over dijken in Nederland. Om de resultaten van Future Dikes in een breder perspectief te kunnen plaatsen is het immers nodig om inzicht te hebben in eerdere onderzoeken van dijken en dijk-vegetaties en de resultaten ervan. De rapportage van Thema 0 beschrijft de uitgebreide beschouwing van eerdere onderzoeken met betrekking tot dijkvegetaties in het algemeen en specifiek met betrekking tot de sterkte van grasbekledingen. De focus lag hierbij met name op het verkrijgen van inzicht in de vegetatie-eigenschappen, de relatie met standplaatsomstandigheden met als belangrijkste factor de bodem en de sterkte en erosiebestendigheid van soortenrijke dijkvegetaties, en dat in verhouding tot de sterkte en erosiebestendigheid van grasgedomineerde vegetaties.

This contribution presents the development of an electrically small lens antenna using an artificially loaded thermoplastic at 140-170GHz. We will present the on-going development of the Fly’s Eye front end antenna concept that was presented in [1]. The antenna is composed on a dual plastic lens, a core lens and a shell lens, fed by a double slot. The core-lens, being presented in this contribution, is a spherical lens made from an artificially loaded plastic of permittivity 9.5. To the best of our knowledge, this thermoplastic material has not been used for lens antennas in this frequency range before. A 4mm lens prototype has been developed using this material, which includes an antireflective layer synthesized by drilling sub-wavelength holes on the lens contour. Full-wave simulations show a negligible degradation of the performance of the anti-reflection layer compared to an ideal homogeneous matching layer. Physical measurements and antenna measurements confirm that the antenna's performance matches the design specifications., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Tera-Hertz Sensing, Electronics

We report on the first demonstration of dynamic beam steering using a scanning lens phased array. A scanning lens phased array relies on a combination of mechanical and electrical phase shifting to dynamically steer a high-gain beam beyond the grating-lobe free region using a sparse array. These two concepts have been demonstrated separately in the past, here we present, for the first time, a prototype demonstration where active mechanical and electrical phase shifting are combined. For this purpose, we have developed a sparse 4x1 scanning lens phased array at W-band (75-110 GHz) capable of beam steering a directive beam (>30 dBi) towards ± 20° with low grating lobe levels (around -10 dB). The lens array is fed by a waveguide-based leaky-wave feeding architecture that illuminates the lenses with high aperture efficiency over a wide bandwidth, which is required in the proposed scanning lens phased array architecture. The electrical phase shifting has been implemented using IQ-mixers around 15 GHz in combination with x6 multipliers to reach the W-band. The mechanical phase shifting relies on a piezo-electric motor, which is able to achieve displacements of the lens array of 6 mm with an accuracy of a few nanometers. The entire active array is calibrated over the air with an ad-hoc quasi-optical measurement setup. Resulting measurements show excellent agreement with the anticipated performance., Tera-Hertz Sensing, Electronics

This work presents a novel lens antenna architecture based on a core-shell lens design with a leaky-wave in-packaged antenna at 150GHz. An electrically small core lens made of dense dielectric material is used to enhance the radiation of the in-packaged antenna. A low-loss dielectric shell lens with electrically large dimensions is then added to provide high directivity. A microstrip feeding network for connection to a 150GHz chipset is then also discussed. The proposed lens antenna provides good quality patterns with aperture efficiencies above 80% over a bandwidth of 20%., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Tera-Hertz Sensing, Electronics

We report the measured results of a sparse, 4x1 scanning lens phased array prototype at W-band that is capable of beam steering a directive (>30 dBi) beam towards ±20° with sidelobe levels around -10 dB. The array elements are high-aperture-efficiency resonant leaky-wave lens antennas with a feed that suppresses the spurious TM0 mode over a wide bandwidth by using a circular waveguide in a ground plane surrounded by annular corrugations. The scanning lens phased array relies on simultaneous electrical and mechanical phase shifting to steer the beams. We use 15 GHz IQ-mixers followed by x6 multipliers to achieve electronic amplitude and phase control at W-band and a piezo-electric motor for mechanical phase shifting, which allows us to scan this array up to 20°. Measurements at 90 GHz of the lens array are in excellent agreement with simulations. More measurement results will be presented at the conference., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Tera-Hertz Sensing, Electronics

We present a resonant leaky-wave lens antenna, fed by a circular waveguide with annular corrugations in the ground plane. The proposed leaky-wave feed reduces the impact of the spurious TM0 leaky-wave mode in all planes over a wide bandwidth while reducing assembly complexity compared to previous methods. The proposed leaky-wave antenna has an aperture efficiency above 80%, a return loss below -15 dB, and a cross-polarization level below -20 dB over a bandwidth from 110-220 GHz (2:1). We have fabricated and measured a WR-5 band (140-220 GHz) antenna prototype with a lens diameter of 3 cm that achieves excellent agreement between measurement and simulation in terms of return loss, directivity, and gain., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Tera-Hertz Sensing

In this contribution, we present a plastic resonant leaky-wave lens antenna with high aperture efficiency (>80%) over a 1:2 bandwidth centered at 180 GHz. This antenna can be integrated in a scanning lens phased array architecture for next-generation wireless and sensing applications that require high-directivity steerable beams. The high aperture efficiency is achieved thanks to the combination of annular corrugations in the ground plane with a leaky-wave resonant cavity. A WR-5 (140-220 GHz) prototype is manufactured and measured in terms of reflection coefficient, radiation patterns, directivity, losses, cross-polarization and scan performance, showing excellent agreement with simulations., Accepted author manuscript, Tera-Hertz Sensing

For the Environmental Data Compendium, including the Digital Environmental Balance, ecosystem quality and trends in availability of nutrients are assessed by using indices based on plant species. This report presents a study to determine the most suitable indicator system for assessing nitrogen availability to plants. Three existing indicator systems were compared: ITERATIO, Ellenberg indicator value and Wamelink-NO3. First, correlations between the different indices were examined, then indices were calculated for different plant communities and the outcomes were evaluated by vegetation experts. Subsequently, three datasets on species composition and biomass/fertilisation rates were analysed in order to relate biomass/fertilisation data to trophic indicator values. Lastly, trends in trophic level were calculated for eleven time series of permanent vegetation recordings of the Strabrechtse Heide heathland. Based on these analyses it was concluded that ITERATIO and Ellenberg produced the most reliable results. Neither Wamelink-NO3, nor other Wamelink indicator values are deemed suitable for assessing nutrient availability as they each focus on a single macronutrient. This is not sufficient to grasp the complexity of nutrient availability in ecosystems., Voor het Compendium van de Leefomgeving en de Digitale Balans wordt voor de kwaliteit en trend van milieucondities gebruikgemaakt van indicatiewaarden van planten. In dit document wordt geprobeerd antwoord te geven op de vraag wat een goed indicatiesysteem is voor de nutriëntenbeschikbaarheid van planten als indicator voor veranderingen in voedselrijkdom (vermesting). Op verschillende manieren is getracht deze vraag te beantwoorden, waarbij de aandacht zich voornamelijk richt op drie indicatiesystemen, namelijk ITERATIO-trofie, Ellenberg-trofie en Wamelink-NO3. Op de eerste plaats is gekeken naar hoe de verschillende indicatoren met elkaar correleren. Daarnaast zijn voor de verschillende indicatoren ecologische diagrammen opgesteld van plantengemeenschappen die onderling zijn vergeleken door experts. Verder is een drietal opnamensets doorgerekend waarbij per opname bekend is wat de biomassa/mestgift is, zodat berekende trofie-indicaties direct hieraan konden worden gekoppeld. Ten slotte zijn van een elftal meerjarige PQ-reeksen van de Strabrechtse heide de trends in trofie doorgerekend. Op basis van deze analyses is geconcludeerd dat ITERATIO- en Ellenberg-trofie goede indicatoren voor nutriëntenbeschikbaarheid zijn, zeker ook als het gaat om het detecteren van temporele veranderingen in de vegetatie. WW-NO3 of ieder andere WW-indicator kan niet als trofie-indicator worden ingezet, omdat slechts één macronutriënt niet voldoende is om de complexiteit van nutriëntenbeschikbaarheid te vatten.