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Global barley production is threatened by plant pathogens, especially the rusts. In this study we used a targeted genotype-by-sequencing (GBS) assisted GWAS approach to identify rust resistance alleles in a collection of 287 genetically distinct diverse barley landraces and historical cultivars available in the Australian Grains Genebank (AGG) and originally sourced from Eastern Europe. The accessions were challenged with seven US-derived cereal rust pathogen races including Puccinia hordei (Ph-leaf rust) race 17VA12C, P. coronata var. hordei (Pch-crown rust) race 91NE9305 and five pathogenically diverse races of P. striiformis f. sp. hordei (Psh-stripe rust) (PSH-33, PSH-48, PSH-54, PSH-72 and PSH-100) and phenotyped quantitatively at the seedling stage. Novel resistance factors were identified on chromosomes 1H, 2H, 4H and 5H in response to Pch, whereas a race-specific QTL on 7HS was identified that was effective only to Psh isolates PSH-72 and PSH-100. A major effect QTL on chromosome 5HL conferred resistance to all Psh races including PSH-72, which is virulent on all 12 stripe rust differential tester lines. The same major effect QTL was also identified in response to leaf rust (17VA12C) suggesting this locus contains several pathogen specific rust resistance genes or the same gene is responsible for both leaf rust and stripe rust resistance. Twelve accessions were highly resistant to both leaf and stripe rust diseases and also carried the 5HL QTL. We subsequently surveyed the physical region at the 5HL locus for across the barley pan genome variation in the presence of known resistance gene candidates and identified a rich source of high confidence protein kinase and antifungal genes in the QTL region.

The mitochondrial genome of Liriodendron tulipifera exhibits many ancestral angiosperm features and a remarkably slow evolutionary rate, while mitochondrial genomes of other magnoliids remain yet to be characterized. We assembled nine new mitochondrial genomes, representing all genera of perianth-bearing Piperales, as well as for a member of the sister clade: three complete or nearly complete mitochondrial genomes from Aristolochiaceae and six additional draft assemblies including Thottea, Asaraceae, Lactoridaceae, and Hydnoraceae. For comparative purpose, a complete mitochondrial genome was assembled for Saururus, a member of the perianth-less Piperales. The average number of short repeats (50–99 bp) was much larger in genus Aristolochia than in other angiosperm mitochondrial genomes, and approximately 30% of repeats ( T:A substitutions of all other investigated angiosperm groups. Our study reports the first mitochondrial genomes for Piperales and uses this new information for a better understanding of the evolutionary patterns of magnoliids and angiosperms in general.

Leaf rust, caused byPuccinia hordei, is one of the most widespread and damaging foliar diseases affecting barley (Hordeumspp.). The barley leaf rust resistance locusRph7, located on the short arm of chromosome 3H, confers defence at all growth stages and was previously shown to have unusually high sequence and haplotype divergence. Earlier, four candidate genes forRph7were reported and, despite an in-depth comparative sequence analysis and haplotypic characterisation, the causal gene could not be resolved. Here, we successfully clonedRph7utilising a fine mapping approach in combination with an RNA-Seq based expression analysis. We identified three up-regulated and pathogen-induced genes with presence/absence variation (PAV) at this locus. Sequence analysis of chemically inducedRph7knockout mutant lines identified multiple independent non-synonymous variants, including a premature stop codon in a single non-canonical resistance gene that encodes a 302-amino acid protein. Progeny from four independent transgenic lines segregated for the expected avirulentRph7infection type in response to several avirulentP. hordeipathotypes, however, all plants were susceptible to a single virulent pathotype confirming the specificity. Structural analysis using an AlphaFold2 protein model suggests thatRph7encodes a putative NAC transcription factor, as it shares structural similarity to ANAC019 fromArabidopsis, with a C-terminal BED domain. A global gene expression analysis suggestsRph7is involved in the activation of basal defence.

Most resistance genes thus far isolated from wheat have a very limited number of functional alleles, with the exception of the powdery mildew PM3 resistance locus. Here we report the isolation of most of the alleles at wheat stem rust resistance gene locus SR9, representing the largest multi-allelic rust resistance locus in common wheat. The seven previously reported resistance alleles (Sr9a, Sr9b, Sr9d, Sr9e, Sr9f, Sr9g, and Sr9h) at the locus were characterised using a synergistic strategy. Loss-of-function mutants and/or transgenic complementation were used to confirm Sr9b, two haplotypes of Sr9e (Sr9e_h1, Sr9e_h2), Sr9g, and Sr9h. Each allele encodes a highly related nucleotide-binding site leucine-rich repeat (NB-LRR) type immune receptor, containing a previously unreported motif at their N termini and an unusual long LRR domain, that confers resistance to a unique spectrum of isolates of the wheat stem rust pathogen. The only SR9 protein effective against stem rust pathogen race TTKSK (Ug99), SR9H, differed from SR9B by a single amino acid. SR9B and SR9G resistance proteins were also distinguished by only a single amino acid. The SR9 allelic series found in the B subgenome are orthologs of wheat stem rust resistance gene Sr21 located in the A subgenome with around 85% identity in protein sequences.

Summary Leaf rust, caused by Puccinia hordei, is a devastating fungal disease affecting barley (Hordeum vulgare subsp. vulgare) production globally. Despite the effectiveness of genetic resistance, the deployment of single genes often compromises durability due to the emergence of virulent P. hordei races, prompting the search for new sources of resistance. Here we report on the cloning of Rph15, a resistance gene derived from barley’s wild progenitor H. vulgare subsp. spontaneum. We demonstrate using introgression mapping, mutation and complementation that the Rph15 gene from the near‐isogenic line (NIL) Bowman + Rph15 (referred to as BW719) encodes a coiled‐coil nucleotide‐binding leucine‐rich repeat (NLR) protein with an integrated Zinc finger BED (ZF‐BED) domain. A predicted KASP marker was developed and validated across a collection of Australian cultivars and a series of introgression lines in the Bowman background known to carry the Rph15 resistance. Rph16 from HS‐680, another wild barley derived leaf rust resistance gene, was previously mapped to the same genomic region on chromosome 2H and was assumed to be allelic with Rph15 based on genetic studies. Both sequence analysis, race specificity and the identification of a knockout mutant in the HS‐680 background suggest that Rph15‐ and Rph16‐mediated resistances are in fact the same and not allelic as previously thought. The cloning of Rph15 now permits efficient gene deployment and the production of resistance gene cassettes for sustained leaf rust control.

For the first time, a liquid crystal (LC) filled lens antenna is investigated for beam steering in this paper. The LC’s anisotropy is applied inside a semicircular shaped parallel-plate waveguide to achieve a deflection of the propagating electromagnetic wave at the interface of lower and higher permittivities. Using an electrode network, the direction of the sector of higher permittivity can be adjusted and, therefore, so can the beam direction. The main advantage of this antenna concept is that neither phase shifters nor switching networks are needed, resulting in a very simple approach for beam steering. Operating at $V$ -band, from 50 to 75 GHz, the first demonstrator proves the antenna concept by reconfiguring the beam in predefined directions of −30°, 0°, and +30° to simplify the electrode biasing network. Furthermore, it is feasible and being demonstrated to adjust the beamwidth and to generate multiple beams. In the measurements, the antenna exhibits a measured input reflection below −10 dB over the complete frequency range. For the unsteered radiation pattern, the sidelobe level is between −8 and −12 dB, whereas these values degrade to −4.5 to −6 dB for the steered radiation pattern at ±30°. The measured gain is between 13 and 15 dBi.

In this study, we evaluated a new aspect of negative pressure wound therapy (NPWT) as an analytical tool for pharmacokinetic studies. Twenty-one patients with soft tissue defects scheduled to receive NPWT were included in this study. Concomitant to NPWT, all patients received intravenous moxifloxacin (MX). At different time intervals, blood plasma levels of MX were sampled and compared with synchronous concentrations of MX in the exudate obtained from the NPWT drainage system. Serial measurements were performed upon initiation of the therapy as well as in the steady state (after 5 days). At steady state, wound tissue was obtained intraoperatively. High-performance liquid-chromatography (HPLC) was used for analysis. At 1 hour post-administration, the exudate/plasma levels (mg/L) were 1.92/3.07; at 12 hours, 0.80/1.14; at 24 hours, 0.26/0.43; and at 120 hours (steady state), 0.42/0.47. There was a correlation between exudate and plasma levels reaching approximately 0.75. Until now, methods for pharmacokinetic studies concerning interstitial fluid are difficult to apply in the clinical context. The presented method showed limitations, but we believe that, after methodological improvements, measurements of substances in the interstitial fluid by means of NPWT are feasible.

Universal angiosperm enrichment probe sets designed to enrich hundreds of putatively orthologous nuclear single-copy loci are increasingly being applied to infer phylogenetic relationships of different lineages of angiosperms at a range of evolutionary depths. Studies applying such probe sets have focused on testing the universality and performance of the target nuclear loci, but they have not taken advantage of off-target data from other genome compartments generated alongside the nuclear loci. Here we do so to infer phylogenetic relationships in the orchid genus Epidendrum and closely related genera of subtribe Laeliinae. Our aims are to: 1) test the technical viability of applying the plant anchored hybrid enrichment (AHE) method (Angiosperm v.1 probe kit) to our focal group, 2) mine plastid protein coding genes from off-target reads; and 3) evaluate the performance of the target nuclear and off-target plastid loci in resolving and supporting phylogenetic relationships along a range of taxonomical depths. Phylogenetic relationships were inferred from the nuclear data set through coalescent summary and site-based methods, whereas plastid loci were analyzed in a concatenated partitioned matrix under maximum likelihood. The usefulness of target and flanking non-target nuclear regions and plastid loci was assessed through the estimation of their phylogenetic informativeness. Our study successfully applied the plant AHE probe kit to Epidendrum, supporting the universality of this kit in angiosperms. Moreover, it demonstrated the feasibility of mining plastome loci from off-target reads generated with the Angiosperm v.1 probe kit to obtain additional, uniparentally inherited sequence data at no extra sequencing cost. Our analyses detected some strongly supported incongruences between nuclear and plastid data sets at shallow divergences, an indication of potential lineage sorting, hybridization, or introgression events in the group. Lastly, we found that the per site phylogenetic informativeness of the ycf1 plastid gene surpasses that of all other plastid genes and several nuclear loci, making it an excellent candidate for assessing phylogenetic relationships at medium to low taxonomic levels in orchids.

In this work, multimode interference is investigated for the design of a two-dimensional fully dielectric power divider, well suited for the usage of dielectric waveguides. Most important, power division is achieved in a single device without the need of cascading multiple dividers. This allows to design a very compact and lightweight power divider, well applicable for dielectric rod antenna arrays. As a proof of concept for the used technique, a 16-way power divider with 4 × 4 output ports, made out of Rexolite, is realized, working in a frequency range between 90 and 105 GHz. For the S-parameter measurements, a special measurement setup, including a modular pin probe technique as well as radiation taper for waveguide termination, is proposed. The measurements are in good agreement with the simulations with a power split of − 15 dB for all output ports within the desired frequency range. This is equal to an additional insertion loss of 3 dB. To demonstrate the usability for antenna arrays, a fully dielectric rod antenna array is realized based on the proposed power divider. With this array, a gain of 22.5 dBi at 97.5 GHz was achieved.

Tunable microwave devices will play an important role in future wireless systems, in which high-frequency bands, e.g. millimeter waves, will become promising, due to its huge spectrum availability. At such frequency bands, liquid crystals (LCs) exhibit low microwave loss, which is excellent compared with the other tuning elements. In this paper, LC-based microwave components are fabricated by using low temperature co-fired ceramic technology, allowing the integration of the LC into microwave structures. The first component, the amplitude tuner, controls the signal's amplitude by using the interference concept, which exhibits a tunable attenuation range from 11 dB to 30 dB at 30 GHz. The second component is a 3-pole tunable bandpass filter, which is realized by using a substrate integrated waveguide topology, enabling a device with comparatively high-quality factors (Q-factors). The measurement results show Q-factors in the range of 68 to 100 for a frequency tuning of 29.4–30.1 GHz, i.e. a tuning range of 700 MHz, accompanied by an insertion loss 2 dB to 4 dB.

This study presents the first continuously tuneable, interference-based W-band single-pole double-throw (SPDT), fully implemented in subwavelength (sWL) dielectric fibre topology. Key components are the phase shifters in the two branches of the SPDT, which are realised as line sections filled with liquid crystal. They allow not only to adjust the signal ratios at the two output ports but also to tune the operating frequency between 93 and 110 GHz with isolation >25 dB. The first proof-of-concept SPDT demonstrator is realised and characterised at W-band. However, concept and technology are scalable to higher frequencies. The complete SPDT with the WR10-to-sWL fibre transitions exhibits an insertion loss (IL) at the thru-port between 5 and 7 dB in the frequency range from 85 to 110 GHz, where back-to-back measurements of the transitions itself already indicate an IL of up to 1.6 dB. The measurements at the isolated port of the SPDT exhibit transmission coefficients of less than -25 dB between 93 and 110 GHz with a minimum of -40 dB.

In this work, a CAD approach to model the effective dielectric properties of binary composite ceramics with high dielectric contrast is presented. Further, composite materials consisting of the tunable ferroelectric material barium strontium titanate (BST) with ɛ f ≈ 2000 ɛ 0 and magnesium borate (MBO) with ɛ d ≈ 7 ɛ 0 were fabricated in 10 volume percent steps. The morphology of the real materials was used to generate a micro granular sample for the CAD model. The material samples were processed to 0.5 mm thick and 8.5 mm wide discs and covered with silver electrodes, forming a parallel-plate capacitor. The dielectric properties of the composites were extracted from the capacitors by means of impedance spectroscopy at 100 MHz. The measured dielectric properties are compared to the proposed numerical model and to a widely used equivalent medium approximation model with regard to effective permittivity, quality factor and tunability.

In this letter, we present a fully dielectric antenna array for the first time, including a single multimode interference power divider as feeding network. This allows a lightweight and compact antenna design in single dielectric waveguide technology since a cascading of multiple power dividers is avoided. Furthermore, the use of a single power divider instead of several cascaded ones reduces parasitic radiation, which occurs at discontinuities, such as bends or curvatures of dielectric waveguides. As demonstrator, we present a 1 $\times$ 4 antenna array fed by a single, four-port, multimode interference power divider, operating in the frequency range from 85 to 105 GHz. It is made from a single sheet of cross-linked polystyrene Rexolite. Each antenna element of the array consists of a tapered dielectric rod antenna of rectangular shape. In the measurements, the antenna array exhibits a half-power beamwidth of 12° in the H -plane and a gain of 16.9 dBi at 95 GHz accompanied by a sidelobe level of around $-$ 11 dB. The antenna array shows a good matching with a return loss higher than 15 dB in the desired frequency range.

Fine mapping of the barley leaf rust resistance locus Rph13 on chromosome 3HL facilitates its use in breeding programs through marker-assisted selection. Barley leaf rust (BLR—caused by Puccinia hordei) is a widespread fungal disease that can be effectively controlled by genetic resistance. There is an ongoing need to both diversify and genetically characterise resistance loci to provide effective and durable control given the ongoing threat of rapidly evolving P. hordei populations. Here, we report on the molecular genetic characterisation of the Rph13 locus, originally derived from wild barley and transferred to barley accession Berac (then referred to as PI 531849). The 2017 reference genome of cv. Morex was used as a road map to rapidly narrow both a genetic and physical intervals around the Rph13 resistance locus. Using recombination-based mapping, we narrowed the physical interval to 116.6 kb on chromosome 3H in a segregating population of a cross of the Rph13 carrying resistant line PI 531849 with the leaf rust-susceptible cultivar Gus. We identified two nucleotide-binding leucine-rich repeat genes as likely candidates for the Rph13 resistance. Sequences from the candidate genes enabled the development of a KASP marker that distinguished resistant and susceptible progeny and was found to be predictive and useful for MAS.

This paper presents the design of a planar miniaturized 4x4 Butler matrix, with implementation of 4 tunable 135° delay line phase shifters for a 160 GHz application. The Butler matrix and phase shifters are both realized with a metallic nanowire filled alumina membrane (NaM) technology, using slow-wave microstrip line to miniaturize the size. Tunability is achieved by filling in a microwave liquid crystal. Comparing with commonly used corporate feed network, the simulation results show such a Butler matrix with 135°-phase shifters has less insertion loss and reduced size.

This paper presents a continuously tunable nonradiative dielectric waveguide (NRD) phase shifter based on liquid crystal (LC) technology at W-band. LC is inserted in the NRD’s dielectric core to obtain tunability. Compared to other dielectric waveguides, which are prone to radiation losses, the NRD is radiation free even at bends and discontinuities. A maximum differential phase shift of 280° was achieved with an electric biasing voltage of ±150 V, accompanied with insertion losses between 2.9 dB to 4.9 dB, resulting in a maximum Figure-of-Merit of 85 °/dB.

TILLING (Targeting Induced Local Lesions IN Genomes), a popular reverse genetics approach in barley research, combines plant mutagenesis with efficient mutation detection for studying biological function of a specific gene. The high mutation frequency within a TILLING population principally enables the identification of induced variations in (almost) all genes of a given species (more precisely a given genotype of a species) of interest, which can be tested for their functional impact on morphological and/or physiological characteristics of the plant. Several TILLING populations induced by chemical mutagenesis were established for barley (Talame et al., Plant Biotechnol J 6:477-485, 2008; Gottwald et al., BMC Res Notes 2:258, 2009; Caldwell et al. Plant J 40:143-150, 2004) and showed the possibility for adapting protocols to develop further populations. This chapter describes a chemical mutagenesis protocol for barley seeds and two independent procedures for efficient single nucleotide polymorphism (SNP) detection in a large number of mutagenized plants either by slab-gel- or capillary gel-based electrophoreses on the LI-COR 4300 DNA Analyzer and the AdvanCE FS96 instruments, respectively.

TILLING (Targeting Induced Local Lesions IN Genomes), a popular reverse genetics approach in barley research, combines plant mutagenesis with efficient mutation detection for studying biological function of a specific gene. The high mutation frequency within a TILLING population principally enables the identification of induced variations in (almost) all genes of a given species (more precisely a given genotype of a species) of interest, which can be tested for their functional impact on morphological and/or physiological characteristics of the plant. Several TILLING populations induced by chemical mutagenesis were established for barley (Talame et al., Plant Biotechnol J 6:477-485, 2008; Gottwald et al., BMC Res Notes 2:258, 2009; Caldwell et al. Plant J 40:143-150, 2004) and showed the possibility for adapting protocols to develop further populations. This chapter describes a chemical mutagenesis protocol for barley seeds and two independent procedures for efficient single nucleotide polymorphism (SNP) detection in a large number of mutagenized plants either by slab-gel- or capillary gel-based electrophoreses on the LI-COR 4300 DNA Analyzer and the AdvanCE FS96 instruments, respectively.

Tunable power dividers are a key-component for adaptive arrays employing full beam synthesis. Here, the concept of a tunable reflection-type power divider is presented, which utilizes the edge slope of a tunable filter. In this work, the filter's transmission and reflection are separated by a hybrid coupler circuit. Design equations are derived on basis of a Butterworth prototype function and a proof-of-concept demonstrator is realized for 12 GHz. The tunable filter is implemented by liquid crystal. The measurement proofs the functionality of the presented concept, achieving a dynamic range of 9 dB for both output branches. To the authors' best knowledge, this is the first time, such a concept is presented.

This paper presents the design and characterisation of a new liquid crystal (LC) based single-pole double-throw (SPDT) with continuously adjustable power splitting ratio in low temperature co-fired ceramic (LTCC) technology. It is designed for a centre frequency of 30 GHz, including a key component, the fully embedded LC phase shifter in stripline topology. The SPDT shows a good matching with $\vert S_{11}\vert =-10\mathrm{dB}$ over a bandwidth of 18 %. It exhibits an insertion loss of 9 dB to 11 dB and an isolation between 22 dB to 32 dB. The continuous tuneability not only allows the selection of each preferred power splitting ratio at the output ports, but also a tuning of the centre frequency. The high insertion loss arises from a certain surface roughness as well as a decreased conductivity of the gold metallisation used.

Genebanks hold comprehensive collections of cultivars, landraces and crop wild relatives of all major food crops, but their detailed characterization has so far been limited to sparse core sets. The analysis of genome-wide genotyping-by-sequencing data for almost all barley accessions of the German ex situ genebank provides insights into the global population structure of domesticated barley and points out redundancies and coverage gaps in one of the world's major genebanks. Our large sample size and dense marker data afford great power for genome-wide association scans. We detect known and novel loci underlying morphological traits differentiating barley genepools, find evidence for convergent selection for barbless awns in barley and rice and show that a major-effect resistance locus conferring resistance to bymovirus infection has been favored by traditional farmers. This study outlines future directions for genomics-assisted genebank management and the utilization of germplasm collections for linking natural variation to human selection during crop evolution.

International audience; This letter presents the realization of a miniaturized liquid crystal slow wave phase shifter at V -band. It is based on a microstrip topology, where the ground plane is realized by a porous alumina membrane filled with metallic nanowires, all of them being connected with each other by a metallic ground plane at the membrane's back. While the magnetic field can pass the nanowires almost unperturbed, the electric field is confined in between the signal electrode and the tips of the nanowires. After deembedding, the meander line phase shifter shows a matching always better than -10 dB, while exhibiting an insertion loss between 1.5 and 2.5 dB from 40 to 67 GHz. This results in a figure-of-merit for passive phase shifters of 33 dB to 45°/dB, accompanied with a phase shift of 55°-100°.

In this paper, the beam steering capabilities of a fully dielectric antenna array made out of Rexolite are investigated. The antenna array, which is designed for W-band frequencies, consists of four dielectric rod antennas fed by a special power divider, which is based on a multimode interference phenomenon. In order to achieve different beam steering angles, different lengths of the dielectric waveguides, feeding the rod antennas are used. Two different beam steering configurations are designed, providing a beam direction of 15° and 8° at 95 GHz. The measured antenna patterns are in good agreement to the simulations with side lobe levels between -6.2 to -10.5 dB.

This work presents a compact and lightweight dielectric waveguide (DW) switch at W-band, which uses liquid crystal (LC) technology for tuning multimode interference (MMI). The device, designed for 85 to 105 GHz, is based on the interference pattern also known as self-imaging, which occurs due to a higher order mode propagation in a multimode waveguide. If the multimode waveguide is asymmetrically excited, a phase shift difference arises between two occurring field maxima. By placing LC in the region of one field maximum the phase shift can be adjusted by means of the tunable permittivity. This allows to control the interference pattern and therefore the position of the field maximum at the output of the multimode waveguide, where single mode DWs are connected. In the measurements, a port isolation of 40 dB at 94 GHz was achieved, while the other switching configuration shows a port isolation of 10 dB at 110 GHz. For both cases, the input reflection is below −15 dB over the whole frequency range.

This work demonstrates 50 µm (2.0 mil) thin SCHOTT glass AF32eco as a RF substrate. Superior electrical performance and miniaturized component or package size in both vertical and lateral dimensions compared to traditional components and two-dimensional (2D) packages are shown to be feasible with the 3D fabrication approach with such thin glass. Vias with a diameter of 50µm are made at SCHOTT using laser structuring. Either sides of the glass substrates are coated with a thin layer of a polymer dielectric. The through-holes are re-opened and metallization processes are performed to simultaneously create a thick copper metallization on both surfaces as well as on the vias to make them conducting. The metallization is structured with semi-additive patterning using photolithography and etching to obtain solenoid inductors for matching networks of filter elements. The magnetic field of the components is mainly parallel to the glass substrate. Inductances with 1.7 nH and 1.9 nH are designed and fabricated using different structures for shielding. The performance metrics of the demonstrated glass-integrated passive devices (IPDs) and modules were characterized. Excellent correlation between modeling and measured results were observed. Characterization of the inductances revealed quality factors (Q-values) of 60 and more at 2.35 GHz. The Q-values of the inductances are confirmed by three independent measurement methods and correspond well to field simulation results. The basic building blocks demonstrated in this paper can lead to a new generation of ultra-thin 3D RF modules with substrate-embedded matching networks and filters, superior performance and lower cost compared to laminate and FO-WLP based approaches.

This work represents the evolution of micro- and millimetre wave optimized nematic liquid crystal mixtures and their applications. Starting with the well-known liquid crystal mixture K15 used in the display technology, microwave optimized LC mixtures have been developed. For that, novel characterization setups have been developed, which play an essential factor in the optimization process for the micro-, millimetre wave and THz regime. By using a specialized LC simulation tool, different tuneable waveguide topologies are compared in terms of tuneability, transmission loss and tuning speed. Based on that, a phase shifter for W-band frequencies has been fabricated, which reached a measured figure of merit for passive phase shifters of up to 148° /dB.

The design and characterisation of two different power divider techniques, i.e. Y-branch and multimodal power dividers, based on subwavelength dielectric fibre technology is presented. Both have been successfully established in the optical domain for dielectric waveguides and are adapted to W-band frequencies (75–110 GHz). Both power dividers are made out of the cross-linked polystyrene Rexolite 1422 and have been processed by milling. Simulations predicted insertion losses between 3.5 and 4 dB while the electrical characterisation showed insertion losses between 3.5 and 5 dB. The multimodal power divider has the best performance with 1–1.5 dB lower insertion losses compared with the Y-branch divider.

This work presents a simple approach for a continuously tunable phase shifter design based on liquid crystal (LC) technology for the V-band. The main component of the phase shifter is a partially dielectric filled parallel-plate waveguide. For continuous tunability, liquid crystal is inserted inside the dielectric slab. This assembly, being fed by WR15 waveguides, maintains a simple and efficient way to realize the necessary electric biasing in comparison to hollow waveguide based LC phase shifter. A novel stepped impedance design, which is fabricated on an Ultralam 3850HT substrate is presented. The electrode design is based on Babinet's principle to obtain a homogeneous distribution of the biasing field. Using a voltage of ±150 V, a maximum differential phase shift of 380°, accompanied with an insertion loss between 2.4 to 3.6 dB could be achieved, yielding a high figure of merit of around 113 °/dB at 68 GHz.

A 30 GHz liquid-crystal-based amplitude tuner is proposed for the first time. The amplitude of a signal can be controlled by using the interference principle. An input signal is divided into a tunable liquid crystal phase shifter and a fixed transmission line. Later, the divided signals are combined together at the output port. The output amplitude depends on the phase difference between the tunable and the fixed line. The low temperature co-fired ceramic technology is utilized to fabricate the device. The measurement shows an attenuation range of 11 dB to 30 dB with a maximum biasing voltage of 100 V.

This work presents a liquid crystal (LC) based phase shifter in a dielectric waveguide (DW) topology consisting of core and cladding for the W-band. For continuous tunability, a part of the core material is replaced by liquid crystal. Furthermore, suggestions of materials for designing such a DW, i.e. for core and cladding, are given in this paper. In comparison to other topologies, the advantage of this topology is that the necessary electric biasing can be realized easily, by placing electrodes directly on the cladding. With an electric biasing of ±550 V, a maximum differential phase shift of 430°, accompanied with insertion losses between 2.8 to 5.5 dB with standard WR10 connections, could be achieved. The maximum figure of merit is around 100 °/dB at 102 GHz.

This paper presents an in-plane hollow waveguide crossover for W-band frequencies. This kind of crossover can be implemented e.g. into a Butler matrix, to simplify the fabrication process significantly. It is based on a partially dielectric filling of the waveguide, focussing the field in the center. The dielectric is placed in the center of a hollow waveguide crossing and has a star-shape. Inside the dielectric filled region, a higher order mode propagation is possible, which has no significant influence on the overall performance of the crossover. It shows an insertion loss between 0.8 dB to 1.0 dB in the frequency range of 101.5 GHz to 108.0 GHz, while the matching is better than −10 dB and even down to −20 dB between 105 GHz to 108 GHz. The isolated ports show transmission coefficients better than −20 dB over the whole frequency range and even down to −50 dB in the best performing frequency range.