Design Procedure for Band-Pass Filters based on Integrated Coaxial and Rectangular Waveguide Resonators

In this paper, we present a novel band-pass filter based on dual-mode resonators. The dual-mode operation is based on integrated coaxial and rectangular waveguide cavities. Furthermore, we also discuss a systematic design procedure for the selection of the dimensions of the various constituent elements of the filter, that is based on the well-known aggressive space mapping technique. The design of a 5-pole band-pass filter operating in the X-band is discussed in detail, including also measured data. The comparison between simulations and measurement shows very good agreement, thereby fully validating both the new filter structure, and the design procedure

Compensation of the impact of low-cost manufacturing techniques in the design of E-plane multiport waveguide junctions

In this work, a full-wave tool for the accurate analysis and design of compensated E-plane multiport junctions is proposed. The implemented tool is capable of evaluating the undesired effects related to the use of low-cost manufacturing techniques, which are mostly due to the introduction of rounded corners in the cross section of the rectangular waveguides of the device. The obtained results show that, although stringent mechanical effects are imposed, it is possible to compensate for the impact of the cited low-cost manufacturing techniques by redesigning the matching elements considered in the original device. Several new designs concerning a great variety of E-plane components (such as right-angled bends, T-junctions and magic-Ts) are presented, and useful design guidelines are provided. The implemented tool, which is mainly based on the boundary integral-resonant mode expansion technique, has been successfully validated by comparing the obtained results to simulated data provided by a commercial software based on the finite element method.All the data necessary to understand, evaluate, replicate, and generate the figures and results presented in this paper have been included in the present manuscript. A full-wave custom code and the commercial software Ansys HFSS have been used to generate the simulated results provided by the authors. This work was supported by the Ministerio de Economia y Competitividad, Spanish Government, under the Research Projects TEC2013-47037-C5-1-R and TEC2013-47037-C5-4-R.San Blas Oltra, ÁA.; Roca, JM.; Cogollos Borras, S.; Morro, JV.; Boria Esbert, VE.; Gimeno Martinez, B. (2016). Compensation of the impact of low-cost manufacturing techniques in the design of E-plane multiport waveguide junctions. Radio Science. 51(6):619-628. https://doi.org/10.1002/2016RS006027S61962851

LIPSS manufacturing with regularity control through laser wavefront curvature

Laser-Induced Periodic Surface Structures (LIPSS) manufacturing is a convenient laser direct-writing technique for the fabrication of nanostructures with adaptable characteristics on the surface of virtually any material. In this paper, we study the influence of 1D laser wavefront curvature on nanoripples spatial regularity, by irradiating stainless steel with a line-focused ultrafast laser beam emitting 120 fs pulses at a wavelength of 800 nm and with 1 kHz repetition rate. We find high correlation between the spatial regularity of the fabricated nanostructures and the wavefront characteristics of the laser beam, with higher regularity being found with quasi-plane-wave illumination. Our results provide insight regarding the control of LIPSS regularity, which is essential for industrial applications involving the LIPSS generation technique

Wideband generalized admittance matrix representation for the analysis and design of waveguide filters with coaxial excitation

A very efficient technique for the full-wave analysis and design of complex passive waveguide filters, including rectangular cavities with metallic cylindrical posts and coaxial excitation, is presented. This novel technique provides the wideband generalized admittance matrix representation of the whole structure in the form of pole expansions, thus extracting the most expensive computations from the frequency loop. For this purpose, the structure is properly segmented into its key building blocks, all of them characterized in terms of wideband admittance matrices. Then, an efficient iterative algorithm for combining these matrices, and finally providing the wideband generalized admittance matrix of the complete structure, is followed. In order to validate the accuracy and efficiency of this full-wave modal technique, four different waveguide filters have been considered. In particular, the design of a compact four-pole in-line filter with tuning screws and of an evanescent-mode filter, both operating in the X-band and including a standard (vertical) coaxial excitation, are first presented. Finally, two C-band six-resonator comb-line filters, one of them with a cross-coupling configuration, and both excited with a collinear end-launcher transition based on a disc-ended coaxial, are also designed. Numerical data from a commercial software, as well as measurements of a manufactured prototype, are included for verification purposes.Mira Pérez, FE.; San Blas Oltra, ÁA.; Boria Esbert, VE.; Rogla Madrid, LJ.; Gimeno Martinez, B. (2013). Wideband generalized admittance matrix representation for the analysis and design of waveguide filters with coaxial excitation. Radio Science. 48:1-11. doi:10.1002/rds.20013S11148Alessandri, F., Bartolucci, G., & Sorrentino, R. (1988). Admittance matrix formulation of waveguide discontinuity problems: computer-aided design of branch guide directional couplers. IEEE Transactions on Microwave Theory and Techniques, 36(2), 394-403. doi:10.1109/22.3528Alessandri, F., Mongiardo, M., & Sorrentino, R. (1992). Computer-aided design of beam forming networks for modern satellite antennas. IEEE Transactions on Microwave Theory and Techniques, 40(6), 1117-1127. doi:10.1109/22.141343Arcioni, P., & Conciauro, G. (1999). Combination of generalized admittance matrices in the form of pole expansions. IEEE Transactions on Microwave Theory and Techniques, 47(10), 1990-1996. doi:10.1109/22.795073Arcioni, P., Bozzi, M., Bressan, M., Conciauro, G., & Perregrini, L. (2002). Frequency/time-domain modelling of 3D waveguide structures by a BI-RME approach. International Journal of Numerical Modelling: Electronic Networks, Devices and Fields, 15(1), 3-21. doi:10.1002/jnm.429Boria, V. E., Guglielmi, M., & Arcioni, P. (1998). Computer-aided design of inductively coupled rectangular waveguide filters including tuning elements. International Journal of RF and Microwave Computer-Aided Engineering, 8(3), 226-235. doi:10.1002/(sici)1099-047x(199805)8:33.0.co;2-hBozzi, M., Perregrini, L., & Wu, K. (2009). A novel technique for the direct determination of multimode equivalent circuit models for substrate integrated waveguide discontinuities. International Journal of RF and Microwave Computer-Aided Engineering, 19(4), 423-433. doi:10.1002/mmce.20360Chang, H.-C., & Zaki, K. A. (1991). Evanescent-mode coupling of dual-mode rectangular waveguide filters. IEEE Transactions on Microwave Theory and Techniques, 39(8), 1307-1312. doi:10.1109/22.85405Gentili, G. G. (2001). Multiport analysis of arbitrary circular-rod insets in rectangular waveguide by the generalized admittance matrix. IEEE Transactions on Microwave Theory and Techniques, 49(8), 1438-1442. doi:10.1109/22.939924Gimeno, B., & Guglielmi, M. (1997). Multimode equivalent network representation for junctions between coaxial and circular waveguides. International Journal of Microwave and Millimeter-Wave Computer-Aided Engineering, 7(2), 180-194. doi:10.1002/(sici)1522-6301(199703)7:23.0.co;2-wGuglielmi, M. (1994). Simple CAD procedure for microwave filters and multiplexers. IEEE Transactions on Microwave Theory and Techniques, 42(7), 1347-1352. doi:10.1109/22.299728Hoft, M., & Yousif, F. (2011). Orthogonal Coaxial Cavity Filters With Distributed Cross-Coupling. IEEE Microwave and Wireless Components Letters, 21(10), 519-521. doi:10.1109/lmwc.2011.2165533Ihmels , R. F. Arndt 1993 Field theory CAD of L-shaped iris coupled mode launchers and dual-mode filters IEEE MTT-S Int. Microw. Symp. DigLevy, R., Hui-Wen Yao, & Zaki, K. A. (1997). Transitional combline/evanescent-mode microwave filters. IEEE Transactions on Microwave Theory and Techniques, 45(12), 2094-2099. doi:10.1109/22.643743Liang, J.-F., Chang, H.-C., & Zaki, K. A. (1992). Coaxial probe modeling in waveguides and cavities. IEEE Transactions on Microwave Theory and Techniques, 40(12), 2172-2180. doi:10.1109/22.179878Mansour, R. R., & Macphie, R. H. (1986). An Improved Transmission Matrix Formulation of Cascaded Discontinuities and its Application to E-Plane Circuits. IEEE Transactions on Microwave Theory and Techniques, 34(12), 1490-1498. doi:10.1109/tmtt.1986.1133568Marcuvitz, N. (1986). Waveguide Handbook. doi:10.1049/pbew021eMira, F., Bressan, M., Conciauro, G., Martinez, B. G., & Esbert, V. E. B. (2005). Fast S-domain modeling of rectangular waveguides with radially symmetric metal insets. IEEE Transactions on Microwave Theory and Techniques, 53(4), 1294-1303. doi:10.1109/tmtt.2005.845762Mira , F. A. A. San Blas V. E. Boria B. Gimeno G. Conciauro 2005b Fast and accurate CAD tool of passive rectangular waveguide devices including cylindrical conducting posts Proc. 35th Eur. Microw. ConfMira , F. A. A. San Blas V. E. Boria B. Gimeno 2008 Efficient pole expansion of the generalized admittance matrix representation of planar waveguide junctions Proc. 38th Eur. Microw. ConfMira, F., San Blas, A. A., Boria, V. E., & Gimeno, B. (2009). Wideband impedance matrix representation of passive waveguide components based on cascaded planar junctions. Radio Science, 44(1), n/a-n/a. doi:10.1029/2008rs003886Morini, A., Venanzoni, G., & Rozzi, T. (2006). A new adaptive prototype for the design of side-coupled coaxial filters with close correspondence to the physical structure. IEEE Transactions on Microwave Theory and Techniques, 54(3), 1146-1153. doi:10.1109/tmtt.2005.864112Morini, A., Venanzoni, G., Farina, M., & Rozzi, T. (2007). Modified Adaptive Prototype Inclusive of the External Couplings for the Design of Coaxial Filters. IEEE Transactions on Microwave Theory and Techniques, 55(9), 1905-1911. doi:10.1109/tmtt.2007.904329Quesada , F. D. A. Vidal F. J. Pérez A. Berenguer A. A. San Blas F. Mira V. E. Boria B. Gimeno A. Álvarez 2010 Broad band analysis of arbitrarily shaped microwave filters using a novel singular value decomposition technique Proc. 4th Eur Conf. Ant. Prop. (EuCAP)San Blas , A. A. F. Mira V. E. Boria B. Gimeno G. Conciauro M. Bressan P. Arcioni 2006 Efficient CAD of generalized coaxial probes in rectangular waveguide using the 3D BI-RME method Proc. 36th Eur. Microw. ConfHui-Wen Yao, Zaki, K. A., Atia, A. E., & Hershtig, R. (1995). Full wave modeling of conducting posts in rectangular waveguides and its applications to slot coupled combline filters. IEEE Transactions on Microwave Theory and Techniques, 43(12), 2824-2830. doi:10.1109/22.47564

Spain: Underwater Exploration on a Narrow Continental Shelf

In spite of Spain’s long coastline (nearly 8000 km) and its well-established tradition in underwater archaeology, the prehistoric settlement of the continental shelf is practically unknown with very few finds. Underwater research has focused on naval archaeology and, until very recently, no attempt had been made to look for prehistoric underwater sites. In the past decade,new research projects have been launched to explore selected areas on the Cantabrian shelf and offshore of Gibraltar. This chapter summarises the currently available evidence of submerged prehistoric archaeology and the preliminary results of these new project

Small bowel enteroscopy - A joint clinical guideline from the spanish and portuguese small bowel study groups

The present evidence-based guidelines are focused on the use of device-assisted enteroscopy in the management of small-bowel diseases. A panel of experts selected by the Spanish and Portuguese small bowel study groups reviewed the available evidence focusing on the main indications of this technique, its role in the management algorithm of each indication and on its diagnostic and therapeutic yields. A set of recommendations were issued accordingly.Estas recomendações baseadas na evidência detalham o uso da enteroscopia assistida por dispositivo no manejo clínico das doenças do intestino delgado. Um conjunto de Gastrenterologistas diferenciados em patologia do intestino delgado foi selecionado pelos grupos de estudos Espanhol e Português de intestino delgado para rever a evidência disponível sobre as principais indicações desta técnica, o seu papel nos algoritmos de manejo de cada indicação e sobre o seu rendimento diagnóstico e terapêutico. Foi gerado um conjunto de recomendações pelos autores

Lack of Galectin-3 Drives Response to Paracoccidioides brasiliensis toward a Th2-Biased Immunity

There is recent evidence that galectin-3 participates in immunity to infections, mostly by tuning cytokine production. We studied the balance of Th1/Th2 responses to P. brasiliensis experimental infection in the absence of galectin-3. The intermediate resistance to the fungal infection presented by C57BL/6 mice, associated with the development of a mixed type of immunity, was replaced with susceptibility to infection and a Th2-polarized immune response, in galectin-3-deficient (gal3−/−) mice. Such a response was associated with defective inflammatory and delayed type hypersensitivity (DTH) reactions, high IL-4 and GATA-3 expression and low nitric oxide production in the organs of infected animals. Gal3−/− macrophages exhibited higher TLR2 transcript levels and IL-10 production compared to wild-type macrophages after stimulation with P. brasiliensis antigens. We hypothesize that, during an in vivo P. brasiliensis infection, galectin-3 exerts its tuning role on immunity by interfering with the generation of regulatory macrophages, thus hindering the consequent Th2-polarized type of response