Analysis of multireflector antenna clusters by spectral methods

This paper analyzes multireflector antennas making use of spectral domain techniques. The behaviour of the multireflector antenna is determined by means of a transference function that relates the plane wave spectrum of an incident signal on this antenna to the plane wave spectrum reflected by the structure. Multireflector antenna clusters that synthesize specific radiation patterns have also been undertaken. The paper allows us to generalize the identification of every reflecting object through a transference function that relates the incident spectrum to the reflected one. This will permit us to analyze reflection problems with multiple structures.Peer ReviewedPostprint (published version

A new hybrid mode-matching method for the analysis of inductive obstacles and discontinuities

A new and efficient hybrid mode-matching method for the analysis of arbitrarily shaped inductive obstacles and discontinuities is presented. An open-space spectral method is used to model the electrical behavior of the inductive problem, and the mode-matching technique is then employed for obtaining a multimode scattering matrix representation. This new method is revealed very useful for the accurate and efficient analysis of inductive problems including very arbitrary geometries. Results for some classical inductive problems covered in the literature are shown, thus confirming the accuracy of the results provided by the new technique.Peer ReviewedPostprint (published version

Novel empty substrate integrated waveguide for high performance microwave integrated circuits

"(c) 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works."Abstract Over the last years, a great number of substrate integrated circuits has been developed. These new circuits are a compromise between the advantages of classical waveguide technologies, such as high quality factor and low losses, and the advantages of planar circuits, such as low cost and easy compact integration. Although their quality factor and losses are better than for planar circuits, these characteristics are worse than in the case of waveguides, mainly due to the presence of the dielectric substrate. In order to improve the performance of the integrated circuits, a new methodology for manufacturing empty waveguides, without a dielectric substrate, but at the same time completely integrated in a planar substrate, is proposed in this work. A wideband transition with return losses greater than 20 dB in the whole bandwith of the waveguide allows the integration of the empty waveguide into the planar substrate so that the waveguide can be directly accessed with a microstrip line. Therefore, a microwave circuit integrated in a planar substrate, but at the same time with a very high quality factor (measured quality factor is 4.5 times higher than for the same filter in the substrate integrated waveguide), and very low losses is successfully achieved.This work was supported by the Ministerio de Ciencia e Innovacion, Spanish Goverment, under Research Project TEC2010-21520-C04-03 and Research Project EC2010-21520-C04-01, and by the Autonomous Government of Castilla-La Mancha under Research Project PPII10-0047-0220.Belenguer Martínez, Á.; Esteban González, H.; Boria Esbert, VE. (2014). Novel empty substrate integrated waveguide for high performance microwave integrated circuits. IEEE Transactions on Microwave Theory and Techniques. 62(4):832-839. https://doi.org/10.1109/TMTT.2014.2309637S83283962

Design of Miniaturized Substrate Integrated Filters Using Aggressive Space Mapping

[EN] An optimization procedure for the design of miniaturized substrate integrated quasi-lumped filters based on aggressive space mapping techniques is presented in this paper. A gradient-descent approach based on a lossy coarse model is employed. Thus, a 3-pole bandpass filter response centered at 10 GHz is designed, manufactured and measured, showing the validity of the technique even if strong dependencies between the different electrical and physical parameters are present.Martínez Pérez, JD.; Sirci, S.; Boria Esbert, VE. (2019). Design of Miniaturized Substrate Integrated Filters Using Aggressive Space Mapping. IEEE. 1-4. https://doi.org/10.1109/NEMO.2019.8853742S1

Distributed Models for Filter Synthesis

The limitations of filter synthesis methods based on classic equivalent circuits with the enhanced distributed models and synthesis procedures able to overcome such limitations are presented. A modified procedure that corrects the waveguide lengths has been proposed. The input and output reflection coefficients of the ideal prototype steps are real. The shunt capacitive effect introduces a phase shift in the reflection coefficients of each waveguide step. The representation of the filter structure can be improved if the waveguide steps are analyzed with a full-wave electromagnetic (EM) simulator, and their responses are stored in the form of ABCD matrices. The desired filter passband cutoff frequency was 11 GHz, with a specified return loss of 25 dB, and a gap height greater than 4.25 mm. High-power applications with wide stopbands often require impractical waveguide sections. The accurate EM simulators are used to find an almost exact equivalence between the prototype and the filter parts.Boria Esbert, VE.; Soto Pacheco, P.; Cogollos Borras, S. (2011). Distributed Models for Filter Synthesis. IEEE Microwave Magazine. 12(6):87-100. doi:10.1109/MMM.2011.942010S8710012

Analysis and design of re-configurable combline filters using dielectric tuners

[EN] This article describes different tunable structures for typical waveguide combline filters. In this context, several configurations using dielectric tuners have been studied for resonators, inter-resonator couplings, and input/output couplings. All configurations are analyzed in a wide frequency range showing advantages and drawbacks. Using the best structures in terms of performance, a fully re-configurable filter has been designed. The filter provides a wide tuning range in terms of center frequency while maintaining a high Q factor, and a constant bandwidth and return losses. A first filter prototype has been designed at L-band. The structure demonstrates a tunability in terms of frequency range of about 400 %, thereby clearly demonstrating that the approach we propose is indeed a very promising candidate for implementing tunable combline filters based on dielectric tuners.Sharma, A.; Cogollos, S.; Boria Esbert, VE.; Guglielmi, M. (2022). Analysis and design of re-configurable combline filters using dielectric tuners. IEEE. 122-125. https://doi.org/10.23919/EuMC50147.2022.978434512212

Miniaturized Ultra-Wideband Bandpass Filter Based on Substrate Integrated Quasi-Lumped Resonators

[EN] A compact ultra-wideband bandpass filter employing substrate integrated quasi-lumped resonators is presented in this paper. A multi-layer hybrid structure is proposed, combining quasi-lumped resonators and surface mount components. This allows a huge miniaturization degree due to the high capacitive loading. Moreover, strong magnetic and electric couplings can be implemented thus enabling the introduction of transmission zeros for improving response selectivity. A filter example centered at 5.35 GHz with a prescribed channel bandwidth of 2.9 GHz has been designed, manufactured and measured. The filter size is smaller than 7×7 mm2. The obtained results show the feasibility of the proposed approach.This project has received funding from the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 811232, the European Space Agency (ESA) under contract 4000124983, and the Ministerio de Ciencia e Innovación (Spanish Government) under project PID2019-103982R-C41Messaoudi, EM.; Martínez Pérez, JD.; Boria Esbert, VE. (2021). Miniaturized Ultra-Wideband Bandpass Filter Based on Substrate Integrated Quasi-Lumped Resonators. IEEE. 201-203. https://doi.org/10.1109/IMFW49589.2021.964238220120

A Novel Magnetic Coupling for Miniaturized Bandpass Filters in Embedded Coaxial SIW

[EN] In this paper, embedded coaxial substrate integrated waveguide (CSIW) filters with innovative magnetic couplings are presented and studied. By creating the loading capacitance of a combline topology using inner layers of a low-temperature co-fired ceramic (LTCC) stack-up, it is possible to achieve resonator miniaturization while improving the spurious-free band and providing full-packaged solutions. Moreover, a new magnetic coupling scheme consisting of short-ended stripline probes is proposed and analyzed in detail, both for direct and external couplings. An in-line three-pole filter at L-band is designed, manufactured, and measured proving how the proposed approach can be used for designing wideband bandpass filter (BPF) with extremely compact size. The designed BPF is centered at 1.5 GHz with 10% fractional bandwidth (FBW), while the layout size is just 35 x 9.5 mm(2). The experimental results validate the coaxial SIW technology that allows for, at the same time, easy integration, compact size, flexible design, and enhanced stop-band performance.This research was funded by Ministerio de Economia, Industria y Competitividad, Spanish Government, under Research Project TEC2016-75934-C4-3-R.Sirci, S.; Martínez Pérez, JD.; Boria Esbert, VE. (2019). A Novel Magnetic Coupling for Miniaturized Bandpass Filters in Embedded Coaxial SIW. Applied Sciences. 9(3):1-14. https://doi.org/10.3390/app903039411493Chen, X.-P., & Wu, K. (2014). Substrate Integrated Waveguide Filters: Practical Aspects and Design Considerations. IEEE Microwave Magazine, 15(7), 75-83. doi:10.1109/mmm.2014.2355751Rhodes, J. D. (1969). The Stepped Digital Elliptic Filter. IEEE Transactions on Microwave Theory and Techniques, 17(4), 178-184. doi:10.1109/tmtt.1969.1126929Grigoropoulos, N., Sanz-Izquierdo, B., & Young, P. R. (2005). Substrate integrated folded waveguides (SIFW) and filters. IEEE Microwave and Wireless Components Letters, 15(12), 829-831. doi:10.1109/lmwc.2005.860027Li, L., Wu, Z., Yang, K., Lai, X., & Lei, Z. (2018). A Novel Miniature Single-Layer Eighth-Mode SIW Filter With Improved Out-of-Band Rejection. IEEE Microwave and Wireless Components Letters, 28(5), 407-409. doi:10.1109/lmwc.2018.2813883Martinez, J. D., Sirci, S., Taroncher, M., & Boria, V. E. (2012). Compact CPW-Fed Combline Filter in Substrate Integrated Waveguide Technology. IEEE Microwave and Wireless Components Letters, 22(1), 7-9. doi:10.1109/lmwc.2011.2174215Nassar, S. O., & Meyer, P. (2017). Pedestal substrate integrated waveguide resonators and filters. IET Microwaves, Antennas & Propagation, 11(6), 804-810. doi:10.1049/iet-map.2016.0120Ho, M.-H., Li, J.-C., & Chen, Y.-C. (2018). Miniaturized SIW Cavity Resonator and Its Application in Filter Design. IEEE Microwave and Wireless Components Letters, 28(8), 651-653. doi:10.1109/lmwc.2018.2845101Sirci, S., Sanchez-Soriano, M. A., Martianez, J. D., Boria, V. E., Gentili, F., Bosch, W., & Sorrentino, R. (2015). Design and Multiphysics Analysis of Direct and Cross-Coupled SIW Combline Filters Using Electric and Magnetic Couplings. IEEE Transactions on Microwave Theory and Techniques, 63(12), 4341-4354. doi:10.1109/tmtt.2015.2495287Riblet, H. J. (1983). An Accurate Approximation of the Impedance of a Circular Cylinder Concentric with an External Square Tube. IEEE Transactions on Microwave Theory and Techniques, 31(10), 841-844. doi:10.1109/tmtt.1983.1131615Yang, T., Ho, K., & Rebeiz, G. M. (2014). Compact Self-Shielded 2–3 GHz High-Q Coaxial Fixed and Tunable Filters. IEEE Transactions on Microwave Theory and Techniques, 62(12), 3370-3379. doi:10.1109/tmtt.2014.236481

A New Family of Multiband Waveguide Filters Based on a Folded Topology

[EN] In this article, we describe a new family of multiband waveguide filters based on a folded topology. The folded topology allows to use the filters of different orders and the introduction of transmission zeros. The design of the multiband filter is based on the aggressive space mapping (ASM) technique and is able to take into account manufacturing details, such as round corners and tuning elements. The filter structure is validated by designing, manufacturing, and measuring a triband filter. The agreement between simulations and measurements is shown to be excellent, thereby fully validating both the filter topology and the design process.This work was supported in part by the La Caixa Foundation under Grant B004442 and in part by the Agencia Estatal de Investigacion (AEI) and Union Europea through the Fondo Europeo de Desarrollo Regional (FEDER) "Una manera de hacer Europa" (AEI/FEDER, UE) under Research Project TEC2016-75934-C4-1-R.Melgarejo, JC.; Cogollos, S.; Guglielmi, M.; Boria Esbert, VE. (2020). A New Family of Multiband Waveguide Filters Based on a Folded Topology. IEEE Transactions on Microwave Theory and Techniques. 68(7):2590-2600. https://doi.org/10.1109/TMTT.2020.2989111S2590260068

Multipactor discharges in parallel-plate dielectric-loaded waveguides including space-charge effects

[EN] The objective of this paper is to study the time evolution of multipactor discharges in a parallel-plate dielectric-loaded waveguide. The electron discharge phenomena investigated in this paper include the effects of space charge, as well as the presence of time varying static fields. In order to perform the simulations presented in this paper, an approach considering simultaneously multiple effective electrons has been used. The results obtained demonstrate that multipactor discharges do turn off by themselves under certain circumstances when they occur in such dielectric-loaded structures.This work was supported by the Spanish Government's Ministerio de Educacion y Ciencia under Project TEC2007-67630-C03-01. The review of this paper was arranged by Editor W. Menninger.Coves, A.; Torregrosa-Penalva, G.; Vicente, C.; Gimeno, B.; Boria Esbert, VE. (2008). Multipactor discharges in parallel-plate dielectric-loaded waveguides including space-charge effects. IEEE Transactions on Electron Devices. 55(9):2505-2511. https://doi.org/10.1109/TED.2008.927945S2505251155