http://hdl.handle.net/2117/653 2013-05-21T13:57:40Z http://hdl.handle.net/2117/18576 Title: Uniplanar bandpass filters based on multimodal immitance inverters and end-coupled slotline resonators Authors: Contreras Lizarraga, Adrián Arturo; Ribó, Miquel; Pradell i Cara, Lluís; Blondy, Pierre Abstract: This paper presents the design and implementation of uniplanar bandpass filters that use end-coupled slotline resonators and a new kind of multimodal immitance inverter. These inverters are based on an asymmetric shunt-short-circuit coplanar waveguide (CPW) transition, and are modeled using a multimodal circuit model, which takes into account both fundamental modes of the CPW (the even and the odd modes). From this model, analytical design expressions for the inverters are obtained. These structures are used as input/output inverters of a new class of compact low-loss arbitrary-order easily reconfigurable uniplanar filters featuring half-wavelength and quarter-wavelength end-coupled resonators. A multimodal model is obtained for these filters, which allows an accurate analysis, design, and prediction of their behavior. By using these multimodal tools, three second- and fourth-order prototypes, and a second-order frequency-tunable prototype, were designed and implemented. The fourth-order filter has an insertion loss of 2.2 dB at 2 GHz with an out-of-band rejection better than 20 dB in an extremelywide frequency band. The frequency-tunable filter features a tuning range from 1 to 1.37 GHz with quasi-constant 3-dB bandwidth from 121 to 135 MHz. The measurements show a good agreement with the proposed multimodal model, thus validating the model and the design methodology. 2013-04-03T14:07:47Z http://hdl.handle.net/2117/17453 Title: A new space technology for ocean observation: the SMOS mission Authors: Font Ferré, Jordi; Ballabrera Poy, Joaquim; Camps Carmona, Adriano José; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Duran Martínez, Israel; Emelianov Kolomitski, Mikhail; Enrique González, Luis; Fernández Gallego, Pedro; Gabarró Prats, Carolina; González, Cristina; González, Veronica; Gourrion, J.; Guimbard, S.; Hoareau, N.; Julià, A; Kalaroni, S.; Konstantinidou, Anna; Aretxabaleta, L.; Martínez, Justino; Miranda, Jorge Miguel; Monerris Belda, Alessandra; Montero, Sergio; Mourre, B.; Pablos Hernández, Míriam; Pérez Villar, Fernando; Piles Guillem, Maria; Portabella, M.; Sabia, R.; Salvador, Joaquin; Talone, Marco; Torres Torres, Francisco; Turiel Martínez, Antonio; Vall-Llossera Ferran, Mercedes Magdalena; Villarino Villarino, Ramón Abstract: Capability for sea surface salinity observation was an important gap in ocean remote sensing in the last few decades of the 20th century. New technological developments during the 1990s at the European Space Agency led to the proposal of SMOS (Soil Moisture and Ocean Salinity), an Earth explorer opportunity mission based on the use of a microwave interferometric radiometer, MIRAS (Microwave Imaging Radiometer with Aperture Synthesis). SMOS, the first satellite ever addressing the observation of ocean salinity from space, was successfully launched in November 2009. The determination of salinity from the MIRAS radiometric measurements at 1.4 GHz is a complex procedure that requires high performance from the instrument and accurate modelling of several physical processes that impact on the microwave emission of the ocean’s surface. This paper introduces SMOS in the ocean remote sensing context, and summarizes the MIRAS principles of operation and the SMOS salinity retrieval approach. It describes the Spanish SMOS high-level data processing centre (CP34) and the SMOS Barcelona Expert Centre on Radiometric Calibration and Ocean Salinity (SMOS-BEC), and presents a preliminary validation of global sea surface salinity maps operationally produced by CP34. 2013-01-21T17:31:17Z http://hdl.handle.net/2117/17158 Title: Compact closed-form expressions for the propagation parameters of a finite ground width coplanar transmission waveguide with thick electrodes Authors: Ibarra Fuste, Jose Antonio; Santos Blanco, M. Concepción; Rodríguez Rodríguez, Enric Abstract: Compact closed-form mathematical expressions are presented for the effective permittivity, characteristic impedance and attenuation constant of coplanar waveguides with thick electrodes and high-frequency dispersion. Excellent agreements, for a wide range of frequencies, up to 100 GHz and for conductor thicknesses up to 40 m are found with full-wave finite-element results from commercial software (HFSS) in a margin of geometric parameter values and frequencies of interest for the design and optimisation of high-speed electro-optical modulators. The formulae are simple and specially tailored to the narrow gap widths and thick electrodes typical of electro-optical modulator applications. Other approaches to closed-form formulae for CPW parameters are also compared and analysed. 2012-12-19T16:54:56Z http://hdl.handle.net/2117/14140 Title: Downscaling SMOS-derived soil moisture using MODIS visible/infrared data Authors: Piles, Maria; Camps Carmona, Adriano José; Vall-Llossera Ferran, Mercedes Magdalena; Corbella Sanahuja, Ignasi; Panciera, Rocco; Ruediger, Christoph; Kerr, Yann H.; Walker, Jeffrey Abstract: A downscaling approach to improve the spatial resolution of Soil Moisture and Ocean Salinity (SMOS) soil moisture estimates with the use of higher resolution visible/infrared (VIS/IR) satellite data is presented. The algorithm is based on the so-called “universal triangle” concept that relates VIS/IR parameters, such as the Normalized Difference Vegetation Index (NDVI), and Land Surface Temperature (Ts), to the soil moisture status. It combines the accuracy of SMOS observations with the high spatial resolution of VIS/IR satellite data into accurate soil moisture estimates at high spatial resolution. In preparation for the SMOS launch, the algorithm was tested using observations of the UPC Airborne RadIomEter at L-band (ARIEL) over the Soil Moisture Measurement Network of the University of Salamanca (REMEDHUS) in Zamora (Spain), and LANDSAT imagery. Results showed fairly good agreement with ground-based soil moisture measurements and illustrated the strength of the link between VIS/IR satellite data and soil moisture status. Following the SMOS launch, a downscaling strategy for the estimation of soil moisture at high resolution from SMOS using MODIS VIS/IR data has been developed. The method has been applied to some of the first SMOS images acquired during the commissioning phase and is validated against in situ soil moisture data from the OZnet soil moisture monitoring network, in South-Eastern Australia. Results show that the soil moisture variability is effectively captured at 10 and 1 km spatial scales without a significant degradation of the root mean square error. 2011-12-01T16:09:11Z http://hdl.handle.net/2117/14137 Title: MIRAS calibration and performance: results from the SMOS in-orbit commissioning phase Authors: Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; González Gambau, Veronica; Pablos Hernández, Míriam; Duran Martínez, Israel; Martín Neira, Manuel Abstract: After the successful launching of the Soil Moisture and Ocean Salinity satellite in November 2009, continuous streams of data started to be regularly downloaded and made available to be processed. The first six months of operation were fully dedicated to the In-Orbit Commissioning Phase, with an intense activity aimed at bringing the satellite and instrument into a fully operational condition. Concerning the payload Microwave Imaging Radiometer with Aperture Synthesis, it was fully characterized using specific orbits dedicated to check all instrument modes. The procedures, already defined during the on-ground characterization, were repeated so as to obtain realistic temperature characterization and updated internal calibration parameters. External calibration maneuvers were tested for the first time and provided absolute instrument calibration, as well as corrections to internal calibration data. Overall, performance parameters, such as stability, radiometric sensitivity and radiometric accuracy were evaluated. The main results of this activity are presented in this paper, showing that the instrument delivers stable and well-calibrated data thanks to the combination of external and internal calibration and to an accurate thermal characterization. Finally, the quality of the visibility calibration is demonstrated by producing brightness temperature images in the alias-free field of view using standard inversion techniques. Images of ocean, ice, and land are given as examples. 2011-12-01T15:29:05Z http://hdl.handle.net/2117/13686 Title: RF-MEMS uniplanar 180° phase switch based on a multimodal air-bridged CPW cross Authors: Llamas Morote, Marco Antonio; Girbau, David; Ribó, M.; Pradell i Cara, Lluís; Giacomozzi, Flavio; Colpo, S Abstract: In this paper, a new compact broadband uniplanar 180 phase switch, based on an air-bridged coplanar-waveguide (CPW) cross loaded with two capacitive-contact microelectromechancial systems (MEMS) switches in opposed (ON/OFF) states, is presented. The two phase-switch states 0 180 are defined by actuating the MEMS switches from ON/OFF to OFF/ON. The asymmetry in the states of the MEMS switches results in a complex multimodal interaction between the two fundamental even and odd CPW modes at the air-bridged cross. Using the multimodal theory, the phase switch is analyzed, its frequency-independent 180 -phase-shift properties are proven, and a set of design equations for perfect port matching are derived. A multimodal circuit model for the phase switch is then presented, and design equations and conditions for compact phase switches are derived. Finally, a very compact phase switch is designed and fabricated using an eight-mask surface micromachining process, featuring a measured phase shift of 180 1.8 in a very wide frequency range (1–30 GHz) and an insertion loss better than 2.1 dB in the design band (10–20 GHz). Experimental results are in very good agreement with electromagnetic and multimodal circuit simulations, thus alidating the proposed approach and design procedure. 2011-10-27T17:06:36Z http://hdl.handle.net/2117/13316 Title: Tunable dual-band resonators for communication systems Authors: Girbau, David; Lázaro Guillén, Antoni; Obiols Pérez, Alberto; Martínez, Ester; Pradell i Cara, Lluís; Villarino Villarino, Ramón Abstract: This paper proposes the design of tunable dual-band resonators for multi-band multi-standard systems. The main objective is to provide frequency tunability in the second resonance while maintaining the first resonance fixed. To this end, two tunable resonators are proposed: the capacitive-loaded stepped-impedance resonator and the capacitive-loaded hole resonator. The work is divided into two main parts. In the first part, an in-depth analysis of the capacitive-loaded stepped-impedance resonator (SIR) structure is done; it provides analytical closed-form design equations that ease the resonator design in contrast to the several approaches available in the literature to date. The analysis is also particularized to the case of the capacitive-loaded constant-section resonator and extended to the capacitive-loaded hole resonator. In addition, a study of the quality factor in capacitively tuned SIRs is also provided. In the second part, resonators are integrated in three dual-band tunable filters, one based on the capacitive-loaded constant-section resonator, another one on the capacitive-loaded SIR, and finally on the capacitive-loaded hole resonator. Two of these filters demonstrate operation in wireless local-area network frequency bands, with a fixed first band at 2.45 GHz and a second band which can be tuned between 5.75 and 5.25 GHz. 2011-09-23T14:29:12Z http://hdl.handle.net/2117/13248 Title: Polymer-based micromachined rectangular coaxial filters for millimeter-wave applications Authors: Jaimes Vera, Edith Aline; Llamas Garro, Ignacio; Ke, M.; Wang, Y.; Lancaster, Michael J.; Pradell i Cara, Lluís Abstract: In this paper, micromachined devices for millimeter-wave applications at U- and V-bands are presented. These structures are designed using a rectangular coaxial line built of gold-coated SU-8 photoresist layers, where the coaxial center conductor is suspended in air by stubs. The designs include a stepped coplanar waveguide (CPW)-to-coaxial transition at 63 GHz, with an insertion loss of 0.39 dB at 67.75 GHz and a return loss better than 210 dB across the band of operation between 54.7 and 70.3 GHz. Two filters have been designed; one centered at 42 GHz with a 10% bandwidth, and another at 63 GHz with a 5% bandwidth. Measured insertion losses of 0.77 and 2.59 dB were obtained for these filters, respectively. Measured return loss lower than 13.8 dB over the passband was achieved for both designs. The structures presented in this paper involve a low-cost manufacturing process suitable to produce integrated subsystems at millimeter waves. 2011-09-19T17:24:36Z http://hdl.handle.net/2117/11816 Title: Passive intermodulation due to self-heating in printed transmission lines Authors: Rocas Cantenys, Eduard; Collado Gómez, Juan Carlos; Orloff, Nathan; Mateu Mateu, Jordi; Padilla Díaz, Alberto; O'Callaghan Castellà, Juan Manuel; Booth, James C. 2011-03-14T17:02:08Z http://hdl.handle.net/2117/11634 Title: RF-MEMS uniplanar 180º Phase Switch based on switching between two out-of-phase paths Authors: Llamas Morote, Marco Antonio; Pradell i Cara, Lluís; Girbau Sala, David; Ribó, Miquel; Lázaro Villa, José Antonio; Giacomozzi, Flavio; Margesin, Benno Abstract: A phase switch based on switching between two twoport passive networks with a phase difference of 180º is reported. Two RF MEMS single-pole-double-throw structures are used to select the phase path. The fabrication is made on both highresistivity silicon and quartz substrates using the eight-mask FBK-irst surface micromachining process. The measured phase shift is 180º±5º in the frequency range 14−20 GHz on quartz wafers and in the range 8−20 Ghz on silicon wafers. 2011-03-03T10:25:39Z http://hdl.handle.net/2117/10921 Title: Polarimetric formulation of the visibility function equation including cross-polar antenna patterns Authors: Camps Carmona, Adriano José; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Vall-Llossera Ferran, Mercedes Magdalena; Duffo Ubeda, Núria Abstract: The European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) mission will be the first one using two-dimensional aperture synthesis radiometry for earth observation. This study presents the formulation that relates instrument observables and brightness temperature maps including cross-polar antenna voltage patterns, which may be also different from element to element. Finally, the radiometric accuracy degradation if cross-polar patterns are neglected in the image reconstruction is studied. 2011-01-07T13:05:59Z http://hdl.handle.net/2117/10143 Title: Application of CAD load-pull techniques in mixer design Authors: Velázquez, A.; Lázaro Guillén, Antoni; Pradell i Cara, Lluís; Comerón Tejero, Adolfo Abstract: This work describes the application of a commercial CAD software to implement load-pull techniques in the design of microwave mixers. This method is used to generate conversion-loss regions when a diode is pumped and operated as a mixer circuit. Emphasis is placed on the inclusion of image and out-of-band terminations to optimize the operating conditions required to obtain low conversion loss. An X-band 5-dB conversion-loss mixer is designed and tested using this method 2010-11-05T13:05:12Z http://hdl.handle.net/2117/10108 Title: The emissivity of foam-covered water surface at L-band: theoretical modeling and experimental results from the FROG 2003 field experiment Authors: Rodríguez, R; Monerris Belda, Alessandra; Sabia, Roberto; Miranda Mendoza, Jorge José; Camps Carmona, Adriano José; Vall-Llossera Ferran, Mercedes Magdalena; Villarino Villarino, Ramón; Reul, N; Chapron, B; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Torres Torres, Francisco Abstract: Sea surface salinity can be measured by microwave radiometry at L-band (1400–1427 MHz). This frequency is a compromise between sensitivity to the salinity, small atmospheric perturbation, and reasonable pixel resolution. The description of the ocean emission depends on two main factors: 1) the sea water permittivity, which is a function of salinity, temperature, and frequency, and 2) the sea surface state, which depends on the wind-induced wave spectrum, swell, and rain-induced roughness spectrum, and by the foam coverage and its emissivity. This study presents a simplified two-layer emission model for foam-covered water and the results of a controlled experiment to measure the foam emissivity as a function of salinity, foam thickness, incidence angle, and polarization. Experimental results are presented, and then compared to the two-layer foam emission model with the measured foam parameters used as input model parameters. At 37 psu salt water the foam-induced emissivity increase is 0.007 per millimeter of foam thickness (extrapolated to nadir), increasing with increasing incidence angles at vertical polarization, and decreasing with 2010-11-04T12:28:56Z http://hdl.handle.net/2117/10105 Title: MIRAS end-to-end calibration: application to SMOS L1 processor Authors: Vall-Llossera Ferran, Mercedes Magdalena; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Camps Carmona, Adriano José; Colliander, A; Martín Neira, Manuel; Ribó, S; Rautiainen, K; Duffo Ubeda, Núria Abstract: End-to-end calibration of the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) radiometer refers to processing the measured raw data up to dual-polarization brightness temperature maps over the earth's surface, which is the level 1 product of the Soil Moisture and Ocean Salinity (SMOS) mission. The process starts with a self-correction of comparators offset and quadrature error and is followed by the calibration procedure itself. This one is based on periodically injecting correlated and uncorrelated noise to all receivers in order to measure their relevant parameters, which are then used to correct the raw data. This can deal with most of the errors associated with the receivers but does not correct for antenna errors, which must be included in the image reconstruction algorithm. Relative S-parameters of the noise injection network and of the input switch are needed as additional data, whereas the whole process is independent of the exact value of the noise source power and of the distribution network physical temperature. On the other hand, the approach relies on having at least one very well-calibrated reference receiver, which is implemented as a noise injection radiometer. The result is the calibrated visibility function, which is inverted by the image reconstruction algorithm to get the brightness temperature as a function of the director cosines at the antenna reference plane. The final step is a coordinate rotation to obtain the horizontal and vertical brightness temperature maps over the earth. The procedures presented are validated using a complete SMOS simulator previously developed by the authors. 2010-11-04T11:38:19Z http://hdl.handle.net/2117/8064 Title: On-ground characterization of the SMOS payload Authors: Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín Neira, Manuel; González Gambau, Veronica; Camps Carmona, Adriano José; Vall-Llossera Ferran, Mercedes Magdalena Abstract: The on-ground characterization of the synthetic aperture radiometer onboard the Soil Moisture and Ocean Salinity mission is described. Characterization includes basic functionality, internal calibration, thermal cycling, response to point and flat sources, self-radio-frequency interference, and others. The description of the different tests performed as well as the detailed results are provided. The results show that the instrument is very stable and has all gains and offsets consistent with the ones obtained at subsystem level. On the other hand, the phase of the visibility has a larger variation with temperature than expected, a small signal leakage from the local oscillators is present, and a small interference from the X-band transmitter during short periods of time has been detected. The implementation of internal-calibration procedures, along with the accurate thermal characterization performed, have been used to produce highly accurate brightness-temperature values well within specifications. 2010-07-08T08:18:59Z