Unidad externa para una estación terrena del experimento CODE

Peer Reviewe

Unidad externa para una estación terrena del experimento CODE

Peer Reviewe

Instantaneous model of a MESFET for use in linear and nonlinear circuit simulations

A formal approach for nonlinear modeling of FETs is presented. The intrinsic transistor is described by current and charge generators, that are instantaneously dependent on the two internal voltages. The extrinsic parasitic elements are also included. This instantaneous model is obtained from the small signal equivalent circuit computed at a number of bias points, by integration of the bias dependent elements. A program for using this model in nonlinear circuit analysis has been developed. The process has been carried out for two transistors, one being of low noise, and the other a power MESFET. Good agreement has been observed when comparing the nonlinear analysis with measured data. A solid-state power amplifier at 28 GHz has been designed using the power transistor, delivering 21 dBm at 1 dB compression point.Peer ReviewedPostprint (published version

Criterios y métodos de reducción del ruido de fase en osciladores de microondas con MESFET

This paper gives several building criteria for the design of microwave oscillators with MESFET (MESFET-MWO) in order to achieve low phase noise. From device low frequency noise model and identification of phase noise mechanisms generation and sources in MESFET-MWO, a novel expression of 1Hz single side noise power ro carrier power relation or ~(t) function is obtained. A low cost X band oscillator with high efficiency and medium power is built to prove the methods of phase noise reduction derived of that expression. The phase noise measured of the built oscillator allows us to doubt of the device noise model used.Peer ReviewedPostprint (published version

Control automático de nivel (ALC) de un SSPA en banda Ka

This communication describes the design of an Automatic Level Control (ALC) for the transmiter of a CODE (Co-operative Olympus Data Experiment) earth station. The goal of the ALC system is to keep constant the transmited the RF output signal (28 GHz). The results show that the ALC has optimal behavior in Ka band transmiter chains.Peer ReviewedPostprint (published version

Amplificador de potencia en banda ka

Peer ReviewedPostprint (published version

Exact representation of antenna system diversity performance from input parameter description

A simplc formulation Io compute thc envelope correlation of an antenna divemiry system is dcrired. 11 is shown how to compute the envelope correlation hom the S-parameter descnplian of the antenna system. This approach has the advantage that i t does not require the computation nor the measurement of the radiation panem of the antenna system. It also offers the advantage of providing a clca understanding ofthe effects ofmutual coupling and input match on the diversity performance of the antcnnii system

The correlation of visibility noise and its impact on the radiometric resolution of an aperture synthesis radiometer

The correlation between the visibility samples' noise of an aperture synthesis radiometer are required for the computation of the recovered temperature noise of a given pixel and of the improvement introduced by baseline redundance. A general expression for this correlation and noise examples for a linear array are presented.Peer ReviewedPostprint (published version

Compensation of elevation angle variations in polarimetric brightness temperature measurements from airborne microwave radiometers

This paper presents a method for compensating the elevation angle fluctuations occurring in airborne radiometry due to aircraft roll and pitch. The correction is based on a radiative transfer model, and is demonstrated by real data from conical scans over the ocean, showing good results.Peer Reviewe

Ocean salinity observations with SMOS mission

The purpose of this paper is to present the capabilities of SMOS (Soil Moisture and Ocean Salinity mission) for the global mapping of ocean salinity from space. SMOS has been selected by the European Space Agency as the second Earth Explorer Opportunity with a launch date in June 2005. The sensor embarked on SMOS is MIRAS, a Microwave Imaging Radiometer with Aperture Synthesis. MIRAS works at L-band, in the two-polarisations, and has full polarimetric capability. The measurement of sea surface salinity (SSS) is one of the challenges of SMOS. This paper presents first the scientific requirements for a number of oceanographic applications. The scientific requirements are then translated into instrument accuracy, sensitivity, stability and spatial resolution. Major sources of error in the retrieval of ocean salinity will be addressed through an experimental campaign which is described.Peer ReviewedPostprint (published version