Fernando Las Heras

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In this work, a millimetre/sub-millimetre wave imaging system for the analysis, characterisation and detection of hidden elements in artwork is presented. The practical implementation of the system relies on a novel generation of purpose developed frequency multiplier and mixer topologies, based on graphene non-linear devices. The proposed set-up will be(More)
The phase error distribution caused by the selection of the working point and synchronization characteristics of an array of mutually coupled harmonic self-oscillating mixers (HSOMs) in a receiving topology is studied using simplified models and a nonlinear analysis. The influence in the phase error of the synchronization phase and the mismatches between(More)
A fourth harmonic oscillator based 4×4 active antenna array has been presented. The fourth harmonic oscillator circuits generate the carrier at 10 GHz with a level of -15 dBm, whose phase can be controlled in a continuous range greater than 360°. The beam steering capability has been experimentally validated through preliminary radiation(More)
In this paper an in-depth study of the behavior of rationally synchronized oscillators (RSO) is presented. The circuit is optimized in order to achieve a broad synchronization bandwidth with low reference signal power through the selection of the adequate harmonic content. The nonlinear dynamics of the RSO is analyzed, focusing on the different bifurcation(More)
In this work, a 7<sup>th</sup> order sub-millimeter wave frequency multiplier for Terahertz applications is presented. The multiplier is based on a microstrip line with a small gap where a graphene film layer is deposited. The multiplication phenomena is reached via the nonlinear behavior of the graphene film using an input signal provided by the WR28(More)
In this work, an injection-locked third harmonic self-oscillating mixer has been designed for its use as a variable phase-shifter in an active microstrip phased antenna array. The novel circuit design provides the double functionality of variable phase-shifter and down-converter. Maximum conversion gain is obtained, through the optimization of a new(More)
An 8x1 frequency scanning antenna array has been presented for its operation in the 255-330 GHz frequency band. The antenna has been implemented using WR-3 rectangular waveguide structures and power combiner waveguide-structures in brass metal using mechanical micro-milling facilities. The antenna has been measured using a vector network analyzer and two(More)
In this work, a coherent Tx-Rx system, which generates two carrier signals with frequencies f<sub>o,1</sub>=3 GHz and f<sub>o,2</sub>=3.75 GHz, with a known constant phase relation with a reference signal, with frequency f<sub>r</sub>=5 GHz, is designed, analyzed and implemented in microstrip technology. In order to experimentally characterize the behavior(More)
A new optimization technique for the design of wideband high-gain harmonic self oscillating mixers is presented. The method combines the use of non-linear optimization tools and bifurcation detection and control techniques. High conversion gain is obtained through operation near to Hopf bifurcation points. The technique has been applied to the design of an(More)
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