Vicente González-Posadas

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Multifrequency microstrip patch antennas partially filled with left-handed (LH) structures are presented. The presence of LH structures also enables miniaturized antennas. Thus, multifrequency, dual-mode, and miniaturized antennas based on single patches partially filled with LH structures have been obtained. First, multiple operation over several band(More)
This paper presents a study of the short circuited ring patch antenna based on the cavity model. Special attention has been paid to the fundamental mode in this geometry: the TM/sub 01/ mode. Analytical expressions for resonant frequency, fields, radiation pattern and input impedance based on this model have been developed. Simulations based on this(More)
Unique properties exhibited by metamaterial transmission lines have been previously used to design a large number of dual-band microwave passive devices, but not active ones. In this paper, a novel dual-band active filter scheme based on composite right/left-handed transmission lines is proposed. The inclusion of these types of lines as feedback sections in(More)
The results of a parametric study and design of an ultrawideband dual-polarized array of differentially-fed tapered slot antenna elements are presented. We examine arrays of bunny-ear antennas and discuss the capabilities and limitations of differential antenna technology. As we focus on radio astronomical applications, the absence of a balancing-feed(More)
A novel approach to design dual-frequency printed dipoles is presented. This approach is based on an antipodal printed dipole loaded with split ring resonators (SRRs). This technique allows the choice of any pair of working frequencies. Two prototypes, the first one working at 1.32 and 2.83 GHz and the second one working at 1.2 and 2.05 GHz, have been(More)
Differential amplifiers have been proposed as an efficient solution for the planar aperture arrays in the low frequency band of the SKA project. The characterization of this type of devices is not the typical one, and they need of some specific techniques. On the other hand, the use of antennas matched to a non-50 Ω impedance requires of source-pull(More)
Stability is the biggest problem in the matching of Electrically Small Antennas (ESAs) using non-Foster reactances realized by Negative Impedance Converters (NICs). However, it is not usually studied properly. In this paper we propose the Normalized Determinant Function (NDF) as a powerful method to test the stability of the systems formed by the NIC and(More)
A novel method to obtain the dispersion diagram of a composite right/left-handed (CRLH) unit-cell is presented. This method is based on CRLH transmission-line (TL) theory and on the structure eigenfrequencies. First, it is shown that computing the dispersion diagram of an M unit cell CRLH TL only needs three eigenfrequencies. Then, it is shown that this(More)
In this study, the use of dual-composite right-left-handed (D-CRLH) transmission lines is proposed for the design of diplexers. The D-CRLH diplexers present advantages over conventional diplexers such as smaller size (especially in the ultra high frequency band). The design procedure and the design equations are presented in this paper. The non-linear phase(More)
Arrays of coherently driven photomixers with antenna (antenna emitter arrays, AEAs) have been evaluated as a possibility to overcome the power limitations of individual conventional photomixers with antenna (“antenna emitters”, AEs) for the generation of continuous-wave (CW) THz radiation. In this paper, “large area emitters”(More)