Dual-band Sierpinski fractal monopole antenna

A new top-loaded reduced-sized dual-band (1.9 GHz and 3.5 GHz) monopole antenna for wireless communications is presented. The antenna provides better than -15 dB input return loss and keeps the same radiation pattern over both bands. In addition, a low-profile performance is achieved.Peer ReviewedPostprint (published version

Truncation errors in cylindrical near to far field transform. A plane wave synthesis approach

Cylindrical Near to far field antenna transformation is expressed as a plane wave synthesis problem where a plane wave is produced by a cylindrical current distribution that encloses the Antenna Under Test (AUT). The current distribution that produces the plane wave is directly derived from the near to far field transformation algorithm.Peer ReviewedPostprint (published version

Multiband Sierpinskl fractal patch antenna

The multiband behavior of the Sierpinski patch antenna is described, and a new technique to improve the multiband behavior from the point of view of the radiation patterns is introduced. The technique suppresses the effects of the high order modes and a patch antenna with similar radiation patterns can be designed. Once the high order mode has been suppressed for the second band, the next step is to try eliminate it for the third and fourth band breaking the appropriate junctions.Peer ReviewedPostprint (published version

Dual band fss with fractal elements

Experimental and computed results of a frequency selective surface (FSS) based on a certain type of fractal element are presented. The fractal element is a two iteration Sierpinski gasket dipole. Owing to the dual band behaviour of the two iteration Sierpinski gasket dipole, two stopbands are exhibited within the operating frequency band. This behaviour is obtained by arraying one simple element in a single layer frequency selective surface (FSS)Peer ReviewedPostprint (published version

near field to far field tranfsormation of bipolar measurements by equivalent magnetic current approach

An equivalent magnetic current (EMC) approach has been proposed as an alternative method to the classical modal formulation for computing the far-field pattern of a radiating antenna from planar near-field measurements. The attractiveness of this EMC approach includes the possibility of producing the correct far-field pattern in all regions in front of a planar antenna under test (AUT), a drawback of the classical modal formulation due to its dependence on the Fourier transform and assumptions which must be made about the field outside of the measurement zone, and its adaptability to both irregularly sampled and non-canonical near-field measurement surfaces. A drawback of the EMC approach, however, is its significantly larger computational requirements. A comparison of the EMC and classical modal approaches for near-field to far-field transformation is examined in terms of the resultant far-field patterns. Measurement results for a waveguide-fed slot array using the UCLA bi-polar planar near-field measurement scanner are presented. An implementation of the EMC approach for the bi-polar geometry is described and results obtained using different subsets of the measured bi-polar near-field data are presented and compared to that obtained using the classical modal approach.Peer ReviewedPostprint (published version

Infrared thermograms applied to near-field testing

Electromagnetic fields close to radiant structures can be measured quickly using an infrared camera. Examples of induced fields by wire antennas over a detection screen at distances shorter than one wavelength are presented. The measured thermograms agree with simulations that take into account heat propagation on the detection screenPeer ReviewedPostprint (published version

An energy flow study of a double-deck tunnel under quasi-static and harmonic excitations

© 2016. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/This paper presents a comparison between the vibration energy flow radiated by a double-deck tunnel and the one radiated by a simple tunnel when both are excited by constant or by harmonic moving loads. For both cases, the radiated energy is computed using a three-dimensional semi-analytical model of the system. The total energy radiated upwards is presented for a wide range of load speeds, when a constant moving load is considered, and for a wide range of excitation frequencies, when the excitation is a harmonic moving load. Significant differences have been obtained, first, for constant loads moving at very high speeds and, second, for harmonic loads moving at typical speeds for underground trains.Peer ReviewedPostprint (author's final draft

High directivity modes in the koch island fractal patch antenna

The article shows that a patch antenna with fractal boundary exhibits, at a frequencies above the fundamental mode, localized modes. These modes can have broadside directive patterns. As an example of this phenomenon experimental data on the Koch island patch antenna is presented.Peer ReviewedPostprint (published version

Ultra-wideband narrow wall waveguide-to-microstrip transition using overlapped patches

An ultrawideband rectangular waveguide to microstrip line transition operating at the whole LMDS and Ka band is presented. The transition is based on exciting three overlapped transversal patches that radiate into the narrow wall of the waveguide, making the design feasible to be used in ¿g/2 spaced phased arrays. Both top-side and bottom-side versions were designed and compared to show their differences. They were validated by means of a manufactured back-to-back (B2B) configuration, with a measured fractional bandwidth of 21.2% (top-side) and 23% (bottom-side). The maximum single transition measured insertion losses were 0.67 dB (top-side) and 0.85 dB (bottom-side) in the whole band of operationThis work was supported by the Spanish “Comision Interministerial de Ciencia y Tecnologia” (CICYT) under projects DI2020-043, Agencia Estatal de Investigación PID2019-107885GBC31/AEI/ 10.13039, and Catalan Research Group 2017 SGR 219.Peer ReviewedPostprint (published version

Receptor VSAT d'ones mil·limètriques per la mesura de fading de pluja i obtenció de mesures radiomètriques a 40 GHZ

Peer Reviewe