Open Access
High efficient dipole antennas by using left-handed superstrates
(2004) Sáenz Sáinz, Elena; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Maagt, Peter de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
This paper deals with pass band properties of Left Handed Media (LHM) to enhance dipole antenna performances. The LHM properties have been used in order to make high directivity antennas with good return loss features. The LHM structure is used as superstrate and placed over a dipole antenna. This superstrate is determining the characteristics of radiation patterns. Simulations of different types of LHM configurations are presented. The improvements of the radiation and matching parameters for each configuration are presented. High efficient antennas are obtained with this technique.
Open Access
Dipolos y metamateriales: mejora de las características de radiación
(2004) Sáenz Sáinz, Elena; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Maagt, Peter de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, pass band properties of Left Handed Media (LHM) are demonstrated. These properties have been used in order to make a LHM super-substrate that is put over a dipole antenna. This super-substrate is going to determine the characteristics of radiation patterns. Simulation with different types of configurations are presented in order to enhance the features of radiation patterns at bore-sight direction.
Open Access
Research on metamaterials for antenna applications
(2005) Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Iriarte Galarregui, Juan Carlos; Martínez Pascual, Beatriz; Sáenz Sáinz, Elena; Cantora Álvarez, Pablo; Maagt, Peter de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
During the last 20 years a lot of attention has been paid to apply Electromagnetic Band Gap (EBG) technology in different frequency ranges, from microwaves to optics. EBG technology is based on the use of periodic structures to prevent the electromagnetic propagation in certain frequency ranges, known as the bandgap [1]. In the last years the new and revolutionary field of Metamaterials is trying to be applied to similar applications. Although different, both technologies have some similitudes as it has been proven for different authors. For instance when working with EBG structures Left-Handed properties can be obtained in some frequency ranges. In this paper, research efforts focussed on applying EBG technology and the more recent Metamaterials, in particular, left-handed materials, to antenna subsystems at microwave and (sub)millimetre wave frequencies are introduced.
Open Access
Study of photonic crystal structures and their applications in the field of antennas
(2000) Gonzalo García, Ramón; Maagt, Peter de; Sorolla Ayza, Mario; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
El propósito principal perseguido en esta tesis ha sido el diseño de estructuras “Photonic Crystal” y sus aplicaciones como substratos para antenas. Estos “Photonic Crystal” se definen como estructuras periódicas en una, dos o tres dimensiones las cuales no permiten la propagación de una onda electromagnética en su interior para cualquier dirección de propagación de la onda incidente en un determinado rango de frecuencias (“bandgap”). Uno de los principales problemas que presentan hoy en día las antenas es la potencia que se transfiere a los modos de substratos. Esta energía no contribuye a la radiación principal de la antena, considerándose un mecanismo de pérdidas. Además, esta energía, dependiendo de la constante dieléctrica del substrato y de su grosor puede suponer más del 70% de la potencia total. Incluso algunas veces esta energía contribuye de forma negativa a la radiación principal, deteriorando en gran medida el diagrama de radiación de la antena. La idea fundamental es utilizar estructuras “Photonic Crystal” como substratos de antenas. Al no permitir la propagación de la onda electromagnética en su interior, no se excitarán modos de substrato y toda la potencia será radiada por la antena. Esto se traducirá en un incremento de la eficiencia y de la directividad de la antena, en la obtención de diagramas de radiación más simétricos y en la reducción de la radiación trasera.
Open Access
Enhanced radiation properties of a rectangular waveguide by means of a left handed media
(2005) Sáenz Sáinz, Elena; Ederra Urzainqui, Íñigo; Gonzalo García, Ramón; Maagt, Peter de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, the results of experimental investigations to improve the gain between two antennas by means of a Left Handed Material (LHM) are presented. The basic idea is the use of a LHM media acting as a resonator to concentrate the power radiated by a rectangular waveguide achieving larger directivities and consequently larger gains. The transmission and radiation properties of this metamaterial (MTM) have been measured using a network analyser and two rectangular waveguides in the X band. Comparing the transmission parameter S21 with and without the LHM media between the waveguides, an appreciable improvement in the power received can be observed.
Open Access
Resultados experimentales de la mejora de potencia radiada por un dipolo mediante un superstrato left-handed
(2006) Sáenz Sáinz, Elena; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Maagt, Peter de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper a comparison between the measured radiation performances of a single dipole and a dipole with a left handed superstrate based on a finite periodic repetition of a unit cell is presented. First of all the return losses and resonant frequency of the dipole has been measured for different sizes of the superstrate, having a good impedance matching and a decrease in the resonant frequency as the number of cells increase. By using an anechoic chamber and a receiver horn antenna, the power transmitted at boresight has been measured for different frequencies, observing a filtering behaviour due to the resonant characteristic of the superstrate and an improvement of the power transmitted at the resonant frequency of around 3.5 dB. Comparing the H and E plane radiation patterns of a dipole and the dipole with superstrate, more symmetrical and directive radiation patterns can be observed. Finally, a comparison between the simulated and measured aperture efficiency is presented with a good agreement between them.
Open Access
Review on electromagnetic band gap technology and applications
(URSI, 2004) Maagt, Peter de; Gonzalo García, Ramón; Vardaxoglou, J.; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
This paper reviews the primary application areas of Electromagnetic BandGap (EBG) technology at microwave and (sub)millimetre wave frequencies. Examples of EBG configurations in the microwave region are shown and include array antennas, high precision GPS, mobile telephony, wearable antennas and diplexing antennas. In the submillimetre wave region a 500 GHz dipole configuration and a novel heterodyne mixer is shown. Some emphasis is also placed on EBG waveguides, high impedance planes (AMC s), resonators and filters. As most fundamental components would be available in EBG technology, a fully integrated receiver could be developed in order to take full advantage of this technology. True integration of passive and active components can now begin to materialise using EBG technology.
Open Access
Metamaterials as super-substrate to enhance dipole antenna performances
(2004) Sáenz Sáinz, Elena; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Maagt, Peter de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, pass band properties of Left Handed Media (LHM) are demonstrated. These properties have been used in order to make a LHM super-substrate that is put over a dipole antenna. This super-substrate is going to determine the characteristics of radiation patterns. Simulation with different types of configurations are presented in order to enhance the features of radiation patterns at bore-sight direction.
Open Access
Choked-gaussian corrugated horn antenna design small global coverage horn antenna for TT&C with extremely low sidelobe level
(2003) Teniente Vallinas, Jorge; Gonzalo García, Ramón; Río Bocio, Carlos del; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
Extremely low sidelobe horn antennas are often required for the actual technology. This type of horn antennas are important to avoid interference with other systems. In this paper we describe a new design implementing a radical change in the current technology. It consists in attaching together a choked-waveguide antenna with a classical pure gaussian output corrugated horn. A really impressive radiation pattern with very low sidelobes and crosspolar levels in a very short antenna is obtained. This antenna shape was firstly presented in [1]. In this paper an improvement in size, weight, bandwidth and crosspolar level of the design is shown. This improvement has been possible due to the optimisation of the profile by means of the use of a mode matching code (mwave Wizard) instead of a time consuming finite element code.
Open Access
Diseño de filtros en guía rectangular usando estructuras PBG's
(2000) Mendióroz, Luis; Martínez de Espronceda Cámara, Beatriz; Gonzalo García, Ramón; Río Bocio, Carlos del; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
A new application of dielectric periodic structures (also known as PBG) to build and design waveguide filters is presented. The periodic structures have some stop frequency bands, band gaps, defined by the geometry, within any mode can propagate through the structure. One could use this particular feature of the periodic structures to implement waveguide filters, or any other device with some frequency dependence [1,2]. In particular, we will focus in the description through an example of all the different effects produced by this kind of structures within a rectangular waveguide.