Open Access
A gap waveguide-based compact rectangular waveguide to a packaged microstrip inline transition
(MDPI, 2020) Pérez Escudero, José Manuel; Torres García, Alicia E.; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Institute of Smart Cities - ISC
In this paper two different simple to design and easy to manufacturing transitions from a microstrip to rectangular waveguide based on ridge and groove gap waveguides are studied. The first one is based on a combination of a groove and ridge gap waveguide. In this case, the microstrip substrate occupies the whole bottom metallic housing block, namely, the transition and the gap between the bed of nails and the lid; therefore, it does not require any substrate shaping. Nevertheless, the transition needs to replace groove waveguide by ridge gap waveguide sections to avoid higher-order mode excitation. In the second approach, based on only a groove gap waveguide, the substrate is shaped to be only in the microstrip section, that is, outside the bed of nails area. This leads to a simplification of the design procedure. Prototypes of both transitions have been characterized, showing good agreement with the simulations taking into account the manufacturing tolerances. Performance comparable to the state-of-the-art in this frequency band has been achieved.
Open Access
A gap waveguide fed circular polarization antennas in the millimeter wave range
(IEEE, 2020) Pérez Quintana, Dayan; Torres García, Alicia E.; Ederra Urzainqui, Íñigo; Beruete Díaz, Miguel; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In this work, a novel circular polarization (CP) antennas in ridge gap waveguide (RGW) working in the V-band of the millimeter-wave spectrum is presented. CP is generated in a simple and effective way by means of two orthogonal feeder arms that excite a CP in a rotated square-shaped slot placed on top metallic lid. Parametric simulation studies demonstrate that a difference between both arms length of approximately λ/4 leads to high-purity CP within a relatively broad bandwidth. A square-shaped slot antenna is manufactured and experimentally analyzed. A broadband matching with a reflection coefficient magnitude below -10 dB (S11 <; -10 dB) is achieved from 60.5 to 69.3 GHz. Applying the axial ratio criterion (AR <; 3 dB) the bandwidth in CP is 10.74%, with respect to the central frequency. The maximum gain at broadside is 5.49 dB at 66.8 GHz.
Open Access
Planar DNG superstrate for dipole antenna gain enhancement
(2007) Sáenz Sáinz, Elena; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Ikonen, Pekka; Tretyakov, Sergei A.; Maagt, Peter de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, a volumetric double-negative (DNG) superstrate based on grids of dipoles and wires for dipole antenna applications is proposed.
Embargo
Experimental validation of a Ku-band dual circularly polarized metasurface antenna
(IEEE, 2018) Tellechea Pereda, Amagoia; Caminita, Francesco; Martini, Enrica; Ederra Urzainqui, Íñigo; Teniente Vallinas, Jorge; Iriarte Galarregui, Juan Carlos; Gonzalo García, Ramón; Maci, Stefano; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
The experimental validation of a Ku-band dual circularly polarized (CP) broadside-beam metasurface (MTS) antenna is presented. A radially modulated anisotropic single layer MTS has been synthesised employing sub-wavelength elliptical slotted metallic patches printed on top of a thin Arlon grounded substrate. In the structure, two decoupled phasematched transverse magnetic and transverse electric surface waves (SWs) are excited, which interact with the modulated surface leading to a CP broadside radiation. Two different orthomode transducers have been designed to excite the SWs with orthogonal polarization and equal amplitude. The first feeding system is composed of a metallic stepped septum inside an airfilled square waveguide. A conical section is included to match the output port of the square waveguide with the terminal, dielectric filled circular waveguide. The second feed is much more compact and efficient and it is composed of a circular waveguide completely filled by a dielectric. Depending on the input port excited on the feeds, two TE11 modes are excited with ±90° phase shift, which determine the right-hand or left-hand sense of the broadside beam generated by the MTS. Manufacturing details of the MTS and excitations are given and the measurements are compared with the simulation results. Finally, conclusions are drawn.
Open Access
Comparison of modified Soret lenses for dual band integrated detectors
(IEEE, 2020) Torres García, Alicia E.; Pérez Escudero, José Manuel; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
This paper presents the comparison of different modified Soret lenses suitable for a millimeter and submillimeterwave dualband integrated pixel detectors. The approach is based on the modification of a printed planar Soret lens, designed to operate in the sub-mm range, to obtain an antenna at the millimeter region. Three modifications of a transmission-mode Soret Lens at 850 GHz based on spiral, logarithmic and meander antennas geometries have been analyzed with a combination of Kirchhoffs Diffraction and full-wave simulation methods. The performance of the designs has been experimentally demonstrated in the submillimeterwave band, showing good agreement with simulation results.
Open Access
New hexagonal CORPS-BFN for multibeam antenna applications
(IEEE, 2020) Biurrun Quel, Carlos; Montesano, Antonio; Ederra Urzainqui, Íñigo; Iriarte Galarregui, Juan Carlos; Río Bocio, Carlos del; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
This work presents a new topology of a Coherently Radiating Periodic Structure - Beam Forming Network (CORPS-BFN) and its application for multibeam systems. A unit cell, consisting of a transition from a coaxial input to an intersection of three strip-lines with an angular span of 120 degrees, is proposed and analysed. A periodical replication of the cell gives rise to a uniform layer, allowing a proper matching of the ports of the network. Stacked layers allow in-phase propagation and distribution of the energy through the structure, increasing the number of output ports with each layer.
Open Access
Design of a multifrequency antenna array with the use of left-handed superstrates
(2005) Sáenz Sáinz, Elena; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Maagt, Peter de; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, the radiation performances of different antenna configuration based on Left-Handed superstrates are presented. First of all, the behaviour of a Left- Handed (LH) unit cell is analysed, showing a resonant response with pass band and stop band frequencies. In order to improve the radiation performances of a single dipole, ie., to increase the directivity and efficiency and to reduce the back radiation, diverse LH superstrates working at the resonant frequency of the dipole are analysed. With these configurations, improvements in terms of directivity higher than 6 dB with efficiency closer to 100 % have been obtained.
Open Access
Least upper bounds of the powers extracted and scattered by bi-anisotropic particles
(IEEE, 2014) Liberal Olleta, Íñigo; Ra'di, Younes; Gonzalo García, Ramón; Ederra Urzainqui, Íñigo; Tretyakov, Sergei A.; Ziolkowski, Richard W.; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
The least upper bounds of the powers extracted and scattered by bi-anisotropic particles are investigated analytically. A rigorous derivation for particles having invertible polarizability tensors is presented, and the particles with singular polarizability tensors that have been reported in the literature are treated explicitly. The analysis concludes that previous upper bounds presented for isotropic particles can be extrapolated to bianisotropic particles. In particular, it is shown that neither nonreciprocal nor magnetoelectric coupling phenomena can further increase those upper bounds on the extracted and scattered powers. The outcomes are illustrated further with approximate circuit model examples of two dipole antennas connected via a generic lossless network.
Open Access
Superbackscattering antenna arrays
(IEEE, 2015) Liberal Olleta, Íñigo; Ederra Urzainqui, Íñigo; Gonzalo García, Ramón; Ziolkowski, Richard W.; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This article discusses the theory, design and practical implementation of superbackscattering antenna arrays. In analogy with Uzkov’s maximal directivity theorem, it is demonstrated that the maximal backscattering cross-section, normalized to the wavelength squared, of a linear array of N isotropic scatterers whose separation tends to zero is N2(N + 1)2=(4pi). This analytical result is validated via numerical optimization of the excitation coefficients, and the same procedure is utilized to assess the maximal backscattering of arrays of electric Hertzian dipoles (EHDs). It is found that electrically small arrays of two and three EHDs can enhance the backscattering by factors of 6.22 and 22.01, respectively, with respect to the maximum value generated by a single element. In addition, physical realizations of arrays featuring comparable enhancement factors can be straightforwardly designed by using a simple procedure inspired by Yagi-Uda antenna concepts. The practical implementations of such arrays based on copper wires and printed circuit technologies is also addressed.
Open Access
Decoupling of multifrequency dipole antenna arrays for microwave imaging applications
(Hindawi Publishing Corporation, 2010) Sáenz Sáinz, Elena; Guven, K.; Ozbay, Ekmel; Ederra Urzainqui, Íñigo; Gonzalo García, Ramón; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
The mutual coupling between elements of a multifrequency dipole antenna array is experimentally investigated by S-parameter measurements and planar near-field scanning of the radiated field. A multifrequency array with six dipoles is analyzed. In order to reduce the coupling between dipoles, a planarmetasurface is placed atop the array acting as superstrate. Themutual coupling of the antenna elements in the absence and presence of the superstrate is presented comparatively. Between 3 and 20 dB mutual coupling reduction is achieved when the superstrate is used. By scanning the field radiated by the antennas and far-field measurements of the radiation pattern, it is observed that the superstrate confines the radiated power, increases the boresight radiation, and reduces the endfire radiation.