SwePub - sökning: WFRF:(Rajo Eva 1972)

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1.	Fernández, M.J., et al. (författare) Comparison of blockage widths of ideally hard cylinders of different cross-sectional shapes 2008 Ingår i: 2008 IEEE International Symposium on Antennas and Propagation and USNC/URSI National Radio Science Meeting, APSURSI; San Diego, CA; United States; 5 July 2008 through 12 July 2008. - 9781424420421 Konferensbidrag (refereegranskat)
2.	Kildal, Per-Simon, 1951, et al. (författare) Reducing Sidelobes from Blocking Struts by Metamaterials Cloaking and Shape Optimization 2007 Ingår i: 29th ESA Antenna Workshop on multiple beam and reconfigurable antennas, 18-20 April 2007. Tidskriftsartikel (refereegranskat)
3.	Alfonso, E., et al. (författare) Design of microwave circuits in ridge gap waveguide technology 2010 Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781424460564 ; , s. 1544 - 1547 Konferensbidrag (refereegranskat)abstract This paper presents recent advances is a new waveguiding technology referred to as ridge gap waveguides. The main advantages of the ridge gap waveguides compared to hollow waveguides are that they are planar and much cheaper to manufacture, in particular at high frequencies such as for millimeter and submillimeter waves. In these waveguides there are no mechanical joints across which electric currents must float. The gap waveguides have lower losses than microstrip lines, and they are completely shielded by metal so no additional packaging is needed, in contrast to the severe packaging problems associated with microstrip circuits. The gap waveguides are realized in a narrow gap between two parallel metal plates by using a texture on one of the surfaces. The waves follow metal ridges in the textured surface. All wave propagation in other directions is prohibited (in cutoff) by realizing a high impedance (ideally a perfect magnetic conductor) through the textured surface at both sides of all ridges. Thereby, cavity resonances do not appear within the band of operation. The paper studies the characteristic impedance of the line and presents simulations and measurements of circuits designed using this technology.
4.	Algaba Brazalez, Astrid, 1983, et al. (författare) Design and Validation of Microstrip Gap Waveguides and Their Transitions to Rectangular Waveguide, for Millimeter-Wave Applications 2015 Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 63:12, s. 4035-4050 Tidskriftsartikel (refereegranskat)abstract The paper describes the design methodology, experimentalvalidation and practical considerations of two millimeterwave wideband vertical transitions from two gap waveguide versions (inverted microstrip gap waveguide, and microstrip packaged by using gap waveguide) to standard WR-15 rectangular waveguide. The experimental results show S11 smaller than -10 dB over relative bandwidths larger than 25% and 26.6% when Rogers RO3003 and RO4003 materials are used respectively. The vertical transition from standard microstrip line packaged by a lid of pins to WR-15, shows measured return loss better than 15 dB over 13.8% relative bandwidth. The new transitions can be used as interfaces between gap waveguide feed-networks for 60 GHz antenna systems, testing equipment (like Vector Network Analyzers) and components with WR-15 ports, such as transmitting/receiving amplifiers. Moreover, the paper documents the losses of different gap waveguide prototypes compared to unpackaged microstrip line and Substrate Integrated Waveguide (SIW). This investigation shows that in V-band the lowest losses are achieved with inverted microstrip gap waveguide.
5.	Algaba Brazalez, Astrid, 1983, et al. (författare) Design of a Butler Matrix at 60GHz in Inverted Microstrip Gap Waveguide Technology 2015 Ingår i: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest). - 1522-3965. ; 2015-October, s. 2125-2126 Konferensbidrag (refereegranskat)abstract A four-port Butler matrix is designed at 60GHz in the new gap waveguide technology, inverted microstrip type. The simplicity of doing this circuit in a printed technology and the low loss characteristic makes this design very promising. All the different components of the matrix have been designed and optimized and the complete matrix is currently under optimization.
6.	Algaba Brazalez, Astrid, 1983, et al. (författare) Design of a transition from WR-15 to microstrip packaged by gap waveguide technology 2015 Ingår i: ISAP 2014 - 2014 International Symposium on Antennas and Propagation, Conference Proceedings, Taiwan, 2-5 December 2014. - 9789869147408 ; , s. 235-236 Konferensbidrag (refereegranskat)abstract The gap waveguide technology is an advantageous way of packaging passive microstrip components. This work presents a wideband transition from a standard microstrip line packaged by using a bed of nails, to a rectangular waveguide operating in V band. The transition is designed by means of a T-shaped patch that couples the fields into a rectangular waveguide extending vertically from the microstrip circuit. The simulated results show more than 28.5% bandwidth with S11 lower than -10 dB. This transition is intended to be used as a WR-15 port of a planar array antenna for 60 GHz applications, where the array elements are fed by microstrip distribution networks packaged by gap waveguide technology. Thereby, radiation is avoided from the distribution network itself.
7.	Algaba Brazalez, Astrid, 1983, et al. (författare) Design of Millimeter-Wave Wideband Gap Waveguide Transitions Considering Integration into the Antenna System 2015 Ingår i: 9th European Conference on Antennas and Propagation, EuCAP 2015, Lisbon, Portugal, 13-17 May 2015. - 9788890701856 Konferensbidrag (refereegranskat)abstract Two wideband vertical transitions from inverted microstrip gap waveguide to rectangular waveguide (WR-15) for 60 GHz antenna array applications are proposed. Thesetransitions are aimed to interconnect the WR-15 with the gap waveguide feed-network employed to provide feeding to the radiating elements of slot/horn antenna arrays. The wideband field transformation is achieved without the need of adding a quarter-wavelength cavity backshort on a metal block placed over the transition. First, we replace this backshort by creating a cavity in the radiating layer when this is made in Substrate Integrated Waveguide (SIW) technology, and thereafter we use an air-filled pin cavity in the radiating layer. The simulated Sparametersshow that the presented transitions cover the unlicensed 60 GHz band (57-64 GHz) with good margins.
8.	Algaba Brazalez, Astrid, 1983, et al. (författare) Improving microstrip filters with gap waveguide packaging 2011 Ingår i: Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011. Rome, 11-15 April 2011. - 9781457702501 ; , s. 1080-1084 Konferensbidrag (refereegranskat)abstract A study is presented of the performance of microstrip filters packaged with Perfect Magnetic Conductor (PMC) and realization of the PMC using a lid of nails. A 3rd order parallel coupled-line bandpass filter is designed and packaged with a lid of nails at the Ku-band. The study shows the PMC packaging technique is very efficient in improving the filter characteristics including the insertion loss in the bandpass region.
9.	Algaba Brazalez, Astrid, 1983, et al. (författare) Investigation of Transitions for Use in Inverted Microstrip Gap Waveguide Antenna Arrays 2014 Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014, The Hague, The Netherlands 6-11 April 2014. - 9788890701849 ; , s. 995 - 999 Konferensbidrag (refereegranskat)abstract The main purpose of this work is to create good transitions for inverted microstrip-based versions of gap waveguide that are used to feed slot or horn antenna arrays. Two new millimeter-wave transitions from inverted microstrip gap waveguide to rectangular waveguide are presented. Both geometries are similar and consist of a planar probe, which contains a rectangular patch or T-section. The planar probe is inserted inside the rectangular waveguide through an opening made in the broadside wall of the waveguide. The main difference between the two geometries is that one of them extends upwards and the other one downwards with respect to the planar inverted microstrip gap waveguide circuit. The simulated S-parameters show promising results.
10.	Caiazzo, Marco, 1975, et al. (författare) Numerical investigation of bandgaps of different soft surfaces: Corrugations and strip loaded substrate with vias 2005 Ingår i: IEEE AP-S International Symposium Washington D.C., 3-8 July 2005. ; 2B, s. 312 - 315 Konferensbidrag (refereegranskat)
11.	Kildal, Per-Simon, 1951, et al. (författare) Challenges When Developing the New Wideband Metamaterial EBG-based Gap Waveguide Technology for Millimeter and Submillimeter Wave Applications 2009 Ingår i: Joint 5th ESA Workshop on Millimetre Wave Technology and Applications and 31st ESA Antenna Workshop on “Millimetre and sub-millimetre waves - From technologies to systems”, 18 - 20 May 2009, ESTEC, Noordwijk, The Netherlands. Konferensbidrag (refereegranskat)
12.	Kildal, Per-Simon, 1951, et al. (författare) Design and experimental verification of ridge gap waveguides in bed of nails for parallel plate mode suppression 2011 Ingår i: IET Microwaves, Antennas and Propagation. - : Institution of Engineering and Technology (IET). - 1751-8725 .- 1751-8733. ; 5:3, s. 262-270 Tidskriftsartikel (refereegranskat)abstract This study describes the design and experimental verification of the ridge gap waveguide, appearing in the gap between parallel metal plates. One of the plates has a texture in the form of a wave-guiding metal ridge surrounded by metal posts. The latter posts, referred to as a pin surface or bed of nails, are designed to give a stopband for the normal parallel-plate modes between 10 and 23 GHz. The hardware demonstrator includes two 90 bends and two capacitive coupled coaxial transitions enabling measurements with a vector network analyser (VNA). The measured results verify the large bandwidth and low losses of the quasi-transverse electromagnetic (TEM) mode propagating along the guiding ridge, and that 90 bends can be designed in the same way as for microstrip lines. The demonstrator is designed for use around 15 GHz. Still, the ridge gap waveguide is more advantageous for frequencies above 30 GHz, because it can be realised entirely from metal using milling or moulding, and there are no requirements for conducting joints between the two plates that otherwise is a problem when realising conventional hollow waveguides.
13.	Kildal, Per-Simon, 1951, et al. (författare) Local metamaterial-based waveguides in gaps between parallel metal plates 2009 Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 8, s. 84-87 Tidskriftsartikel (refereegranskat)
14.	Kildal, Per-Simon, 1951, et al. (författare) Mushroom Surface Cloaks for Making Struts Invisible 2007 Ingår i: IEEE AP-S 2007 in Hawai, 10-15 June 2007. Konferensbidrag (refereegranskat)
15.	Kildal, Per-Simon, 1951, et al. (författare) Packaging active and passive microwave circuits using a grid of planar conducting elements on a grid of vertically arranged substrates 2012 Annan publikation (övrigt vetenskapligt/konstnärligt)
16.	Kildal, Per-Simon, 1951, et al. (författare) Progress report on developing metamaterial EBG-based gap waveguide components and packaging solutions between 1 GHz and several 100 Ghz 2011 Ingår i: URSI National Radio Science Meeting, Spokane, USA, 3-8 July, 2011. Konferensbidrag (refereegranskat)
17.	Kildal, Per-Simon, 1951, et al. (författare) Progress report on developing the metamaterial EBG-based gap waveguide technology for millimeter and submillimeter waves 2010 Ingår i: URSI Radio Science Meeting, Toronto, July 11-17, 2010. Konferensbidrag (refereegranskat)
18.	Kildal, Per-Simon, 1951, et al. (författare) The gap waveguide as a metamaterial-based electromagnetic packaging technology enabling integration of MMICS and antennas up to THz 2011 Ingår i: Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011. Rome, 11-15 April 2011. - 9788882020743 ; , s. 3715-3718 Konferensbidrag (refereegranskat)abstract This paper presents new topics that will be lectured in the short course Metamaterials for Antennas within the European School of Antennas in Spring 2012. These relates to new so-called gap waveguides that are advantageous for use above 30 GHz, because they are quasi-TEM over wide bandwidth, and do neither require dielectric material nor conductive joints between metal parts. The gap waveguides originate from research on soft and hard surfaces that also are forerunners for EBG surfaces (acting as isotropic soft surfaces) and metamaterial cloaks (realized first by hard surfaces). The course will contain material related to all these topics, and in addition an overview of the last years research on the gap waveguides including experimental demonstration of principles as well as working hardware components. In this presentation special emphasis will be given to electromagnetic (EM) packaging, the principle of PMC packaging and integration of MMICs.
19.	Kildal, Per-Simon, 1951, et al. (författare) Theoretical and experimental challenges when developing the metamaterial EBG-based gap waveguide technology for millimeter and submillimeter wave circuitry 2009 Ingår i: URSI National Radio Science Meeting, Charleston, USA, 1-5 June 2009. Konferensbidrag (refereegranskat)
20.	Kildal, Per-Simon, 1951, et al. (författare) Wideband, lowloss, low-cost, quasi-TEM metamaterial-based local waveguides in air gaps between parallel metal plates 2009 Ingår i: International Conference on Electromagnetics in Advanced Applications (ICEAA 2009), Torino, Italy, September 14-18, 2009. - 9781424433858 ; 1-2, s. 565-568 Konferensbidrag (refereegranskat)abstract The paper presents a new waveguide appearing in the air gap between two parallel metal plates. One of the plates has a metal texture, and confined local waves follow ridges in the texture whereas they are prohibited from propagating in other directions by metal pins in the texture. The pins (or bed of nails) provide a high impedance surface that creates a stop band when used together with a metal surface, i.e. a parallel plate cut-off. The principle performance of the ridge gap waveguide is explained by numerical simulations of the dispersion diagram, both to show the parallel plate cut-off generated by the pin surface, but also to see the quasi-TEM wave propagating along the ridge. The performance is validated by numerical simulations and experimentally of a ridge gap waveguide with two 90 deg bends, including transitions to coaxial connectors. The ridge gap waveguide has a large potential for use up to THz because it can be realized without conducting joints between metal parts, and it lends itself to co-design and integration with active components.
21.	Kishk, A.A., et al. (författare) EBG-based gap waveguide for applications up to THz 2010 Ingår i: META'10, International Conference on Metamaterials, Photonic crystals and Plasmonics, Cairo, 22-25 February 2010. Konferensbidrag (refereegranskat)
22.	Kishk, A., et al. (författare) Packaging of active and passive microwave circuits using lid or bed of curved posts 2010 Annan publikation (övrigt vetenskapligt/konstnärligt)
23.	Morocco,, et al. (författare) Blockage reduction in thick cylinders by shaping hard cross sections 2008 Ingår i: META'08 & NATO Advanced Research Workshop on Metamaterials, Plasmonics and related Materials, 7-10 May, 2008, Marrakesh. Konferensbidrag (refereegranskat)
24.	Pucci, Elena, 1982, et al. (författare) Design of a Dual-Mode Horn Element for Microstrip Gap Waveguide Fed Array 2013 Ingår i: 7th European Conference on Antennas and Propagation, EuCAP 2013, Gothenburg, Sweden, 8-12 April 2013. - 9781467321877 ; , s. 3086-3089 Konferensbidrag (refereegranskat)abstract The low loss microstrip gap waveguide provides an easy and suitable solution to be used as feed network for antennas at high frequency. This paper presents the design of a slot coupled dual-mode horn element fed by microstrip gap waveguide for array applications at 60 GHz. The directive dual mode horn is used to reduce the grating lobes which are generated when the slot array elements have a distance bigger than lambda. Simulation results of the proposed design are presented in terms of return loss and grating lobe level.
25.	Pucci, Elena, 1982, et al. (författare) Design of a four-element horn antenna array fed by inverted microstrip gap waveguide 2013 Ingår i: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest). - 1522-3965. - 9781467353175 ; , s. 1226-1227 Konferensbidrag (refereegranskat)abstract The paper presents the design of a four-element slot coupled dual-mode horn array with microstrip gap waveguide as feed network. We present simulated results for return loss for the feed network both with and without the radiating horn array. We also compare results for two ways to generate the stopband of the parallel-plate modes: the ideal Perfect Magnetic Conductor used during the initial design, and the real bed of nails used in the practical realization. The study is performed at 60 GHz obtaining about 10% bandwidth.
26.	Pucci, Elena, 1982, et al. (författare) Enhancing the efficiency of compact patch antennas composed of split ring resonators by using lumped capacitors 2012 Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 11, s. 1362-1365 Tidskriftsartikel (refereegranskat)abstract A new type of small patch antenna with low profile and enhanced radiation efficiency is proposed in this letter. The antenna is realized with a double layer of low-permittivity material (polypropylene, εr = 2.2). The lower layer is used for the feeding of the antenna, and split ring resonators (SRRs) are printed on top of the upper layer acting as radiating elements. The compactness is provided by shorting the rings to the ground plane with two metal pins. Although this antenna presented initially a dual band of operation, it has been demonstrated how the use of a lumped capacitor in the inner ring can increase the total radiation efficiency of the antenna performing a single-band response. Therefore, when the two original operation frequency bands coincide, a manufactured prototype of the antenna demonstrated a measured radiation efficiency of 73% that can be provided at the operation frequency of 1.29 GHz.
27.	Pucci, Elena, 1982, et al. (författare) Evaluation of losses in microstrip gap waveguide for slot antennas applications 2012 Ingår i: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest). - 1522-3965. - 9781467304627 ; , s. 1-2 Konferensbidrag (refereegranskat)abstract The new microstrip gap waveguide supports a quasi-TEM mode in the air by the use of artificial magnetic conductors which force the field to travel in the air rather than in the substrate. This paper presents an evaluation of losses by measuring the Q-factor of a resonator made in this technology, made using a mushroom-type EBG surface. Losses are crucial when using printed circuits to feed slot antennas, thereby motivating this work. Comparisons with standard microstrip lines will be provided, showing promising results.
28.	Pucci, Elena, 1982, et al. (författare) Losses in ridge gap waveguide compared with rectangular waveguide and microstrip lines 2010 Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010. - 9781424464319 Konferensbidrag (refereegranskat)abstract A study and quantification of losses in ridge gap waveguide, compared to losses in ideal standard rectangular waveguide and microstrip transmission line is presented. The study is performed by evaluating the quality factor of resonators made of ridge gap waveguide, rectangular waveguide and microstrip line. Results will show that the ridge gap waveguide has a very low loss.
29.	Pucci, Elena, 1982, et al. (författare) New low loss inverted microstrip line using gap waveguide technology for slot antenna applications 2011 Ingår i: Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011. Rome, 11-15 April 2011. - 9788882020743 ; , s. 979-982 Konferensbidrag (refereegranskat)abstract Recently, a new transmission line concept, called gap-waveguide, has been introduced. This technology generates a quasi-TEM mode in the gap between parallel metal plates and prohibits all other modes to propagate by making use of artificial magnetic conductors (AMCs) in the forms of e.g. lid of nails or mushrooms-type EBG surfaces. It has been shown how such geometry can replace standard microstrip lines and waveguides since it needs neither dielectric nor metal joints, being then an advantageous alternative that can be used for several applications at high frequency. This paper shows how the gap waveguide can also be realized in printed technology creating a new type of inverted microstrip line, called microstrip gap waveguide, which has low loss and large bandwidths can be achieved.
30.	Pucci, Elena, 1982, et al. (författare) New Microstrip Gap Waveguide on Mushroom-Type EBG for Packaging of Microwave Components 2012 Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 22:3, s. 129-131 Tidskriftsartikel (refereegranskat)abstract The gap waveguide has been recently presented as a new transmission line technology using artificial magnetic conductors (AMCs) to allow the wave propagation only along a desired path. The first validation has been provided using a lid of metal pins as AMC for high frequency applications. In this letter, simulations and measurement results are presented for another version called microstrip gap waveguide, working as inverted microstrip line and realized using a mushroom-type EBG surface. The transmission line is surrounded by mushrooms which create a parallel plate stop band, suppressing cavity modes and unwanted radiations compared to standard packaged microstrip transmission lines. The field propagates in the air gap between the upper lid and the mushrooms layer, providing a low loss compact circuit made in printed technology.
31.	Pucci, Elena, 1982, et al. (författare) Planar Dual-Mode Horn Array with Corporate-Feed Network in Inverted Microstrip Gap Waveguide 2014 Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 62:7, s. 3534 - 3542 Tidskriftsartikel (refereegranskat)abstract The gap waveguide technology was recently introduced as an alternative to hollow waveguides and substrate integrated waveguides for millimeter-wave applications. This paper presents the design of a 4 x 4 planar dual-mode horn array with low loss corporate feed network realized by using an inverted microstrip gap waveguide. The dual-mode horns are compact and designed to reduce the power losses in grating lobes. It is because the diameters of the horn apertures are larger than two wavelengths to allow more space for the feed network and thereby lower conductive losses. The measurements show very good agreement with simulations, with 10% bandwidth of the return loss, 25 dBi realized gain and about 60% aperture efficiency.
32.	Pucci, Elena, 1982, et al. (författare) Q-factor comparisons between new gap waveguide technology and standard rectangular waveguide 2010 Ingår i: Gigahertz Symposium 2010, Lund University, 9-10 March 2010. Konferensbidrag (refereegranskat)
33.	Pucci, Elena, 1982, et al. (författare) Study of Q-Factors of Ridge and Groove Gap Waveguide Resonators 2013 Ingår i: IET Microwaves, Antennas and Propagation. - : Institution of Engineering and Technology (IET). - 1751-8725 .- 1751-8733. ; 7:11, s. 900-908 Tidskriftsartikel (refereegranskat)abstract The gap waveguide technology for millimeter waves applications has been recently presented. The new structure is made by generating a parallel plate cut-off region between an artificial magnetic conductor (AMC) and a metallic plate. Propagating waves will be only allowed to follow a metal ridge or groove surrounded by the AMC. The gap waveguide can be made of only metal and does not need any contact between the metal joints compared to standard waveguides. In this study, a study of Q-factors of resonators made in ridge and groove gap waveguides are presented. The resonators are made of copper and the AMC used is a textured surface of metallic pins. Simulated and measured unloaded Qs are presented and compared with Q of a standard rectangular waveguide. High Q-factors are measured for the prototypes presented, approaching 90-96% of the simulated values. Furthermore, it is shown how the lid of pins can easily stop the leakage loss at the joints of the circuit, which is the typical cause of reduced Q-factor of standard waveguides at high frequency.
34.	Quevedo Teruel, Oscar, et al. (författare) Compact loaded PIFA for multifrequency applications 2010 Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 58:3, s. 656-664 Tidskriftsartikel (refereegranskat)abstract A new multifrequency microstrip patch antenna is presented. The antenna can be considered a PIFA since it has a metallic wall on one of its sides. The different bands of operation are independent of each other, and different radiation patterns for each band can be achieved if desired. In addition, a circuital model is introduced to explain the operation of the antenna. This model presents some similarities with composite right left handed models presented in the literature. Some prototypes have been manufactured and measurements of return losses, efficiencies and radiation patterns, have been performed for a thorough characterization of the antenna as well as to validate the simulation results.
35.	Quevedo Teruel, Oscar, et al. (författare) Numerical and experimental studies of split ring resonators loaded on the sidewalls of rectangular waveguides 2009 Ingår i: IET Microwaves, Antennas and Propagation. - : Institution of Engineering and Technology (IET). - 1751-8725 .- 1751-8733. ; 3:8, s. 1262-1270 Tidskriftsartikel (refereegranskat)abstract This work investigates the use of a lattice comprising split ring resonators (SRRs) as a negative permeability medium to achieve backward travelling modes within a rectangular waveguide. The loadings of such SRR-type periodic structures into a waveguide can be tailored such that the backward mode exists in a passband below the ordinary basic modal cutoff frequency, thus affording filtering capabilities and miniaturisation. Theoretical studies by two approaches are performed here, a moment method spectral domain analysis, and a commercial simulation tool. Parametric studies that characterise the effects of various dimensional and electrical properties on the dispersion behaviour of the SRR-loaded waveguide shall also be conducted. The SRR parameters are then optimised using the ant colony optimisation (ACO) algorithm to achieve a low backward passband, for a high degree of miniaturisation and isolation. Experimental results of measurements performed on a manufactured prototype of the optimised SRR-loaded waveguide will also be presented.
36.	Quevedo Teruel, Oscar, et al. (författare) On the Increase of the Efficiency and Bandwidth of Compact PIFAs based on SRR by Making Use of Lumped Capacitors 2010 Ingår i: 2010 IEEE International Symposium on Antennas and Propagation, Toronto, July 11-17, 2010. - 1522-3965. - 9781424449675 Konferensbidrag (refereegranskat)abstract In this communication, a new compact microstrip patch antenna based on shortcircuited SRRs is presented. This design, in its basic version, provides a dual band response. This initial configuration will be modified by making use of lumped elements (capacitors), in order to achieve a single band with large bandwidth or higher radiation efficiency.
37.	Quevedo Teruel, Oscar, et al. (författare) Soft Surfaces for Reducing Mutual Coupling Between Loaded PIFA Antennas 2010 Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 9, s. 91-94 Tidskriftsartikel (refereegranskat)abstract The use of planar soft surfaces to reduce mutual coupling in a new type of planar inverted-F antenna (PIFA) is demonstrated in this work. The proposed antenna is dual-band, single-port, and quite compact, especially for the low frequency of operation. At that frequency band, the mutual coupling is more critical. With the purpose of decreasing this coupling, a solution based on soft surfaces made of simple printed strips with grounded vias is presented, achieving a simultaneous reduction on the mutual coupling level at the two bands of operation of the antenna. In this particular example, only two strips are used and a reduction on the coupling of more than 6 dB is experimentally verified for these two bands and for different distances between elements. The use of a multilayer substrate is a key aspect in the proposed design.
38.	Rajo, Eva, 1972, et al. (författare) Alternative ridge gap waveguide design using a mushroom-type EBG surface 2009 Ingår i: IEEE AP-S International Symposium on Antennas and Propagation, Charleston, USA, June 1-5, 2009. - 1522-3965. - 9781424436477 Konferensbidrag (refereegranskat)
39.	Rajo, Eva, 1972, et al. (författare) Bandgaps and bandwidths of different soft surfaces used as finite ground planes of small antennas 2005 Ingår i: EPFL LATSIS Symposium 2005. Konferensbidrag (refereegranskat)
40.	Rajo, Eva, 1972, et al. (författare) Bed of Springs for Packaging of Microstrip Circuits in the Microwave Frequency Range 2012 Ingår i: IEEE Transactions on Components, Packaging and Manufacturing Technology. - 2156-3985 .- 2156-3950. ; 2:10, s. 1623-1628 Tidskriftsartikel (refereegranskat)abstract After the use of the bed of nails for removing cavity modes in microstrip circuit packages, we propose herein a new version of this periodic structure, based on helices (springs) instead of nails. This new structure, named bed of springs, is much more compact, and this allows its use at low frequencies where the bed of nails is not suitable as it is too bulky due to the required height of the nails (pins). The bandwidth of the proposed structure turns out to be similar to the case of bed of nails. Parametric studies are presented as a design tool and a demonstrator is manufactured and measured.
41.	Rajo, Eva, 1972, et al. (författare) Blockage reduction of rhombic cylinders using meta-surfaces 2008 Ingår i: 2008 IEEE International Symposium on Antennas and Propagation and USNC/URSI National Radio Science Meeting, APSURSI; San Diego, CA; United States; 5 July 2008 through 12 July 2008. - 9781424420421 Konferensbidrag (refereegranskat)
42.	Rajo, Eva, 1972, et al. (författare) Comparison between bandgaps and bandwidths of back radiation of different narrow soft ground planes 2005 Ingår i: IEEE AP-S International Symposium Washington D.C., 3-8 July 2005. ; 1A, s. 697-700 Konferensbidrag (refereegranskat)
43.	Rajo, Eva, 1972, et al. (författare) Comparison of bandgaps and bandwidths of mushroom-type EBG surface and strip-type soft surfaces when used as narrow ground planes 2006 Ingår i: First European Conference on Antennas and Propagation (EuCAP), 2006, Nice, France, 6 - 10 November 2006. Konferensbidrag (refereegranskat)
44.	Rajo, Eva, 1972, et al. (författare) Comparison of bandgaps of mushroom-type EBG surface and corrugated and strip-type soft surfaces 2007 Ingår i: IET Microwaves, Antennas and Propagation. ; 1:1, s. 184-189 Tidskriftsartikel (refereegranskat)
45.	Rajo, Eva, 1972, et al. (författare) Comparison of bandwidths of mushroom-type EBG surfaces and corrugated and strip-type soft surfaces when used as narrow ground planes 2008 Ingår i: IET Microwaves, Antennas and Propagation. Tidskriftsartikel (refereegranskat)
46.	Rajo, Eva, 1972, et al. (författare) Cut-off bandwidth of metamaterial-based parallel plate gap waveguide with one textured metal pin surface 2009 Ingår i: Eucap 2009, 3rd European Conference on Antennas and Propagation - 23-27 March 2009 in Berlin, Germany. - 9783000245732 ; , s. 33-36 Konferensbidrag (refereegranskat)abstract This work explores the possibilities of creating stop bands (or bandgaps) for TEM mode in parallel plate waveguides by using artificial surfaces in one of the plates. Particularly, as artificial surface a textured periodic surface made of metal pins has been selected. The present paper reports a parametric study of the "Fakir's bed of nails" structure in terms of the size of the achieved bandgap when the structure is placed within a parallel plate waveguide. Bandwidths larger than 2:1 are seen to be possible. The proposed structure could be used for the design of the new type of waveguides named gap waveguides.
47.	Rajo, Eva, 1972, et al. (författare) Developing hard waveguides based on gap waveguide concept 2011 Ingår i: Metamaterials '2011, The Fifth International Congress on Advanced Elec-tromagnetic Materials in Microwaves and Optics, Barcelona, Spain, 10-15 October 2011. Konferensbidrag (refereegranskat)abstract The use of periodic elements loading rectangular waveguides to miniaturize them allowing the propagation of new (backward) modes has been proposed several years ago. However all the proposed solutions have a strong limitation in terms of bandwidth and impedance matching. We propose for the first time a wide band miniaturized waveguide based on the use of artificial surfaces and the gap waveguide philosophy
48.	Rajo, Eva, 1972, et al. (författare) Gap Waveguide Technology 2019 Ingår i: Surface Electromagnetics: With Applications in Antenna, Microwave, and Optical Engineering. - : Cambridge University Press. ; , s. 198-230 Bokkapitel (övrigt vetenskapligt/konstnärligt)
49.	Rajo, Eva, 1972, et al. (författare) Gap waveguide technology for millimeter-wave antenna systems 2018 Ingår i: IEEE Communications Magazine. - 0163-6804 .- 1558-1896. ; 56:7, s. 14-20 Tidskriftsartikel (refereegranskat)abstract Millimeter-wave communication systems require many innovative antennas adapted for future application scenarios such as the upcoming 5G cellular networks. Due to the strong path loss in free space at the millimeter-wave frequency range, high gain and low-cost antennas are in great demand. Also, advanced features such as multi-beam for multiple user, dual-polarization, or even complete phased arrays with enormous degrees of freedom in beamforming are some of the key research lines for antenna designers nowadays. In this article an overview of a new type of family of low-loss antennas and components based on the recently developed gap waveguide technology is presented. With the advent of new millimeter-wave applications, this low-cost and low-loss waveguide technology can be considered as a good candidate to be used as the core RF building block.
50.	Rajo, Eva, 1972, et al. (författare) Groove gap waveguide - A rectangular waveguide between contactless metal plates enabled by parallel-plate cut-off 2010 Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010. - 9788476534724 Konferensbidrag (refereegranskat)abstract This work presents a numerical study of a topology of gap waveguide referred to as groove-type gap waveguide, including dispersion diagrams and field distributions for different groove geometries. The main difference between this groove gap waveguide and the ordinary rectangular waveguides is that there is no need of electrical contact between upper and lower plate constituting the waveguide. This is a clear advantage at high frequencies when designing cavity filters and other components which require the fabrication of the waveguide based on two pieces and consequently requiring a large number of screws to ensure good conducting contact and avoid leakage.

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