Compact loaded PIFA for multifrequency applications

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

K a-Band Fully Metallic TE40 Slot Array Antenna with Glide-Symmetric Gap Waveguide Technology

Gap waveguide has recently been proposed as a low-loss and low-cost technology for millimeter-wave components. The main advantage of the gap waveguide technology is that the microwave components can be manufactured in two metallic pieces that are assembled together without electrical contact. The leakage through a thin air gap between the two pieces is prevented by a 2-D periodic structure offering an electromagnetic bandgap (EBG). This EBG is conventionally implemented with metallic pins. Here, we propose the usage of a holey glide-symmetric EBG structure to design a 4 × 4 slot array antenna that is fed with a TE 40 mode. The TE 40 excitation is designed based on a TE 10 -TE 20 mode converter whose performance is initially evaluated by radiation pattern measurements. The final antenna, the 4×4 slot array antenna, was manufactured in aluminum by computer numerical control (CNC) milling. The antenna has a rotationally symmetric radiation pattern that could find application as a reference antenna as well as for 5G point-to-point communications.This work was supported in part by the Spanish Government under Project TEC2016-79700-C2-2-R, in part by the Vinnova Project High-5 through the Strategic Programme on Smart Electronic Systems under Grant 2018-01522, and in part by the Stiftelsen Åforsk Project H-Materials under Grant 18-302. (Corresponding author: Qingbi Liao.

Design Guidelines for Gap Waveguide Technology Based on Glide-Symmetric Holey Structures

The behavior of a glide-symmetric holey periodic structure as electromagnetic bandgap is studied in this letter. A number of numerical simulations have been carried out in order to define the importance of each constituent parameter of the unit cell. Our proposed structure finds potential application in antennas and circuits based on gap waveguide technology for the millimeter band. The experimental verifications confirm the effects previously analyzed with the numerical studies.This work was supported in part by the Spanish Government under Project TEC2013-44019-R and Project TEC2016-79700-C2-2-R and in part by the Madrid Regional Government under Project S2013/ICE-3000

Cost-Effective Gap Waveguide Technology Based on Glide-Symmetric Holey EBG Structures

We present a novel electromagnetic bandgap (EBG) structure, which can be used to manufacture low-cost waveguiding structures at high frequencies. The unit cell of the proposed EBG consists of glide-symmetric holes in parallel plate waveguide. Using this unit cell in groove gap waveguide technology has a number of advantages over pin-type EBG at high frequencies, such as acquiring higher accuracy because of larger periodicity as well as an easier and cheaper manufacturing process. The performance of the proposed waveguiding structure is demonstrated using both a straight and a double 90 degrees bent lines through simulation and measurement.This work was supported in part by the Swedish STINT Postdoctoral Transition Grants Programme under Grant PT2014-5813, in part by the Spanish Government under Project TEC2013-44019-R and Project TEC2016-79700-C2-2-R, and in part by the Madrid Regional Government under Project S2013/ICE-3000

Periodic Structures With Higher Symmetries: Their Applications in Electromagnetic Devices

Higher symmetries frequently amaze human beings because of the illusions and incredible landscapes such symmetries can produce. For example, imagine the unearthly pictures of the Dutch graphic artist M.C. Escher. He made use of glide symmetry and reflection to produce unbelievable transitions and transformations of objects and beings, as illustrated in Figure 1(a). However, the history of higher symmetries started much earlier. Escher was partially inspired by the Moorish tessellations in the Alhambra in Granada, Spain, such as the ones pictured in Figure 1(b).The authors would like to thank Oskar Zetterström for providing the photo in Figure 5(a). This work was partly funded by the Spanish Government, under grant TEC2016-79700-C2-2-R; the French Government, under National Research Agency (ANR) Modeling and De - sign of Holey Metasurfaces project grant ANR JCJC 2016, ANR-16-CE24-0030; the Vinnova project High-5 (grant 2018-01522), under the Strategic Program on Smart Electronic Systems; the Stiftelsen Åforsk project Higher-Symmetric Materials for 5G Communications (grant 18-302); and COST Action SyMat CA18223, supported by COST (European Cooperation in Science and Technology), www.cost.eu

Enhancing the efficiency of compact patch antennas composed of split ring resonators by using lumped capacitors

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

Low-Dispersive Leaky-Wave Antenna Integrated in Groove Gap Waveguide Technology

In this paper, the use of a dispersive prism with a triangular shape is proposed to reduce the dispersive radiation nature of a leaky-wave antenna (LWA) in groove-gap waveguide technology. The operation of gap waveguide technology is based on the use of metallic pins that act as an artificial magnetic conductor, so the electromagnetic fields are confined and guided in the desired directions. To control a leaky-wave radiation of these confined fields is possible by tailoring the height of the pins, its periodicity, and the waveguide width. This radiation, as in any conventional LWA, is dispersive, leading to beam squint as the frequency is varied. Here, we mitigate this beam squint by using a prism made of dispersive pins and choosing appropriately their periodicity and height. With this prism, the leaky-wave radiation is focused into one single direction in a wide frequency band. This concept is demonstrated with a prototype designed to radiate at phi = 41 degrees with a central frequency of 12 GHz and the high gain of 16.5 dBi. A 22% frequency bandwidth for the 3 dB realized gain at phi = 41 degrees is achieved, and the main radiating direction, with half-power beamwidth of 5 degrees, steers only +/- 0.5 degrees from 11.4 to 13.4 GHz.This work was supported in part by the Alexander von Humboldt Foundation, in part by the Spanish Government under Project TEC2016-79700-C2-2-R, and in part by the Madrid Regional Government under Project S2013/ICE-3000

Gap Waveguide Leaky-Wave Antenna

A novel leaky-wave antenna, realized using gap waveguide concept, is here proposed. Both, the feeding structure and the antenna are realized in groove gap waveguide technology, thus simplifying the whole structure. A complete design procedure, starting from a given groove waveguide to the final radiation mechanism, is described in this communication. The results are supported with measurements of a prototype that operates in the X-band. The realized antenna has a gain around 18 dB between 9 and 11.5 GHz, demonstrating the potential of the proposed radiation technology.This work was supported in part by the Unity through Knowledge Fund (UKF), Croatia, under the project 9/13;, in part by the ESF Research Networking Programme NEWFOCUS, in part by Spanish Government under the project TEC2013-44019-R, and in part by Madrid Regional Government under the project S2013/ICE-3000

Northern Shrimp (Pandalus borealis, Krøyer) from Spanish Bottom Trawl Survey 2009 in NAFO Div. 3LNO

The Spanish Institute of Oceanography carried out in 2009 two bottom trawl surveys in the NAFO Regulatory Area in Division 3NO and 3L during the months of June, July and August respectively. The results on Northern shrimp (Pandalus borealis) are presented and compared with those from previous surveys from the same series. In 2009 the catch (33 kg.) and estimated biomass (139 t.) confirm the decrease of shrimp importance from 2004 in 3NO. In 2009 the biomass estimated of northern shrimp in 3L Division was 74091 t. showing a drastic decline (50% with respect to 2008) after the upward trend a long the whole period studied. Catch results from the surveys and data analysis are discussed in this paper