Wearable Fabry-Pérot Antenna

A wearable version of Fabry-Perot antenna is presented. This is a simple way of designing a medium- to high-gain antenna with low back radiation. The study of the effect of antenna bending in the performances is presented. Besides, the replacement of a superstrate layer by a metallic frequency selective surface is proposed. In this way, there is no need of finding a specific material and thickness for a targeted gain and frequency. Experimental validation confirms the viability of this design.This work has been funded by projects TEC2013-44019-R and TEC2016-79700-C2-2-R and S2013/ICE-3000

Array of stacked leaky-wave antennas in groove gap waveguide technology

The design of an array of stacked leaky-wave antennas in groove gap waveguide technology is presented in this work. The proposed array is formed by simply stacking a number of leaky-wave antennas one on top of the other and feeding all of them with uniform amplitude and phase. The inter-element distance is studied in order to avoid grating lobes and to maximize the directivity. A feeding network based on vertical coupling is designed, where the input port feeds the bottom element, and then the energy is equally coupled to the other elements. To obtain maximum directivity the phase is corrected at each element separately. The central frequency of the proposed design is 28 GHz. With this technique of stacking the elements a pencil beam is achieved, i.e. the radiated energy is focalized in the two main planes. The designed array with four elements achieves an enhancement of + 5 dB, reaching 24.5 dBi of directivity in comparison to 19.6 dBi of directivity of the single leaky-wave antenna made in this technology. A prototype is manufactured and measured and its results are presented and compared with the simulations.This work has been partly funded by the Spanish Government through projects TEC2016-79700-C2-2-R and PID2019-107688RB-C21

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.

3D-printed sievenpiper metasurface using conductive filaments

This article belongs to the Special Issue Development and Application of 3D Printing Technology in Electromagnetic Devices.This article presents the design, construction and measurement of different 3D-printed Sievenpiper metasurfaces. The structures were printed using a conductive filament combined with regular polylactic acid PLA. Measurement shows a good agreement on the electromagnetic behaviour of the stop-bands generated by the fully 3D-printed metasurface and the simulated ideal cases, but with higher transmission losses due to the characteristics of the conductive filament

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

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

Evaluation of losses in microstrip gap waveguide for slot antennas applications

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

3D-printing for transformation optics in electromagnetic high-frequency lens applications

This article belongs to the Special Issue Development and Application of 3D Printing Technology in Electromagnetic Devices.This article presents the design, construction and analysis of a 3D-printed transformed hyperbolic flat lens working on the 30 GHz band. The transformed lens was printed using only one ABS dielectric filament of relative permittivity of 12, varying the infill percentage of each transformed lens section in order to achieve the permittivity values obtained with the transformation optics. The 3D-printed hyperbolic transformed lens exhibits good radiation performance compared to the original canonical lens.This research was funded by ANID INICIACION 11180434, ANID PCI MEC80180108, DI-PUCV 039.437, and the Spanish Ministry of Economy under project TEC2016-79700-C2-2-R

New Microstrip Gap Waveguide on Mushroom-Type EBG for Packaging of Microwave Components

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