Coupling in multilayer devices

Novel design for devices in multilayer stacked is proposed. Split Ring resonators and Complementary Split Ring resonators are used, in microstrip or dual stripline-microstrip configuration to build different devices. A double frequency resonator and a multilayer triplexer are presented among the paper

Frequency selective properties of coaxial transmission lines loaded with combined artificial inclusions

The properties of a modified coaxial transmission line by periodic inclusions will be discussed. The introduction of split ring resonators, conductor stubs, air gaps, and combination of these gives rise to new frequency selective properties, such as stopband or passband behavior, observable in planar as well as volumetric metamaterial structures. These results envisage new potential applications and implementation of devices in coaxial transmission line technology

Narrowband characterization of near-ground radio channel for wireless sensors networks at 5G-IoT bands

This article belongs to the Special Issue Selected Papers from the 4th International Electronic Conference on Sensors and Applications.In this contribution, a narrowband radio channel model is proposed for rural scenarios in which the radio link operates under near-ground conditions for application in wireless sensor networks dedicated to smart agriculture. The received power attenuation was measured for both transmitter and receiver antennas placed at two different heights above ground: 0.2 and 0.4 m. Three frequency ranges, proposed for future 5G-IoT use case in agriculture, were chosen: 868 MHz, 2.4 GHz and 5.8 GHz. Three ground coverings were tested in a rural scenario: soil, short and tall grass fields. The path loss was then estimated as dependent of the radio link range and a three-slope log-normal path loss model was tailored. Results are explained in terms of the first Fresnel zone obstruction. Commercial Zigbee sensor nodes operating at 2.4 GHz were used in a second experiment to estimate the link quality from the experimental Radio Signal Strength Indicator (RSSI) received values. Two sensor nodes were placed at the same elevation above ground as in the previous experiment, only for short grass field case. The Quality of Service performance was determined in terms of theoretical bit error rate achieved for different digital modulations-BPSK, 8PSK and 16QAM-concluding remarkable results for an obstructed radio link.This research was funded by the Xunta de Galicia Predoctoral Research Grants 2017, and the research project GRC1015/019 also supported by the Xunta de Galicia. The APC was funded by Sensors for the Special Issue Selected Papers from 4th International Electronic Conference on Sensors and Applications

Hybrid computational techniques: electromagnetic propagation analysis in complex indoor environments

In this article, we compare deterministic methodologies for characterizing channel behavior in heterogeneous and composite scenarios. These techniques include one that combines a 3D ray launching (RL) approach based on geometrical optics (GO), a second based on GO and the uniform theory of diffraction (UTD), and another that includes a diffusion equation (DE) method based on the equation of transfer. A new methodology based on the GO and DE is presented and shown to achieve accurate results when compared with real measurements. The proposed technique provides a computational time reduction of up to 90% compared to the conventional approach using GO with the UTD and DE.This work was funded by the Ministerio de Ciencia, Innovación y Universidades, and Gobierno de España (MCIU/AEI/ FEDER,UE), RTI2018-095499-B-C31

Isolation improvement in UWB-MIMO antenna system using slotted stub

Multiple-input multiple-output (MIMO) scheme refers to the technology where more than one antenna is used for transmitting and receiving the information packets. It enhances the channel capacity without more power. The available space in the modern compact devices is limited and MIMO antenna elements need to be placed closely. The closely spaced antennas undergo an undesirable coupling, which deteriorates the antenna parameters. In this paper, an ultra wide-band (UWB) MIMO antenna system with an improved isolation is presented. The system has a wide bandwidth range from 2–13.7 GHz. The antenna elements are closely placed with an edge to edge distance of 3 mm. In addition to the UWB attribute of the system, the mutual coupling between the antennas is reduced by using slotted stub. The isolation is improved and is below −20 dB within the whole operating range. By introducing the decoupling network, the key performance parameters of the antenna are not affected. The system is designed on an inexpensive and easily available FR-4 substrate. To better understand the working of the proposed system, the equivalent circuit model is also presented. To model the proposed system accurately, different radiating modes and inter-mode coupling is considered and modeled. The EM model, circuit model, and the measured results are in good agreement. Different key performance parameters of the system and the antenna element such as envelope correlation coefficient (ECC), diversity gain, channel capcity loss (CCL) gain, radiation patterns, surface currents, and scattering parameters are presented. State-of-the-art comparison with the recent literature shows that the proposed antenna has minimal dimensions, a large bandwidth, an adequate gain value and a high isolation. It is worth noticeable that the proposed antenna has high isolation even the patches has low edge-to-edge gap (3 mm). Based on its good performance and compact dimensions, the proposed antenna is a suitable choice for high throughput compact UWB transceivers.The authors extend their appreciation to the Deanship of Scientific Research at Majmaah University for funding this work under Project Number RGP-2019-32. This work is partially supported by RTI2018-095499-B-C31, Funded by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE)

Design of UWB compact slotted monopole antenna for breast cancer detection

This work presents a new breast tumor detection system based on an omnidirectional microstrip ultra wideband antenna. The localization coordinates of the tumor are studied in detail for better tumor detection. The coordinates of the corresponding maximum value of SAR are identified in order to accurately detect different locations of tumor inside the breast. The results show that relying on these coordinates; the tumor can be detected with high accuracy. The possibility of mutual interferences with other systems operating at the FCC frequency band is considered as a major issue in UWB systems. Therefore, rejected out-band interference signals is introduced by etching single and double U-shaped slots on the radiating element, then a first and second frequency band are successfully produced respectively. The proposed antenna is a compact antenna that can be used on microwave imaging detection. The antenna gain was larger than 2 dBi with an omnidirectional radiation pattern over the whole frequency-band. A relatively flat group delay of the antenna response is also achieved. Antenna prototype has been manufactured and measured; results prove the performance of the proposed antenna

Implementation of an interactive environment with multilevel wireless links for distributed botanical garden in university campus

In this contribution, an end to end system to enable user interaction with a distributed botanical university campus garden is designed, implemented and tested. The proposed system employs different wireless links to collect data related to different bio physiological parameters of both the vegetation mass and the surrounding environment. Detailed analysis of these multilevel communication links is performed by using deterministic volumetric wireless channel estimation and considering underground, near ground and over ground radio propagation conditions. An in-house developed technique enables accurate wireless channel characterization for complete campus scenario considering the multiple link types and all its composing elements. Node definition and network topology is thus obtained by wireless channel analysis of over ground, near ground and underground communication for both 868 MHz and 2.4 GHz Wireless Sensor Networks in an inhomogeneous vegetation environment. Connectivity to enable user interaction as well as for telemetry and tele-control purposes within the campus is achieved by combining ZigBee and LoRaWAN transceivers with the corresponding sensor/actuator platforms. Coverage studies have been performed in order to assess communication capabilities in the set of multiple underground/near ground/over ground links, by means of deterministic channel analysis for the complete university campus location. Measurement results in lab environment as well as full system deployment are presented, showing good agreement with deterministic simulations. Moreover, system level tests have been performed over a physical campus cloud, providing adequate quality of experience metrics. The proposed solution is a scalable system that provides real time trees status monitoring by a cloud-based platform, enabling user interaction within a distributed botanical garden environment in the university campus.This work was supported in part by the 2017 Predoctoral Research Grant supported by the Xunta de Galicia and the Research Projects under Grant TEC2017-85529-C03-3R and Grant RTI2018-095499-B-C31, in part by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España [MCIU/Agencia Estatal de Investigación (AEI)/Fondo Europeo de Desarrollo Regional (FEDER), Unión Europea (UE)], and in part by the European Union’s Horizon 2020 Research and Innovation Program (Stardust-Holistic and Integrated Urban Model for Smart Cities) under Grant 774094.This work was supported in part by the 2017 Predoctoral Research Grant supported by the Xunta de Galicia and the Research Projects under Grant TEC2017-85529-C03-3R and Grant RTI2018-095499-B-C31, in part by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España [MCIU/Agencia Estatal de Investigación (AEI)/Fondo Europeo de Desarrollo Regional (FEDER), Unión Europea (UE)], and in part by the European Union’s Horizon 2020 Research and Innovation Program (Stardust-Holistic and Integrated Urban Model for Smart Cities) under Grant 774094

Characterization of near-ground radio propagation channel for wireless sensor network with application in smart agriculture

Trabajo presentado al 4th International Electronic Conference on Sensors and Applications (ECSA 2017), 15–30 November 2017; Available online: https://sciforum.net/conference/ecsa-4.In this contribution, we present a narrowband radio channel model for a scenario wherein the radio link operates under near-ground conditions, occurring on a ZigBee wireless sensor networks applied to smart agriculture. A near-ground network deployment can be useful to avoid tall antenna masts, or once crops grow. Among the examined scenarios, we analyzed path loss caused when placing sensor nodes in soil, short and tall grass fields. We measured the received power when locating both transmitter and receiver antennas at two different heights. The path loss was then estimated as dependent of the radio link range. In another scenario, RSSI were obtained to analyze the communication quality between sensor nodes using same antennas heights as the previous scenarios, only for the case of a short grass field.This research is supported by the Xunta de Galicia Predoctoral research grants 2017

A compact wide bandpass filter for satellite communications with improved out-of-band rejection

This paper presents a compact C-band bandpass filter with improved out-of-band rejection. It consists of a symmetric three-pole parallel coupled line microstrip loaded with complementary split ring resonators (CSRRs) and slot resonators. Enhancements regarding the filter responses are obtained by etching these two parasitic shapes successively. When, CSRRs are introduced in the ground plane, exactly in the back of the transmission line of 50 Ω, improvements on the filter selectivity level are achieved. Whereas, the slot resonator elements are implemented on the feed line to per-mit the suppression of the second harmonics. To reduce the second harmonics of 11.1−13 GHz, the parasitic elements are both combined, widen the filter rejection of 5.81%. The surface current distribution together with the equivalent circuit are also studied in order to demonstrate the slots and the CSRRs effect parameters on the behavior of the proposed filter. A prototype of the optimal filter is fabricated and measured.Theory and experiment results prove the validity of the new design procedure

Impact of body wearable sensor positions on UWB ranging

In recent years, Ultrawideband (UWB) has become a very popular technology for time of flight (TOF) based localization and tracking applications but its human body interactions have not been studied yet extensively. Most UWB systems already proposed for pedestrian ranging have only been individually evaluated for a particular wearable sensor position. It is observed that wearable sensors mounted on or close to the human body can raise line-of-sight (LOS), quasi-line-of-sight (QLOS), and non-line-of-sight (NLOS) scenarios leading to significant ranging errors depending on the relative heading angle (RHA) between the pedestrian, wearable sensor, and anchors. In this paper, it is presented that not only does the ranging error depend on the RHA, but on the position of the wearable sensors on the pedestrian. Seven wearable sensor locations namely, fore-head, hand, chest, wrist, arm, thigh and ankle are evaluated and a fair comparison is made through extensive measurements and experiments in a multipath environment. Using the direction in which the pedestrian is facing, the RHA between the pedestrian, wearable sensor, and anchors is computed. For each wearable sensor location, an UWB ranging error model with respect to the human body shadowing effect is proposed. A final conclusion is drawn that among the aforementioned wearable locations, the fore-head provides the best range estimate because it is able to set low mean range errors of about 20 cm in multipath conditions. The fore-head's performance is followed by the hand, wrist, ankle, arm, thigh, and chest in that order.This work was supported in part by the Research Training Grants Program of the University of Deusto, in part by REPNIN+ under Grant TEC2017-90808-REDT and in part by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España under Grant RTI2018-095499-B-C31