Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

In this article, a study is made on Single Frequency Networks (SFN) and their influence on television systems that currently exist. A comparison is made with the technology used in analog and digital television systems, as is the case with Multiple Frequency Networks (MFN). Defining the SFN as a set of transmitting devices in charge of propagating the same information simultaneously and synchronized using the same channel. This will be possible thanks to the insertion of the guard interval in the Orthogonal Frequency Division Multiplexing (OFDM) signal, which will allow the echoes or multipaths that come from the different transmitters to be treated in such a way that the signal can be reconstructed in the receiver. In addition, some of the most widely used implementations in the world using SFNs are discussed, such as the standard of Integration of Digital Transmission Services - Territorial of Brazil (ISDB-Tb) and Digital Terrestrial Television (DTT), with the purpose of improving the transmission in some areas, where there is not a good reception of the transmitted signal, so that a more efficient use of the radio spectrum is made, maintaining a coverage similar to that provided by the MFN.

The following work deals with the design, manufacture, modifications and the current situation for the commercialization of a Multiband Log-Periodic Antenna proposed especially for use with a 75 Ω coaxial cable which was chosen after a brief study and technical considerations of agreement to utility, competition with foreign antennas and prices. Various prototypes have been developed in conjunction with the various technologies for their manufacture. Zero productions have been manufactured for tests and validations in some localities within the national territory that are comprised in areas with difficulties in receiving DTT. So far they have been marketed in some state entities along with their installation service by the Villa Clara Antenna Company. As a final result, a group of techno-logical considerations, criteria and market requirements to carry out the manufacturing of an antenna with high performance and intended to cover Band III of VHF, from channel 7 to 13, and UHF from channel 14 to 51 mainly for the purposes of receiving Digital Terrestrial Television (DTT).

The Gap Waveguide (GW) technology is an alternative to conventional transmission lines for use in the design of antennas in the millimeter-wave band (3 - 300 GHz). Compared to other lines used in microwave systems, higher efficiency values are obtained, with the consequent increase in antenna gain, because in most cases the GW does not use substrate. Besides, due to its physical characteristics, the GW technology has greater resistance to solar radiation. These two advantages are very useful in satellite applications because they operate in extreme conditions of solar radiation and with batteries that limit the life of the satellite.  The present work is aimed at the design of a 2x2 element slot antenna array for satellite applications in the Ka-band with circular polarization, using the Ridge Gap Waveguide (RGW) variant. The simple element of the array consists of an L-terminated structure and a rotated slot in the top metal plate for circular polarization. A maximum gain of 12.5 dB is obtained, a circular polarization bandwidth of approximately 18.4%, and total efficiency of 99% for the design frequency (35 GHz), falling at the ends of the band up to 85%.

The Slotted Waveguide Antenna (SAW) are chosen as very economical antennas because they have high relative gain values and a structure with little complexity. Therefore, the present work is aimed at the design and manufacture of a type of slotted waveguide antenna for Wi-Fi wireless network applications to satisfy the needs existing by customers who wish to connect entities through network connection wireless fundamentally in the 2.4 GHz band. Due to the new technological changes in which the Cuban Telecommunications Company (ETECSA) is immersed, it raises the need for import substitution with their development. To fulfill the purpose of this work, several documents were analyzed with which the characteristics of the grooved waveguide antennas could be studied where there is no clarity about the design methodology. That is why we start with the proposal of an antenna design methodology. With the support of a 3D modeling and electromagnetic simulation software, the typical parameters within the operating frequency band are obtained. Finally, the experimental results obtained in the measurements made to various prototypes of antennas are provided for validation.

The study of holographic antennas dates from the 60s; although they were initially relegated to the background, interest in them has been increasing since the development of new wireless communication systems thanks to their ease of integration and low costs. The present article aims at the design and simulation of a single-layer holographic antenna in the Ka band at 30GHz with a normal radiation pattern to the holographic surface to be used in LMDS applications. For this, a study of the state of the art of this technology was carried out, a design with a horn antenna as feeding antenna was proposed and the substrate plate feeder system in the HFSS software was simulated.From the obtained results, the conclusion is obtained of obtaining a pattern directed in a normal way to the holographic surface, a small design of easy integration and construction.

The fifth-generation (5G) network has been designed to support highly reliable and fast communication technologies to satisfy the increasing demands for higher values of data rates, device density, user mobility, spectrum, and energy efficiency [1].  In these networks, a service-oriented architecture is developed to support a wide range of emerging applications and services with a demanding requirement of quality of user experience (QoE). 5G systems are designed as flexible, customizable, scalable and deployable networks where new paradigms as network function virtualization (NFV), software-defined networking (SDN), artificial intelligence (AI) and network slicing have emerged [2]. Besides, new radio access network (RAN) schemes have been developed by several standard development organizations (SDO) to meet the demanding key performance indicators (KPIs) of 5G communication systems. This technically speaking is addressed to illustrate the new use-cases in 5G networks and the required KPIs to achieve these emerging applications. Main insights regarding the RAN technologies are also described focusing on millimeter wave (mmWave) communication, massive multiple inputs multiple outputs (mMIMO), small cells (SCs), interference management (IM), and energy harvesting (EH).

This paper proposes the design and simulation of an antenna with circular polarization for the 2.4 GHz band that can be used in radiofrequency identification or RFID (radiofrequency identification), using a microstrip feeding line and the grooved ground plane. Circular polarization is achieved through a lightning-shaped groove and optimized by automatically adjusting the proportions of that groove. The designed and simulated model has a good coupling, a gain of 3.49 dB and a bandwidth of 705 MHz for the desired frequency, reaching an efficiency of approximately 60%. It also has an axial bandwidth of 220 MHz, a sufficient range to meet its objective in RFID applications.

Policy-based network management (PBNM) allows the dynamic control and coordination of network elements and the automatization of the decision-making process in the network. In distributed and heterogeneous environments, it is necessary to incorporate elements that hierarchize decision making and create the ability to understand different definitions of different information models to reduce the complexity and costs of network management associated with installation and updating. of computer hardware and software, its configuration and maintenance. This document proposes a set of modifications to the PBNM architecture using two information models: Common Information Model (CIM) and Directory Enabled Network- next generation (DEN-ng) which facilitate the integration of standardized and proprietary management models. Besides, the decision takes to process is hierarchized and it gives it the ability to identify and resolve conflicts between the policies implemented.

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