This document describes the design and construction of an active antenna called the AA-7 that can amplify radio signals from 3 to 3000 MHz. It contains two independent preamplifiers that can be selected using a switch. One preamplifier is optimized for HF signals using a MOSFET and the other is for VHF/UHF using an NPN transistor. The circuit board layout and assembly instructions are provided to allow homemade construction. The active antenna requires minimal external components and can be built on a small printed circuit board, making it compact and portable. It is powered by a single 9V battery and does not require an enclosure, though one can be added.
The final thesis defense presentation for my master's project. The purpose of this thesis was to compare alternative wireless links for transfer of data from sink motes of remote wireless sensor networks to a central repository. A few different protocol stacks to be implemented in the WSN (Wireless Sensor Network) uplink gateway and along with them a few implementation environments based on open source software and low-power hardware were discussed. To facilitate measurements and experimental validation, some of the alternatives have been implemented. Experiments have been made using two of the amateur radio bands, the 144 MHz band (VHF) and the 433 MHz band (UHF). The parameters studied include throughput, range, power-requirements, portability and compatibility with standards.
Using different protocol stacks, different bands and sometimes different hardware 5 solutions were designed, implemented, tested and experimented with. Namely these solutions are called Radiotftp, Radiotftp_process, Radiotunnel, Soundmodem and APRX in this thesis.
After the implementation phase, there was an open-field experimentation to measure the aforementioned parameters. The tests were conducted in Riddarholmen, Stockholm of Sweden. These open-field experiments helped us obtain real-life measurements about power, throughput, stability etc. Experiments were conducted in a range of from a minimum of 2 meters to a maximum of 2.1 kilometers with some of the solutions.
In the end, some of these solutions proved themselves to be viable for the purpose of data communications for remote wireless sensor networks. Radiotftp gave the best throughput in both bands where it proved itself to be difficult to develop further applications. Radiotftp_process removed the necessity for a Linux running gateway machine but it was unable to work with faster baud rates. Radiotunnel opened up the path for a range of network applications to use radio links, but it also proved that it was unstable. On the other hand Soundmodem and APRX which were based on standard and open-source software proved that they were stable but rather slow. It was proven that every approach to problem has its advantages and disadvantages from different aspects such as throughput, range, power-requirements, portability and compatibility.
UHF/VHFEnergy Harvesting Radio System Physical and MAC Layer Considerationxiaohuzhang
This is my defence slides. There are three parts been talked :
(1) Background and challenges on wireless sensor networks and nodes;
(2) Solutions for the challenges of wireless sensor nodes;
(3) Summary and future research directions.
A very small aperture terminal (VSAT) is a small telecommunication earth station that receives and transmits real-time data via satellite.
A VSAT transmits narrow and broadband signals to orbital satellites. The data from the satellites is then transmitted to different hubs in other locations around the globeT.
The final thesis defense presentation for my master's project. The purpose of this thesis was to compare alternative wireless links for transfer of data from sink motes of remote wireless sensor networks to a central repository. A few different protocol stacks to be implemented in the WSN (Wireless Sensor Network) uplink gateway and along with them a few implementation environments based on open source software and low-power hardware were discussed. To facilitate measurements and experimental validation, some of the alternatives have been implemented. Experiments have been made using two of the amateur radio bands, the 144 MHz band (VHF) and the 433 MHz band (UHF). The parameters studied include throughput, range, power-requirements, portability and compatibility with standards.
Using different protocol stacks, different bands and sometimes different hardware 5 solutions were designed, implemented, tested and experimented with. Namely these solutions are called Radiotftp, Radiotftp_process, Radiotunnel, Soundmodem and APRX in this thesis.
After the implementation phase, there was an open-field experimentation to measure the aforementioned parameters. The tests were conducted in Riddarholmen, Stockholm of Sweden. These open-field experiments helped us obtain real-life measurements about power, throughput, stability etc. Experiments were conducted in a range of from a minimum of 2 meters to a maximum of 2.1 kilometers with some of the solutions.
In the end, some of these solutions proved themselves to be viable for the purpose of data communications for remote wireless sensor networks. Radiotftp gave the best throughput in both bands where it proved itself to be difficult to develop further applications. Radiotftp_process removed the necessity for a Linux running gateway machine but it was unable to work with faster baud rates. Radiotunnel opened up the path for a range of network applications to use radio links, but it also proved that it was unstable. On the other hand Soundmodem and APRX which were based on standard and open-source software proved that they were stable but rather slow. It was proven that every approach to problem has its advantages and disadvantages from different aspects such as throughput, range, power-requirements, portability and compatibility.
UHF/VHFEnergy Harvesting Radio System Physical and MAC Layer Considerationxiaohuzhang
This is my defence slides. There are three parts been talked :
(1) Background and challenges on wireless sensor networks and nodes;
(2) Solutions for the challenges of wireless sensor nodes;
(3) Summary and future research directions.
A very small aperture terminal (VSAT) is a small telecommunication earth station that receives and transmits real-time data via satellite.
A VSAT transmits narrow and broadband signals to orbital satellites. The data from the satellites is then transmitted to different hubs in other locations around the globeT.
Sinewave Generation 1. Problem Statement The goal of t.docxjennifer822
Sinewave Generation
1. Problem Statement
The goal of this project is to generate a sinusoidal waveform with the Arduino. Software is
provided that outputs a binary sinewave signal on pins D8-D11 which is converted to an
analogue voltage using a special type of digital to analogue converter (DAC), called an R-2R
ladder. The sinewave's frequency is roughly 200 Hz. Your task is to design and construct
both the R-2R ladder and a reconstruction filter which converts the “staircase” output of the
R-2R DAC into a “smooth” sinusoidal signal of amplitude 3 Vpk-pk and mean value zero.
2. Background
Many modern devices utilise digital circuits for analysing and processing data but still require
an interface to the analogue world, for example, to drive a speaker or control a motor's speed.
The conversion of digital data to analogue voltages is performed with a circuit known as a
digital to analogue converter, or DAC. In this project you will be implementing a simple
DAC circuit built solely of resistors, called the R-2R ladder.
To generate an analogue signal DACs will update their output at a specified frequency known
as the sample rate. The DAC's output voltage will only change value once per sample,
resulting in a “staircase” looking waveform. In order to produce a smooth waveform a circuit
known as a reconstruction filter is used. There are many different ways of implementing this
filter but in this project you will use a combination of active (op-amp based) low-pass and
high-pass filters.
2.1. R-2R ladder
The R-2R ladder DAC uses a network of resistors to convert a binary number to an analogue
voltage. The digital number is given from the Arduino by the digital output pins. In fact
these pins act as a controlled voltage source. If a bit in the 4-bit binary represented number is
1, the corresponding output pin is set HIGH and acts as a voltage source. If the bit is 0 on the
other hand, the corresponding output pin is set LOW and acts as a ground connection.
Although simple this circuit has several limitations. Specifically, it has a high output
impedance (ie: the Thevenin equivalent resistance is high) and the precision of the output
voltage is limited by the low number of bits and the precision of the resistors chosen. The
1% tolerance resistors available in the lab become the limiting factor beyond 6 bits so this
DAC architecture is rarely used for high precision DACs (10+ bits).
In this project you can use op-amp circuits to act as buffers to compensate for the high output
impedance of the R-2R ladder. The precision of the output will be limited by the chosen 4-bit
bit depth and will result in “noise” on the output (ie: random voltage amplitude errors) which
are impractical to remove. Nonetheless a smooth-looking waveform should still be possible
to generate.
The basic circuit is shown in Figure 1.
Exercise 1. Find expressions for the output (Vout) in terms o.
Vovô Coruja fez este album para O Meu Neto, Em Homenagem ao seu Nascimento.
<br>
*Visite:.http://www.gertech.xpg.com.br/mininudivovo.html
<br>
*Visite A Gertech Manutencoes::.
*http://www.gertech.xpg.com.br/
*http://www.slideshare.net/gertech
MANUAL EXPERIMENTAL DE CONSTRUCCION DE ANTENAS WIFI DE FORMA PROFESIONAL EN PVC
V.1.0
CONSTRUCCION y Diseño en PVC
Por Norbert R. Ibañez
31 de Julio de 2007
ESPAÑA, EU. 2007,
Producido por
Norbert R. Ibañez
*Visite A Gertech Manutencoes::.
*http://www.gertech.xpg.com.br/
*http://www.slideshare.net/gertech
CURSO de EDUCAÇÃO FÍSICA
*ENSINO MÉDIO
*SECRETARIA DE ESTADO DA EDUCAÇÃO
*Este livro é público - está autorizada a sua reprodução total ou parcial.
*Autores:
*Claudia Sueli Litz Fugikawa
*Cristiane Pereira Brito
*Fabiano Antonio dos Santos
*Felipe Sobczynski Gonçalves
*Gilson José Caetano
*Mauro José Guasti
*Neusa Maria Domingues
*Rita de Cássia Wielewski
*Sergio Rodrigues da Silva
*Rodrigo Tramutolo Navarro
*Mario Cerdeira Fidalgo
*Cíntia Müller Angulski
*Equipe técnico-pedagógica
*Claudia Sueli Litz Fugikawa
*Cristiane Pereira Brito
*Fabiano Antonio dos Santos
*Felipe Sobczynski Gonçalves
*Rodrigo Tramutolo Navarro
*Mario Cerdeira Fidalgo
*Cíntia Müller Angulski
*Assessora do Departamento de Ensino Médio
*Agnes Cordeiro de Carvalho
*Coordenadora Administrativa do Livro Didático Público
*Edna Amancio de Souza
*Equipe Administrativa
*Mariema Ribeiro
*Sueli Tereza Szymanek
*Técnicos Administrativos
*Alexandre Oliveira Cristovam
*Viviane Machado
*Consultor
*Alexandre França Salomão – UNICENP
*Leitura Crítica
*Alda Lúcia Pirolo
*Consultor de direitos autorais
*Alex Sander Hostyn Branchier
*Revisão Textual
*Renata de Oliveira
*Projeto Gráfico e Capa
*Eder Lima / Ícone Audiovisual Ltda
*Editoração Eletrônica
*Ícone Audiovisual Ltda
*Produzido Em:.2007
*Visite A Gertech Manutencoes::.
*http://www.gertech.xpg.com.br/
*http://www.slideshare.net/gertech
*
InstaladorSistemaTvCaboViaSatelite.
Ministério da Educação - MEC
Secretaria de Educação Profissional e Tecnológica (SETEC)
Instituto Federal de Educação, Ciência e Tecnologia do Ceará
Elevating Tactical DDD Patterns Through Object CalisthenicsDorra BARTAGUIZ
After immersing yourself in the blue book and its red counterpart, attending DDD-focused conferences, and applying tactical patterns, you're left with a crucial question: How do I ensure my design is effective? Tactical patterns within Domain-Driven Design (DDD) serve as guiding principles for creating clear and manageable domain models. However, achieving success with these patterns requires additional guidance. Interestingly, we've observed that a set of constraints initially designed for training purposes remarkably aligns with effective pattern implementation, offering a more ‘mechanical’ approach. Let's explore together how Object Calisthenics can elevate the design of your tactical DDD patterns, offering concrete help for those venturing into DDD for the first time!
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
zkStudyClub - Reef: Fast Succinct Non-Interactive Zero-Knowledge Regex ProofsAlex Pruden
This paper presents Reef, a system for generating publicly verifiable succinct non-interactive zero-knowledge proofs that a committed document matches or does not match a regular expression. We describe applications such as proving the strength of passwords, the provenance of email despite redactions, the validity of oblivious DNS queries, and the existence of mutations in DNA. Reef supports the Perl Compatible Regular Expression syntax, including wildcards, alternation, ranges, capture groups, Kleene star, negations, and lookarounds. Reef introduces a new type of automata, Skipping Alternating Finite Automata (SAFA), that skips irrelevant parts of a document when producing proofs without undermining soundness, and instantiates SAFA with a lookup argument. Our experimental evaluation confirms that Reef can generate proofs for documents with 32M characters; the proofs are small and cheap to verify (under a second).
Paper: https://eprint.iacr.org/2023/1886
Accelerate your Kubernetes clusters with Varnish CachingThijs Feryn
A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
This presentation was delivered at K8SUG Singapore. See https://feryn.eu/presentations/accelerate-your-kubernetes-clusters-with-varnish-caching-k8sug-singapore-28-2024 for more details.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Alt. GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using ...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
GenAISummit 2024 May 28 Sri Ambati Keynote: AGI Belongs to The Community in O...
Coletanea booter antenatv
1. =|== ↓▼↓= M inha Coletanea de CIRCUITOS ELETRONICOS = ↓▼↓==|=
18dB FM /UHF/VHF High Power TV Booster (TV Signal Amplifier) Circuit Diagram using 2sc3355
Today, we introduce simple & small High Power FM/UHF/VHF booster (TV signal amplifier) circuit. It covers the frequencies from
40MHz to 900MHz and boosts the VHF signals up to 23dB and UHF signal up to 18dB. An External power supply not necessary
for this circuit, it operates using the coaxial cable as feed line. It’s very easy to build, but try to maintain the terminals of component
as close as possible to discharge involved frequencies. Make this circuit on good quality PCB for best performance.
Frequency response – 40MHz – 900MHz
Typical Gain – 18dB
Maximum output level – 90μV
Impedance – 75Ω
Components:
D1, D2 – IN4148
D3, D4, D5, D6- IN4007
C1, C4 – 100PF (101) Ceramic
C2 – 2.2PF Ceramic
C3 – 1000PF (102) Ceramic
C5 – 470μf / 16V Electrolytic
C6 – 1000μf / 16V Electrolytic
C7 – 0.24μf (224) Ceramic
R1 – 82K/0.25W
R2 – 1.5K/0.25W
R3 – 270Ω/0.25W
R4 - 120Ω/0.25W
Q1 – 2SC3355
T1 – 230V – 12V/300mA step-down transformer
L1, L2 – Wire thickness – 0.5mm (25 SWG / 24 AWG)
Diameter – 5mm
Turns - 8
L3, L4 – Wire thickness - 0.5mm (25 SWG / 24 AWG)
Diameter – 3mm
Turns - 25
=|== ↓▼↓ = →►→► == →→►►= ↓▼↓=|== ↑▲↑ == ◄◄←← ================
MAR-6 VHF-UHF wide band amplifier circuit
2. design electronic project
This wide band amplifier circuit is designed using the M AR-6 IC manufactured by M ini Circuits . This
M AR-6 VHF-UHF wide band amplifier circuit will providing stable gain of at least 9dB up to 2GHz.
Because the M AR-6 is designed to receive its power via the signal output pin, it’s very suitable for use as a
masthead amplifier. It requires about 3.5V DC, at a working current of around 16mA.
As you can see in the circuit diagram this masthead amplifier electronic project , require few external electronic
parts , so if you will use SM D components you’ll have a very compact design . With power applied, the LED
should glow reassuringly and you should be able to measure about 6.8 - 7V DC at the end of R1 nearer IC2 and
C5 . If the LED doesn’t glow and you get no voltage reading, chances are that you’ve wired the DC input with
reverse polarity .If the LED doesn’t glow but there’s almost the full plug-pack voltage present at R1, you’ve
almost certainly wired the LED in backwards.
=|== ↓▼↓ = →►→► == →→►►= ↓▼↓=|== ↑▲↑ == ◄◄←← ================
Active Antenna AA-7 HF/VHF/UHF,
3-3000MHz
by Fred Blechman and Tony van Roon
"Lift those hard-to-hear signals out of the mud with
this handy receiver accessory."
3. If you have a shortwave or high-frequency receiver or scanner that is struggling to capture signals with a short,
whip antenna, and you'd like the kind of performance that a 60-foot longwire antenna can provide but lack the
space to put one up, consider building the AA-7 HF/VHF/UHF Active Antenna described in this article. The
AA-7 is a relatively simple antenna that is designed to amplify signals from 3 to 3000 M egaHertz, including
three recognized ranges: 3-30M hz high-frequency (HF) signals; 3-300M hz very-high frequency (VHF) signals;
300-3000M Hz ultra-high (UHF) frequency signals. Those bands are typically occupied by shortwave, ham,
government, and commercial radio signals.
Active Antennas:
In its simplest form, an active antenna uses a small whip antenna that feeds incoming RF to a pre-amplifier,
whose output is then connected to the antenna input of a receiver. Unless specifically designed otherwise, all
active antennas are intended for receive-only operation, and thus should not be used with transceivers;
transmitting into an active antenna will probably destroy its active components. A well designed broadband
active antenna consider field strength of the desired signal (measured in microvolts per meter of antenna length),
atmospheric and other noise, diameter of the antenna, radiation resistance, and antenna reactance at various
frequencies, plus the efficiency and noise figure of the amplifier circuit itself.
Circuit Description:
Fig. 1 shows the schematic diagram of the AA-7, which contains only two active elements; Q1 (an M FE201
N-Channel dual-gate M OSFET) and Q2 (a 2SC2570 NPN VHF silicon transistor). Those transistors provide
the basis of two independent, switchable RF pre-amplifiers. Two double-pole double-throw (DPDT) switches
play a major role in this operation of the AA-7. Switch S1 is used to select one of the two pre-amplifier
circuits (either HF or VHF/UHF). Switch 2 is used to turn off the power to the circuit, while coupling the
incoming RF directly to the input of the receiver. That gives the receiver non-amplified access to the auxiliary
antenna jack, at J1, as well as the on-board telescoping whip antenna. With switch S2 in its power-on position,
the input and output jacks are disconnected and B1 (a 9 volt battery) is connected to the circuit. With switch
S1 in the position shown in the schematic, incoming RF is directed to the HF pre-amp circuit built around Q1
(an M FE201 N-Channel dual-gate M OSFET). The HF pre-amp operates with an exceptionally low noise level,
and is ideal for copying weak CW and singe-side band signals. When S1 is switched to the other position, the
captured signal is coupled to the VHF/UHF pre-amp built around Q2 (a 2SC2570 NPN VHF silicon
transistor), which has excellent VHF through microwave characteristics. With the on-board whip antenna
adjustable to resonance through much of the VHF-UHF region (length in feet = 234 divide by the frequency in
M Hz), the VHF/UHF mode is ideal for indoor and portable use with VHF scanners and other receivers. Either
mode can be used when tuning 3-30 M Hz HF signals. The VHF/UHF pre-amp offers higher gain than the HF
pre-amp, but also has a higher noise level. You can easily choose either amplifier for copying any signal; of
interest--just try both positions. The RF gain control (R5) can be used to trim the output of either amplifier.
Caution: The AA-7 is not intended for transmitting operation (be it Ham, M aritime, or CB); if it is used
with a transceiver of any kind, make sure it is not possible to transmit by accidentally pressing a mike button
or CW keyer. Transmitting RF into the AA-7 is likely to ruin one of both of the transistors in the circuit.
Construction:
4. The AA-7, which can be built from scratch or purchased in kit form from the supplier listed in the Parts List,
was assembled on a printed circuit board, measuring 4 by 4-11/16 inches. A template for the pcb board is
shown in fig. 2. You can either etch your own board from that template, or purchase the circuit board or the
complete kit of parts (which includes the pcb and all parts, but not the enclosure). The kit comes with a
16-page kit instruction manual that gives step-by-step assembly instructions and contains additional
information not covered in this article. Kit assembly time, working slowly and carefully, should take less than
an hour. M ost of the parts specified in the Parts list are standard components and can be procured through
conventional hobby electronics suppliers. However, some parts--J1, J2, S1, S2, and R5-- have particular
physical mounting dimensions; the Printed Circuit Board is designed to accept these particular parts. In
addition, Q1 and Q2 can be hard to find; however, it is possible to make substitutions provided that you can
find a supplier. Suitable replacements for Q1 and Q2 are given in the Parts List.
The telescoping whip antenna screw-mounts to the board; the screw provides contact between the printed
circuit board traces and the antenna. To save time and trouble locating and ordering hard-to-find parts, a Special
Parts Kit is also offered by the supplier listed in the Parts List.
A parts placement (layout) diagram for the AA-7's printed circuit board is shown in figure 3. When assembling
the circuit, be especially careful that transistors Q1 and Q2, and the electrolytic capacitor C4, are oriented as
shown.
Although not shown in the schematic (Fig. 1) or the layout (Fig. 3) diagrams, an optional led power indicator
can be added to the circuit. Adding a power indicator to the circuit allows you to tell at a glance if the circuit is
on; leaving the circuit on, even though the AA-7 draws only about 0.7 mA, will eventually discharge the
battery. Of course, adding an led will increase the current drain to by about 7 mA, but the red glow makes it
obvious when the unit is on.
If you decide to include the LED indicator in your project, power for the indicator can be easily taken from the
switched 9-volt DC terminal of S2 (center terminal, right side, looking at the top of S2). Simply connect the
positive voltage to the anode (longer wire) of the led and connect her cathode lead through a current limiting
resistor of about 1000 ohm to a ground point on the printed circuit board, or as the author did from the frame
of R5. M ount the led at any convenient point near the switch.
Although not supplied with the kit, a custom plastic enclosure (with front and back panels) or a regular 'hobby'
case of some sorts, and knobs for the switches and gain control can be purchased from most local electronics
stores or mail-order.
Test and Use:
Prepare a coaxial cable to connect the RF output of the AA-7 to the antenna input of your receiver or
scanner. One end of the interconnecting cable must be terminated with an RCA phono plug; the other end
connector depends on the target receiver or scanner. With some receivers, the only practical connection is to
clip the output of the AA-7 to the receiver's antenna, although that connection won't be as effective as
conventional (ground-return type) coupling.
To increase signal strength, especially for the lower frequencies, you can connect a simple supplementary
portable antenna of any design (a dipole, random-length wire with Earth ground, a bigger vertical whip of some
kind, etc.) to the circuit. Just use a small-diameter coaxial cable terminated in an RCA plug for mating with J1.
No alignments are required. If you're using the whip antenna, simply connect the output of the AA-7 to your
receiver, with the unit turned off (that's the bypass position) and the RF gain control (R5) turned fully
counter-clock wise. Turn on the receiver and tune-in a weak station. Switch S2 on, and adjust the gain control
5. clockwise to increase the output signal. Toggle S1 back and forth to see which setting gives you the best
results. Don't be surprised if the gain control overloads the receiver; if so, back it off.
Troubleshooting:
The fact that there are two independent pre-amplifiers in the AA-7 makes faults easier to diagnose than with
many other devices. If a problem occurs, only at one setting of S1, concentrate on that part of the circuit. If the
problem is common to both settings, the components and the connections common to both preamps should be
checked. M ake sure the jumper wires are in place!
There are other characteristics or phenomena associated with preamplifiers and active antennas that does not
mean that your circuit is malfunctioning. For example, if you have strong AC hum in the HF setting, the
antenna is too close to an AC cord or powerline. HF signals may be clearer at the VHF/UHF setting than in the
HF setting. Why? Although either pram may be used for HF, the signal strength will be greater with the
VHF/UHF pram. However, the HF signal-to-noise ration is better with the dual-gate-M OSFET-based pram.
Try both and use the best for your particular receiver conditions.
Some portable receivers not enclosed in metal cases may break into oscillation when connected to any RF
preamplifier. Try reducing the AA-7's gain and make sure that good grounds are provided with the
interconnecting coax cables. A preamplifier will intensify any problems due to poor receiver design:
overloading, images, or any other problems with selectivity and image rejection.
Parts List and other components:
Semiconductors:
Q1 = MFE201, SK3991, or NTE454. N-Channel, dual-gate MOSFET (see text)
Q2 = 2SC2570, NTE10, NTE107. NPN VHF/UHF silicon transistor (see text)
Note: If you use the NTE107 as a replacement, make sure to insert it correctly
6. into the pcb. The orientation is different than as shown on the parts layout
diagram. (e-c-b seen front view for NTE107). See this Data Sheet
Resistors:
All Resistors are 5%, 1/4-watt
R1 = 1 Mega Ohm
R2 = 220K
R3,R6 = 100K
R4 = 100 ohm
R5 = 10K potentiometer, (pc mount)
Capacitors:
C1,C2,C5,C6 = 0.01uF, ceramic disc
C3 = 100pF ceramic disc
C4 = 4.7 to 10uF, 16WVDC, radial lead electrolytic
Additional Parts & Materials:
B1 = 9-volt alkaline battery
S1,S2 = DPDT PC mount pushbutton switch
J1,J2 = PC mount RCA jack
ANT1 = Telescoping whip antenna (screw mount)
MISC = PCB materials, enclosure, enclosure, battery holder and connector,
wire, solder, etc.
If you wish to purchase a parts kit and pcb, [CLICK HERE]
Fig. 1. "The AA-7 Active Antenna contains only two active elements: Q1 and Q2 (a 2SC2570 NPN VHF
silicon transistor), which provide the basis of two independent, switchable RF preamplifiers."
Fig. 2. "The AA-7 was assembled on a printed-circuit-board (PCB), measuring about 4 by 4-11/16
inches. A template for the printed-circuit-board is shown here. Note that it may not be to scale.
8. •
•
•
•
•
im prove d stability
prote ction against powe r supply transie nts
e x act footprint substitute ** MAR -8 and MSA-0885
3.2...4.2 volt @ pin 3
Schematic with external power supply
Components:
40Mc...2GHz
IC 1 = MAR -6 or MAR -8 or MSA-0685 and MSA-0885 re spe ctive ly
IC 2 = 78L05
C 1 = 56pF
C 2 & C 3 = 100pF
R 1 Bias* = 120 (re v1.3)
C 4 & C 7 = 4.7uF/25v
C 5 & C 6 = 100nF
C 8 = 560pF
L1 = 3 a 4 turns of 0.2 C u wire through a fe rite be ad
L2 = 2,7uH or 4 turns of 0.2 C u wire through a fe rite be ad (optional, static ble ad)
D1 & D2 = 1N4148
1Mc...1GHz
C 1 = 1000pF
C 2 & C 3 = 2200pF
L1 = 100uH
L2 = 47uH (optional, static ble ad)
PreAmp features:
• High gain, 22.5 dB (31.5dB MAR 8) at 100 MHz, 20dB @ 1GHz
• C an be use d for TV and ATV re ce ption too.
• Fre que ncy range from +/- 30Mc to 2GHz (1Mc to 2GHz se e above com pone nts list)
9. •
•
•
•
•
•
•
•
•
Voltage inde pe nte nd (8...20volts)
Low curre nt drain
Static drainage (L2)
O utput prote ction (D1 D2 inve rte d diode s) for accide ntal TX
50 O hm s input and output im pe dance
Voltage inde pe nte nd (8...20volts)
Dynam ic range 14.5 dBm - 20dBm MAR 8
VSW R in 1.5 out 1.8
Noise < 3dB
* Biasing R 1 =
120 O hm s @ 5v
270 O hm s @ 9v
470 O hm s @ 12v
Tips:
The be st place to put a pre -am plifie r is with out a doubt as close st to the ante nna as possible .
If possible , dire ctly m ounte d at the fe e de r (dipole ) and using phantom -type powe ring of the
am plifie r. The R F/DC splitte r com e s inside the shack just be fore your re ce ive r.
Ke e p the conne ctions as short as possible @ R F IN and R F O UT and k e e p the m in 50 O hm s
im pe dance starting at the le ads from the IC . Mount it in a shie lde d casing.
W ith use with an transce ive r: This pre am p is prote cte d to a ce rtain de gre e for accide ntal TX
(+/- 5watt) at the output, but no guare nte e is give n that your MAR -6 will survive . So m ak e the
ne e de d pre cautions to pre ve nt this from occuring whe n use d in a TX type situation (lik e
be twe e n your ante nna and transce ive r). Use a R F-se nsing circuit inste ad.
W he n using it only with a re ce ive r: you can le ave out the paralle l inve rte d diode s and C 3.
L2 can be le ft out if your ante nna has alre ady som e type of static ble e de r build in (or DC
shorte ne d, lik e a folde d dipole e tc...). If you don't k now for sure , just tak e your O hm -m e te r
and m e asure be twe e n the ce ntre and the braid of the coax which should re ad som e thing lik e <
1k or so. Inve rte d paralle l diode s are also use d to ble e d of static build up. Te st this with your
diode te ste r. Eve r so now and the n (m ostly with olde r type of R X ve rticals) a ne on bulb is use d
he nce ne ve r can be m e asure d. Just le ave L2 as it is (can't do m uch harm in any case state d
above anyway).
Schematic with phantom power supply using the coax as feedline
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This wideband antenna preamplifier has a gain of around 20 dB from 40 to 860 MHz,
covering the entire VHF, FM, commercial, and UHF bands.
11. =|== ↓▼↓ = →►→► == →→►►= ↓▼↓=|== ↑▲↑ == ◄◄←← ================
comprei o cabo RGC 213, que no meu caso foi o DLC 213 premium, da datalink, que no fundo é a mesma
coisa...
fiz o cálculo de medida para cada gomo..
= (v * c) ÷ (2 * f)
12. = (0,82 * 299792458) ÷ (2 * 2441000000)
= (245829815,56) ÷ (4882000000)
= 0,050354325186399016796394920114707
(multiplica por 100)
= 5,0354...
v = velocidade do cabo ou velocidade de propagação - nesse link tem essa velocidade dos cabos
da datalink Data Link.
c = velocidade da luz = * 299792458 km/s.
f= freqüência do sinal = 2441000000 (2.4 Ghz).
então cada gomo terá que ter 5,03 cm! Isso no meu caso, de acordo com o cabo que usei e de
acordo com a potência do meu roteador!!
não é cada gomo ter isso.. na realidade 5,03 cm é a distância que o início de um gomo terá do
início do outro gomo, veja o gráfico abaixo..
13. é isso aí.. espero ter contribuido..
demorou cerca de 4 horas pra fazer!!
e funciona mesmo!
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Faça Sua Antena Omni
Um bom tipo de antena bem fácil de fazer é a antena omni, a antena omni tem como principal
característica irradiar os sinais de RF em todas as direções, por isso é uma antena muito
utilizada para curta e média distância.
A proposta deste texto é dar condições para que possa ser montada uma antena omni de acordo
com as necessidades do montador, sendo assim, em razão da disponibilidade do material e da
necessidade do ganho em dB, pode ser feita uma antena de três dB a dez dB, obviamente que
maior for o ganho desejado, também será usado mais material.
De qualquer modo, para ganho de três dB, devem ser usados quatro elementos, nesse caso a
antena irá ficar com pouco mais de 30 centímetros.
Quem desejar ganho de seis dB, deverá usar seis elementos, para 9 dB devem ser usados 16
elementos, para 10 dB devem ser usados 20 elementos, observe que com vinte elementos a
antena terá seu tamanho um pouco maior do que um metro e trinta centímetros.
Quem optar pela construção da antena para maior ganho, se usar um Acess Point de 400 mW,
poderá irradiar o sinal para aproximadamente 7 quilômetros com visada, isso é uma previsão
até bem pessimista para antenas com visada.
Mas também poderá nem chegar a um quilômetro, se a altura em que a antena for instalada for
baixa, e se houverem obstáculos no caminho, pois o sinal poderá nem chegar, mas isso não é
característica da antena, mas sim da faixa de freqüência (UHF) que é praticamente a linha do
visual.
Dependendo do ganho que você deseja para sua antena, você vai precisar de tantos elementos
iguais ao da figura abaixo, os elementos são feitos com o próprio cabo coaxial que é cortado em
pedaços com medidas certas e descascado uma parte da capa do cabo coaxial para possibilitar
a soldagem.
14. Lembrando que em se tratando de freqüências altas, mexer com equipamentos e antenas,
requer muito cuidado e todo e qualquer detalhe é importante, principalmente em se tratando de
medidas.
Cada elemento deve ter 6.7 centímetros (67 milímetros), deve ser tirada a capa de um centímetro
de cada lado do elemento, de forma que fique em cada uma extremidades um centímetro livre,
deve ser tirado um pedaço da capa que protege o fio malha, ele é muito importante, pois agira
como elemento inversor de fase do sinal captado e emitido.
15. A montagem deve ser feita com cuidado, as soldas devem ser feitas rápidas para não ficar uma
bicheira (solda fria) no local da solda. O detalhe das medidas é mostrado na figura abaixo:
Note que é soldado fio central no fio malha, e no estágio seguinte, o fio malha é soldado no fio
central, assim deve ser quantos elementos forem necessários na antena, mas devem ser
respeitadas as medidas conforme a figura acima: O elemento da antena fica na realidade com
57 milímetros(5.7 cm), separados um do outro por 5 milímetros (0.5 cm), note que nos
elementos da antena já foi descontado o fator de velocidade do cabo coaxial RGC 213, que é de
0.85, por isso, siga as medidas indicadas para esse tipo de antena.
Note também que o final da parte de cima da antena tem um elemento que é ligeiramente
diferente o tamanho:
Essa antena foi calculada para operar na freqüência central na faixa utilizada por redes Wlan,
16. note que a faixa utilizada começa em 2.4000 e termina em 2.4835, para obter a freqüência central
basta que seja realizado o seguinte cálculo:(2.4000 + 2.4835) / 2 4.8835 / 2, e teremos como
resultado 2.441 GHz, e é nosso objetivo montar a antena para essa freqüência.
Essa antena é projetada para trabalhar em meia onda, e o fator de velocidade do cabo coaxial
RGC 213 já foi incluído nos cálculos, em todo caso, relembro que o fator de velocidade para o
cabo coaxial RGC 213 é 0.85.
Conforme deve ser de seu conhecimento, a velocidade de propagação de RF no vácuo é de
300000 km/s, mas a propagação através de outro meio que não seja o vácuo sofre redução de
velocidade.
Para cada material tipo de material utilizado, o fator de velocidade terá um valor diferente, como
nosso material é o cabo coaxial RGC 213, o cálculo para obter a velocidade da propagação de
RF através do cabo é o seguinte: 300000 x 0.85, e como resultado,nesse caso, temos 255000
Km/s.
E a antena pronta deve ficar com aspecto parecido com o da figura abaixo:
E para quem gosta de conectores que compre dois, um macho e um fêmea, eu soldo a antena
no cabo coaxial, faço da mesma forma que faço com os elementos da antena, tiro um centímetro
de capa com a malha e tiro um pedaço do plástico da capa do cabo coaxial para permitir a
soldagem.
Como dados técnicos adicionais: o comprimento total de cada seção de cabo coaxial é ½ onda
mais 15 milímetros, onde o resultado é 67 milímetros, note que arredondei o valor, que na
realidade era 67.2 milímetros.
Para ficar bem claro, esclareço que o condutor central do elemento feito com cabo coaxial deve
ser de 10 milímetros expostos de cada lado de cada seção.
A malha que reveste o elemento feito de cabo coaxial é importante, as soldagens devem ser
feitas rapidamente para não deformar a malha e para evitar que a malha venha a sair do lugar.
O último elemento que vai à ponta, aquele do final da antena, fique atento, porque ele tem
medidas diferentes.
O último elemento é acrescentado para fazer o acoplamento inicial da antena, se você montar
uma antena com seis elementos, esse elemento final será o sétimo elemento.
Depois de tantos detalhes, acho que chega, então finalmente, para montar a antena é só ir
soldando com cuidado os elementos, de maneira que o dielétrico de um elemento fique
exatamente a 5 milímetros de distância do dielétrico do outro elemento.
Depois da antena montada é só colocar tudo em um pedaço de tubo de PVC do tamanho da
17. antena recém montada, desde que seja hermeticamente fechado, eu uso um tampão e um cano
de PVC de 25, duas abraçadeiras e um parafuso para prender o cabo coaxial, isso é o que
possibilita que a antena seja instalada em ambientes externos.
É isso, boa sorte.
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Antena WiFi biquad com antena SKY
Entusiastas do wireless vêm transformando antenas a anos. Estabeleceram uma marca de
mais de 200 km, usando velhas parabólicas de 3m. O que é muito se comparado com os
modernos pratos, tipo sky. O prato parabólico permite focalizar a ondas de rádio para uma antena
direcional. É utilizada uma antena biquad, pois é bastante tolerante a erros de montagem e tem
um rendimento muito bom. No final a biquad é acoplada a uma velha sky e… eureka,
conseguiram detectar APs a mais de 12km.
Construindo a ANTENA:
As antenas biquad podem ser construídas a partir de materiais comuns, o que é bom, contudo
algum material você terá que comprar.3060000000054037 A coisa mais importante aqui é o
pequeno conector N, não me perguntem onde tem. Aqui em Joinville eu sei, na sua cidade…
O “N-conector” é padrão na maioria das antenas comercial e você pode conectá-los aos seus
dispositivos sem fio usando “pigtails”.
O cabo longo é um pigtail com conectores RP-TNC para N-macho que será usado para conectar
a antena a um AP Linksys WRT54G.
O curto é um RP-MMCX para N-macho para que possamos ligar a antena a nosso cartáo PCI
Senao 2511CD PLUS EXT2 WiFi.
Também se utilizam 10 metros de cabo coaxial WBC 400 pora não ter de se sentar com o prato
no colo. Além é claro, da valha antena SKY
.
Trevor Marshall construiu uma das primeiras antenas WiFi biquad encontradas na internet. Aqui
se foi um pouco mais fundo nas instruções encontradas em martybugs.net e aqui estão as
matérias-primas com que começar:
18. Um fio padrão de núcleo rígido, utilizado em instalações elétricas residenciais. Como os
executores do projeto não tinham uma placa de circuito impresso disponível, utilizaram uma
chapa fina de cobre colada a um suporte plástico, mas é mais recomendável e prático, utilizar
uma placa de CI virgem.
O primeiro passo na construção do elemento foi descascar e cortar um padaço de 244
milímetros de fio.
O fio foi marcado em intervalos de 31 milímetros e começou a fase das dobras. Ele deverá ser
dobrado em forama de um duplo diamantae. Tenta-se alcançar a maior aproxiomação de cada
perna a 30,5 milímetros.
19. A maneira mais fácil de fazer curvas muito acentuado no fio de cobre sólido é usar dois pares de
alicates.
Como fica o elemento com todas as curvas completas:
Em seguida, um quadrado de 110 milímetros de lado, de plástico, para apoio da chapa de cobre
ou diretamente um quadrado de circuito impresso virgem com as mesmas medidas deverá ser
confeccionado.
20. Agora deve-se soldar dois pedaços de fio de cobre ao pino N, começando pelo fio externo, pois
precisa de um aquecimento maior para uma boa solda.
Após esfriar, fixe o pinco (conector-N)
a base de cobre e solde a parte
externa a placa (quadrado de 110
milimetros de lado).
O próximo passo é a solda do laço,
elemento em forma de diamante
duplo, aos fios verticais. O elemento
deve ser apoiado em calços de 15 milímetros para garantir a
posição correta.
21. Em seguida, corta-se o excesso dos fios verticais e fica assim:
Para fazer a do nosso elemento ao prato, a maneira mais fácil é modificar o lbnf original,
utilizando partes do mesmo. Esta é a aparecncia inicial.
22. Após a remoção da caixa e dos elementos internos, ficamos com isto:
Anexamos nosso elemento a essa caixa e fica assim, com o cabo coaxial conectado:
23. Prontinho para anexar no prato da sky:
Se sua antena é do tipo com offset, ficará como na figura. Para saber se está apontada para o
horizonte, deverá ser alinhada a 45º e montada num tubo de suporte com inclinação de, também
45º. Parece apontada para o chão mas está certo. Se for sem offset (modelo em que o elemento
fica no centro da parábola) então deverá ser apontada diretamente mesmo.
24. Segundo os desenvolvedores, o resultado é exelente e conseguiram se conectar a 12km de
sitancia.
Este eu ainda não teste. Assim que montar a minha informo.
Para os que já montaram a sua sinhantena, explicada neste site, segui uma serie de fotos
animadoras:
2leep.com
Originally posted 2009-08-17 15:02:02. Republished by Blog Post Promoter
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WIFI 16dBi Super Antenna Pictorial
http://antenaswireless.aarca.com/2011/11/01/que-tal-fazer-uma-antena-wifi-de-16-dbi-baratissimo-e-facil/
Que tal fazer uma antena WiFi de 16 dBi baratíssimo e fácil?
Que tal fazer uma antena WiFi de 16 dBi baratíssimo e fácil?
25. Encontre esta antena wireless, no artito: Que tal fazer uma antena WiFi de 16 dBi
baratíssimo e fácil? e achei incrível. Parece realmente muito fácil de fazer e encontrei muta coisa boa sobre ela na internet. Ainda não
testei, mas tem tudo para funcionar bem.
E vejam. Pela lista de material é bem simples mesmo:
Quais são os materiais?
1 placa de cobre, latão ou metal comum fino de 12x12cm
1 Chassi de conector BNC
1 Conector de cabo BNC
placa de isopor na densidade do styrofoam de 35mm de espessura
Fio elétrico de 1.5mm2
No site você vai encontrar até um vídeo para ajudar.
http://www.tecnomodo.com/2009/03/que-tal-fazer-uma-antena-wifi-de-16-dbi.html
Q ue tal faz e r uma ante na WiFi de 16 dBi baratíssimo e fácil?
Nós postamos aqui há alguns anos atrás um hackeamento da antena WiFi tradicional para obter um ganho no sinal. Agora a intenção
é demonstrar que podemos criar uma antena inteira com preço acessível.
26. Quais são os materiais?
1 placa de cobre, latão ou metal comum fino de 12x12cm
1 Chassi de conector BNC
1 Conector de cabo BNC
placa de isopor na densidade do styrofoam de 35mm de espessura
Fio elétrico de 1.5mm2
27.
28. Mais informações você pode achar na página do instructables
fonte: instructables.
http://www.instructables.com/id/10--WIFI-16dBi-Super-Antenna-Pictorial/
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High Gain Wi-fi Helical Antenna
Presented here is a versatile, durable, and rather unique wi fi antenna that can greatly extend your wireless networking range and
speed. When built with ten or more turns, this helical wi fi antenna vastly outperforms the cantennas and wi fi wok tops often seen
on the internet. A short five turn helical makes a very good feeder for a wi fi parabolic dish antenna. A special quality of this antenna
is that it radiates and receives a circularly polarized signal. It does not favor vertically or horizontally polarized signals. Thus, this
antenna works well with wi fi signals reflecting off of buildings, moving vehicles, or antennas oriented at odd angles. Circularly
polarized signals are less affected by rain, so you can reach distant access points in stormy weather. There is a 3 dB loss of gain when
using this antenna with linearly polarized signals; high gain is maintained by making the antenna long - at least ten turns for
stand-alone usage.
Design parameters for this helical wi fi antenna were calculated using the online helical antenna calculator and was inspired by
similar designs used for the AMSAT OSCAR 40 satellite.
PARTS REQ UIRED FO R THE WIFI HELICAL ANTENNA:
1.
2.
3.
4.
5.
6.
one square piece of copper sheet metal or single sided PC board for a ground plane.
one PVC kitchen drain tailpiece (3.8 cm / 1.5" diameter) to hold the helical windings
six 1/8" plastic cable ties
a length of copper circuit tape (adhesive backed, width 3mm or 1/8") or #14 copper wire
one suitable chassis connector (I used a reverse sma type matching the connector on my adaptor)
one 90 degree angle bracket with screws and bolts to fit
CO NSTRUCTIO N:
29. 1. Center the tailpiece on the PC board, copper side, and mark the circumference in ink.
2. Mark four locations on the circumference, spaced 90 degrees, where the cable ties will hold down the PVC tube.
3. Mark one location on the circumference, exactly between two 90 degree markings, where the coaxial connector will be
mounted.
At this point you should have a PC board with a circle in the center, four tick marks on the circle at 90 deg intervals, and
one tick mark exactly between two others.
4. Drill 1/8" holes on the inside and outside of the circumference at the cable tie locations.
5. Drill a hole directly on the circumference suitable for the chassis connector. Carefully measure and drill other holes for this
connector if necessary.
6. Drill four holes, spaced 90 deg apart near the bottom end of the PVC tailpiece.
7. Drill holes to accomodate a small 90 degree corner bracket.
8. Drill holes on opposite side of board to accomodate USB wi-fi adapter that will be affixed with cable ties.
9. Tin the copper around the connector mounting hole, then mount the connector. Clip the center pin to keep it only long
enough for connection to the helix windings.
10. Cut out a notch to accomodate the connector; it should clear center conductor, but avoud cutting out excess PVC material.
11. Feed cable ties through from the back side of the board, through holes in the tube, and back through the board. Tighten the
cable ties, making sure the tube is firmly held to the copper ground plane.
12. Use a ruler and the edge of a sheet of paper to create a template for positioning the windings on the PVC tube. Distance zero
represents the ground plane, then add the feedpoint distance, then ticks matching the turns spacing. Use the template to mark
your tube on both the feedpoint side and the opposite side.
The objective is to precisely wind the helical wi-fi antenna using an accurate guide...
30. Space the turns 2.5 cm on a
tube of 3.9cm outer diameter.
Here is a table used for my prototype helical wi-fi antenna and its connector. Note that turn 1 starts at 0.8 cm (height above ground
plane of feedpoint). Turns Spacing is 2.5 cm, and the diameter is 3.9 cm (close enough for 1.5" PVC tailpiece). If your connector
can be trimmed to allow a feed connection closer to the ground plane than 0.8CM, then simply run the helix as low as
necessary. Most impartant is keeping the proper spacing between turns.
S pacing=2.5cm
Diameter=3.9cm
(fits 1.5" PVC tailpiece)
Turn #
Height (cm) above Half Turns
groundplane Height (cm)
1 (feedpoint)
0.8
2.05
2
3.3
4.55
3
5.8
7.05
4
8.3
9.55
5
10.8
12.05
6
13.3
14.55
7
15.8
17.05
8
18.3
19.55
9
20.8
22.05
10
23.3
24.55
11
25.8
27.05
12
28.3
29.55
13
30.8
32.05
13. Carefully wind the helix, using circuit tape or wire, then solder to center conductor of chassis connector. Double check against
the turns template. Polarization will be right-handed if the turns spiral clockwise (looking outward from feedpoint).
31. 14. Attach the angle bracket and wi-fi adapter, making sure all parts are secure and ready for service, as seen in the images below.
The high gain wi-fi helical antenna.
10 turn stand alone version
Cable losses avoided by
mounting wi-fi adapter
at base of antenna.
Short wi-fi helix feeding a long range
parabolic wi-fi
antenna.
At this point, helical wi-fi antenna is ready for its smoke test...plug in the cables and look for some signals! Theoretical gain of the
prototype helical was about 18 dB over an isotropic radiator; it beat my biquad by about 7 to 13 RSSI units, and indeed seemed
less sensitive to polarization and rainfall. Signals still seem to fluctuate much from second to second. If your antenna is functioning
satisfactorily at this point, I suggest spray painting three layers of clearcoat onto the windings and groundplane for stability and
corrosion prevention.
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