rf shield

rf shield

Antennas : 40M : 40 meter Dipole Antennas

• 40m loaded dipole - This is an short dipole for 7 MHz. Total length of this dipole is just 10 meters, 33 feet. Missing lenght is balanced by a coil made of 49 turns of a 40mm diameter pvc pipe. The use of a choke balun is recommended, as always, to adapt the unbalanced coax cable to the balanced antenna, and to prevent RF feed back along the coax shield.
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• Build your own HF balun - A balun is a MUST for dipoles or similar antennas when they are feed with coaxial cable. From the RF point of view, the shield can be modeled as two conductors, the internal shield (the real shield, this is, ground) and the external shield, who is really far to be ground. In this way, your dipole has 3 arms, the two from the dipole and the coaxial cable shield (external face)
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• Multi-Band End-Fed Antenna Design for Limited Space - This document details the construction of a multi-band end-fed antenna, suitable for situations with limited space for larger antennas. The design utilizes a 1:49 to 1:60 impedance transformer to match a half-wave wire antenna fed at one end. Compared to a traditional dipole, this antenna resembles a highly unbalanced Windom antenna with one very long leg and a virtual short leg. The design eliminates the need for radials but relies on the coax cable shield for grounding. The document recommends using at least 10 meters of coax and installing a common mode filter at the entry point to the shack for improved performance.
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• Wide Band Active Loop Antenna - A shielded broadband (~200 MHz) active loop antenna offers more quiet and relatively less interference reception.
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• DIY Dual Band 144-440 MHz vertical antenna - A homemade VHF/UHF vertical antenna made essentially with RG58 coax cable, with a 9 turns choke balun to prevent the shield acting as a RF Radiator.
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• APRS Radio Shield for Arduino - The Radio Shield is an add-on kit for the Arduino development board that provides AX.25 packet radio send and receive capability, a prototyping area, and an HD44780-compatible LCD interface.
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• LBA Technology - LBA - DTV & RF test systems; AM antennas; RF shielding; RF compliance, safety, interference, intermodulation services; AM detuning, Antenna SWR Analyzers
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• Ramsey - RF Test Enclosures - RF Shielded Test Enclosures and I/O devices, Forensic Enclosures, RF Test Enclosures products. In addition to RF Test Enclosures, Ramsey also offer the latest I/O devices to keep your RF test environment well isolated.
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• Aaronia AG - Spectrum Analyzers - Handheld RF Spectrum Analyzer, EMC & Pre-Compliance Antennas, USB Analysers, Near Field Probes, EMF Shieldings
  [ Hits: 334 | Votes: 1 | Rating: 10 ]

• HamShield for Arduino - HamShield is a powerful VHF UHF transceiver that lets your Arduino talk to far away people using ham radio bands
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• Arduino RF Network Analyzer - Network Analyzer on an Arduino Shield which covers from 0-72MHz using an Analog Devices AD9851 DDS chip
  [ Hits: 285 | Votes: 2 | Rating: 3 ]

• Stop RFI from Solar PV Systems - Stop EMI RFI Interference in Off Grid Solar PV Systems, in this article the author provides hints on tracking down the EMI or RFI source, shielding and grounding in order to eliminate interferences on the whole HF and VHF ham radio bands
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• Prevention and Suppression of RF Interference to Audio Systems - In this study, the author builds upon Muncy's research, demonstrating that radio-frequency current on cable shields affects audio systems through the "pin 1 problem" and shield-current-induced noise (SCIN). An enhanced equivalent circuit for ferrite chokes is proposed, addressing dimensional resonance and inductor self-resonance. Field tests confirm that chokes reduce interference across 500 kHz to 1,000 MHz. Guidelines for diagnosing and mitigating EMI from various sources are provided for product development and field installations.
  [ Hits: 47 | Votes: 0 | Rating: 0 ]