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Presents a detailed construction guide for a **Quadrifilar Helix Antenna** (QHA) optimized for 137 MHz, specifically for receiving weather satellite transmissions. The resource outlines the author's experience building previous QHA designs, highlighting challenges with tuning and nulls, and then focuses on a refined design by John Boyer, documented by Steve Blackmore, which proved easier to build and yielded superior reception. The guide provides precise element dimensions, including 1.5m of 32mm PVC pipe for the mast and 8mm soft copper tubing for the helix elements. It specifies lengths for horizontal tubes (190mm, 90mm) and helix elements (903mm, 1002mm), along with instructions for drilling, assembly, and forming a **balun** by wrapping RG58 coax around the mast. The text emphasizes critical steps like ensuring elements are square and twisting in the correct direction to avoid phase issues. It includes references to original QST articles by Buck Ruperto (W3KH) and the WxSat program for decoding satellite transmissions, contextualizing the antenna's purpose. The article concludes with a sample NOAA 12 image from September 1998, demonstrating the antenna's reception capabilities.

A page dedicated to the Quadrifilar Helical Antennas, with projects, pictures and antenna plans by OH2GVB

The Compaq Computer Corporation radio club

Basic information in spanish hon how to become ham radio operators, or radioaficionados

UN Amateur Radio News, curated by Artur UN6QC, presents information relevant to Kazakh radio amateurs, including details on their account activity and participation in **WFF Kazakhstan** expeditions. The resource also documents various diplomas issued within Kazakhstan, such as those related to WFF Kazakhstan and special programs like the "50th Anniversary of the first manned space flight by Yuri Gagarin" and "The Columbus of the Cosmos" Award. It aggregates international ham radio news and maintains a calendar of international HAM competitions. The site, operational since May 14, 2010, serves as a central point for information on HAM competitions organized in Kazakhstan. It also references external resources like WWW.CQHAM.KZ for award details and WWW.EQSL.KZ for UN EQSL services. The platform aims to be a useful hub for both local and international amateur radio enthusiasts interested in Kazakh-specific operations and awards. Key events like the **UN DX Contest** and the First UN Field Day, held May 19-20, 2012, are highlighted.

This project details the construction of a compact, circularly polarized Quadrifilar Helix Antenna (QHA) designed for 146 MHz operation. The antenna features a 1/2λ1/2λ helical design with a 2.6:1 aspect ratio, providing 4.5 dB gain and a spheroid radiation pattern. It is ground plane independent and compatible with both vertical and horizontal polarizations, making it ideal for terrestrial and space communications. The design includes step-by-step instructions for building the antenna using readily available materials like aluminum rods, PVC pipes, and RG-58 coaxial cable. The antenna's performance has been validated through comparisons with commercial omnidirectional antennas, showing superior results.

This page provides information and links about Quadrifilar Helix Antennas, the best antenna for APT satellite reception. It explains the basic design and configuration of QHA, including the research and developments that have been made over the years. The page offers insights into the radiation patterns and benefits of using QHA for APT ground stations, with examples of polar diagrams. If you are interested in learning more about QHA and its applications, this page is a valuable resource.