Building and Designing Quadrifilar Helix Antennas
Find resources and projects for constructing Quadrifilar Helix (QFH) antennas, ideal for receiving weather and amateur radio satellite signals.
The Quadrifilar Helix Antenna (QFH) is a specialized antenna design widely used by hams for satellite operation, particularly for receiving signals from low-earth orbit (LEO) weather satellites like NOAA. Its unique construction provides a hemispherical radiation pattern and circular polarization, which are ideal for capturing weak, circularly polarized signals from satellites as they pass overhead. Operators often build these antennas for bands around 137 MHz, but designs for other frequencies, such as 436 MHz for amateur radio satellites, are also common.
Many hams enjoy building QFH antennas as a practical antenna project, often using common materials like PVC pipe and coaxial cable. This category offers various QFH antenna designs and construction guides, including detailed plans for specific frequencies. Operators can also find QFH antenna calculators to help with design parameters, along with articles explaining the electrical characteristics and advantages of the quadrifilar helix over other antenna types for satellite reception.
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This article describes how to make a quadrifilar helix (QFH) antenna easily, from inexpensive materials: uPVC plumbing pipe and RG-58U co-axial cable. A low-cost, easy-to-build Quadrifilar Helix (QFH) antenna for weather satellite reception using uPVC plumbing pipe and RG-58U coaxial cable. Unlike traditional designs requiring copper pipe and plumbing skills, this approach enables construction with basic tools and minimal technical expertise. The antenna's shorter, wider proportions favor higher elevation angles, reducing interference from horizon-level pager transmitters. Electrical connections are simplified at the antenna's apex, with the coaxial cable forming the radiating elements. Testing demonstrated consistent signal strength throughout satellite passes, proving effective weather satellite reception is achievable without precision engineering to sub-millimeter tolerances. -
Construction guide for a 137 MHz Quadrifilar Helix Antenna (QHA) for weather satellite reception, detailing materials and assembly steps. -
NOAA Satellite Signals With a PVC QFH Antenna and Laptop, this website also link to a github where you can find files and supporting documentation for constructing a QFH Antenna -
This article describes how to make a quadrifilar helix (QFH) antenna easily, from inexpensive materials: uPVC plumbing pipe and RG-58U co-axial cable -
Design your own quadrifilar helix, the site even generates a drilling pattern in a PDF file. Several different construction methods are shown. -
Calculate design for a quadrifilar helicoidal antenna -
This is an antenna that author just built. Was intend for receiving the AO-27 downlink (at 436.800 +/- doppler). It is built with right hand circular polarization, and the gain is supposed to be in the neighborhood of 3 DB. -
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. -
How to build a QFH (Quadrifilar Helix Antenna) to download images from weather satellites. A complete tutorial on assembling QFH antenna at home with simple and common tools -
How to receive NOAA weather satellite with a home made QFH Antenna. This project includes some easy and efficient notch filters to suppress noise from FM frequencies -
A page dedicated to the Quadrifilar Helical Antennas, with projects, pictures and antenna plans by OH2GVB