You can build QFH Antenna's of various sizes that are sensitive to different frequency bands, but we'll be focusing on the dimensions for 137.5 MHz in this instructable. The QFH is very easy to make and is an omnidirectional antenna, meaning that you don't have to aim it to have it pick up the signals and it has excellent performance across the ...

Building a QFH-Antenna and How I Did It: To receive images from NOAA satellites, I've built myself a QFH-antenna out of copper tubing. Whilst building I had trouble finding useful information on how to do it exactly...so here is my way of doing it :D

2020年3月7日 · When you have a satellite orbiting the earth, even if the antenna is pointed straight down, its polarization to you on earth will change as it goes from horizon to horizon. …

The QFH, on the other hand, is used to provide uniform coverage over the sky hemisphere; as John Portune, W6NBC wrote, “The curious egg-beater-like configuration of the QFH has useful characteristics — an almost perfectly spherical radiation pattern as well as circular polarization throughout the pattern.”

2022年11月22日 · The Quadrifilar Helix (QFH) antenna, with its unique design and circular polarization, ensures efficient NOAA satellite signal reception. This article explores the history, key characteristics, and practical modeling of QFH antennas using AN-SOF, providing valuable insights for RF engineers and enthusiasts.

2024年12月1日 · These satellites transmit Automatic Picture Transmission (APT) signals in the 137 MHz band, which requires a specialized antenna to pick up the data clearly. The QFH antenna, known for its excellent circular polarization and omnidirectional reception, is one of the best choices for this task.

The UC-1464-531, +4dBic VHF Amateur Satellite Antenna is a Quadrifilar Helix Antenna (QFHA), measuring 16 cm/6" OD x 62 cm/24.5" H, designed to operate through Amateur Radio satellites without requiring an antenna rotator.

QFH antenna is one among various antennas used to capture images from low level non geosynchronous satellites. It is very simple, effective and efficient antenna. It does not have null spots directly overhead or at other in-opportune locations like other antennas. It is popular antenna used for GPS applications. The QFH antenna consists of two ...

2020年9月30日 · If you want to build an antenna to receive signals from a weather satellite, you will need a special kind of circular polarized antenna known as a quadrifilar helix antenna. In this video, we'll go through the theory and practice behind how to build a QFH antenna.

John Coppens ON6JC/LW3HAZ describes how to make a Quadrifilar Helicoidal antenna Taming the QFH Antenna by Bill Sykes G2HCG and Bob Cobey G0HPO