Unlike previous two styles, Quadrifilar Helix (QFH) antenna contains a single wire that wound in the form of a helix.This antenna style has a safety concern: every dipole is sharp-pointed to outside. Each of the four dipole supports is tilted 30 degrees from vertical. Each dipole should have length of 38.25 inches and 21.5 inches spacing. Double cross antenna contains four dipoles.We also have to move the antenna direction based on the location of satellites. To receive signals from NOAA, we need to set two dipoles with leg length 53.4cm and spread apart 120 degrees. It is based on a very simple linearly polarized dipole. V-dipole antenna is the most trivial antenna during the construction.In the beginning, we did some research and considered three different kinds of antenna for receiving signals from NOAA satellites: V-dipole Antenna, Double Cross Antenna and QFH (Quadrifiliar Helix) Antenna. The figure below shows the components of our design. The tools we used are Raspberry Pi, piTFT touchscreen, SDR USB dongle and satellite signal receiving (QFH) antenna.
The final outcome of this program is to process/decode the weather images and display them on the touchscreen as they become ready. This system is capable of displaying the time remaining for the next satellite overhead event and recording the signals autonomously for decoding. In specific, we were trying to develop and test a design for incorporating this SDR dongle into the Raspberry Pi ecosystem and developing a nice yet simple graphical interface for receiving the live weather image from the NOAA satellites. Thererfore, we wanted to do some experiments with it. Because of that, it can be applied to receive signals from FM radios, HAM communications, and even satellite signals. We found it very interesting because it has a very broad range of frequency detections and leaves all the filtering & processing stuff to the software. In the beginning of the autumn semester, we came across some videos from Youtube introducing the SDR (Software Defined Radio).