Spin (spiral) antenna
The antenna is mounted horizontally and has a narrow focus. It is possible to construct a lattice of several spin off antennas.
The metal plate is a reflector antenna, not a counterweight, as it may seem at first glance.
A metal rod with a dielectric spacer attaches to the antenna mechanical strength. On satellite antennas this rod has a Directors and long spiral tenfold.
The antenna is designed for operation in the frequency range 814-960 MHz. It is easy to manufacture, has a very solid construction and, like all spiral antenna has a circular polarization wave.
Circular polarization provides better passage in urban areas. Apparently it fully shows the classical property of spin.
Is supplied with this antenna through a cable characteristic impedance of 75 Ohms.
Tuning the resonant frequency produced by compression or stretching of the turns of the antenna, and a strong deviation between the resonant frequency desired by shortening the length of the conductor.
All parameters of spiral antennas obtained experimentally.
The diameter of the spiral - 100mm;
Number of turns - 7,5
Winding pitch - 30mm
Author: Vasily Vasilenko, Yakutsk; Publication: www.inspector_v.chat.ru, www.cxem.net