To be able to experiment with the antenna and to tune it to different frequencies, I decided to build a antenna where the elements can be changed in length.
Looking around the Internet and the "Rothammel" I found that the "sleeve antenna" is ideal. It easy to construct and the elements can be build using expendable antennas from r/c remote controls.
Step 1: Mechanical construction
Two antennas will be used for the sleeve antenna, being a vertical polarized dipole. The antenna will be small because it is build for a frequency range 470Mhz to 740Mhz. This makes the mechanical construction easy. Just use some heat shrinkable tubing to fix them.
The antenna can be tuned by changing the length of the dipole elements. The antenna can be mounted using a vacuum cup because it doesn't wight much.
All measurement is done in the metric system using meters not inches ... I am German ;-)
- two r/c remote control antennas
- about 40cm RG-174 coax cable (don't use to much because the damping of this cable is high)
- coax connector that can be plugged into your receiver, i used a bnc blug
- vacuum cup, for easy mounting
- hexagonal brass nut, size M3 (in my case, could be other size for you)
- soldering iron
- sharp knife
- small screw driver
- fine sanding paper
- maybe some silicone spray or oil