I found descriptions of
different Slinky Antennas in the Internet and I decided make my
own one. At first, I need a metal Slinky. I bought this one in
one of the local toy store. Figure
1 shows the slinky toy. Length of the Slinky was a
bit more the 19 meters, so the antenna should work at the 40 meter
band. (you may found information on spiral antennas at: http://www.antentop.org/library/shelf_helical.htm)
In several hours the antenna was made and
installed inside of my room. Figure 2 shows the slinky antenna in the room.
Balun is sitting in the central box at the antenna. Antenna
analyzer was hook up to the antenna terminals and measured the
antenna impedance and antenna SWR. Figure 3
shows antenna impedance/SWR Vs frequency. Antenna has SWR less
the 2 at 40 and 15 meter band.
So the antenna
test shows that the antenna could operate at the two bands without
ATU. After the test antenna was reinstalled on my balcony. Balcony was at four floor of the building and the main
direction for antenna radiation was closed by nearest building.
Figure 4 shows slinky antenna installed on the