Antenna by HenniC4

Last crawled date: 3 years ago

John Doe's Dipole Antenna.
My Setup (I assume, if you build this you know what you are doing, anyway):
4mm Brass rod (for indoors it should be ok and is easy to solder) from hardware store. Carefully enlarge 4mm hole in Socket. Move drill inside socket a bit, until rod can be moved with some force. Unstrip Coax inner lead for some cm and fold the shield back. Wrap inner lead 2 Times around very End of rod. Heat with a gas torch, add Solder. Be careful, the heat will make the socket material soft.
I plucked 3 rubber feet from a broken Ethernet switch and sticked them to the bottom of: http://www.ebay.de/itm/331727191044 But that thing really is a bit on the ultra heavy side. Use some reasonable weight to hold your Antenna straight up. Glue it all up with a huge amount of strong, elastic glue (I used Pattex Kraftkleber, but i am sure you have equal stuff in the anglophone world), so that the shield touches the Steel plate and coax inner lead/brass rod do not, which i assured with a bit of isolation tape.
The little ball is for the other end of rod.
Crimp BNC to other End of Coax.
To generate the cubic curve I use FreeCAD and this Julia snippet to generate coordinates:
x=40
y=60
for i=0:.1:1
print("($(ix),$(i^2x))\n")
end
Brass (and Copper) is not the perfect material for an antenna. At high frequency, the skin effect dominates and if your antenna "skin" is made of badly conducting oxide, your antenna will perform badly. For indoors, beautiful, shiny, golden brass should be quite ok, brass itself conducts pretty well. However, aluminium is much better, but not quite as easy to solder.