 |
A Trap
Dipole, often referred to as a W3DZZ, is now hanging in my garden too.
There are plenty of descriptions of this antenna type around. So I
won't wast your time explaining the basics, just show you how I did It.
The trap
dipole is supported by the trees in the garden. One leg is hanging
straight between two trees. The other leg is hanging in a 45 degree angle from one tree and bend almost 90 degrees along the garden
fence.
|
|
|
I have chosen a version with coax traps
and a 1:1 balun. The coax
traps are calculated using the very good program developed by
VE6YP. You can download the program
here. |
 |
|
 |
The traps are wound on PVC
plumbing pipe. Note that I have used two tubes spaced about 10 mm. The space
hide the connections, and is sealed using silicone making a very good
protection. The weight is still kept to a minimum.
|
|
|
On the right picture you see the
trap mounted. I've used plenty selvamalgating tape, just in case.
The wire is actually loudspeaker
cable which is cheap and has a reasonable tensile-strength.
|
 . |
|
 |
In order to obtain a good balanced feeding at the low
frequencies, I have used a 1:1 balun made of a ferrite core and 7 turns of RG400 cable. The
cable is crimped on a female UHF connector. |
 For the housing I adapted a good
idea from a fellow Ham OZ1PIF, using a conduit box from the house wiring (I
bougt a new one!).
The balun ready to be pulled
into place in the tree. |
|
| The
balun and wires are attached to the trees using simple rubber ties. They
should enable the tree to continue growing improving my antenna performance
over the next 50 years or so (if not somthing else breaks down in between). |
 |
|
 |
Talking about performance I did
measure the SWR as can be seen from the graph. |
|
Finally the
schematic with wirelength etc. |
 |
|
|
|
)
)
)
)
)
)
)
)
)