2200m loaded inverted L Antenna
2200m (137kHz) backyard, suburban, wire antenna
Suburban antenna for 2200m.
Again,yes. It is possible to put up loaded antenna for the 2200m amateur radio (HAM) band in a suburban backyard. As stated before,
if you have a suitably located tree or two and/or a flagpole or like, then go for it. Try to get as much wire
in the air. It doesn't just have to be vertical. A long horizontal component will act as a capacity hat and
help get that current up the wire to where it can be radiated more effectively. It will definitely be better
than a single short vertical wire or mast.
The idea in principal, is to provide additional inductance for an already short antenna and a suitable matching network
to get the maximum power transfer from the transmitter to the antenna.
More wire is better ...
Utilising the three wire capacity hat as opposed to the original single wire, the loading (and variometer) coil had decreased from about 5.7mH to about 2.8mH. Less loading means higher radiation efficiency.
The auto-transformer style matching coil replaces the ferrite impedance transformer, so I can run more power and the details are as follows: 87 turns (total) of 2.5mm building wire, over 110mm diameter PVC storm-water pipe. This is measured to be about 271uH. The tap point was found to be on the 22nd turn from the ground end. This was measured to be 45.6uH. These details are provided only as a guide to what I am currently using. YMMV.
Initial 160m design.
Using the 160m 1/4 λ three wire antenna as a starting point.
Variometer schematic.
Schematic of the loading and matching circuit.
Loading coil & variometer.
Earlier version being measured. Used with single wire antenna.
Latest version.
2 buckets(!) of wire removed from the loading coil.
Inside variometer photo #1.
Here's how I fed the wires to the outside of the coil - through the shaft.
Inside variometer photo #2.
This is what the inner variometer coil looks like.
Useful Links
- A short antenna tuner
- 2200m (136kHz) Amateur Experimentation