The Antenna System at OH0AW & OH0Z
The antenna system consists of two rotating towers with
no less than 9 yagis on them, all
made and designed by Finnish Antenna LTD.
Tower #1 140ft with 4 stacked tribanders + 2 over 2 yagis
for 40 meters.
Tower #2 100ft with 2 stacked tribanders + 2el yagi for 40 meters.
Why did we pick tribanders for our stacks? Good question!
We wanted the antenna
system to be as simple as possible, given a certain desired level of performance.
One
should understand, that the antennas are located on a hilltop near the waterïs
edge and the
winds often are extremely strong. The tribanders we use are relatively small,
thus making
them easier to handle and repair, if needed. Extensive computer studies by OH1JT
showed, that a good level of performance is possible by stacking enough of those
antennas
and thatïs exactly what we did at OH0AW & OH0Z.
Another reason why we chose tribanders was to avoid the serious interaction
that can
result from stacking several monobanders closely together.
As one can see, we have two different tribander stacks,
one on each tower. Thatïs because
we wanted to be able to beam two directions simultaneously, e.g. USA/EU or USA/JA.
A
Finnish Antenna LTD switchbox inside the shack controls the different antenna
combinations.
We also have 40m yagis on separate towers for the same reason, to cover two
directions
simultaneously. This usually means keeping one antenna system on DX and the
second
one on Europe to run the EU boys and also to keep our frequency clear!