having installed the latest remote RX system only one week ago I´m
still in a very early state of a learning process ;-). First of
all the configuration used here:
Living in an urban region of Amberg I have to use whatever is
possible. Please have a look to the satellite foto on my QRZ.com
site with the highest resolution. I own the terrace house with the
solar panel array on the roof. Moving the picture to the right you
will see a row of 14 garages from ferroconcrete (thank Goodness
without any utility mains!), the fourth from the top is mine
having something on its roof. It´s an older picture with ony a
small solar panel for the remote controlled door opener -
meanwhile the roof is filled pretty good! The earth dipole is laid
out on the ground parallel to the garage row at its lower rim,
true bearing of the wire being 150°<>330° . It´s fed in my
garage via a ferrite transfomer with 12 turns, the secondary
having 4 turns for the Perseus RX which is a compromise for the
earth dipole impedances measured on VLF, LF and MF. So the
"dipole" looks HF-wise more like a Windom, the upper branch having
about 11 m, the lower one about 31 m length. Each end has a
grounding post (originally threaded metal hulls for parasols)
which is 0.6 m long and screwed into the soil, connected to the
dipole via a relay contact so that I can remotely define the
grounding condition of each branch. In this way I can change
between "earth dipole" (both ends grounded), "Windom on ground"
(both ends free) and something like "Mini-Beverage with special
feeding" (right side or left side grounded) - and all of them
loaded capacitivey and inductively by 14 ferroconcrete garages ...
Each configuration has its own characteristic which in addition
depends on frequency - it remains a lot to learn about it! Besides
the earth dipole there a two more antennas on the garage roof: an
Miniwhip from Bonito and a small fixed passive loop with 2 sqm
winding area. Up to now I simply change the antennas via the
remote control until the best SNR is achieved.
Concerning the directivity of the "real" earth dipole: it seems
significant on VLF, LF and MF where it forms a large lossy loop
throgh the ground. For example with the earth dipole I can´t see
the Russian Alpha stations which are usually strong with the
Miniwhip on the garage roof. On the other hand DHO38 is coming
stronger with the earth dipole - and the very LA1BCN last night.
On HF the directivity seems to be not very significant but up to
now I have no general idea about this.
Sorry - it would be fine to have an additional earth dipole at
right angles to the existing one but the satellite foto shows why
this is nearly impossible! But perhaps there will follow another
remote antanna on the garage roof with a ferrite rod turnable in
azimuth and elevation - there are two more free channels on my 433
MHz remote control ;-)
73 and hpe to cuagn!
Am 28.08.2016 um 11:16 schrieb John Rabson [email protected]