Hydro Logger H40
User manual
FIEDLER
electronics for ecology
15
When installing the station outdoors, it is
often the case that the station is placed in
a metal enclosure, in the head of a bore-
hole or otherwise shielded from the exter-
nal GSM field. In this case, it is advanta-
geous to use a special hemispherical an-
tenna that is placed on the outer surface
of the metal casing. This special type of
antenna can be ordered together with the
station from its manufacturer under the
designation AGSM-3db/P-SMA. The an-
tenna shall be fixed in a 12 mm diameter hole and secured against theft from below with
an overmolding nut.
In underground objects such as sumps, transfer shafts and similar objects equipped with
a metal inlet cover, it has proven useful to simply attach the magnetic antenna to the
lower metal part of the inlet cover frame (the rod antenna points downwards). Only when
this simple, and surprisingly often successful, solution fails, is it necessary to proceed to
external antenna placement. A suitable solution may be, for example, a plastic tube (pro-
tector) with a cap that contains the supplied rod antenna. The positioning of the protector
above the ground should take into account the height of the snow cover at the installation
site.
In locations with very weak GSM signal,
the supplied magnetic antenna with 6 dB
gain can usually be replaced by a larger
omnidirectional magnetic antenna with 9
dB gain or a small directional antenna with
12 dB gain (the long directional antenna
requires precise antenna pointing and ho-
mogeneity of the electromagnetic field and
its use has not been proven in practice).
Beware of the usual vertical polarization in
GSM networks when installing a directional antenna! A small directional antenna 60 cm
long can be ordered together with its bracket from the manufacturer of the telemetry
assembly.
Finding the optimal antenna location often requires exper-
imentation, sometimes with SIM cards from other opera-
tors. A coaxial extension cable can also help, which can be
ordered with the set or as an option. The length of this ex-
tension cable can range from 2 to 10 m.
TREATMENT OF THE GSM ANTENNA CONNECTOR AGAINST MOISTURE
PENETRATION
The used GSM antenna connector type SMA is waterproof after screwing and the mu-
tually adhering dielectric prevents the penetration of air moisture to the central antenna
conductor.
However, when installing the station in a humid environment, we recommend treating
this connector joint with a suitable insulating tape or applying a thin layer of silicone
petroleum jelly to the antenna connector before connecting it to the station.
M e t a l e n c l o s e d
o b j e c t s
U n d e r g r o u n d
o b j e c t s
M o r e p o w e r f u l G S M
a n t e n n a s
G S M e x t e n s i o n
c a b l e
AGSM-3dB/P-SMA
Directional antenna AGSM-12dB-SMA
Extension coaxial cable PK-GSM-5M-SMA
