FIEDLER H1, Руководство пользователя

Страница: 26 / 82

Hydro Logger H1 User manual
26
electronics for ecology
FIEDLER
The basic and most common type of antenna supplied is AGSM-3dB-SMA. It is a
dual-band rod antenna with a magnetic mount and a 3 m long cable terminated
with an SMA-M connector. This antenna is usually placed inside a -A or -S type
plastic enclosure and only in case of weak GSM signal it is necessary to place the
antenna in a suitable place outside the enclosure and feed the coaxial cable to
the unit through one of the cable glands.
The antenna is usually placed vertically because of the vertical polarization in
the GSM network. If the signal level is not good, it is recommended to try hori-
zontal placement of the antenna.
When installing the station outdoors, it is often the case that the station is pla-
ced in a metal enclosure, in the head of a borehole or otherwise shielded from
the external GSM field. In this case, the station is supplied with a special he-
mispherical AGSM-3dB/P-SMA antenna, which is placed on the outer side sur-
face of the metal enclosure. The antenna is mounted in a 12 mm diameter hole
and secured against theft from the inside of the enclosure with a lock nut.
In locations with very weak GSM signal, the usually supplied magnetic antenna
with 3 dB gain can be replaced by a lar-
ger omnidirectional magnetic antenna
with 9 dB gain type AGSM-9dB-SMA, or
a small directional antenna with 12 dB
gain type AGSM-12dB-SMA. The long di-
rectional antenna puts high emphasis on
precise antenna pointing and homoge-
neity of the electromagnetic field, and
its use has not been successful in
practice. Beware of the usual vertical
polarization in GSM networks when in-
stalling directional antennas! A small directional antenna (60 cm long) together
with its bracket can be ordered from the manufacturer of the telemetry set.
In underground objects such as sumps, transfer shafts and similar objects equip-
ped 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, it is ne-
cessary to proceed to the external antenna placement. A suitable solution may
be, for example, a plastic capped protector that con-
tains the supplied rod antenna. The positioning of the
shield above the ground should be done taking into
account the height of the snow cover at the installa-
tion site.
Finding the optimal antenna location often requires
experimentation, sometimes with SIM cards from
other operators. A coaxial extension cable, which can
be ordered from the station supplier as an option, can
also help. The length of this extension cable can range
from 3 m to 10 m.
When using an external larger rod or directional an-
tenna outdoors, it is generally recommended to terminate the coaxial line just
before the unit with a coaxial surge protector that must be well grounded.
S t a n d a r d r o d
a n t e n n a
A GS M -
3 d B -S M A
E x t e r n a l a n t e n n a
f o r m e t a l
e n c l o s u r e s
M o r e p o w e r f u l
G S M a n t e n n a s
U n d e r g r o u n d
o b j e c t s
E x t e n s i o n C a b l e s
C o a x i a l s u r g e
p r o t e c t o r
Directional antenna AGSM-12dB-
SMA
Extension cable
PKGSM-5-SMA