VEGA VEGAPULS 81 - Manual (Page 7)

VEGAPULS 64 and 81 7
1.4 Antennas
The antenna is the eye of the radar sensors.
The antenna shape does not lead to assume
how precise the geometrical form of an an-
tenna must be adapted to the physical fea-
tures of the electromagnetic fields. A shape,
deciding on the sensitivity, similar to the sensi-
tivity of a directional microphone.
Four antenna systems are available for differ-
ent applications and process requirements.
Each system is featured out beside the focus-
ing characteristics by special chemical and
physical features.
Horn antenna
Horn antennas are best suited
for most applications. They
focus the radar signals very
well. Manufactured out of
1.4571 (stst), alloy C4, alloy
C22 or Tantalum are very rug-
ged and physically as well as
chemically resistant. They are
suitable for pressures up to
64 bar and with appropriate
cooling for product temperatures of more than
1000 ° C.
Product description
Rod antenna
Rod antennas with high chemi-
cal resistance require smaller
flange diameters (DN 50). The
antenna rod and the wetted
flange parts are completely
manufactured from PTFE so
that the rod antenna can be
easily cleaned and is hence
insensitive to condensation.
The rod antenna is suitable for
pressures up to 16 bar and
temperatures up to 200 ° C.
Pipe antenna
Pipe antennas on surge or
bypass pipes only form a
complete antenna system in
conjunction with a measuring
pipe which can be also bent.
Pipe antennas are best suited
for products with strong prod-
uct movements or products
with low dielectric constant.
The measuring pipe means a
conductor for the radar sig-
nals. The running period of the
radar signals changes in the
pipe and depends on the pipe diameter. The
electronics must be programmed against the
pipe inner diameter so that the running period
can be adapted.