VEGA VEGAPULS 41 4 … 20 mA; HART compact sensor - Manual (Page 10)

10 VEGAPULS 41 – 4 … 20 mA
26620-EN-041227
1.5 Antennas
The antenna is the eye of the radar sensor.
An uninitiated observer would probably not
realise how carefully the antenna geometry
must be adapted to the physical properties
of electromagnetic fields. VEGAPULS 41
radar sensors are equipped with a com-
pletely encapsulated antenna.
PTFE is commonly found in hygienic applica-
tions. The small plastic cone of the
VEGAPULS 41 radar sensor, operating as
antenna, consists of a TFM-PTFE material.
This is a fluorthermoplast, which has further
distinct advantages compared to PTFE, such
as, e.g., reduced load deformation, denser
polymer structure as well as a smoother
surface (Ra < 0.8 µm). The other known ad-
vantages of PTFE, such as, e.g., high tem-
perature resistance (up to 150°C), high
chemical resistance as well as resistance to
brittleness and ageing are still there or have
even been enhanced. Perfluorelastomers
and fluorthermoplasts are resistant to virtually
all chemical media such as, e.g., amines,
ketones, esters, acids (sulphuric acid, phos-
phoric acid, hydrochloric acid, nitric acid),
alkalis (caustic soda), oxidants, fuels and
oils. Beside their use in the chemical industry,
these materials are being applied more and
more in sterilisation and pharmaceutical tech-
nologies. The only limits to these materials are
in applications with fluorine under high pres-
sure or with liquid alkali metals (sodium or
potassium), where explosive reactions may
occur.
Types and versions