PS Magazine - TB 43-PS-742
PS, The Preventative Maintenance Monthly
ISSUE 742
SEPTEMBER 2014
48
PS 742
SEP 14
49
PS 742
Vehicular Antennas…
Sid
and
Cy,
the
Antenna Guys
in
“CheCk Out My MatChing Unit”
Hi. I’m
sid.
and
I’m
Cy.
We’re the
antenna
guys!
Today we’re
going to talk
about the
base matching
unit
of the
vehicular
AS-3900A/VRC
antenna,
NSN 5985-01-
308-8988.
in particular,
we’re going to
focus on the
ground
strap.
Some guys
think they can
get away with
not
using a
ground strap,
NSN 6150-01-
214-5
7
50, with
the antenna.
OoOo.
.. That makes
me soOooO
mad
when
someone ignores the
ground strap.
When a guy pulls
a stunt like that, I
just want to
zap
him with a good dose
of RF energy! I want
to
smack
him upside
the head with my top
element! I want—
Calm down,
Cy. You’re
overheating
again.
Some people
simply
neglect
to use the
ground
strap. Others
actually
believe the
strap’s not
necessary.
They think the
antenna is
grounded by
the RF cable.
But here are
the
facts:
The antenna
must
have
a working
ground strap
that runs
from the base
matching unit
to the vehicle.
Without the
ground
strap, your
radio is
not
fully mission
capable.
The shield braid on the
RF cable offers
some
DC grounding, but it has
a poor RF ground.
The cable runs from
the antenna all the way
to the radio. The cable’s
long length
may make
the braid
ineffective
for
RF grounding because
it may no longer be at
ground potential for
RF frequencies.
For
safe
grounding, the
connection to ground
should be
short.
The ground strap does
just that.
Wow!
You must’ve
taken courses in
advanced anten-
naology and
RF frequencyation
theory.
As
well aS
quantum
ground
strap-
olism.
742 48-49.indd
1-2
7/21/14
5:07 PM
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