NEQ Tests the
AS3900 SINCGARS Vehicle Mount Antenna
as a
Quick Deploy Temporary Base Antenna

AS3900 Antenna on Quick Tennis Stand AS3900 Antenna Measurements With Mount
Coaxial Feed from base to whip
On Test Stand Near Palm Trees

Big Mount on a Chevy Astro Van
A Quick Deploy
Center Fed VHF Vertical

Here's a standard AS3900
military antenna assembly.

It's the center fed VERTICAL dipole
that you currently see on every Hum Vee,
Bradley, Tank and Patriot Missle Battery
in the US Military today (2008 as I type this).

Top section of the antenna
is sixty-one inches long.


The bottom section
of the vertical dipole
(including mount and spring)
is fifty inches long.

Should be pretty close to the
6m band. But I measured it on
10, 6 and 2m just to see what happened

The Military calls it
"Broadband Vehicular Whip Antenna"
It is certainly that - Broadband.



Design Specs:
Application: Secure Communications
Frequency: 30 to 87.975 MHz
Impedance: 50 Ohms Nominal
VSWR: 3.5 to 1 Maximum
Polarization: Vertical
Pattern: Omni-Directional
Connector: BNC
Max Weight: 11.6 lb
RF Power Capacity: 150 Watts CW
Gain: Dependent on Frequency. Ranges
from a minimum of -7.6 dBmp @ 30 MHz
to -1.1 dBmp @ 87.975 MHz

Not particularly great looking
specs with it's negative gain and
potentially high SWR.

But!...



Rugged as hell!

It will survive a 20 kilovolt hit
if you drive under a power line.
The Spring to Antenna Junction - Center and Ground Contacts Designed as a
Vertical Dipole...

... the signal is fed like coax
up through the spring and bottom
half of the vertical antenna.

The spring threads, and the female
threads on the bottom of the element
are both solid brass. Very heavy.

Note the rubber O ring and
ground screw on spring mount.

Missing: Rubber weather cap
for use when the vertical element
is unscrewed and dismounted from
the spring and base.



Hand Assembly
Only...

... no tools needed or recommended,
once you have the base and spring
installed.

Unscrew/remove the antenna as
social situations dictate.
Test setup for checking SWR, reactance, impedance, resonance
Yes, it can be fender mounted!
Testing the AS3900
for SWR, reactance,
impedance, resonance

The tripod stand I use for testing
was once some kind of tennis racket
re-stringing stand that someone
discarded as trash.

The mast (recycled of course)
is a recycled round landscape timber
pushed into the open top of the
tripod stand.

At the top of the mast,
a simple U bolt and
one machine bolt hold the
metal antenna mount at a height
of 8 feet off the ground.

The horizontal wires you see in the
background are not related to this
test setup. They are attached to a separate
antenna, which is mounted on the
corrugated tin roof behind the test stand.

The antenna is a center fed dipole,
PROBABLY works independant
from any additional counterpoise.
And in the interest of rapid setup
I did NOT install any kind of
radials.

Surely mounting the AS3900 on my tin roof
or on a metal vehicle will change
the pattern/test results of this antenna

More vehicle mounting pics elsewhere
on these pages.

MFJ Analyzer Readings
MFJ meter reading at 28 MHzMFJ meter reading at 28.5 MHz
MFJ meter reading at 29 MHzMFJ meter reading at 29.5 MHz
MFJ meter reading at 29.7 MHz
Here's the 10m readings
from the MFJ analyzer...

From 28.0 to 29.7 MHz
SWR is -
Best case 2.3:1
Worst case 2.8:1

Reactance is -
Best case 40
Worst case 59
I try and shoot for
a max reactance of 10 for any antenna.
The AS3900 is pretty high in reactance

Impedance is -
Highest at 59 ohms
Lowest at 39 ohms.

Impedance is acceptable, but
reactance and SWR are pretty far
away from desirable.



MFJ meter reading at 50  MHzMFJ meter reading at 51 MHz
MFJ meter reading at 52  MHzMFJ meter reading at 53 MHz
MFJ meter reading at 54 MHz
Here's the 6m readings
from the MFJ analyzer...

From 50.0 to 54.004 MHz
SWR is -
Best case 1.7:1
Worst case 1.8:1

Reactance is -
Best case 4
Worst case 25
Here too, reactance is pretty high

Impedance is -
Highest at 83 ohms
Lowest at 29 ohms.

Not exactly an ideal 6m antenna


MFJ meter reading at 144  MHzMFJ meter reading at 145 MHz
MFJ meter reading at 146  MHzMFJ meter reading at 147 MHz
MFJ meter reading at 148 MHzMFJ meter reading at 121.13 MHz
Here's the 2m readings
from the MFJ analyzer...

From 144 to 148 MHz
SWR is -
Best case 1.5:1
Worst case 1.8:1

Reactance is -
Best case ZERO
Worst case 25

Impedance is -
Highest at 33 ohms
Lowest at 91 ohms.

Not bad at all for 2m,
a band that it's
not designed for














Best readings I found
seemed to be near the AM
aircraft band.
I'm testing as we speak, so to speak.
It's making contacts on 2 and 6.
More testing tonight.

I just finished installing the antenna on my Astro Van.
Details and pics of that to follow.
Preliminary findings suggest that it doesn't seem to
tune up well to any ham frequencies
when mounted to the vehicle. It's really
resonant around 71-72 MHz. But at 2/6/10m
the reactance, impedance and SWR are all
beyond what I consider good figures.


Parking Lot Walk Up Viewpoint


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Map of my world wide QRP contacts!
My Contacts
Vertical emt Conduit Antenna
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Blending in to the desert, or anywhere!
Desert Camo
2m Beam from neighborhood garbage!
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AS3900 Mil Mobile Antenna as Temp Base
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Where Am I?
APRS Tracking
Repainting the Yaesu 857 - OLIVE DRAB!?
Green Radios
Take Me Home!
Return to QTH

Craig@n0eq.com

The rest of my life?
Craig 'Lumpy' Lemke www.LumpyMusic.com