"Kickin' Ass and Takin' Names" wrote in message
...


It's a long story, here's the short version.

Our volunteer rescue squad dispatch operates in the 152 - 154 MHz
range -- transmit on 154.XXX, receive 152.XXX.

Our main antenna barely survived contact with a tree limb and needs to
be replaced.

Our local Motorola sales rep has his head stuck firmly up his ass and
keeps trying to sell us some basic 1/4-wave verticals.

The current antenna is a vertical whip with a loading coil wound
along the length of the antenna.

The dimensions a

-- Overall height: 14.25 inches
-- 4 inches from the base the antenna is wound into a coil, about 3/8
inch diameter, 5 turns
-- the coil is 1.75 inches long
-- above the coil is 8.5 inches of antenna
-- NMO base

I suspect this antenna is an old model 5/8-wave VHF antenna, shortened
by winding a coil in the antenna.

If it is a 5.8-wave, it should be giving us a few dB gain. The
1/4-wave whip he wants me to install would give unity or less gain. In
our rural area, we need all the antenna help we can get. I an
thinking about installing a full-length 5/8-wave whip, but, we go into
a lot of driveways with low tree limbs and I doubt a full-length
antenna would survive very long.


I have Googled every term I can think of to find this antenna,
Motorola sales rep tells me he thinks its a "cellular antenna" . .
.which it clearly is not. My MFJ antenna analyzer shows a resonance
at 154 MHz.

Anyone help me identify this antenna?

I don't think the Motorola man has his head anywhere, but maybe your head
is.

To be a 5/8 wave or gain antenna at 154 mhz the antenna will be about 35 to
45 inches long. If the antena you have is only 14.25 inches long, it is
less than 1/4 and will have even less gain than a 1/4 wave whip. A 1/4
whip will be about 18 inches at 154 mhz.

You do not shorten a 5/8 antenna by winding coils. The coils are either
matching or phasing coils.