[aprssig] NMO

[kd7nm]

NMO = "New Motorola", as in a specific mobile antenna base
style.  It's not really new any longer, since it's existed
since at least the mid-70's, since that's about when I
started looking at Larsen antenna models, with the wide
variety of mounts they work on.

One of the mechanical properties of the NMO antenna mount is
that all of the versions I've seen of it to date are based
on being mounted through a 0.75" hole.  The mount is popular
enough that both Motorola, and at least one other company,
have created a special drill bit for making that hole
through the roof of a car, while minimizing how far below
the roof the bit extends - so as to protect the interior
ceiling liner of the car from being damaged by the bit.  One
of them also has a surface designed to expose bare metal to
improve the grounding of the antenna base to the vehicle
roof sheet metal.

I suspect that whatever the original (or older) Motorola
antenna mount was like, didn't work well at UHF.  And the
NMO mount has been improved since then, to make it work at
even higher frequencies without as much of an impedance
bump.

73, Bob, KD7NM

----- Original Message Follows -----
From: "Rod,VE1BSK" <rodpadmore at ns.sympatico.ca>
To: "TAPR APRS Mailing List" <aprssig at lists.tapr.org>
Subject: [aprssig] NMO
Date: Tue, 9 May 2006 14:51:33 -0300

>Pse tell me what this acronym means in antenna adverts. I
>can only find it meaning,"Nuns, Mothers and Others" on the
>web and I suspect this is not the meaning I am looking
>for(hihi), tnx es 73 de VE1BSK,Rod.
>
>
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