[maemo-users] How is the N800 antenna implemented?

From: Larry Battraw lbattraw at gmail.com
Date: Mon Jul 30 20:23:22 EEST 2007
On 7/30/07, david.hagood at gmail.com <david.hagood at gmail.com> wrote:
> Does anybody know how the antenna in the N800 headphones is implemented?
> Are they using the ground conductor as the antenna, are they using the two
> headphone lines as a dipole antenna, or what?

  Using the ground connector wouldn't really work since I believe it's
directly connected to "system" ground and wouldn't produce a net
difference in field strength.  When I last checked the ground
connector acted as a ground plane and one of the headphone wires
served as the actual antenna.  It doesn't work that well in practice
(in its stock configuration) simply because there's not enough
exposed/non-twisted-pair portion of the headphone wire pair to receive
a good signal (Only one wire/ground pair acts as the antenna and I
can't remember which right now).  Once you expose a few inches of the
heaphone wire from the ground sheath/pair it works very well as long
as you don't go crazy and expose so much antenna that it overloads the
RF frontend
> There are 2 reasons I ask: first, I'd like to be able to do a calibrated
> sensitivity check on the FM receiver, which means I need a proper RF
> interface to inject the signal from my sig-gen on. Secondly, I work in
> what can best be described as RF hell (as you might deduce by the fact
> that I have ready access to a calibrated RF sig-gen), and I'd like to be
> able to couple my external antenna drop into the N800.

I wouldn't do that if I were you.  Any time you connect something to
you and a external (out-door) antenna you're betting against the
possibility of a lightning strike, static discharge, accidentally
touching something live and becoming the shortest path to ground, or a
host of other unpleasant possibilities.  Stick with something cheaper
and purpose-built for listening to the radio on; you could even go for
one with a remote so you don't have to touch it every time you want to
adjust the volume or switch stations.


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