[Vwdiesel] One antenna solved!

[Tad]

Nope, no 3rd conductor.  Just the center wire and shield/ground of the coax.

It's possible to pass DC along the same wire without interfering (much) with
the radio signals passed from the antenna.  Ordinarily the RF is just a
small 'warble' on the wire, oscillating above and below zero volts.

Using a capacitor in series, you can block the DC while allowing AC (the RF
signal in this case) to pass.  So all they do is tie the antenna wire to
+12v (at the radio end) and the antenna amplifier (at the antenna end).
That way, instead of 'warbling' around 0, it warbles around +12v.  That's
referred to as a bias voltage.
Then they couple the wire to the antenna and antenna circuit at both ends
through a capacitor, which blocks out the +12v but allows the RF signal to
pass through.

Come to think of it, they might not even need the capacitor at the antenna
end. :)

On Tue, Jun 9, 2009 at 4:04 PM, <LBaird119 at aol.com> wrote:

> In a message dated 6/9/2009 11:43:46 AM Pacific Daylight Time,
> tadc at europa.com writes:
>
> > The reason you didn't see a power wire is because there isn't one - the
> > power is fed along the same antenna coax as a DC bias voltage that's
> > injected either by the deck (stock) or an adapter (aftermarket).
> >
>
>  It'd have more than a pin and outer sleeve for connection though
> wouldn't it?  That's all I saw.  Didn't have my glasses...  The only
> other thing would be if it had a "collar" secondary connection like
> on a stereo  1/4" or headphone jack.
>     Loren
>
>
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