I want to put a stick on DAB exterior aerial on the top centre of the windscreen but I notice there is a dark meshy looking area behind the rear view mirror. Is this metallic ? What does it do and will it block the through glass signal?

I suspect it is bit of a sunvisor.  On my mk1 elegance I used to have a 'mini' 3rd sunvisor I could fold down to block the sunshine which was missed by the two traditional visors.  Guess the built in bit the windscreen is cheaper and easier to produce.

 

I doubt it would block the signal, but don't quote me.  Could you try hold the aerial parts either side and see if it works?

Yes I think you are right, I'll try the aerial with sello tape first.

If it's black then it's simply a painted cosmetic screen to mask the mirror fitment.

It's all around the glass, again so you don't see the edge where the glass is bonded.

If we have athermic windshields, it will block the signal ... 

 

Try it with the sello tape first - that's a good idea!

it's a sun block wher the sun visors can't reach.

Somewhere in the dusty reaches of my mind I think it's the recomended spot for toll tags, etc. Possibly it's in the manual???

just saw on a peugeot site that their windshields also have the dimply dots and that's where their toll tags went and they worked.

Just make sure you don't have the auto dipping rear mirror as I believe this might interfere with the sensor?

I do have the auto dipping rear mirror- Sorry which sensor does it interfere with?

As has been mentioned this is just to help prevent the sun getting into your eyes in between the two sun visors.

 

I have my dash cam mounted to them!

I do have the auto dipping rear mirror- Sorry which sensor does it interfere with?

 

It won't interfere with the auto dimming mirror sensor. The mirror uses two sensors, one mounted on the mirror itself facing backwards and also the forward facing one on the windscreen that is also used for auto wipers and auto headlights....you won't interfere with this sensor by mounting something on the inside of the windscreen.