Hi All,
Interesting discussion here, just to clarify a few points and to add some input.
Legal Eagle will find that a loss of GPS signal is due to a few factors, the heated windscreen, being one. Moving the antenna to a lesser wired position of the windscreen will improve the signal slightly. You should be able to see the small elements passing through the laminate. On most vehicles the heating elements don't start across the first couple of inches of the either edge.
Another interesting point that a lot of people dont even realise or consider, is the fact that actual urathane, that is used to glue the windscreen to the car, can weaken the signal received by sat nav systems. Up to 75% can be lost by the windscreen being fitted with a non conductive urethane. However a lot a companies, whether they be replacements or body shops, use a cost cutting urethane. This is due to 2 factors, one being, the first thing people ask when calling us is what is the price for, this has driven a few companies to go down the cheap glue route. This atitude of the customer not considering the fact they are buying a windscreen, urethane and fitting service has been one reason for driving this and the other factor is the insurance industry finding the cheapest option for themselves and not the best quality for the policy holder. Urethane at wholesale price ranges from £1 to £6 for 400ml. I know plenty of body shops where we supply only, windscreens that buy in cheap nasty glue's because in order to do insurance work at £30 an hour and have to give the owner a loan car F.O.C. are paying no more than £1 for urethane to fit that screen to YOUR car.
In my 24 years I have always had an atitude of quality and a fair price for this service. However I can see that this atitude can sway in others that ONLY consider costs.
Of course the alternative to having this loss of signal could be cured by placing a water proof antenna through the glue line when having a replacement screen or passing the wire through the bulkhead (through where the main loom passes into the car from under the bonnet is good place) and situating the antenna under the plastic scuttle between the windscreen and bonnet, most Range Rovers with heated windscreens and sat nav, place the antenna in this region, therefore the antenna is not being affected by the heating elements, reflective coatings or urethane.
Hope this helps.
