You can get a Reradiating Antenna
Give your GPS signal a boost by installing this product on the outside of your car. The RA-45 reradiating antenna increases your GPS signal. If you drive a car that has a heat reflective windscreen then this product is essential for the operation of your Satellite Navigation System.
You simply place the antenna at a point in your car where a signal can be received, then trail the cable so it is close to your original GPS receiver. It needs to be powered from your 12V accessory socket, but is carries a pass-through connector so you can have two devices powered at the same time.
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