Fabricating antenna components

摘要

IMAGINE driving down a country road, rounding a bend, and coming across a couple of cars in the ditch. You're the first person on the scene so you use your mobile phone to call emergency services. In a minute or so police cars, ambulances, and a fire truck are on their way. Dialing 911 isn't a big deal, but getting your telephone signal routed to the emergency responders is. Your call went to the closest cell phone tower, and from there it was directed to another tower, and another, until it reached the closest town, and then to an operator at the emergency services desk.