Chapter 3
External Antenna
The external antenna is the first member of the antenna family in the world of mobile phones. It appeared in the first commercial mobile phone, the Motorola DynaTAC 8000X, in 1983. External antennas were the only players in the mobile phone antenna market for more than 15 years. In the late 1990s, phones with internal antennas started to emerge. Candy-bar phones, also called single piece phones, with internal antennas rapidly expanded their market share in Europe; in the meantime external antennas in clam shell phones kept dominating the North America market for another five or more years. Eventually internal antennas took over the global antenna market.
The driving forces behind the fading of external antennas are both fashion and technical progress. Of the two, technical progress is the necessary condition. Even ten years after mobile phones came onto the market, there were just over one million users in the world at the end of 1993. In comparison, mobile subscriptions were more than three billion at the end of 2007. It is easy to imagine the user density was quite low after those limited users spread out. At that time, the most urgent issue was coverage. All mobile phone service providers wanted to expand their network coverage as much as possible with all the money they could spare. The coverage area of each base station depends on transmitting power, receivers' sensitivity, the path loss of electromagnetic wave, the antenna gain of base stations, ...
