Intelligent Transport Systems

7 Novel In-car Integrated and Roof-mounted Antennas

Rus Leelaratne†

7.1 Introduction

The initial automotive antenna for radio reception was a simple quarter wave length monopole, designed specifically for FM frequencies. The rod was typically 75–80 cm in length and still to date remains one of the best performing antennas. The antenna was mounted on a vehicle typically next to the A pillar or on the fender.

As the infotainment system of the car evolved, many additional functions were introduced. These were typically in the form of television, mobile telephone and satellite navigation frequencies in the late 20th century. The early 21st century saw a rapid expansion of frequencies used in the car, with the uptake of additional mobile telephone frequencies, digital radio, satellite radio, Wi-Fi^® and more recently emergency call and car to car communications.

The styling requirements of vehicles in the late 20th and early 21st century have also had important implications on how the automotive antenna has evolved. Visible antennas are not welcomed, especially by the European consumer. This resulted in the growth of the hidden antenna, typically printed on a vehicle windshield or hidden underneath a composite body panel.

Enhancements in semiconductor technology and digital signal processing saw the growth of switched diversity and phase diversity as a technique for significantly improving the performance of these hidden antennas. Today, almost all luxury cars utilize phase ...