The demand for wireless connectivity of vehicles is growing rapidly. Today, a typical modern vehicle may have more than 10 antennas to provide wireless services. Some of these antennas can be mounted on the rooftop of the vehicle to access to an open field of view from the horizon to the sky. A rooftop antenna module integrates several antenna elements into one package for different services, such as broadcast radio, satellite digital audio radio service (SDARS), global navigation satellite system (GNSS), long-term evolution (LTE), Wi-Fi, Car-2-Car communications, etc.
However, the rooftop location limits the allowable size and the shape of the antenna module, because these features must have acceptable minimal impacts on the aerodynamic performance of a vehicle. This size limitation brings challenges to the designs of the antenna elements packaged in the same antenna module. Besides meeting each antenna’s performance requirements, an important design goal is to minimize the mutual couplings between the antenna elements. A known challenge is to minimize the impacts from other antenna elements to the SDARS antenna in the rooftop antenna designs.
This paper presents a novel LTE antenna design using a three-dimensional Inversed-F Antenna (IFA). It has a simple structure which can be produced using sheet metal stamping method. Besides the benefit of being a low cost, easily manufactured and installed design, this antenna has dual frequency bands, low profile, and it provides high gain and omni directional coverage in the horizontal plane, so it functions well as a LTE antenna. Three design approaches are implemented to minimize this antenna’s impacts on the adjacent SDARS antenna’s performance. It also has very small impacts on all other co-packaged antenna elements in the same antenna module.