A complementary self-structuring antenna for use in a vehicle environment

A self-structuring antenna (SSA) is capable of changing its structure, and thus its performance as an antenna, in response to changes in its environment. A microprocessor is used to control the electrical connections between components of a skeletal antenna template using information from a sensor to optimize a desired quantity, such as received signal strength or VSWR. Because the number of possible configurations is large (2^N for N switches), efficient algorithms such as genetic algorithms or simulated annealing are used to find acceptable switch states in real time. Until recently the template consisted of wire segments interconnected by switches. This template is useful for automotive applications where the template is placed in the rear window of the automobile since a vertically polarized component to the antenna pattern is present. However, this template cannot be placed in the roof of an automobile since no vertical field is produced. To allow for such an application we propose the use of complimentary antenna elements, such as slots, in the antenna template. We investigate the behavior of such a complementary SSA (CSSA) both in free space and in an automotive environment.