Traveling-Wave Wide-Band Microstrip Antennas

The present invention is directed to microstrip antennas, and more specifically to a microstrip radiator that has wideband capabilities.

In the past, microstrip antennas have been used in numerous forms and applications, but all of them suffered from the limitation imposed by their inherent narrow bandwidths. In situations where wideband performance (more than 5-10%) was required, microstrip antennas of differing sizes had to be stacked or interlaced in order to try to provide the proper band coverage for the application. This led to antennas that were large, had complex feed configurations, and were very expensive to produce and operate. One of the basic characteristics of a microstrip antenna that limits its bandwidth is its resonant behavior. The resonance of a normal antenna, due to the reflection of the electric current wave at the open-circuited ends of the antenna causes a standing wave of electric current to form along the antenna structure. This standing wave can only be efficiently supported when the antenna's length is a multiple of a half wavelength (for center-fed dipole antennas). As the antenna's length moves away from these select wavelengths, the antenna will not operate efficiently, hence limiting its bandwidth. What is needed is an antenna that provides greatly improved bandwidth performance over current microstrip antennas, without the cumbersome task of having to stack or interlace antenna elements of different sizes in order to achieve wider band widths.