A vertical integration of high-Q filters with patch antennas with enhanced bandwidth and high efficiency

A new approach to integrate high quality (Q)-factor 3-D vertical cavity filters with patch antennas into a single unit is presented in this paper. This integrated filter/antenna system exhibits small footprint, high efficiency, and enhanced bandwidth. The patch antenna is designed to provide an additional transmission pole for the filtering function and work as a highly efficient radiator. In addition, this integrated patch antenna with a filter can achieve a bandwidth much larger than a standalone patch antenna with the same geometry. A prototype three-pole Chebyshev filter/antenna is demonstrated at X band. The center frequency and fractional bandwidth of the filter/antenna system are 10.27 GHz and 8.7%, respectively. Due to the high Q factor (~700) of the cavity resonator and near loss-less transition between the antenna and filter, the overall efficiency of the filter/antenna system is simulated to be as high as 91%. The reduced footprint, enhanced bandwidth, and low-loss performance of these integrated filter/antenna systems make them particularly useful for phased array applications. The measured impedance matching, efficiency, gain, and radiation pattern closely agree with simulation results.