Integrated filter/antennas with high efficiency and increased bandwidth

Abstract

Two methods of integrating high-Q 3-D filters with antennas are presented to achieve very high efficiency and increased bandwidth. In one approach, a three-pole cavity filter is integrated with a slot antenna, which acts as an equivalent load of the filter. A total filter/antenna efficiency of 83% and an antenna efficiency of 98%, respectively, are achieved with a filter/antenna bandwidth of 4.8%. In the other approach, a two-pole cavity filter is integrated with a patch antenna, which adds an additional pole and forms a three-pole filter/antenna. A total filter/antenna efficiency of 91% is realized with a filter/antenna bandwidth of 8.5%. This novel filter/antenna integration technique also significantly reduces the form factor of the integrated RF front end. Prototype three-pole Chebyshev filter/antennas for both cases are demonstrated at X band. The measured impedance matching, efficiency, gain, and radiation pattern closely match simulation results.