Bandwidth property of folded planar inverted-F antennas

The bandwidth property of a folded planar inverted F antenna (PIFA) is investigated. In a folded PIFA, a part of the radiating element of the antenna is patterned on the backside of the substrate, resulting in both bandwidth enhancement and size reduction. Between the radiating elements on the top and bottom of the substrate, an electrical connection is maintained by two via holes. When these two via holes are positioned at different locations, a secondary electrical path is provided and a bandwidth enhancement is achieved. Experimental results show that the relative bandwidth of the proposed PIFA is more than 2% larger than that of a conventional PIFA on the same size substrate, while maintaining nearly the same radiation patterns. Both the simulated and experimental results for the proposed PIFA are provided along with a comparison with a conventional PIFA.