In this paper, we report our investigation into single-feed dual-frequency
planar inverted F antenna (PIFA) designs which make use of LC resonators (o
r "RF traps"), We introduce three basic methods for incorporating the LC re
sonator into the PIFA, including a variant of the meandering PIFA, Experime
ntal results are provided and these show that dual-frequency operation at 9
00 and 1800 MHz can be achieved for all three designs.