it is relatively easier to design PIFA for GSM/DCS PCS if you are given enough height limit, IFA might not give you enough BW. FJA is placed around 8cm away from PCB, two arms are folded into J shapre, just imagine 2 J shaped monopole combined together and feeded with one single feedrod. FJA actually looks like PIFA but it is not placed ontop of groundplane, instead away from gp.